It not only characterizes a service but also allows for services comparison based on aggregated values of non-functional parameters and, in consequence, selection of a service most suite
Trang 1a user and are a part of the QoR concept.
Users’ feedback (assessment) understood
•
as their satisfaction from the returned result
(not from the interface through which they
communicate with a service) expressed in
a defined scale However, it would be very
difficult, if not impossible, to collect such
information from users They would rather
provide an overall evaluation of both a
service implementation and real service
effects
The QoR concept is domain specific In fact,
it is very difficult, if not impossible, to define a
measure that would hold for all possible services
It is not the case with QoE, which is independent
of the domain and rather easy to compute The
quality of execution relates to the underlying
technology (i.e., technical and network-related
aspects) The following properties may be a part
of the QoE model:
• Response latency: Time needed for the
control data to get to the service and back
to the client
• Maximal throughput: How many
re-quests a provider is able to process in a given time period
• Execution duration: Time needed to fulfil
a user request (time between sending a quest and receiving an answer)
re-• Execution price: Amount of money a user
needs to pay in order to use an interface to the service
• Service robustness: The ability of a
ser-vice to act properly if some of the input rameters are missing or incorrect (e.g., the wrong coordinates or incorrect data types, etc.)
pa-The following table summarizes our short discussion on the differences between the QoR and QoE concepts
Another aspect that needs to be mentioned is
Table 3 RoutePlanning service example (Noll, 2004)
Service name Route Planning Service
Description Creates a route description for the customer’s coordinates and the given attraction The route
de-scription consists of a coloured high-resolution picture and a textual dede-scription.
Nonfunctional Properties
Service Name Map24RoutePlanningService
Provider Name Map24.de
Information Quality High
Functional Properties
Preconditions Location ls, Location lg
Positive Effects RouteDescription rd, hasRoute (rd, r)
Table 4 Comparison of QoR and QoE
Quality of Result Quality of Execution
Trang 2the difference between an execution price and
a service price A service price is the amount of
money a user has to pay for a real service; for
example, when using a route planning it is a price
of the attraction ticket (e.g., ticket to the cinema)
(it influences QoR) In this case, an execution
price is the amount of money we have to pay for
using the interface to book tickets, not a price of
the ticket itself (it influences QoE) When buying
a book at Amazon.com, the execution price is 0
(using the Amazon Web page to search and order
is free), but the service price is the price of the
book and the delivery costs In case of
informa-tion services (such services where output returned
by a service is equal to the effect we wanted to
obtain) it is rather unclear whether the price we
have to pay for the information is a service price
or execution price, and the classification may
depend on many factors
Most of the current initiatives aiming at
pro-viding definitions and descriptions of quality
dimension address only some generic parameters
(mostly network related), such as execution price
and duration, availability and reliability, and so
forth (Liu, Ngu, & Zeng, 2004; Menasce, 2002;
Zeng, Benatallah, Dumas, Kalagnanam, & Sheng,
2003), and do not differentiate between the QoR
and QoE concepts More parameters, considering
also QoR, are presented by O’Sullivan et al (2002),
but they are not widely used in practice Moreover,
QoR properties are not considered in most of the
methods trying to compute the values of
non-functional properties Therefore, in the remaining
part of this chapter, whenever a reference to QoS
is made, it refers to those quality parameters of
a service that are computable (therefore, in most
cases they exclude QoR parameters) Whenever
a clear differentiation needs to be made between
quality of result and quality of execution,
respec-tive terms are used
Methods And ApproAches
to derIve vAlues of functIonAl propertIes
non-The simplest way to derive values of NFP is to rely
on service providers advertising this information However, taking directly the values advertised
by a service provider is not advisable It requires users to trust the accuracy of the values declared
by service providers However, service providers
do have an interest in overestimating NFP of their services, so a solution allowing measurement of (programmatically) the values of NFP for verifi-cation purposes is needed Moreover, values of non functional parameters are often assumed to
be constant in time and space (service location), but they may change, depending on the details
of the service request, execution environment, and so forth For example, the response time of
a Web service may be less than 5 minutes during the working days, but during the weekends, it may be less than 1 minute as the interest in the particular service decreases
To avoid the problems of accuracy of functional properties’ values given by service providers, some other methods to derive (or verify) their values are needed (Abramowicz et al., 2005) Ran (2003) proposes a QoS model using
non-a QoS certifier to verify published QoS criterinon-a The approach requires all Web services providers
to advertise their services with the QoS certifier However, this approach does not take into account the dynamism of the environment and the fact that the values of a Web service change in time The approach does not provide, for example, methods
to update the QoS values automatically and it lacks the details regarding the verification process.Sheth, Cordoso, Miller, and Kochut (2002) propose a QoS middleware infrastructure that requires a built-in tool to monitor metrics of NFP automatically Such an approach requires the willingness of service providers to give up some
of their autonomy It may also require service providers to cover execution costs Moreover, if
Trang 3the polling interval is set to too long, the QoS will
not be up-to-date If the polling interval is set to
too of a short time, it might incur a high
perfor-mance overhead A similar approach emphasizing
a service reputation, is proposed by Maximilien
and Singh (2002a, 2002b)
Another approach obtains information on
val-ues of QoS parameters from the users themselves
When collecting quality information from the
users feedback, each user is required to evaluate
QoS (and at the same time QoR) of the consumed
service The main advantage of this approach is
that QoS values can be computed based on the
real user experience (up-to-date runtime
execu-tion data) The main disadvantage is the fact that
a user judgment is not objective; users use
dif-ferent definitions of quality, have difdif-ferent past
experiences, and so forth
In other approaches called “a’posteriori
ap-proach” (Casati, Castellanos, Dayal, & Shan,
2004) QoS values are solely collected through
an active monitoring The monitoring can be
performed by a user, service broker or platform,
dedicated QoS registry (Kuropka & Weske,
2006; Liu et al., 2004), or an already mentioned
QoS certifier (Ran, 2003) The data are collected
from the actual consumption of a service and
therefore are accurate and objective One avoids
the necessity to install rather expensive
middle-ware in order to constantly check large numbers
of service providers However, there is a high
overhead since QoS must be constantly checked
for a large number of Web services On the other
hand, the approach that relies on a third party to
rate or endorse a particular service provider is
expensive and static in nature
When the service related data collection is
envi-sioned through, for example, workflow monitoring
or user feedback, another important issue is how to
compute the values of quality-related parameters
from the collected data There are a few initiatives
to solve the problem One of them (Maximilien &
Singh, 2004) suggests performing an analysis of
past executions of atomic and composite services
by using data mining and workflow log mining techniques Moreover, some statistical methods can be applied as well (Liu et al., 2004)
Workflow management systems are a very important infrastructure for complex applications They usually register the start and completion
of activities as well as other events that occur during execution This information is stored as workflow log files (Aalst, Zhang, Shanahas, & et al., 2003) that further are processed using work-flow and process mining techniques The goal of workflow mining is to find a workflow model on
a basis of a workflow log (Aalst et al., 2003) In turn, process mining is a method of distilling a structured process description from a set of real executions (Aalst et al., 2003) Many methods to perform these tasks were developed (e.g., proba-bilistic workflow mining, or Petri nets [Aalst et al., 2003]) and may be successfully applied also
to the Web services area
In the next section, the Web services profiling, being an alternative method to derive the values
of non-functional properties of a Web service, is presented
Web servIce profIlIng, servIce profIle, And Its eleMents
Service profiling is a process of computation of values of non-functional properties The main goal
of service profiling is to create service profiles of atomic and composite services A service profile may be defined as an up-to-date description of a selected subset of non-functional properties of
a service It not only characterizes a service but also allows for services comparison based on aggregated values of non-functional parameters and, in consequence, selection of a service most suited to the requirements of a user
In order to compute the values of tional properties, service profiling needs first to collect information on services executions, aggre-gate it, and then derive required information The
Trang 4non-func-raw data may come from multiple data sources
Every source has its own specific purpose and
provides different information The following
possible sources of information that further feed
the profiling system with appropriate data may
be distinguished: service registries, monitoring
data, data coming from service level agreements
(SLA) storing information on contracted QoS
values, feedback from service consumers about
obtained service quality, and so forth
The aim of the Web services profiling is to
perform fair and open NFP computation
There-fore, as the service execution history data are the
most objective and reliable source of information
on the service, they are in fact the primary source
of information The Web services profiling does
not perform only the core workflow mining It
analyses log files in order to obtain data needed
for the profiling process, but, in addition, it takes
advantage of the raw data collected from service
properties defined in SLA, published by service
providers, and obtained from users’ feedback For
instance, it compares contracted values from SLA
against these from execution In consequence, it
is possible to check to what extent the agreement
between a provider and a consumer is fulfilled
Moreover, appropriate algorithms may discover
which values of particular parameters are, for
example, likely to be guaranteed by providers
Service profiling is, in our opinion, a
trust-worthy method of service quality measurement
It does not rely on providers’ declarations about
quality of their services Statistical procedures used
to compute values, data coming from execution
logs, and so forth, assure high reliability of results
of service profiling The information declared
initially by a service provider might be verified
by what is stated in SLA, being approved by its
provider and then by the results of the analysis of
execution data This kind of verification increases
the reliability of our mechanism and we do not
need a third party to verify the correctness of the
values of profile parameters as procedures are
transparent and parameters precisely defined In
addition, a service profiling mechanism is generic (a number of parameters it operates on may be easy modified) and independent of the service description provided by a service provider
service profile
As already stated, a service profile may be fined as an up-to-date description of a subset of non-functional properties of a service It allows for services comparison based on non-functional parameters and selection of the service most suited
de-to the requirements of a user
In order to create an adequate service tion one needs to consider that the collected or derived data, taken into account by a service profiling mechanism, may differ in terms of its stability in time Regarding the type of informa-tion on services, we can distinguish three main categories:
descrip-• Static Information: Values of service
properties that do not change over time, such as name of the service, and are pro-vided by a service provider
• Semistatic information: Values of service
properties that may change over time, such
as quality of service and price This mation changes periodically, but not very often
infor-• Dynamic Information: Values of service
properties that may be (and usually are) different in every execution of the service
It relates mainly to the network related quality of service
From the profiling point of view, the most interesting parameters are the dynamic and semistatic ones In addition, parameters that are estimated and finally included in a service profile may be simple reflections of service behaviour or adequately aggregated to show an overall quality
of a service Therefore, we consider two groups
of non-functional properties:
Trang 5• Simple Properties: Values of service
properties that can be monitored on an
individual level This is mostly
informa-tion presented in service level agreements
Such properties may include, for example,
latency time, execution cos,t and so on
• Derived Properties: Where additional
manipulation is needed (performed by a
service profiling system) Such properties
may include reliability, availability, or, in
our case, a synthetic indicator
Our belief is that a service profile should be
easily interchanged between building blocks of
SOA systems In order to allow for simple
mes-saging and processing of profiles, we decided to
represent them as XML documents The greatest
advantage of this solution is that XML schema is
easily verifiable and interpretable by machines
A standardized form of a service profile makes it
easy to be adapted in industrial applications
Because of flexibility of service profiling, the
set of parameters included in a profile may vary
due to different quality parameters considered in
different IT systems The exemplary structure of
a profile (as seen in Figure 1) was derived based
on the requirements defined in the already tioned ASG project
men-The excerpt of a service profile schema is sented in the Listing 1 Please note that for some parameters, average, minimal, and maximal values are determined These values may be helpful when
pre-a user precisely expresses the user’s needs on qupre-al-ity parameters Therefore, a user may specify that the user is looking for a service where parameters meet accurately expressed criteria
qual-Additionally, a service profiling system may offer provider profiles that show how, in gen-eral, services of a given provider behave They may be useful to represent the overall quality of services provided by a concrete provider These profiles are more quality-oriented, whereas service profiles are more performance-oriented In this case, quality orientation means that time-related QoS parameters are less important than the fact whether a given service was accessible or produced expected results
Figure 1 Service profile structure - class diagram
Trang 6service profile computation
The most popular information sources for service
profiling are execution logs These log files
usu-ally have a strictly defined structure (Aalst et al.,
2003), so the automated processing of them is
feasible and algorithms are rather straightforward
For example, the execution duration may be
eas-ily counted as a difference between end time and
start time of a service execution (these values are stored in the log file) Of course, to compute the values of other parameters other methods may
be required For instance, in order to compute the value of a reliability parameter, a profiling system needs to keep track of service execution states In our approach, we consider the finite state machine of Web service transitions as shown in the Figure 3
Figure 2 Listing 1: Excerpt of exemplary service profile schema
Trang 7Therefore, it is possible to determine the
num-ber of started services that were completed Thus,
the assessment of reliability parameter is not a
problem A similar approach is used for
acces-sibility parameter computation For more details
please refer Kowalkiewicz, Ludwig, Kaczmarek,
and Zyskowski (2005) In the Table 5 we present
an exemplary set of non-functional properties and
outline methods of their computation
When creating a service profile the time
horizon is taken into account A user may need
a particular instance of a service only once in a
given point of time or may need to use the service
a few times in a given time period Therefore, the
horizon of the prognosis should be considered
In the first case, short-time information about
a service is important, and in the second case,
more attention should be paid to the long-term
behaviour of a service, taking into account also more historical data
Another challenging issue is the set of functional parameters that should be used to describe composite services and the way to compute values of these parameters The possible solutions may be found presented by Liu et al (2004), Maximilien and Singh (2004), and Zeng
non-et al (2003) They suggest using a similar snon-et of attributes, as for atomic services and computing their values using statistical methods
Composite service profiles are the aggregations
of atomic service profiles A description of a posite service profile is very similar to a service profile, because it treats a composite service like an atomic one That is why the structure of its profile does not differ significantly from the profile of
com-an atomic service However, the values of some
Figure 3 Types of Web services events Based on Aalst et al (2003)
Table 5 Some parameters of service profile and their computation methods
Parameter name Computation method
Execution duration Difference between end and start time of service execution
Accessibility Number of successful invocations divided by all the invocations in a given time period
Reliability Number of successful executions divided by all of the executions in a given time period
Synthetic indicator Statistical aggregation of all considered parameters denoting an overall quality of a service
Trang 8parameters are computed as statistical measures
based on characteristics of atomic services
in-cluded in the composed service Moreover, not
all parameters that are computed for an atomic
service profile are included in composite service
profiles For example, the response latency value
is only computable for atomic services
In order to compute a value of quality
pa-rameters of a composite service we can proceed
twofold:
The execution log mining may be
per-•
formed in order to compute values of
pa-rameters using methods similar to these for
atomic services;
A composite service execution plan may
•
be used to compute hypothetical value of
quality parameter Such plans are usually
described using business process execution
language for Web services (BPEL4WS)
language First, the average values for each
atomic service included in the composition
are computed, then the plan is analysed,
the critical path is identified, and the hy-pothetical value is computed For instance,
the execution duration of the composite
service is computed as a sum of execution
durations of services being on the critical
path Other calculations include analysis of
workflow patterns, determination of how
many times services were executed (in case
of loops), and so forth Details about such
computation are given by Kowalkiewicz et
al (2005)
It can be very interesting to rank services
ac-cording their quality In order to do that, a method
that would allow one to compare objects (in our
case, services) with regard to different properties
that describe these objects was defined Our
deci-sion was to take advantage of the multiple criteria
analysis (MCA) that ideally fitted to our needs
We used the MCA method to rank services based
on their quality attributes This ranking was
cre-ated by computing a synthetic indicator reflecting the overall service quality Then, it was possible
to compare the values of synthetic indicators
of several services and make a choice between them The detailed description of MCA and the procedure to compute the value of a synthetic indicator is described by Abramowicz, Haniewicz, Kaczmarek, and Zyskowski (2006b)
dynamic service profiling in the Adaptive services grid project
Taking into account the issues discussed in the previous section, the architecture of the service profiling system should consist of at least a few components It should include the repository that will store the data gathered by the system and should have component(s) responsible for com-munication with the data sources Moreover, it should provide interfaces that allow all interested parties to ask queries Finally, it should have the profiling mechanism, responsible for analysing the data and deriving/computing the values of parameters, to be included in a service profile
As an example of the architecture of service profiling system, the dynamic service profiling component of the Adaptive Services Grid project, may be presented The main goal of the ASG project (Kuropka & Weske, 2006) was to develop
a proof-of-concept prototype of a platform for adaptive services discovery, creation, composi-tion, enactment, as well as negotiations and service profiling In order to support the above-mentioned interactions, the ASG platform and mechanisms require the ability to differentiate and compare different services and service substitutes (services having the same functionality) There are some requirements that need to be met in order to make the service differentiation feasible First, the non-functional parameters must be taken into account,
as every customer perceives the service not only from the side of what functionality it gives, but is also interested in non-functional properties of the service The next issue is to deliver a QoS model
Trang 9that everybody would accept Such a
standard-ized QoS model is the first step to the agreement
on monitoring mechanisms, common SLAs, and
other elements that should be a part of every
ma-ture marketplace The last challenge is to create
adequate description of a service that will give a
user hints about the distinctive features of service
substitutes Thanks to the monitoring, it should be
possible to analyse the information coming from
service executions, SLA violations, and so forth
Based on the execution data and users’
prefer-ences, it is reasonable to create a service profile
which reflects QoS values of a given service in
a considered time horizon Moreover, the user
should be capable of ranking these profiles and
choosing the most suitable Web service Such
a mechanism is implemented in the Adaptive
Services Grid platform (Kuropka & Weske,
2006) using a dynamic service profiling (DSP)
mechanism The ASG service delivery process
is presented in the figure below
The architecture of a dynamic service profiling
(see Figure 5) system, being a part of the entire
ASG platform, consists of a few components
(Abramowicz, Kaczmarek, Kowalkiewicz, &
Zyskowski, 2006):
• Data collector, which is responsible for collecting data (by either a push or a pull method) from different sources, process-ing them, and saving properly aggregated
to the DSP repository
Service profiler, which is responsible for
• deriving QoS attributes to answer requests The Service profiler creates an up-to-date profile of a service (or a provider), when-ever it receives a query Two types of que-ries may be distinguished: a request for a profile of composed service, taking time horizon into consideration; and a request for profiles and a ranking of a set of atomic services, taking time horizon into consid-eration When creating profiles, the service profiler uses the following data about ser-vices: data from the provider’s declaration (service registry), and values of service attributes form the past execution (DSP repository) In order to create a profile, the appropriate values of characteristics, depending on the prognosis horizon, are computed Then, based on the computed values a synthetic indicator for a service is created As an interaction with a user is not
Figure 4 Service delivery process in the ASG ©Krause, 2005 (used with permission)
Trang 10implemented, default user preferences are
used After computing the indicators for all
of the services returned for the given
que-ry, services can be compared and the best
of them can be identified
DSP repository, which is the internal
per-•
sistent data storage fed by the data collector
and responsible for storing all data relevant
to service profiles Only the data collector
can change information in the DSP
reposi-tory Other subsystems have read-only
ac-cess to the repository
Event Manager, which handles workflow
•
events The event manager is the
subcom-ponent responsible for processing
work-flow events and receiving execution logs
If any crucial information is included in
such an event, it is passed to the data
col-lector for further analysis
As verified in the prototype implementation
within the ASG project, such an architecture
ful-fils goals and requirements of a service profiling
system
suMMAry
This chapter familiarizes users with the idea of Web services profiling As a background, the current initiatives in the field of Web services description, especially non-functional properties and methods to derive the values of these proper-ties, were presented Moreover, the readers were introduced to different approaches to the quality-of-service concept The focus of the chapter was placed on Web service profiling successfully implemented within the ASG system A service profile, in its final state, aggregates all measured values of quality parameters to give a user the holistic view on a service quality Taking into account information from profiles, it is possible
to select the most suitable service, with regard to the user-specific quality expectations
references
W3C (2004) Owl-s: Semantic markup for Web
services Retrieved May 26, 2008, from http://
Trang 11Aalst, W D (2003) Workflow mining: A survey
of issues and approaches Data & Knowledge
Engineering, 47(2), 237–267
doi:10.1016/S0169-023X(03)00066-1
Abramowicz, W., Filipowska, A., Kaczmarek, M.,
Kaczmarek, T., Kowalkiewicz, M., Rutkowski, W.,
et al (2006) Service interdependencies: Insights
into use cases for service compositions Paper
presented at the IFIP 2006
Abramowicz, W., Haniewicz, K., Kaczmarek,
M., & Zyskowski, D (2006a) Automatic Web
services interactions - requirements, challenges
and limits from the F-WebS system perspective
Paper presented at the International Conference
on Next Generation Web Services Practices,
Seoul, Korea
Abramowicz, W., Haniewicz, K., Kaczmarek,
M., & Zyskowski, D (2006b) Filtering of
Se-mantic Web services with F-WebS system Paper
presented at the The Semantic Web: ASWC 2006
Workshop
Abramowicz, W., Kaczmarek, M., Kowalkiewicz,
M., & Zyskowski, D (2005) A survey of QoS
computation for Web services profiling Paper
presented at the 18th International Conference on
Computer Applications in Industry and
Engineer-ing (ISCA), Honolulu
Abramowicz, W., Kaczmarek, M., Kowalkiewicz,
M., & Zyskowski, D (2006) Architecture for
service profiling Paper presented at the
Model-ling, Design and Analysis for Service-Oriented
Architecture Workshop in conjunction with the
2006 IEEE International Conferences on Services
Computing (SCC 2006) and Web Services (ICWS
2006), Chicago
Abramowicz, W., Kaczmarek, M., & Zyskowski,
D (2006) Duality in Web services reliability
Paper presented at the International Conference
on Internet and Web Applications and Services
(ICIW‘06) Guadeloupe, French Caribbean
Baida, Z., Gordijn, J., Omelayenko, B., &
Ak-kermans, H (2004) A shared service terminology
for online service provisioning Paper presented at
the Sixth International Conference on Electronic Commerce (ICEC04), Delft, The Netherlands.Casati, F., Castellanos, M., Dayal, U., & Shan, M
C (2004, November 2004) Probabilistic,
context-sensitive and goal-oriented service selection
Paper presented at the ICSOC‘04, New York.Eenoo, C V., Hylooz, O., & Khan, K M (2005)
Addressing non-functional properties in software architecture using ADL Paper presented at the 6th
Australian Workshop on Software and Systems Architectures - AWSA‘05, Brisbane, Australia
Farrel, J., & Lausen, H (2006) Semantic
Annota-tions for WSDL DERI Innsbruck.
Kowalkiewicz, M., Ludwig, A., Kaczmarek, M., &
Zyskowski, D (2005) Documented mechanisms
for dynamic service prpofiling and agreement life-cycle management (ASG internal deliverable,
FP6-IST-004617)
Krause, H (2005) Next generation service
de-livery: Adaptive services grid, European project, 2007.
Kuropka, D., & Weske, M (2006, January) Die
adaptive services grid platform: Motivation, tential, funktionsweise und anwendungsszenarien
po-Paper presented at the EMISA Forum
Kuster, U., Koenig-Ries, B., Stern, M., & Klein,
M (2007, May 8-12) DIANE: An integrated
approach to automated service discovery, making and composition Paper presented at the
match-WWW 2007, Banff, Alberta, Canada
Lara, R., & Olmedilla, D (2005, June) Discovery
and contracting of Semantic Web services Paper
presented at the Position Paper for the Workshop
on Frameworks for Semantics in Web Services, Innsbruck, Austria
Trang 12Liu, C., Peng, Y., & Chen, J (2006) Web services
description ontology-based service discovery
model Paper presented at the International
Con-ference on Web Intelligence (WI 2006)
Liu, Y., Ngu, A H H., & Zeng, L (2004, May)
QoS computation and policing in dynamic Web
service selection Paper presented at the 13th
International Conference on World Wide Web
(WWW), New York
Maximilien, E M., & Singh, M P (2002a)
Reputation and endorsement for Web
ser-vices ACM SIGecom Exchanges, 3(1), 24–31
doi:10.1145/844331.844335
Maximilien, E M., & Singh, M P (2002b)
Conceptual model of Web services reputation
SIGMOD Record
Maximilien, E M., & Singh, M P (2004,
Novem-ber, 2004) Towards autonomic Web services trust
and selection Paper presented at the ICSOC‘04,
New York
Menasce, D A (2002) QoS issues in Web
ser-vices IEEE Internet Computing, 6(6), 72–75
doi:10.1109/MIC.2002.1067740
Noll, J (2004) ASG based scenarios in
telecom-munications, telematics and enhanced enterprise
IT Retrieved May 26, 2008, from
http://asg-platform.org
O’Sullivan, J., Edmond, D., & Hofstede, A T
(2002) What’s in a service? Towards an accurate
description of non-functional properties of Web
services Distributed and Parallel Databases,
(12): 117–133 doi:10.1023/A:1016547000822
Preist, C (2004, November) A conceptual
archi-tecture for Semantic Web services Paper presented
at the International Semantic Web Conference
2004 (ISWC 2004)
Ran, S (2003) A model for Web services discovery
with QoS ACM SIGecom Exchanges, 4(1), 1–10
doi:10.1145/844357.844360
Roman, D., et al (2006) WWW: WSMO, WSML
and WSMX in a nutshell Paper presented at the
First Asian Semantic Web Conference (ASWC 2006)
Rosa, N S., Cunha, P R., Freire, L., & Justo,
(2002, July) QoS for service-oriented middleware
Paper presented at the 6rh World ence on Systemics Cybernetics and Informatics (SCI02)
Multiconfer-Toma, I (2006) Non-functional properties in Web
services DERI.
UDDI (2004) UDDI Version 3.0.2 UDDI Spec
Technical Committee
Zeng, L., Benatallah, B., Dumas, M., Kalagnanam,
J., & Sheng, Q Z (2003, May) Quality driven
Web services composition Paper presented at the
12th International Conference on World Wide Web (WWW), Budapest, Hungary
This work was previously published in Managing Web Service Quality: Measuring Outcomes and Effectiveness, edited by K Khan, pp 96-113, copyright 2009 by Information Science Reference (an imprint of IGI Global).
Trang 13The tremendous growth of the Internet has
intro-duced a number of interoperability problems for
distributed multimedia applications These problems
are related to the heterogeneity of client devices,
network connectivity, content formats, and user’s
preferences The challenge is even bigger for
mul-timedia content providers who are faced with the
dilemma of finding the combination of different
variants of a content to create, store, and send to
their subscribers that maximize their satisfaction and
hence entice them to come back In this chapter, the
authors will present a framework for trans-coding
multimedia streams using an orchestration of
Web-services The framework takes into consideration
the profile of communicating devices, network connectivity, exchanged content formats, context description, users’ preferences, and available adapta-tion services to find a chain of adaptation services that should be applied to the content to make it more satisfactory to clients The framework was implemented as a core component for an architecture that supports personal and service mobility
IntroductIon
The tremendous growth of the Internet has duced a number of interoperability problems for distributed multimedia applications These problems are related to the heterogeneity of client devices, network connectivity, content formats, and user’s preferences The diversity of client devices, network
intro-DOI: 10.4018/978-1-60566-330-2.ch008
Trang 14connectivity, content formats, and user’s
prefer-ences posed also some challenges in aligning and
customizing the exchanged data between different
users with different preferences The challenge is
even bigger for multimedia content providers who
are faced with the dilemma of finding the
combi-nation of different variants of a content to create,
store, and send to their subscribers that maximize
their satisfaction and hence entice them to come
back Most content providers have taken the costly
approach of creating different versions of content
for different access devices and networks
Content adaptation is an effective and attractive
solution to the problem of mismatch in content
format, device capability, network access and
user’s preferences Using content adaptation, a
number of adaptations is applied to the original
content to make it satisfy the device constrains
of the receiving device and the preferences of its
user Most currently available content adaptation
modules are designed to make the Web easier to
use Examples of such adaptations modules include
conversion of HTML pages to Wireless Markup
Language (WML, 2001) pages, enlarging text size,
reducing the size of an image, changing text and
background colors for better contrast, removal of
redundant information, audio to text conversion,
video to key frame or video to text conversion,
content extraction to list a few These adaptation
modules do not have though the same requirements
and challenges of real-time multimedia content
adaptations Real-time multimedia applications
involve large volumes of data making trans-coding
a computationally very expensive task (Chandra
& Ellis, 1999, Han et al.,1998) To address this
challenge, some trans-coding services have been
implemented in hardware and deployed on
inter-mediate network nodes or proxies The
disadvan-tage of this approach is that there are always new
types of clients that cannot be supported by the
deployed hardware A more suitable approach to
address the computational challenge of multimedia
trans-coding is based on the observation that the
general trans-coding process can be defined as
a combinatorial process (Mohan, Smith, & Li, 1999), and that multiple trans-coding services can be chained effectively together to perform a complex trans-coding task So, instead of having all trans-coding done by one single trans-coding service, a number of trans-coding services can collaborate to achieve a composite adaptation task
For instance, trans-coding a 256-color depth jpeg image to a 2-color depth gif image can be carried
out in two stages: the first stage covers ing 256-color to 2-color depth, and the second
convert-stage converts jpeg format to gif format Using
the software approach, transcoders can then be built more easily in software, and deployed and advertised more quickly to meet the needs of the users Software-based trans-coding are also more reliable since its components can be simpler and they can also be replicated across the network Moreover, transcoders can be modularized and re-used in different situations and contexts.Given a composite adaptation task that can be carried out in a number of stages, and given that there could be a number of possible configurations
to adapt the sender’s content to make it presentable
at the receiver’s device, the challenge is to find the appropriate chain of available trans-coding ser-vices that best fits the capabilities of the device, and
at the same time, maximizes the user’s satisfaction with the final delivered content In this chapter,
we will discuss a Quality of Service (QoS) tion algorithm for providing personalized content through web-service composition The function
selec-of the algorithm is to find the most appropriate chain of available trans-coding services between the sender and the receiver, and also to select the values for the configuration parameters for each trans-coding service The proposed algorithm uses the user’s satisfaction with the quality of the trans-coded content as the optimization metric for the path selection algorithm
The rest of the chapter is organized as follows:
In Section 2, we will introduce content adaptation and present the existing different models used in content adaptation Section 3 lists all the required
Trang 15elements for providing customized content
adap-tation In Section 4 we present our methodology
for using the required element from Section 3 to
construct a graph of trans-coding services; the
algorithm for selecting the chain of trans-coding
services is then presented The selection criterion
for the algorithm as well as its characteristics is
also presented in Section 4, and finally, we end
Section 4 with an example that shows
step-by-step the results of the algorithm Our conclusion
is presented in Section 5
content AdAptAtIon
In today’s Internet, there is a wide range of client
devices in terms of both hardware and software
capabilities Device capabilities vary in different
dimensions, including processing power, storage
space, display resolution and color depth, media
type handling, and much more This variety on
device capabilities makes it extremely difficult
for the content providers to produce a content
that is acceptable and appreciated by all the
cli-ent devices (Fox, Gribble, & Chawathe, 1998),
making application-level adaptation a necessity
to cover the wide variety of clients
There are three main approaches for handling
this diversity in content formats: a static content
adaptation, a dynamic content adaptation, and
a hybrid of the static and dynamic approaches
(Chang & Chen, 2002, Lum & Lau, 2002) The
first two approaches differ in the time when the
different content variants are created (Lei &
Georganas, 2001) to match the requested format
In static adaptation, the content creator generates
and stores different variants of the same content
on a content server, with each variant formatted
for a certain device or class of devices Hafid
and Bochmann (1996) presented an architecture
for news-on-demand using this scheme Static
adaptation has three main advantages: (1) it is
highly customized to specific classes of client
devices, and (2) it does not require any runtime
processing, so no delay is incurred, and (3) the content creator has the full control on how the content is formatted and delivered to the client
On the other hand, static adaptation has a number
of disadvantages, mainly related to the ment and maintenance of different variants of the same content (Lum & Lau, 2002): (1) different content formats need to be created for each sort
manage-of device or class manage-of devices, and needs to be done when new devices are introduced, and (2)
re-it requires large storage space to keep all variants
of the same content
With dynamic content adaptation, the content
is trans-coded from one format to the other only when it is requested Depending on the location where the trans-coding takes place, dynamic content adaptation technologies can be classified into three categories: server-based, client-based, and proxy-based In the server-based approach (Mohan, Smith, & Li, 1999), the content server is responsible for performing the trans-coding; the content provider has all the control on how the content is trans-coded and presented to the user Additionally, it allows the content to be trans-coded before it is encrypted, making it secure against malicious attacks On the other hand, server-based adaptation does not scale properly for a large number of users and requires high-end content and delivery server to handle all requests
As for the client-based approach (Björk et a., 1999, Fisher et al., 1997), the client does the trans-coding when it receives the content The advantage of this approach is that the content can
be adapted to match exactly to the characteristics
of the client But at the same time, client-based adaptation can be highly expensive in terms of bandwidth and computation power, especially for small devices with small computational power and slow network connectivity, with large volume of data might be wastefully delivered to the device
to be dropped during trans-coding
The third adaptation approach is the based approach (Chandra & Ellis, 1999, Chandra, Ellis, & Vahdat, 2000, Floyd & Housel, 1998,
Trang 16proxy-Fox, A., Gribble, Chawathe, Brewer, & Gauthier,
1997), where an intermediary computational entity
can carry out content adaptation on the fly, on
behalf of the server or client Proxy adaptation
has a number of benefits including leveraging
the installed infrastructure and scaling properly
with the number of clients It also provides a clear
separation between content creation and content
adaptation On the other hand, some content
provider may argue that they prefer to have full
control on how their content is presented to the
user Also, using proxies for adaptation does not
allow the use of end-to-end security solutions
chArActerIzAtIon And
reQuIreMents for
content AdAptAtIon
Advances in computing technology have led
to a wide variety of computing devices, which
made interoperability very difficult Added to
this problem is the diversity of user preferences
when it comes to multimedia communications
This diversity in devices and user preferences
has made content personalization an important
requirement in order to achieve results that satisfy
the user The flexibility of any system to provide
content personalization depends mainly on the
amount of information available on a number of
aspects involved in the delivery of the content to
the user The more information about these aspects
is made available to the system, the more the
content can be delivered in a format that is highly
satisfactory to the user These relevant aspects are:
user preferences, media content profile, network
profile, context profile, device profile, and the
profile of intermediaries (or proxies) along the
path of data delivery We will briefly describe
here each of these aspects; interested readers
might refer to (El-Khatib & Bochmann, 2003)
for more details
User Profile: The user’s profile captures the
personal properties and preferences of the user,
such as the preferred audio and video receiving/sending qualities (frame rate, resolution, audio quality…) Other preferences can also be related
to the quality of each media types for tion with a particular person or group of persons For instance, a customer service representative should be able to specify in his profile his/her preference to use high-resolution video and CD audio quality when talking to a client, and to use telephony quality audio and low-resolution video when communicating with a colleague at work The user’s profile may also hold the user’s policies for application adaptations, such as the preference of the user to drop the audio quality
communica-of a sport-clip before degrading the video ity when resources are limited The MPEG-21 standard (MPEG-21, 2001) is the most notable standards on user profiles
qual-Content Profile: Multimedia content might
enclose different media types, such as audio, video, text, and each type can have different formats (Lei & Georganas, 2001) Each type has its format characteristics and parameters that can
be used to describe the media Such information about the content may include storage features, variants, author and production, usage, and many other metadata The MPEG-7 standard (MPEG-
7, 2000), formally named “Multimedia Content Description Interface”, offers a comprehensive set of standardized description tools to describe multimedia content
Context Profile: A context profile would
include any dynamic information that is part of the context or current status of the user Context information may include physical (e.g location, weather, temperature), social (e.g sitting for din-ner), or organizational information (e.g acting senior manager) The MPEG-21 standard includes tools for describing the natural environment char-acteristics of the user, including location and time,
as well as the audio and illumination characteristics
of the user’s environment Resource adaptation engines can use these elements to deliver the best experience to the user
Trang 17Device Profile: To ensure that a requested
content can be properly rendered on the user’s
device, it is essential to include the capabilities and
characteristics of the device into the content
ad-aptation process Information about the rendering
device may include the hardware characteristics
of the device, such as the device type, processor
speed, processor load, screen resolution, color
depth, available memory, number of speakers,
the display size, and the input and output
capa-bilities The software characteristics such as the
operating system (vendor and version), audio and
video codecs supported by the device should also
be included in the device profile The User Agent
Profile (UAProf) created by the Wireless
Applica-tion Forum (WAP) and the MPEG-21 standard,
both include description tools for describing
device capabilities
Network Profile: Streaming multimedia
con-tent over a network poses a number of technical
challenges due to the strict QoS requirements of
multimedia contents, such as low delay, low jitter,
and high throughput (Ng, Tan, & Cheng, 2001)
Failing to meet these requirements may lead to a
bad experience of the user (Katchabaw, Lutfiyya,
& Bauer,, 1998, Poellabauer, Abbasi, & Schwan,
2002) With a large variety of transport networks, it
is necessary to include the network characteristics
into content personalization and to dynamically
adapt the multimedia content to the fluctuating
network resources (Wu, Hou, Zhang, 2001)
Achieving this requires collecting information
about the available resources in the network, such
as the maximum delay, error rate, and available
throughput on every link over the content delivery
path A description tool for network capabilities,
including utilization, delay and error characteristics
are included in the MPEG 21 standard
Profile of Intermediaries: When the content
is delivered to the user across the network, it
usually travels over a number of intermediaries
These intermediaries have been traditionally used
to apply some added-value services, including
on-the-fly content adaptations services (Chandra,
Ellis, & Vahdat, 2000, Fox, Gribble, Chawathe, Brewer, & Gauthier, 1997) For the purpose of content adaptation, the profile of an intermedi-ary would usually include a description of all the adaptation services that an intermediary can provide These services can be described using any service description language such as the JINI network technology (JINI, 1998), the Service Location Protocol (Guttman, Perkins, Veizades,
& Day, 1999), or the Web Service Description Language (WSDL, 2002) A description of an adaptation service would include, for instance, the possible input and output format to the service, the required processing and computation power
of the service, and maybe the cost for using the service The intermediary profile would also in-clude information about the available resources at the intermediary (such as CPU cycles, memory)
to carry out the services
Qos selectIon AlgorIthM
In this section, we will describe the overall QoS selection algorithm that finds the most appropriate chain of trans-coding services between the sender and the receiver, and also selects the configuration for each trans-coding service We will first start
by defining the user’s satisfaction as the selection criterion for the algorithm, and then show how to construct the directed graph for adaptation, using the sender’s content profile, receiver’s device pro-file, and the list of available trans-coding services After constructing the graph, we will show how
to apply some optimization techniques on the graph to remove the extra edges in the graph, and finally present the actual QoS path and parameter selection algorithm
user’s satisfaction as selection criteria
Most Internet users are indifferent about the derlying technologies such as protocols, codecs,
Trang 18un-or resource reservation mechanisms that enable
their communication session They are also
indif-ferent about network level QoS characteristics,
such as bandwidth, delay, or throughput All what
is important for these users in the end is making
the communication session work in a satisfactory
way: for instance, hearing without jitter and seeing
without irregularity
As we mentioned earlier, the user’s preferences
expressed in the user’s profile can be classified
as application layer QoS parameters In order to
compute the user’s satisfaction with all values of
the application layer configuration parameters, we
have used the approach presented by Richards,
Rogers, Witana, & Antoniades (1998), where
each application level QoS parameter is
repre-sented by a variable xi over the set of all possible
values for that QoS parameter The satisfaction
or appreciation of a user with each quality value
is expressed as a satisfaction function Si(xi) All
satisfaction functions have a range of [0 1], which
corresponds to the minimum acceptable (M) and
ideal (I) value of xi The satisfaction function Si(xi)
can take any shape, with the condition that it must
increase monotonically over the domain Figure
1 shows a possible satisfaction function for the
frame rate variable
In the case when there are more than one
ap-plication parameter (frame rate, resolution, color
depth, audio quality,…), Richards et al proposed
using a combination function f comb that computes
the total satisfaction S tot from the satisfactions sifor the individual parameters (Equa 1)
s
tot comb n
i i n
We think that the approach described above is a major step towards a simple user-friendly inter-face for user level QoS specification, however, further considerations could be taken into account
as described below A first improvement results from the observation that users in telecommunica-tion session might find some media types more important than others For instance, a user of a news-on-demand service might prefer to receive high quality audio with low quality video as com-pared to average quality audio and average quality video In the case of a user watching a sport event the situation may be the opposite (if the user does not care about the audio of the commenter).This preference to individual media can play a factor when it comes to the calculation of the total satisfaction S tot By assigning different weights
wi to the different parameters xi, S tot will reflect
Figure 1 Possible satisfaction function for the frame rate.
Trang 19the user preference for different media types The
combination function for the total user satisfaction
can be redefined as follows:
w s tot
user
i i i n
=å
( , ,1 2 3 , , , ,1 2 3 , )
1
(2)
where w i is the weight for the individual
satisfac-tion s i and w w
n
i i
n
= å= 1 Equa 2 have similar
properties as Equa 1, which is to:
Prop 1 One individual low satisfaction is enough
to bring the total satisfaction to a low value
Prop 2 The total satisfaction of equal individual
satisfactions si with equal weight is equal to the
satisfactions si
These constants weight factors
(AudioWeight-Factor, VideoWeight(AudioWeight-Factor, ) can be selected
by the user, and stored in the user profile The
selection of these weights depends on the type
of service the user is willing to receive when
using a specific service or communicating with
a given callee
Additionally, we have so far considered only
the QoS preferences of a single user But all
conversational multimedia applications involve
several users It is therefore important to determine
how the possibly conflicting preferences of the
different users are reconciled in order to come
up with QoS parameters that are suitable for all
participating users
In certain circumstances, some given
param-eters may be determined simply based on the
preferences of a single user This may be the case
in a two-way teleconference between two users
A and B, where the parameters of the video
vis-ible by User A would be determined based on the
preferences of User A alone, and the video in the opposite direction based on the preferences of User
B However, the situation may be more complex
if the cost of the communication is paid by User
A and the selection of the video received by User
B has an impact on the communication cost
In other circumstances, as for instance in the case of the joint viewing of a video clip by sev-eral participants in a teleconference, the selected quality parameters should be determined based
on the preferences of all participating users In such circumstances, we propose to use the same combination function for user satisfaction con-sidered above and (optionally) introduce a weight
for each of the participating users, called the QoS
selection weight, which determines how much
the preferences of the user influences overall QoS parameter selection The total satisfaction (computed for all users) is then given by
a s
tot comb tot
usr tot usr tot usr
i
=
(3)
where s tot usr i is the total satisfaction for user i, and
a i is the QoS selection weight for user i In the
case that the weight of a given user is zero, the preferences of this user are not taken into account for the selection of the QoS parameters
constructing a directed graph
Trang 20adapta-content The elements of the directed graph are
the following:
1 Vertices in the graph represent trans-coding
services Each vertex of the graph has a
number of properties, including the
com-putation and memory requirements of the
corresponding trans-coding service Each
vertex has a number of input and output links
The input links to the vertex represent the
possible input formats to the trans-coding
service The output links are the output
formats of the trans-coding service Figure
2 shows a trans-coding service T1, with two
input formats, F5 and F6, and four possible
output formats, F10, F11, F12 and F13 The
sender node is a special case vertex, with
only output links, while the receiver node
is another special vertex with only input
links
To find the input and output links of each
vertex, we rely on the information in
differ-ent profiles The output links of the sender
are defined in the content profile, which
includes as we mentioned earlier, meta-data
information (including type and format) of
all the possible variants of the content Each
output link of the sender vertex corresponds
to one variant with a certain format The input
links of the receiver are exactly the possible
decoders available at the receiver’s device
This information is available through the
description of the receiver’s device in the
device profile The input and output links
of intermediate vertices are described in the service description part of the intermediaries profile Each intermediary profile includes the list of available trans-coding services, each with the list of possible input and out-put formats Each possible input format is represented as an input link into the vertex, and the output format is represented as an output link
2 Edges in the graph represent the network connecting two vertices, where the input link of one vertex matches the output link
of another vertex
To construct the adaptation graph, we start with the sender node, and then connect the outgoing edges of the sender with all the input edges of all other vertices that have the same format The same process is repeated for all vertices To make sure that the graph
is acyclic, the algorithm continuously fies that all the formats along any path are distinct
veri-Figure 3 shows an example of an adaptation graph, constructed with one sender, one receiver, and seven intermediate vertices, each representing a trans-coding service
As we can see from the graph, the sender node is connected to the trans-coding service T1 along the edge labeled F5 This means that the sender S can deliver the content in format F5, and trans-coding service T1 can convert this format into format F10, F11, F12, or F13
Adding constraints to the graph
As we have discussed earlier, the optimization criterion we have selected for the QoS selection algorithm is the user’s satisfaction computed
using the function f comb presented in Section 4.2 The maximum satisfaction achieved by using
a trans-coding service Ti depends actually on a number of factors
Figure 2 Trans-coding service with multiple input
and output links
Trang 21The first factor is the bandwidth available for
the data generated by the trans-coding service
Ti The more bandwidth is available to the
trans-coding service, the more likely the trans-trans-coding
service will be able to generate trans-coded
con-tent that is more appreciated by the receiver The
available bandwidth between two trans-coding
services is restricted by the amount of bandwidth
available between the intermediate servers where
the trans-coding service Ti is running and the
intermediate server where the next trans-coding
service or receiver is running We can assume
that connected trans-coding services that run on
the same intermediate server have an unlimited
amount of bandwidth between them
Other factors that can affect the user’s faction are the required amount of memory and computing power to carry out the trans-coding operation Each of these two factors is a function
satis-of the amount satis-of input data to the trans-coding service
graph optimization
By looking at the graph in Figure 3, we can see that there are some edges like F1, F2 or F17 that are connected only to one trans-coder These edges cannot be a part of any path from the sender to the receiver The same principle also applies to trans-coders other than the sender and receiver that are not on any path from the sender to the receiver T5 is an example of a trans-coder that cannot be used to send data through it on the way from the sender to the receiver Removing these edges and vertices help reduce the computational time of the algorithm, since it helps pruning dead-ends from the graph Applying optimization for the graph in Figure 3 would result in the graph shown in Figure
5 The pseudo-code for the graph optimization is shows in Figure 4
Qos selection Algorithm
Once the directed acyclic adaptation graph has been constructed, the next step is to perform the
Figure 3 Directed trans-coding graph
Figure 4 Pseudo-code for the graph optimization
Trang 22QoS selection algorithm to find a chain of
trans-coding services, starting from the sender node and
ending with the receiver node, which generates
the maximum satisfaction of the receiver
Find-ing such as path can be similar to the problem of
finding the shortest path in a directed weighted
graph with similar complexity, except that the
optimization criterion is the user’s satisfaction,
and not the available bandwidth or the number
of hops
Our proposed algorithm uses two variables
representing two sets of trans-coding services, the
set of already considered trans-coding services,
called VT, and the set of candidate trans-coding
services, called CS, which can be added next on
the partially selected path The candidate
trans-coding services set contains the trans-trans-coding
services that have input edges coming from any
trans-coding service in the set VT At the
begin-ning of the algorithm, the set VT contains only the
sender node, and CS contains all the other
trans-coding services in the graph that are connected
to sender, and also the receiver In each iteration,
the algorithm selects the trans-coding service T i
that, when using it, generates the highest user
satisfaction The user satisfaction is computed as
an optimization function of the audio and video
parameters for the output format for T i, subject
to the constraint of available bandwidth between
T i and its ancestor trans-coding service, and also
subject to the remaining user’s budget T i is then added to VT The CS set is then updated with
all the neighbor trans-coding services of T i The algorithm stops when the CS set is empty, or
when the Receiver node is selected to be added
to VT The complete description of the algorithm
is given in Figure 6
As indicated in Step 2 and Step 8, the algorithm
selects from CS the transcoder T i that can generate the highest satisfaction value for the receiver To compute the satisfaction value for each transcoder
T i in CS, the algorithm selects the QoS parameter
values x i that optimize the satisfaction function in Equa 2, subject only to the constraint remaining user’s budget and the bandwidth availability that
connects T i to Tprev in VT i.e
bandwith_requirement(x 1 x n )≤ Bandwidth_ AvailableBetween(T i,Tprev ) (4)Since each trans-coding service can only reduce the quality of the content, when the algorithm ter-minates, the algorithm would have computed the
best path of trans-coding services from the sender
to the receiver, and the user’s satisfaction value
computed on the last edge to the receiver node
is the maximum value the user can achieve To show this, assume that the selected path is the path
{T 11 ,…T 1n } in Figure 7 If the path {T 21 ,…T 2m} is
a better path, then T 2m should have converted the content into variant that is more appreciated by
the user than the variant generated by T 1n Since transcoders can only reduce the quality of con-
tent, all transcoders along the path {T 21 ,…T 2m}, should have also produced a content with higher satisfaction function than the variant produce by
T 1n, and hence all these transcoders should have
been selected before T 1n, which contradicts with the assumption
Figure 5 Optimized directed trans-coding
graph
Trang 23In this section, we will present an example to show
how the QoS path selection algorithm works We
will assume that the graph construction algorithm
has generated the graph shown in Figure 8 The
graph also shows the selected path with and without
trans-coding service T 7 as part of the graph The selected trans-coding services, user satisfaction,
as well as the best current path produced by the algorithm are also shown in Table 1 Each row
in the table shows the results for one iteration of the algorithm
Figure 6 QoS selection algorithm
Figure 7 Graph selection Figure 8 Example of trans-coding graph
Trang 24future reseArch dIrectIon
In this section, we will outline some potential
directions for future research works
In this chapter, we have not addressed the issues
regarding autonomic service management of
real-time mulreal-timedia services One of the challenges
is the efficient, autonomous management of these
real-time content adaptation services in future
generation networks The autonomous service
management is crucial for the self-management
of real-time multimedia services According to
Ganek and Corbi of IBM (Ganek and Corbi,
2003), the autonomous or self-management
as-pects include optimizing, healing, configuring, and self-protecting The existing approach and framework contributes towards
self-a system thself-at is not fully self-autonomic in self-all four management aspects
Current, we are looking at nature-inspired automatic service management solution that is inspired from the Bee colony metaphor The al-legory comprises how bee agents mimic functional services related to multimedia applications, in order to autonomously monitor and configure multimedia services The objective of this research
is to ensure complete autonomic behaviour of the four main management activities (configura-
Table 1 Results for each step of the path selection algorithm
Round Considered Set (VT) Candidate set (CS) Selected
trans-coding service Selected Path Delivered Frame
Rate
User satisfaction
Trang 25tion, repair, optimization and protection) of an
autonomous system Such direction could enable
customization of the service for the current and
future generation network conditions
conclusIon
Content adaptation is a natural solution to address
the problem of heterogeneity of Internet clients
and users In this chapter, we have presented a
solution to the problem of heterogeneity which
takes into consideration the capabilities of the
cli-ent devices, network connectivity, contcli-ent format,
and users’ preferences An important part of the
framework is the QoS path selection algorithm
that decides on the chain of adaptation services
to add and the configuration parameters for each
service The decision is based on the profile of
communicating devices, network connectivity,
exchanged content formats, context description,
and available adaptation services
references
Björk, S., Holmquist, L E., Redström, J., Bretan, I.,
Danielsson, R., Karlgren, J., & Franzén, K (1999)
WEST: a Web browser for small terminals
Pro-ceedings of the 12th annual ACM symposium on
User interface software and technology
(pp.187-196) Asheville, North Carolina, United States
Chandra, S., Ellis, C., & Vahdat, A (2000)
Application-Level Differentiated Multimedia Web
Services Using Quality Aware Transcoding IEEE
Journal on Selected Areas in Communications,
18(12), 2265–2544 doi:10.1109/49.898736
Chandra, S., & Ellis, C S (1999) JPEG
Compres-sion Metric as a Quality Aware Image Transcoding
Second Usenix Symposium on Internet
Tech-nologies and Systems (USITS ‘99) (pp 81–92)
Boulder, CO
Chang, C Y., & Chen, M S (2002) Exploring gregate Effect with Weighted Transcoding Graphs for Efficient Cache Replacement in Transcoding
Ag-Proxies Proceedings of the 18th IEEE
Interna-tional Conference on Data Engineering (ICDE-O)
(pp 383—392) San Jose, CA, USA
El-Khatib, K., & Bochmann, G v (2003,
Decem-ber) Profiles in Content Adaptation Technical
report University of Ottawa, Canada
El-Khatib, K., Zhang, Z E., Hadibi, N & mann, G v (2004) Personal and Service Mobility
Boch-in Ubiquitous ComputBoch-ing Environments Journal
of Wireless communications and Mobile ing, 4(6), 595-607.
Comput-Fisher, B., Agelidis, G., Dill, J., Tan, P., Collaud, G., & Jones, C (1997) CZWeb: Fish-Eye Views
for Visualizing the World-Wide Web In
Proceed-ing of the 7th Int Conf on Human-Computer Interaction (HCI International ‘97) (pp 719-722)
IEEE Personal Communications, 5(4), 10–19
doi:10.1109/98.709365Fox, A., Gribble, S D., Chawathe, Y., Brewer,
E A., & Gauthier, P (1997) Cluster-Based
Scal-able Network Services In Proceeding of the 16th
ACM Symp On Operating Systems Principles (pp
78–91) Saint-Malo, France
Ganek, A G., & Corbi, T A (2003) The dawning
of the autonomic computing era IBM Systems
Journal, 42(1), 5–18.
Trang 26Guttman, E., Perkins, C., Veizades, J., & Day,
M (1999) Service Location Protocol Version
2 http://ietf.org/rfc/rfc2608.txt
Hafid, A & Bochmann, G.v., (1996)
Qual-ity of Service Negotiation in News-on-Demand
Systems: an Implementation In Proceedings of
the Third International Workshop on Protocols
for Multimedia Systems (pp 299-315) Springer
Berlin/Heidelberg
Han, R., Bhagwat, P., LaMaire, R., Mummert, T.,
Perret, V., & Rubas, J (1998) Dynamic adaptation
in an image trans-coding proxy for mobile WWW
browsing IEEE Personal Communication, 5(6)
JINI network technology (TM) (1998) Http://
java.sun.com/product/JINI
Katchabaw, M., Lutfiyya, H., & Bauer, M (1998)
Driving resource management with
application-level quality of service specifications, (pp 83-91)
ACM Press
Lei, Z., & Georganas, N D (2001) Context-based
Media Adaptation in Pervasive Computing On
Proceeding Can.Conf on Electr and Comp Engg
(pp 913-918) Toronto, Canada
Lum, W Y., & Lau, F C M (2002) On
Balanc-ing Between Trans-codBalanc-ing Overhead and Spatial
Consumption in Content Adaptation [Atlanta,
USA.] Mobicom, 2002, 239–250.
Mohan, R., Smith, J R., & Li, C S (1999)
Adapt-ing Multimedia Internet Content for Universal
Access IEEE Transactions on Multimedia, 1(1),
104–114 doi:10.1109/6046.748175
MPEG-21 (2001): International Standards
Or-ganisation Information technology – multimedia
framework (MPEG-21) – part 1: Vision,
technolo-gies and strategy ISO/IEC 21000-1 Accessed on
Jan 10, 2007
MPEG-7 http://www.chiariglione.org/mpeg/
standards/ mpeg-7/mpeg-7.htm Accessed on
Jan 10, 2007
Ng, C.W., Tan, P.Y., & Cheng, H (2001) Quality
of Service Extension to IRML IETF
INTERNET-DRAFT, ‘draft-ng-opes-irmlqos-00.txt’
Poellabauer, C., Abbasi, H., & Schwan, K (2002) Cooperative run-time management of adaptive
applications and distributed resources In
Proceed-ing of the Tenth ACM Internationalconference on Multimedia, (pp 402-411) ACM Press.
Richards, A., Rogers, G., Witana, V., & toniades, M (1998) Mapping user level QoS
An-from a single parameter In Second IFIP/IEEE
International Conference on Management of Multimedia Networks and Services (pp 14-20)
Versailles, France
Smith, J R., Mohan, R., & Li, C.-S (1999) able Multimedia Delivery for Pervasive Comput-
Scal-ing ACM Multimedia, (pp 131 – 140) Orlando,
Florida, United States
WML: Wireless Markup Language (2001)
Wire-less Markup Language (WML) 2.0 Document Type Definition.
WSDL Web Service Description Language (2002) http://www.w3.org/TR/wsdl
Wu, D., Hou, Y T., & Zhang, Y (2001) Scalable Video Coding and Transport over Broad-band
Wireless Networks Proceedings of the IEEE,
89(1), 6–20 doi:10.1109/5.904503
AddItIonAl reAdIng
Ahmed, I., Wei, X., Sun, Y., & Zhang, Y Q (2005) Video transcoding: an overview of various
techniques and research issues IEEE
Transac-tions on Multimedia, 7(5), 793–804 doi:10.1109/
TMM.2005.854472Ardon, S.(n.d.) MARCH: a distributed content
adaptation architecture International Journal of
Communication Systems, 16, 97–115.
Trang 27Dey, A K (2001) Understanding and Using
Con-text Springer Personal and Ubiquitous
Comput-ing, 5(1), 4–7 doi:10.1007/s007790170019
El Saddik, & Hossain, M S (2007) Multimedia
Streaming for wireless communication In B
Furht (Ed.), Encyclopedia of Wireless and Mobile
Communications CRC Press, Taylor & Francis
Group
El Saddik, A., & Hossain, M S (2006)
Multi-media content repurposing In B Furht, (Ed.),
Encyclopedia of Multimedia Berlin, Germany:
Springer Verlag
Han, J R et al.(1998, December) Dynamic
adaptation in an image transcoding proxy for
mobile WWW browsing IEEE Personal
Com-mun., 5(6).
Han, R., & Smith, J R (1999) Internet
Transcod-ing for Universal Access In J Gibson (Ed.),
Multimedia Communications Handbook.
Hossain, M S., & El Saddik, A (2008) A
Biologi-cally Inspired Multimedia Content Repurposing
System in Heterogeneous Network Environments
ACM/Springer Multimedia Systems J., 14(3),
135-144
Hossain, M S., Alamri, A., & El Saddik, A (2007)
A framework for qos-aware multimedia service
selection for wireless clients In Proc the 3rd ACM
Workshop on Wireless Multimedia Networking and
Performance Modeling (WMuNeP 07), Chania,
Crete Island, Greece, October 22 - 22
Liang, Y., Chebil, F., & Islam, A (2006)
Com-pressed domain transcoding solutions for MPEG-4
visual simple profile and H.263 baseline videos in
3GPP services and applications IEEE
Transac-tions on Consumer Electronics, 52(2), 507–515
doi:10.1109/TCE.2006.1649672
Lum, W Y., & Lau, F C M (2002) On ing between Transcoding Overhead and Spatial
Balanc-Consumption in Content Adaptation In Proc
MobiCom’02, Atlanta, Georgia, USA, Sep
23-26 (pp 239-250)
Maheshwari, A., Sharma, A., Ramamritham, K.,
& Shenoy, P (2002) TransSquid:Transcoding and caching proxy for heterogeneous e-commerce
environments In Proc 12th IEEE Int Workshop
Research Issues in Data Engg, San Jose,
Califor-nia, USA, 26 Feb - 1 March, 2002, (pp 50-59).Mao, M., So, H W., Kang, B., & Katz, R H (2001) Network support for mobile multimedia
In Proc 11th Intl Workshop on Network and
Operating System Support for Digital Audio and Video (NOSSDAV-2001), New York, USA.
Nahrstedt, K., & Balke, W T (2004) A taxonomy
for multimedia service composition In Proc 12th
ACM Conf Multimedia (ACM MM 04), New York,
NY, USA, 10–16 October 2004, (pp 88-95).Nahrstedt, K., & Balke, W T (2005) Towards building large scale multimedia systems and
applications: Challenges and status In Proc the
First ACM Intl.Workshop Multimedia Service Composition, Hilton, Singapore, (pp 3-10).
Nguyen, V A., & Tan, Y P (2005) Efficient video transcoding between H.263 and H.264/
AVC standards In Proc IEEE Intl Symposium
on Circuits and Systems (ISCAS’05), Kobe, Japan,
May 23-26
Richards, A., Rogers, G., Witana, V., & des, M (1998, November) Mapping user level
Antonia-QoS from a single parameter IIn 2nd IFIP/IEEE
Intl Conf Manage Multimedia Networks and Services, Versailles.
Shin, I., & Koh, K (2004) Hybrid Transcoding for
QoS Adaptive Video-on-Demand Services IEEE
Transactions on Consumer Electronics, 50(2).
Trang 28Smith, J R., Mohan, R., & Li, C S (1999)
Scal-able Multimedia Delivery for Pervasive
Comput-ing In Proc ACM Multimedia’ 99, Orlando, FL,
USA, Oct.30 - Nov.5
Vetro, A., Xin, J., & Sun, H (2005) Error resillence video transcoding for wireless communications
IEEE Wirel Commun, 12(4), 14–21 doi:10.1109/
MWC.2005.1497854
This work was previously published in Services and Business Computing Solutions with XML: Applications for Quality Management and Best Processes, edited by P C K Hung, pp 121-135, copyright 2009 by Information Science Reference (an imprint of IGI Global).
Trang 29Chapter 7.15
Reconceptualising Information Literacy for the
This chapter questions whether the shift from
the Web as a vehicle for storing and transmitting
information to the new Web as a series of social
networking environments, requires significant
changes in how students interact with information
when they are studying within a formal learning
environment It explores the origins and growth
of the idea of information skills development, the
translation of this work into frameworks and
se-quential models and the adaptation of these models
to take account of changes in information storage
and transmission brought about by the Internet
The chapter then examines the changing contexts
and changes in learning being brought about by
the Web 2.0 environment and questions whether adjustment of existing information literacy models
is a sufficient response to deal with these changes
We conclude that although Web 2.0 developments are not fundamentally undermining the nature of teaching and learning they do provide important possibilities for more effective information literacy development work A non-sequential framework is offered as a contribution to supporting HE students when seeking to obtain, store and exploit information simultaneously in the informal social world of Web 2.0 and in their formal academic discipline
the rIse of InforMAtIon sKIlls
In the early 1980s a spate of books appeared in the
UK containing a new term in the title: ‘information
DOI: 10.4018/978-1-60566-208-4.ch022
Trang 30skills’ This term was the brainchild of a working
party concerned about school pupils’ competence
in “using libraries, exploring references and
making notes” (Marland, 1981, p7) and arose
out of the Schools Council’s desire to explore
what a curriculum for a changing world might
comprise The working party report asserted that
“Individuals today have an increasing need to be
able to find things out…never before have our lives
depended so much on our ability to handle
infor-mation successfully” (Marland, 1981, p9) Narrow
concerns about library skills and user education
were replaced by a focus on students’ problems
in finding and using information to tackle
assign-ments and conduct their research within a formal
learning environment This intervention was due
to the interest in these skills by educationalists,
who, working alongside librarians, ensured wider
adoption for information skills and a clearer place
for the concept within the learning process
However, despite this development and the
ap-pearance of a number of books exploring the place
of information skills in learning (see, for example,
Markless and Lincoln, 1986, and Wray, 1985)
the concept of information skills was far more
widely accepted by librarians than by teachers
This resulted in heavy emphasis on competence
in resource use and on finding information
Models of InforMAtIon sKIlls
From the outset writers wanted to show the need for
students to develop these ‘new’ information skills
The issue was presented as one of skills deficit
and consequently led to a plethora of information
skills frameworks and models, spelling out what
students should be able to do (Many of these
models were later ‘rounded up’ and described by
Loertscher and Woolls, 2002.) Model constructors
conceived the requisite process as tying together
distinct elements of information-related behaviour
into a logical, sequential process which could then
be taught (e.g Marland, 1981; Brake, in Markless
and Lincoln 1986)
An important retrospective review of these models and frameworks (Eisenberg and Brown, 1992) concluded that
while each author may explain this process with different terms … all seem to agree on the overall scope and the general breakdown of the process
… it appears that the various process models are more alike than different and it may be possible and desirable to begin speaking about a common process approach to library and information skills instruction (p 7)
The approach to information skills as a mon process’ to be applied to library research and information handling unfortunately tended to result in a disregard for the context of learning Skills were perceived as generic; the sequential process outlined in the models was to be adopted at all ages and across different subjects The process formed a ‘curriculum’ to be taught to students and applied by them whenever necessary This view was hardly challenged in the early world of information skills although research on informa-tion behaviour in context and on critical thinking skills was calling into question the whole notion
‘com-of easy transfer, which is also a well-established assumption in mainstream education (Perkins and Salomon, 1992)
Perhaps the most influential of these generic information skills models was advanced as the Big6 This model was created by Eisenberg and Berkowitz (1990); it was widely disseminated in book form and continues to be heavily promoted
in the USA and internationally through their website and through an extensive programme
of workshops We will use this Big6 framework
as the basis of our critique for the remainder of this chapter because it is one of the frameworks most widely used in USA and UK schools to sup-port information skills teaching and because its authors were amongst the first to integrate ICT into information skills in a distinct and transpar-
Trang 31ent manner.
The main elements of this model are outlined
below:
1 Task Definition: (determine the purpose and
need for information)
2 Information Seeking Strategies: (examining
alternative approaches to acquiring the
ap-propriate information to meet needs)
Determine the range of possible
◦
resources
Evaluate the different possible
◦
sources to determine priorities
3 Location and Access: (locating information
sources and information within sources)
Locate sources (intellectually and
5 Synthesis: (integrating information drawn
from a range of sources)
Organize information from multiple
Eisenberg and Berkowitz (1990)
It is not surprising that when the concept of
information skills was new, and people sought to
understand its scope, frameworks such as the Big6 were widely adopted They provided a foundation
on which to build learning activities and ment Would such frameworks survive intact into the ‘information age’ of ICT?
assess-the shIft to InforMAtIon lIterAcy: A broAder vIeW?
With the advent of Worldwide Web and the extensive accompanying investment in ICT in educational institutions of all kinds, concerns about students’ ability to find and use information grew exponentially and a new vocabulary began
to emerge in formal education - that of tion literacy The notion of information literacy developed in the USA in the 1980s in response
informa-to a move informa-towards more active learning in versities and the concomitant need to move away from terms implying passive instruction (Martin, 2006) Use of the term expanded considerably in the 1990s (Bawden, 2001) and has gained some worldwide influence, leading to a declaration by UNESCO (2003) stressing the global importance
uni-of information literacy within the information ety A parallel growth in the UK has seen the term widely adopted in academic libraries and national educational bodies (but with most school libraries until now still preferring to focus on information skills - Streatfield and Markless, 2007)
soci-Did the new term signify any fundamental change in thinking or signal a new characterisa-tion of the skills or processes previously called information skills? National Information Literacy Standards in Australia (CAUL, 2001) and the USA (ACRL, 2000) echoed much of what was in the earlier process models, as did the information lit-eracy model proposed in the UK by the Society of College, National and University Libraries (1999) Despite the fact that ‘literacy’ is a problematic and contested concept (it has been variously described
as encompassing notions of functional competence and skills, of sets of wider cognitive abilities, and
Trang 32as part of a contextualised approach to learning
in its social and economic context - Bowden,
2001), information literacy was usually reduced
in presentation to a series of skills, procedures and
technicalities This inhibited approach attracted
some criticism for being too mechanistic and
some writers moved towards a conceptualization
that includes attitudes, underpinning knowledge
and meta-cognitive abilities (Kuhlthau, 1988;
Bruce, 1997) Although Kuhlthau recognised the
importance of student attitudes and emotions in her
information process model, these elements have
not been integrated into other process models -
although the commentaries accompanying these
models usually refer in some way to motivation
and attitudes
InforMAtIon sKIlls
And the Internet
In this phase of its development, the Internet was
viewed primarily as a new information storage and
delivery system for which existing information
skills frameworks could simply be expanded or
adapted to take account of the growth in access
to information via the Internet Eisenberg and
Johnson (1996) exemplified this view when they
explicitly integrated ICT into the Big6 Skills
model, saying that
Students need to be able to use computers
flex-ibly, creatively and purposefully… (they) should
be able to use the computer as part of the process
of accomplishing their task (p 2)
During the 1990s, the creators of the Big6
confi-dently extended the model to include student use of
ICT when solving learning problems They claimed
that various computer and information technology
skills were integral parts of the Big6 Skills This
claim was sustained as their model continued to
be implemented in schools across the USA and
the UK (Eisenberg and Berkowitz, 2000)
Adher-ents of this and other process models confidently asserted that the basic principles of information seeking and use, derived from years of watching and helping students to interact with print-based information, remained unchallenged
We have chosen to exemplify current process models by citing the Big6 when looking at whether the concept of information literacy needs to be repackaged or reconceptualised because:
the model crystallizes the general process
• approach favoured until now and serves as
an adequate exemplar of the model-driven approach
it serves our purpose because it was the only
• model advanced until recently that system-atically encompasses the ICT dimension
It is still currently being used and promoted
•
in that form
The Big6 framework is useful for this purpose because it is a systematic and widely adopted model Our comments should not be construed
as an attack on this particular framework
exAMInIng the process Models
What are the assumptions underpinning the Big6 and similar models and what are their main char-acteristics?
A
• sequential view of the process of student research, conceived as a series of logical steps
Use of prescriptive language to convey an
•
‘ideal approach’ to information-seeking and use (e.g “After students determine their priorities for information-seeking they must locate information from a va-riety of sources”; “once the information problem has been formulated, the student must consider all possible information sources and develop a plan for searching”)
Trang 33This approach is commonplace in this
pe-riod, despite the warning offered a decade
earlier by Tabberer and Altman (1986)
about the danger of idealising study
behav-iour and promoting ‘the right way to …’
They stressed that success came by diverse
routes and as a result of different choices
made in different situations They warned
that students did not always gain much by
being confronted with ‘the ideal’ because
there is a range of influences that prevent
adoption of ‘best behaviour’
The process models were designed to
sup-•
port information skills teaching (i.e to
pro-vide a ‘curriculum’ for the teachers and a
pathway to be followed by students when
doing their research)
A particular and limited conception of
in-•
formation-related behaviour is represented
in these models, with much emphasis on
information seeking, location and access
Use of information is reduced to
deter-mining relevance and extracting pertinent
items of information (by taking notes or
re-sorting to cut and paste) The words
knowl-edge, understanding and making sense of,
seldom occur in these models, nor does the
idea of creating one’s own viewpoint The
apparent assumptions are that this
short-coming will be addressed in the subject
teaching or that the acts of extracting and
organising relevant information will
them-selves stimulate the construction of
mean-ing What happens instead is frequently cut
and paste activity leading to more or less
unintentional plagiarism In these models,
synthesis is not about transforming
infor-mation to encapsulate new knowledge
Overall they present ways to support
•
teaching (“innovative instructional
meth-ods”) designed to provide a framework to
guide teachers or librarians when
prepar-ing appropriate activities or tasks for their
students
These models reflected the main uses ceived for the Web in this period as a vehicle for storing and transmitting information
con-InforMAtIon lIterAcy And Web 2.0: chAngIng the context, chAngIng the leArnIng?
The ‘orthodoxy’ of information skills within formal learning environments, as enshrined in the Big6 Model, is being increasingly challenged Recent research into information literacy is moving away from technological processes and skills-based models, recognising the complexi-ties inherent in finding and using information A more experiential perspective that recognises the contextual and affective elements of information literacy is emerging (Williams and Wavell, 2007) Two complementary developments have influ-enced this shift in focus: greater interest amongst information literacy researchers and practitioners
in the processes of learning (especially theory about variation in learning and constructivist ap-proaches); and an electronic environment that is increasingly being shaped by its users
Have traditional views of information literacy really been rendered obsolete? Does learning through Web 2.0 require different skills and abilities? Are a new range of cognitive and meta-cognitive strategies needed to learn effectively within the Web 2.0 environment? Or, does the Web 2.0 environment provide tools that enable teachers to engage students more effectively in well-established learning processes than could be achieved hitherto?
In our view, learning is not fundamentally ferent within Web 2.0, nor does the ‘new’ social software change the basic processes of learn-ing Where Web 2.0 has made a difference is in making it easier to engage with some aspects of learning that were previously difficult to address (for example, real collaboration and groupwork, peer critique, hearing students’ authentic voices
Trang 34dif-and construction of new knowledge) None of
these important aspects of effective learning are
new: all can be found in the education literature
of the 20th Century, from Dewey to Ausubel, and
from Vygotsky to Marton However, despite their
importance, few of these elements have found
their way into information literacy models or
practice
When the Worldwide Web was primarily a
ve-hicle for storing and delivering information it was
easy to portray information literacy as an ordered
sequence of skills to be transmitted to students,
whilst ignoring other approaches to learning Web
2.0 effortlessly undermines this approach with its
disregard for authority, hierarchy and order and its
focus on the voice of the individual and on ever
changing constructed groups Any contemporary
approach to information literacy must consider
how to engage more effectively with learners,
by understanding these multiple aspects of how
they can learn
Before we examine in a little more detail
some of these key elements of learning and their
relationship to information literacy and social
software, we need to note two other factors that
may influence this relationship: the reluctance
of individuals and institutions to change; and the
ways in which the ‘Google generation’ of ‘digital
natives’ may interact with information and learn
in new and different ways What are the key
ele-ments of learning as they relate to information
literacy and social software? Some at least of
these key elements are:
1 Reluctance to change (institutions and
teachers)
Faced with the unfamiliar challenge of a new
world of social networking, some education
institutions have tended to react in a predictably
conservative way by blocking access to elements
such as Face book and Second Life As a result
of such embargos, as well as a reluctance by
teachers to engage with this new world, students
are frequently operating in different electronic environments during formal learning from those
in their out of hours experience (especially in schools) This makes teaching of information literacy more problematic
To somewhat over-dramatize the dilemmas created: as a teacher, how can you fully engage with students in helping them to exploit informa-tion if you don’t have easy access to what may constitute their major sources of information? Or, from a student perspective, why should you bother
to engage with all this ‘information literacy stuff’
if your perception is that all you have to do to get the information and help that you need, is to resort
to your social networks? When you are away from the institution, if you can effortlessly manipulate multi-media information to build your own web pages, why jump through what might be seen as sterile and irrelevant information literacy hoops when you are in formal learning mode? Again,
as the world of Web 2.0 becomes increasingly sophisticated, the version of ICT encountered
in formal learning is likely to appear ever more limited and pedestrian
2 Digital natives and others
“ Future students in higher education belong to
a generation that has grown up with a PC mouse in their hands, a TV remote control, a mobile phone,
an i-pod, a PDA and other electronic devices for communication and entertainment … computer games, the Internet, MSN, wikis and blogs being
an integral part of their lives” (Veen, 2007, p.1) Prensky has labelled these young people ‘digital natives’ and has asserted that they now exhibit different characteristics from their forbears (the digital immigrants) due to the extent of their exposure to technology in all its forms.(Prensky, 2001) He claims that changes in activity during development may result in different neural wiring via processes of ‘neuro-plasticity’; a view recently echoed by Martin Westwell of the Institute for the Future of the Mind (2007) Both advocates assert
Trang 35that current students have much better visual skills,
do better at visual-spacial tests, are able to deal
with lots of information at once, and can process
this information and make decisions quickly On
the other hand, this generation of students may
have shorter attention spans, be easily distracted,
may not maintain focus well when interrupted and
may have less ability to reflect on topics than the
previous generation Veen (2007) adds to this list
of differences, talking about non-linear learning
behaviour; clicking and zapping to deal with
in-formation overload; using exploratory approaches
to new situations; and becoming experienced at
problem solving at a young age “We now have
a new generation with a very different blend of
cognitive skills than its predecessors – the digital
natives.” (Prensky, 2001)
As a result of Web 2.0 developments, we can
also anticipate that ‘digital natives’ may have
dif-ferent social skills This is because the Internet
is increasingly used for socialisation rather than
just information-seeking, with even those
seek-ing information often doseek-ing so via peer groups
Westwell claims that more people use Second
Life and Facebook than use Google Whether
or not we believe all these claims, Oblinger and
Oblinger (2005) have forecast that the next
gen-eration of students entering higher education will
be digitally literate, highly Internet-familiar,
con-nected via networked media, used to immediate
responses, and preferring experiential learning
This generation will be highly social: they will
prefer to work in teams and will crave
interactiv-ity in image-rich environments as distinct from
text-intensive environments
Where does this leave traditional
informa-tion literacy, with its focus on using libraries and
finding primary sources, its reliance on laborious
sequential steps and its scant reference to
collabo-ration or to multi-media resources? If Westwood
and others are correct, their picture of our ‘new’
students implies that not only have they gained
from their early digital experiences but they have
also lost in terms of opportunities for reflection and
‘slow-learning’ This picture of gains and losses calls into question the widespread claims that ele-ments of Web 2.0 (wikis etc.) automatically help
to develop meta-cognitive skills However, it is also interesting to note that traditional information literacy frameworks do not emphasise reflection and its role throughout learning
Web 2.0, InforMAtIon lIterAcy And forMAl leArnIng
Where do all these changes leave information literacy? How might traditional models of infor-mation literacy need to be altered to accommodate the experience and expectations of students within formal education? Where does Web 2.0 fit in?The
• sequential view of skills deployment
is now being questioned Learning tasks make a range of different demands on students, which call into question the no-tion of applying the same series of steps
to meet all these demands Observations of pupils from 5-18 in schools and students in further education colleges show that they seldom follow the prescribed sequence (Streatfield and Markless, 1994; Moore, 1997; Markless and Streatfield, 2000) Formal studies of information-seeking be-haviour in universities again challenge this premise (Foster, 2006) To be fair, most
of the process models that are set out in steps are accompanied by some form of caveat recognising or even advising that
it is not necessary to follow the prescribed sequence However, there is usually little help offered on how to use the model in
a non-sequential way, with the result that the framework tends to be taught as a se-quence The desire to inflict sequences on students is remarkably resilient in the world
of information literacy Even writers who are responding to the Web 2.0 environment
Trang 36tend to present a sequence of processes to
be learned in order to become ’information
fluent‘ (e.g the five-stage process of Jukes
(2007): asking questions; accessing data;
analysing and authenticating information;
applying it to real-life problems; assessing
product and process) This approach takes
no account of the influence of context on
any sequence, the influence of learners’
cognitive styles, or the need to make sense
of any information and transform it into
knowledge
In addition, a core characteristic of Web 2.0
tools is that they transfer power, ownership
and authority to the participants This
in-evitably gives people license to design their
own routes through learning tasks in any
way that suits them Finding information is
less likely to involve systematic information
seeking than, for example, interest groups,
peer web pages or social bookmarking
These observations lead to the key
ques-tion - can the Big6 or any similar
infor-mation literacy model be adapted to take
account of how students actually find and
use information, especially in the Web 2.0
environment?
Although the importance of learning as
•
construction is recognised within the
rhet-oric of information skills pedagogy and
“Information literacy is often seen as the
school library version of constructivism”
(Moore, 2005 p.3), much of the observed
planning and practice1 suggests heavy
reli-ance on transmission, learner practice, and
feedback, all heavily structured into
man-ageable segments and strongly ‘teacher’
controlled (that is, the classic behaviourist
approach) Early voices such as Kuhlthau’s
(1993), which present information-seeking
as a process of seeking meaning, were at
first largely ignored in practice In recent
years there have been intensified efforts
to ensure that people who are teaching
information literacy adopt constructivist approaches (e.g Todd, 2001) Limberg (2007) asserts that to learn is not to receive knowledge and information, but is about changing the relationship between a person and the world She claims that information-seeking is too often focussed on teaching technical procedures and on fact-finding rather than on students formulating authen-tic questions and constructing their own positions The concept of authenticity is central to Limberg’s ideas on information literacy Contrived questions and tasks, de-signed solely to meet externally imposed assessment and with no other consequenc-
es for the student, will not engage and tivate students Without a real and personal interest, students will be satisfied with the superficial answer, the first ‘hit’, or ‘good enough’ information There is no incentive
mo-to go beyond using technical skills mo-to lect facts
col-Again, the latest outputs from the USA-based Center for International Scholarship in School Libraries (Kuhlthau and others, 2007) focus on the concept of ‘guided inquiry’ as the basis for teaching and learning of information skills The main characteristics of guided inquiry are:active engagement by students in the learn-
• ing processstudents building on what they already
• knowhigh levels of reflection
•
a recognition of the importance of social
• interaction and of students’ different ways
of learning
(Kuhlthau and Todd 2007)
All these are recognisable characteristics of learning as construction (see, for example, Papert and Harel, 1991) There is little doubt that con-structivist approaches are particularly suited to
Trang 37Web 2.0 tools In this environment, students can
construct artefacts such as video presentations,
blog entries and wiki pages both individually
and collaboratively Teachers can join in with
collaborative editing and can scaffold students’
work It seems likely that the constructivist
ap-proach to teaching and learning so well supported
by Web 2.0 tools may finally lead to information
literacy teaching becoming more attuned to how
students learn
If constructivist principles are used to inform
and guide information literacy work, students will
be required to develop a repertoire of strategies that
are conspicuously absent from most information
literacy models This will involve:
reflection: the ability to reflect
construc-•
tively and to use that reflection in planning
for their own development
evaluation of the processes undertaken as
•
well as of the products of their study
making sense (deep understanding) of the
•
information that they obtain, linked to the
ability to transform the information to
re-flect their own emerging views
We do not think that these aspects of learning
can simply be grafted onto existing frameworks
or inserted after any particular element of a linear,
sequential model They are part of an iterative
process of learning not well represented in
exist-ing information literacy frameworks
the IMportAnce of context
The importance of context in relation to
informa-tion behaviour is well established (e.g Streatfield
and Wilson, 1980; Dervin, 1992; Ingwersen and
Jarvelin, 2005) Context in information-related
behaviour is recognised as multi-dimensional:
with different facets reflecting features of the task;
characteristics of the learner; and features of the
system Louise Limberg observed in a ence presentation that “Influential studies have abandoned the idea of information literacy as a set of generic skills applied anywhere Informa-tion literacy is not generic but should be seen as social practice …” (Limberg, 2007) Looking at secondary schools, Williams and Wavell (2007) warned that if we are trying to to develop pupils’ information literacy we cannot ignore content
confer-in favour of technicalities and procedures - if
we do so, we will get trivial learning outcomes Nevertheless, as we have already noted, informa-tion literacy advocates have persisted in offering generic skills development frameworks that take little no account of context
How can the importance of context be reflected
in an information literacy framework? We believe that a different type of framework is needed; one that moves away from offering a list of abilities
to be taught or applied in an unvarying sequence, irrespective of context
Alongside the challenge of producing an propriate information literacy framework we face another problem: how can we teach information literacy in ways that respect the influence of con-text? Current views on skills development (e.g Luke, 2006; Williams and Wavell, 2006) assert that
ap-if students are to develop their information-related skills through assignments there is a need for:Authentic tasks that are recognised as rele-
• vant by the students (tasks that have mean-ing to students on a personal or academic level; not contrived to allow them to prac-tice particular skills)
Immersion in authentic contexts (realistic
• environments, current information drawn from the real world, engagement with real world problems and concerns)
High quality tasks related to current
aca-• demic work (e.g asking students to con-duct critical evaluation of sources to con-struct a position for an essay, rather than
Trang 38offering general guidance on evaluating
information)
Learning embedded in the relationships,
•
values and discourse of the learning
com-munity (inherently social)
Timely teacher interventions in order to
•
move learners on at transition points in
their work
Web 2.0 can once again be a powerful
sup-port for increasing authenticity and enabling the
deployment of information literacy strategies in
a variety of meaningful contexts The
possibil-ity of a public platform for their work may help
students to take more seriously the underlying
information literacy processes involved in
pro-ducing that work
student reflectIon
If we are to take context into account when
deciding on information literacy strategies, this
immediately introduces the concept of variation
Bowden and Marton (1998) argued that not only
do students need to experience variation in order
to learn, but they must also explore variation by
comparing and analysing their experiences To
do this, students need to:
actively engage in discussion and
reflec-•
tion about finding and using
informa-tion in order to uncover variainforma-tion in their
Since at least the 1970s, reflection has been
seen as a mainstay of learning and this concept
has found its way into many models of learning
(e.g Kolb, 1975; Schon, 1983)
Reflection is a particularly important
ele-ment in developing the processes underpinning
learning and is therefore potentially important in any systematic approach to information literacy Reflection is taken for granted in most models of information literacy or placed at the very end of the process This approach in not likely to enable the development of the meta-cognitive strate-gies necessary to perform problem-solving with information It is likely to be difficult to integrate reflection into existing information literacy frame-works in any meaningful way (see the discussion about constructivism above) The possibilities for learning provided by Web 2.0 may provide a way forward For example, peer critique and the col-laborative production of artefacts may automati-cally stimulate reflection If not, engagement in these processes should provide opportunities for
a more formal emphasis on reflection as part of information literacy teaching
collAborAtIve leArnIng
Collaborative learning has long been seen as a desirable process: for example, groupwork is
a key element of training courses for teachers
in all sectors Web 2.0 tools have turned many students into sophisticated social networkers via YouTube, Facebook, blogs and discussion boards (Ipsos MORI, 2007) The same tools can also be used to facilitate collaboration in formal learning settings, whether the focus is on creating specific interest groups, building learning communities or enabling the collaborative production and editing
of artefacts
Collaborative learning requires many skills
of communication and interaction, but does it make fundamentally different information literacy demands on learners than those made when in-dividually finding and using information? There
is little in recent research to indicate that this is the case (Williams and Wavell, 2007; Kuhlthau, 2007) The influence of context (subject, learner characteristics and teacher expectations) is not just about whether students are working individually or
Trang 39in groups to find and use information At the same
time, Web 2.0 can be seen as working counter to
collaboration through increased personalisation
of learning paths Overall, this aspect of Web 2.0
raises important issues in the wider context of
ap-proaches to learning by providing increased scope
for a variety of activities It may offer valuable
avenues for the teaching of information literacy
but does not seem to fundamentally affect the
information handling skills required
leArners’ expectAtIons
of InforMAtIon
Web 2.0 inevitably raises questions of ownership
and authority of information It is an environment
in the course of creation by its participants These
participants individually and collaboratively
gen-erate content in a form, format and structure that
best suits their own needs and preferences This
process works well when the primary focus is on
participation in social networks or developing
personal interests However, it can create major
difficulties when the same processes are applied
in formal learning Keen (2007) claims that we are
diving headlong into an age of mass mediocrity
because of the absence of gatekeeper expertise
and the increase in user-created content This
view is echoed by Gorman in his Britannica Blog
(2007) which identifies an erosion of traditional
respect for authenticity and expertise in a world
in which everyone is an expert “ignorant of the
knowledge they will never acquire and the rich
world of learning that search engines cannot
cur-rently deliver to them.”
Most students should be able to operate both
in the social world of web 2.0 and in more
for-mal learning environments (even before we take
account of the growing presence of academic
interests and institutions on Web 2.0) However,
to operate effectively in formal learning
envi-ronments, student autonomy may have to give
way to recognised academic authority Students’
preferred use of Wikipedia and social marking, alongside their facility in creating new
book-‘knowledge’ through remixing text, image and audio, or through the collaborative creation and editing of web pages may come into conflict with the necessity to conform to academic norms of using externally-validated information Students will not be able to simply replicate their social/leisure on-line behaviour when engaging in for-mal academic tasks Information literacy should help in this arena: traditional information literacy models do focus on evaluating sources of infor-mation, on considering authority and credibility Such an emphasis should raise students’ aware-ness of the problems associated with following their own preferences and concentrating on their own perspectives A new balance may need to be drawn between encouraging students to use the range of pathways to information that are open
to them in Web 2.0 and ensuring that they have the ability to choose the most appropriate for academic study
However, do we also need to respond more positively to students’ expectations of informa-tion? Should the information literacy field legiti-mise elements of students’ preferred information-related behaviour? For example, should we ensure that information literacy frameworks encompass such concepts as ‘good enough’ information, trial and error, and peer ‘expertise’ rather than focusing primarily on a set of competencies that appear to
be designed to turn all learners into systematic researchers, regardless of the task context?
does fIndIng InforMAtIon reAlly MAtter Any More?
One question likely to worry traditional tion literacy proponents is whether there will be
informa-a continuing need for skills in informinforma-ation ing, given an information world in which search engines are become increasingly sophisticated and in which Web 2.0 offers a range of enticing
Trang 40seek-alternatives to systematic searching According
to Carol Kuhlthau (2007) what is important in
the 21st century is the ability to use information
for problem-solving not “the technology of
find-ing.”
Is A neW Model of InforMAtIon
lIterAcy needed to Meet
the chAllenge of Web 2.0?
We are not convinced that the Web 2.0
environ-ment on its own necessitates the developenviron-ment
of new sets of abilities for finding and using
information It does, however, move learning
into new directions (e.g increased collaboration,
more authentic tasks, peer critique, non-linear
aaproaches to information) In doing so, learning
with Web 2.0 tools should put increasing pressure
on proponents of information literacy to move in
the direction of well recognised learning principles
and practices In particular, information literacy
can be enhanced in a formal learning environment
by exploiting some possibilities offered through
cial bookmarking and folksonomies)
Organising information in new ways (e.g
•
using tagging)
Increasing authenticity of work by
present-•
ing ideas to others in a more public space
and using a wider range of media
Providing ‘just-in-time’ scaffolding to
sup-•
port students
Facilitating student reflection using records
•
of individual and group processes and
pro-viding virtual contemplative spaces
None of these aspirations are new to formal
education but some have been difficult to achieve hitherto without the benefits of advances in Web 2.0
If the information literacy community is pared to design materials, activities and support mechanisms based on the opportunities offered
pre-by Web 2.0, can they adapt existing information literacy frameworks to scaffold their work? Is a framework needed at all to enable information literacy development in formal education set-tings?
Any model or framework will be flawed cause it cannot fully take account of the influence
be-of context on information use or the problems inherent in producing any generic view of infor-mation literacy However, whilst doing research and development work in many further and higher education institutions and schools, we have found that staff and students want to put some sort of framework in place They want a public statement that clarifies what is encompassed by information literacy; a guide to support curriculum planning; and something that students can refer to when doing research and tackling academic tasks.The following framework (Markless and Streatfield, 2007) was originally designed to address problems being encountered by the University of Hertfordshire The University was trying to develop an institution-wide approach
to supporting students when finding and using information in an electronic environment At first
it was thought that an existing framework could
be used or adapted to meet the needs of staff and students However, consideration of the issues explored in this chapter made the shortcomings
of such an approach apparent We concluded that many of the traditional information literacy models had been built on a series of assumptions about learning and information behaviour that were problematic and that the increasing use of Web 2.0 threw these assumptions into stark relief We therefore needed to offer a different solution that
is more in keeping with the changing learning environment