WEB WEB SERVICES SERVICES

 Bind and invoke: After retrieving the service description, the service consumer proceeds to invoke the service according to the information in the service description... SOA - An exa

WEB SERVICES

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Phạm Trần Vũ Nhóm trình bày:

Vũ Văn An

Mã Trường Chu Bùi Thị Dự

Lê Thị Kim Tuyến

I SOA

II Introduction to Web Service

III Web Service’s Architecture

SOA - WHAT IS IT?

organizations to facilitate communication

between the systems running on multiple

platforms

 SOA is a collection of well-defined services,

each individual service can be modified

independently of other services to help respond

to the ever-evolving market conditions of a

business

SOA - WHY USE IT?

Using SOA can:

• Enhance business agility

• Synchronize IT with your business

• Break the barriers between business units and business partners

• Lower the cost of maintaining IT systems

• Focus your resources on innovation rather than maintenance

• Speed delivery of web services to meet business demands

• Provide support for IT process automation

• Protect IT investments by building on your

existing infrastructure

SOA - ADVANTAGES

Business benefits:

 Focus on Business Domain solutions

 Leverage Existing Infrastructure

SOA – DISAVANTAGE &

APPLICABILITY

• Service Oriented Architecture may

not always be the best architectural choice because optimal utilization

of SOA requires additional

development and design attempts

as well as infrastructure which

translates into costs escalation

service providers that

meet required criteria

Service Provider Service

Consumer

SOA - OPERATIONS

 Publish: To be accessible, service description

must be published so that it can be discovered and invoked by a service consumer.

 Find: A service requestor locates a service by

querying the service registry for a service that meets its criteria.

 Bind and invoke: After retrieving the service

description, the service consumer proceeds to invoke the service according to the

information in the service description.

SOA - ELEMENTS

SOA - An example

• Storage Service

– Storing and retrieving data

– Reserving space, monitoring status of storage

service

– Querying and defining the policies that govern who

is allowed access the service.

• Data Transfer Service

– Provide operations for requesting the transfer of

data from one storage service to another

– Managing and monitoring such transfers

– Querying and defining policies that govern how

difference transfer requests are prioritized.

Introduction to Web

service

1 What are Web Services?

2 Why use it?

3 When use it?

4 XML

1 What is Web service?

system, and is not tied to any one

operating system

or programming language

XML XML

Computer A:

Language: Perl OS: Windows 2000

Computer B:

Language: Java

1 What is Web service?

(cont)

• W3C:

– A software system designed to

support interoperable

machine-to-machine interaction over a network

• W3schools.com:

– Application components

– Communicate using open protocols

– Self-contained and self-describing

2 Why use web

service?

• Interoperability has highest priority

• Web Services take Web-applications to the next level

• Web Services have two types of uses

– Reusable application-components

– Connect existing software

2 Why use web service? (cont)

• Web services facilitate collaboration and allow businesses to grow

• Companies can spend less time

developing new applications

• E-businesses can use Web services

to provide their customers with

enhanced shopping experiences

3 When use web

service?

• Applications do not have severe

restrictions on reliability and speed

• Two or more organizations need to

– Google can improve PageRank

implemenation without telling user

– Just don’t change the WSDL

Web Service

1 What are Web Services?

2 Why use it?

3 When use it?

4 XML (eXtensible Markup

Language)

4 XML

• 4.1 A bout XML

• 4.2 The difference between XML

and HTML

4.1 About…

• XML - eXtensible Markup Language

• XML is a markup language much like

HTML

• XML tags are not predefined You

must define your own tags

• XML is designed to be self-descriptive

4.1 About…

• XML does not do anything

• With XML, you invent your own tags

• XML just plain text

<note>

<to> Tove </to>

<from> Jani </from>

<heading> Reminder </heading>

<body> Don't forget me this weekend! </body>

</note>

4.2 The difference between

XML and HTML

XML

• Designed to transport

and store data, with

focus on what data is

• Displaying information

• Both the tag semantics and the tag set are fixed

WEB SERVICE’S ARCHITECTURE

SOAP

Simple Object Access

Protocol

What is SOAP?

• The Service Oriented Architecture

Protocol

• Protocol for messaging and remote

procedure calling between distributed applications

– SOAP is for exchange information between applications

– SOAP is a format for sending messages

– SOAP is platform and language independent

• Developed by the World-Wide-Web

What is SOAP?

• Encoded in XML

• Stateless (request/response)

• SOAP is simple and extensible

• SOAP messages work through proxies and firewalls

SOAP in a Nutshell

• A SOAP client formats a message in XML including a SOAP “envelope” element

describing the message

• The client sends the message to a SOAP server in the body of an HTTP request

• The server determines whether the

message is valid and supported

• The server formats its response in XML and sends it to the client in the body of

an HTTP response

SOAP Use Scenario: RPC

SOAP envelope

SOAP Message Components

• Envelope (required) : identifies the XML

document as a SOAP message

– Contains Header and Body

• Header (optional) : contains header

information

– Contains application-specific information about the SOAP message.

– Specifies which entries must be

understood and by which target “actor”

SOAP Message Components

• Body (required)

– Contains application-specific

message

– May be encoded variously

• Fault element (optional)

– Contained in Body

– Describes error class (version

mismatch, headers not understood,

Skeleton SOAP Message

The HTTP Protocol

• HTTP communicates over TCP/IP An

HTTP client connects to an HTTP

server using TCP After establishing a

connection, the client can send an

HTTP request message to the server:

– POST /item HTTP/1.1

Content-Type: application/soap+xml;

The HTTP Protocol

• The server then processes the

request and sends an HTTP response back to the client The response

contains a status code that indicates the status of the request:

– 200 OK

Content-Type:application/soap+xml;

A SOAP Example

• In the example below, a

GetStockPrice request is sent to a

server The request has a StockName parameter, and a Price parameter

that will be returned in the response The namespace for the function is

defined in

"http://www.example.org/stock"

    <m:StockName>IBM</m:StockName>

  </m:GetStockPrice>

</soap:Body>

The SOAP response

    <m:Price>34.5</m:Price>

  </m:GetStockPriceResponse>

</soap:Body>

WEB SERVICE’S ARCHITECTURE

WSDL

Web Services Description Language

function calls and how to access them

• Then they use this information in your

WSDL file to form a SOAP request to the computer

• The <message> element is used to

define the messages that will be exchanged between the client and the service

• Contains zero or more message

<part> elements, which can refer to

message parameters or message return values

• Combines multiple message elements

to form a complete one-way or round-trip operation

<portType name="Hello_PortType">

</operation>

</portType>

Types of operation

• Define the mechanism that the client will actually use to interact with the web service

• Provide concrete information on what protocol is being used

• The most common choice is

currently SOAP

• The service element defines the address for

invoking the specified service

• Most commonly, this includes a URL for invoking the SOAP service

How do you write WSDL files?

• By hand: some editors have special support for WSDL !

• Automatic generation

WEB SERVICE’S ARCHITECTURE

UDDI

Universal Description,

Discovery and Integration

Introduction to UDDI

• Universal description discovery

and integration(UDDI) is special

directory services which is

implemented to use for indexing all the available services, a company offer.

• UDDI - an XML-based standard for

describing, publishing, and finding Web services

Introduction to UDDI

•

Why UDDI ?

• At a first glane appears extremely

simple

• Nonetheless, it include some subtle

points that are easily overlooked

• Let’s therefore begin examining the

future impact of UDDI within a specific

a industry.

• Currently, approximately 700

companies in the information

technology, electronic component

Why UDDI ?

• Enables a partner to transfer the

contents of an electronic shopping cart

• Enables a partner to query status

on a specific shipment

UDDI technical overview

The UDDI technical architecture

consists of three parts:

• UDDI data model

• UDD API

• UDDI cloud services

UDDI Data Model

Searching UDDI

• When you install Windows Server

2003, it does not install Enterprise UDDI Services by default

• Install the Web service on a new

or existing Web server

Publishing to UDDI

• In this section, we will walk

through the steps involved in

publishing a Web service with the UDDI interface

• Publish the specifications of the

Web service with Enterprise UDDI Services

UDDI Implementations

• A number of UDDI implementations

are currently available

• Here is a brief synopsis of the main

UDDI implementations available.

– Java

– Microsoft COM

– Perl

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