Tài liệu Module 7: Selecting Solution Technologies doc

Module Overview Module 3: A Services-based Approach to Solution Design Module 4: Business Solution Conceptual Design Module 5: Business Solution Logical Design Module 6: Beginning Physic

Module 7: Selecting Solution

Technologies

Module Overview

Module 3: A Services-based Approach to Solution Design Module 4: Business Solution Conceptual Design Module 5: Business Solution Logical Design Module 6: Beginning Physical Design

Module 1: Course Overview Module 2: Solution Design Using the MSF

Module 7: Selecting Solution

Technologies

Module 8: Solution Design and the

Component Object Model

Module 9: Designing Solutions with

Overview

Considerations by Type

of Technology

Activity 7.2: Determining the impact of

Technology on a Windows DNA Design

Review

Distributed ApplicationsUsing Windows DNA

TechnologySelection Process

Activity 7.1: Determining Technology Requirements

Module 7: Selecting Solution Technologies

! Overview

In this module

Technology on a Windows DNA Design

" Review

Physical design involves evaluating solution technologies In this module, you will learn about some of the solution technology types and some evaluation criteria to consider for each of them Later, you will use this information to investigate specific Microsoft® solution technologies

After completing this module, you will be able to:

" Describe Microsoft Windows® Distributed interNet Applications Architecture (Windows DNA) and how it applies to an application’s development

" Describe a process for selecting solution technologies for implementing the designed solution

" Evaluate implementation technologies from the perspective of the solution requirements, business considerations, enterprise architecture

considerations, and whether the technology should be reused, purchased, or built

" Evaluate the technology implications of solution requirements

" Identify technology types and their evaluation criteria

Slide Objective

To provide an overview of

the module topics and

objectives

! Distributed Applications Using Windows DNA

In this section

Windows DNA is an important concept that will be central to developing applications in the future In this section, you will learn what Windows DNA is, the problems it solves, the services it provides, and its key benefits

Slide Objective

To provide an overview of

the topics and activities in

this section

Windows DNA Architecture Model

platform

" Specifies:

$ How to develop services-based applications

$ How to extend existing data and external applications to support the Internet

$ How to support a wide range of client devices and maximize the reach of an application

Windows DNA is the application development model for the Windows platform It specifies how to develop service applications based upon the ideas

of user, business, and data services, in addition to using other system services of the Windows platform

Windows DNA also describes how existing applications and data can be used more easily in an Internet environment The multiple service-layer design allows the development team to quickly move an application to an Internet or intranet system Windows DNA also allows for a varying array of client devices, ranging from Windows clients to Web browsers and hand-held computers

All Windows DNA services are exposed in a unified way through the Component Object Model (COM) Windows DNA is a roadmap for creating solutions that build on existing computing investments Its multiple-service-layer design allows applications to quickly access existing data and provide integration with existing applications

Core Structure of Windows DNA

User Interface

User Services

Business Services

Business Services

Data Access Services

Data Access Services

Data Store

Microsoft System Services

Microsoft System Services

Microsoft Operating Systems

Microsoft Operating Systems

Microsoft Development Tools

Microsoft Development Tools

The Windows DNA architecture consists of a set of system services and component-based application services that support open technology standards that are exposed in a unified way through COM These services can be thought

of as separate layers Each layer has its own characteristics and provides an isolating buffer to the neighboring services These layers are often separated into the following categories:

" User interface consisting of HTML, DHTML, Native Microsoft Win32®, Active Server Pages (ASPs) applications, and code

" User services consisting of ASP, scripting, Microsoft ActiveX® controls, COM+ components, and Win32 application programming interface (API) applications and code

" Business services consisting of COM+ components, Microsoft Transaction Services, and applications based on Microsoft Message Queue Services

" Data access services consisting of COM+ components, ActiveX Data Objects (ADO), OLE DB, and Open Database Connectivity (ODBC) services

" Data storage services using Microsoft SQL Server™, Microsoft Visual FoxPro®, Microsoft MSDE, and Microsoft Access

" System services consisting of Active Directory™, security, management, networking, and communications

" Operating systems consisting of Microsoft Windows CE, Windows 98, Windows NT®, and Windows 2000

" Development Tools consisting of Microsoft Visual Basic®, Microsoft Visual C++®, Microsoft Visual InterDev®, Microsoft Visual J++®, and Microsoft Visual Modeler

Slide Objective

To explain the service areas

that Windows DNA

The technology categories

presented in this section will

be covered in detail in

Module 9

User services and user

interfaces will be covered in

Module 11

Key Benefits of Windows DNA

applications

integrated development tools

Windows DNA provides an integrated platform for building distributed applications The existing Windows DNA system services free the development team from the burden of building or assembling commonly needed, middle-tier services such as asynchronous message queuing, transactions, component services, data access, and Web publishing Applications can be built faster and easier by using the common service infrastructure of the Windows platform.Windows DNA supports a wide choice of programming languages and integrated development tools, which allows the project team to choose the tool that best fits the needs of the current project

Windows DNA is designed to provide a high level of interoperability with existing enterprise applications and legacy systems, which makes it easy to protect and extend current investments

Slide Objective

To describe some of the

benefits of Windows DNA

Lead-in

You will find that Windows

DNA provides many benefits

to application developers

and systems integrators

! Technology Selection Process

In this section

In this section, you will learn about the process of selecting candidate technologies for your solution They are termed candidate technologies because they have not been proven and thereby finalized as the optimal technology for your solution You will learn a set of steps that will assist you in evaluating candidate technologies

Slide Objective

To provide an overview of

the topics and activities in

this section

Determine Technology Requirements

The first step in selecting technologies for an application is to determine the technology requirements and identify the necessary types of technology

The candidate technologies should meet the business goals of an organization Understanding the business goals and requirements is critical when making technology decisions

The candidate technologies should also meet the design goals of the proposed solution Evaluate the technologies to determine if they supply the needed functionality that has been identified so far in the Microsoft Solutions Framework (MSF) Design Process

In addition, be sure that the candidate technologies will work within the project constraints For example, it might take three months to implement a new networking technology, but the application that relies on the new technology must be available in one month

Slide Objective

To explain that there are

already technology

implications in the current

design materials and to

identify the typical set of

technologies required for the

implementation of a

solution

Lead-in

Before you can select any

particular technology, you

must first determine what is

required of that technology

Evaluate Solution Requirements

" One of the first items to consider in the physical design of the solution is the overall performance of the application Even if the solution accomplishes every operation for which it was intended, it will be useless if it does not perform well

" When looking at security for a new application, it is important to understand not only the method of authentication (proving the identity of the user), but also the access rights (what they can see or do) of that user Security is especially important with today’s public systems located on the Internet During physical design, the project team should be looking at the security requirements of the system and determining which of those needs will be met by the existing business environment and which need to be designed into the new system

Understand that the technology selected for security must be supported, just

as the solution built with it must be supported What are the implications of that support for the project and the enterprise? A supportable product has support options such as vendor, outsourcing, and help desk, and it also accumulates support costs such as incidental costs and maintenance

" Other points to consider are deployment, competitive advantage, time to market, and industry perception Keep in mind that supporting an application may mean later upgrades or extended functionality An application development process is not something with an end, but something with a life span Throughout the life of an application, it will likely need updates and extended functionality Attempt to prepare for these changes through the design process to ensure that they are as easy as possible to implement

Slide Objective

To highlight some of the

more common requirements

of any business solution

Lead-in

Every solution will have its

own requirements for a

successful implementation

" With today’s large environments, deployment costs of new applications and the complexity of those deployments can be tremendous Many solutions are developed with no thought about what it will take to deploy the application after it is completed Keep in mind that the initial deployment method and costs are not the only ones Inevitably, there will be updates to the system that will also have to be deployed Attempt to design an easily updateable system

" Scalability is an important aspect of performance An application may perform well for a small number of users, but it must also be able to handle the full load of users after it is in a production environment It is important

to begin looking at the number of users that will ultimately be using a system to ensure that it will meet the scalability requirements when under stress

" When considering the reliability of an application, it is important to determine an application’s required degree of reliability As reliability needs increase, costs for implementing the project increase The type of

application determines its reliability needs For example, consider a new application that is responsible for taking orders for a company’s products For every minute that this application is down, revenue is lost Often, the costs associated with a single hour of unplanned downtime are more than what it would cost to implement a highly available system using today’s latest technologies However, other types of applications have no real impact if they are unavailable for a short period of time For example, consider an application that lets everyone in the company view vacation schedules If this application is unavailable for a short time, it will not affect the overall performance of the company It is probably not necessary to invest huge sums of money in high-availability technologies for this type of application

" Reusability considerations are often ignored until too late in the implementation of a new system However, careful planning can create a solution that will have a longer life and provide the foundation for other systems in the future You need to consider the type of solution and how granular, portable, or modular its implementation must be

Evaluate Business Considerations

" Understand the complete product cost by considering developer, server, and reseller licenses, as well as upgrade costs Any technology has costs

associated with it that may or may not be obvious, but that nevertheless affect the technology through its life These costs can be initial hardware and software costs, support costs, infrastructure costs, and training costs They can also be either short-term or long-term investments An example of

a short-term investment would be something that solves an immediate need temporarily, such as adding additional memory to older machines to improve performance Long-term investments are items that will bring benefit for years in the future, such as rewiring a campus to support higher-speed networks or purchasing leading-edge hardware for servers and workstations

" Each investment must correspond to a return on investment in some way

Do not select a technology simply because it is new The investment in new technologies should return value to the company by bringing in more revenue or reducing costs

" Understand that the development team’s experience or lack thereof can have

a large impact on the appropriate selection of technology You must consider what experience is available in terms of training (costs or time), consultation (costs or availability), and the current developers’ comfort level with the technical solution

" A mature product is accepted in the market, is well understood, is a repeat

of something done before, is stable, and is supported by available resources

An innovative product is the “latest and greatest” or is “ahead of the curve.”

The project team should make technology choices based upon risk analysis

" A major justification for new projects and new technologies is to gain a competitive advantage If a technology can clearly bring a competitive advantage, then it will be supported by business (for example, electronic commerce)

Evaluate Enterprise Architecture Considerations

" Interoperability

A major concern from the perspective of enterprise architecture is the extent of change required by the new technology A new technology such as streaming video might require new wiring and networking capabilities A new imaging system might require larger screens Changes of this nature not only require money to purchase new equipment, but also time to learn about the new technologies and to implement them If two technologies are equal in other areas, often the best choice is the one that aligns more closely to the existing enterprise architecture

In addition to looking at the existing enterprise architecture, the project team should also consider any future directions within the enterprise architecture For example, if the direction of the enterprise architecture is to begin using a Windows 2000 server, then this fact should be considered when evaluating candidate technologies

Technologies can also impact the existing enterprise architecture Be sure to evaluate this impact and determine what negative consequences might arise as a result Enterprise architecture deficiencies can cripple an otherwise well-designed application

Interoperability concerns are also important when considering enterprise architecture Even if the design of an application does not specify interoperability as a design goal, it is always wise to keep it in mind when selecting candidate technologies Most applications, regardless of their nature, will eventually need to communicate with other applications Selecting technologies that allow for this type of interaction will allow the solution to be valuable for a much longer time period

Far too often, businesses outgrow new systems even before they are deployed You should remember that the business can and will grow in many ways Businesses can easily double in size due to mergers and acquisitions

Slide Objective

To highlight the need to take

the enterprise architecture

into consideration when

evaluating technologies

Lead-in

Beyond the needs of the

business, there is also the

matter of aligning with the

current enterprise

architecture

Evaluate Reuse vs Buy vs Build Options

" Reuse by:

$ Extending current components

$ Leveraging system services

$ Reusing code libraries

$ Compliance with enterprise architecture

$ Vendor stability

Reusability of technologies is an important consideration Developing software

is an expensive and time-consuming process Often the best choice is to reuse

or purchase existing components A common phrase that describes this model is

“Reuse before you buy; buy if you can; build only if you must.”

You can reuse technologies in many ways One way is to simply take existing components and extend their functionality to meet new needs This approach saves the time and effort that would be required to develop new components from scratch Reuse can also involve leveraging existing system services, such

as the security features of Windows 2000 or simply reusing code libraries where appropriate

When attempting to buy technologies rather than build new components, there are several factors to consider First, consider whether the technologies are compliant with the enterprise architecture Second, consider the stability of a vendor If a vendor is supplying a critical component for an application, it may

be necessary to have the component updated at a later time In some situations, the vendor will provide the source code for the component for an additional charge and allow the project team to modify it slightly if needed

Building is required when there are specific requirements for the solution that cannot be met by existing components or services Many business-specific components must be developed to fulfill the requirements of the solution

Slide Objective

To explain that after you

have addressed the issues

of selecting an enterprise

architecture, the decision

about reusing, buying, or

building still needs to be

addressed

Lead-in

After you have considered

the solution requirements,

the business requirements,

and the enterprise

architecture, you still need

to determine the best source

of the technology

Iterate Selection Process

$ Ability to meet requirements

$ Acceptably addressing considerations

$ Addressing greatest risks first

$ Creating prototypes

$ Looking at evaluation editions

proves unacceptable

Selecting a candidate technology involves finding technologies that meet the requirements of the proposed solution From the technologies that meet these requirements, the project team must select the technologies that best fit the environment based upon the business, enterprise architecture, and reusability considerations

After the technologies are selected, the project stakeholders should validate the selections to determine the suitability of each technology There are many ways

to validate technologies Look at each of the technologies in terms of risk to determine the shortcomings of each and the possible impact of those drawbacks

on the solution Creating prototypes is another important method of validating technology choices Also, many types of technologies such as operating systems, data storage products, or third-party components have evaluation editions that can be used to compare and contrast the separate candidate technologies

Finally, as with the other stages of the MSF Design Process, you should always look at candidate technologies in an iterative manner to ensure an optimal decision Make the selection, validate the selection, make additional selections for unsuitable technologies, validate the selections, and so on

As with the other aspects of

your design, technology

selection is an iterative

process based on early

validation