Web Services Architecture

Presentation for ECE8813Spring 2003By: Mohamed Mansour

What is a Web Service

Any piece of software that makes itself available over the Internet and uses a standardized XML messaging system

Roles

Service Provider Service Requestor Discovery Agencies

Wire Protocol

Transport HTTP (or other Internet protocols)

Packaging SOAP (or other packaging protocols)

Extensions Context, routing, policy

SOAP Example

<SOAP:Envelope xmlns:SOAP=http://schames.xmlsoap.org/soap/envelope/

<SOAP:Header>

<!– contents of header goes here -- >

</SOAP:Header>

<SOAP:Body>

<!– contents of body goes here -- >

</SOAP:Body>

End-to-End Scenario

Requestor

SOAP run-time

SOAP message

Network Layer

HTTP Request

Server (Provider)

SOAP run-time

Network Layer

Deliver HTTP

Dispatch to appropriateruntime

Description Stack

Interface, Implementation Described in a WSDL (Web Service Description

Language) document Minimum layers for any web service

Stack Components

WSDL Example<message name="GetStockQuotesSoapIn">   <part name="parameters" element="s0:GetStockQuotes" /> </message>

<message name="GetStockQuotesHttpPostOut">  <part name="Body" element="s0:ArrayOfQuote" /> </message>

<portType name="StockQuotesSoap"> <operation name="GetStockQuotes">    <input message="s0:GetStockQuotesSoapIn" />   <output message="s0:GetStockQuotesSoapOut" />   </operation></portType>

WSDL Example – contd.

<service name="StockQuotes"> <port name="StockQuotesSoap" binding="s0:StockQuotesSoap">  <soap:address location="http://www.swanandmokashi.com/HomePage/WebServices/StockQuotes.asmx" /> </port></service>

WSDL Example – contd.<binding name="StockQuotesSoap" type="s0:StockQuotesSoap">  <soap:binding transport="http://schemas.xmlsoap.org/soap/http" style="document" /> <operation name="GetStockQuotes">  <soap:operation soapAction="http://swanandmokashi.com/GetStockQuotes" style="document" /> <input>  <soap:body use="literal" />   </input> <output>   <soap:body use="literal" />   </output>  </operation></binding>

WSDL Example – contd.

<service name="StockQuotes"> <port name="StockQuotesSoap" binding="s0:StockQuotesSoap">  <soap:address location="http://.... />   </port> <port name="StockQuotesHttpGet" binding="s0:StockQuotesHttpGet">  <http:address location="http://......" />   </port> <port name="StockQuotesHttpPost" binding="s0:StockQuotesHttpPost">  <http:address location="http://......" />   </port></service>

Description Stack – contd. Policy

additional description to specify the business context, qualities of service, security requirements and offerings, and management requirements.

Presentation how to render the input and output messages on a screen for a

user to interact with. This is particularly useful for rendering Web services to users on many different types of devices.

Orchestration An orchestration description reflects a simple choreography of

Web service invocations between two business partners to complete a multi-step business interaction.

Composition Service Level Agreements Business Level Agreements

Discovery Stack

Publication Providers produce their service descriptions in a

UDDI document. Direct publish (ftp, CD-ROM, …) UDDI registry

Discovery Discovery methods parallel publication methods

Inspection Web Service Inspection Language (WSIL) a de-centralized, light weight method

Resources

http://www.w3.org/TR/2002/ http://www.xmethods.com http://www.alphaworks.ibm.com/webservices http://www.microsoft.com/webservices http://java.sun.com/webservices http://www.borland.com/webservices