BCS Teesside Web Services

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BCS TeessideWeb Services

• David Fuller

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What I will cover

• What are Web Services?
• What is SOA?
• What is BPEL?
• Demonstrate the construction of a web service

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What are Web Services
A 'Web service' is defined by the W3C as "a
software system designed to support interoperable
machine-to-machine interaction over a network"
In common usage the term refers to clients and
servers that communicate over the HTTP protocol
used on the Web. Such services tend to fall into
one of two camps Big Web Services and RESTful
Web Services.
Source Wikipedia
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What are RESTful Web Services?

• Representational state transfer
• Described by Roy Thomas Fielding
• A key design idiom that embraces a stateless
  client-server architecture in which the web
  services are viewed as resources and can be
  identified by their URLs
• Its what the world-wide-web does

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What are Big Web Services

• "Big Web Services" use XML messages that
  generally follow the SOAP standard
• there is often machine-readable description of
  the operations offered by the service written in
  the Web Services Description Language (WSDL)

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Web Service Architecture
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Acronym Competition
WSDL
Web Service Description Language
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Acronym Competition
UDDI
Universal Description, Discovery and Integration
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Acronym Competition
SOAP
It doesnt stand for anything
It used to be Simple Object Access Protocol
but no more
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Acronym Competition
JAX-RPC
Java Api for Xml-based Remote Procedure Call
Now part of JAX-WS
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Acronym Competition
JSR
Java Specification Request
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Acronym Competition
BPEL
Business Process Execution Language
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Acronym Competition
SOA
Service Oriented Architecture
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What is SOA?
A collection of loosely-coupled, distributed
services which communicate and interoperate via
agreed standards
Source Oxford University
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SOA Principles

• Reuseability
• Service contract
• loose coupling
• Abstraction
• Composability
• Autonomous
• Stateless
• Discoverable

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SOA and Web Services

• Web Services are not inherently reusable
• Web Services have service contracts
• Web Services are loose-coupled
• Web Services support abstraction
• Web Services are naturally composable
• Autonomy has to be designed in
• Web Services support statelessness
• Discoverability is beyond the scope of a Web
  Service

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What is JSR 181?

• Web Services Metadata for the Java Platform
• Simplifies the Java Web service programming model
  by providing a set of annotations that can be
  used to declaratively specify the Web services of
  an application
• JDK 5 or above
• Specification released 27 Jun, 2005

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JSR 181
_at_WebService (    serviceName
"annotatedBank",    targetNamespace
"http//service.annotatedBank")public class
BankServiceImpl .
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JSR 181
_at_WebMethod (operationName
"create-account")public String createAccount(
_at_WebParam(name"accountName") String
acctName,float initBalance) throws      
RemoteException,AccountException     return
m_bank.addNewAccount( acctName,initBalance)

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WS-

• Set of 2nd generation Web Service standards
• They start with WS- prefix

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WS-

• Include
• Messaging Specifications
• WS-Notification
• WS-Addressing
• WS-Transfer
• WS-Eventing
• WS-Enumeration

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WS-

• Metadata Exchange Specifications
• WS-Policy
• WS-PolicyAssertions
• WS-PolicyAttachment
• WS-Discovery

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WS-

• Security Specifications
• WS-Security
• WS-SecureConversation
• WS-Trust
• WS-Federation

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WS-

• Include
• Reliable Messaging Specifications
• WS-ReliableMessaging
• WS-Reliablility

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WS-

• Include
• Business Process Specifications
• WS-BPEL
• WS-Choreography
• WS-CDL

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WS-

• Include
• Transaction Specifications
• WS-AtomicTransaction
• WS-Coordination
• WS-CAF
• WS-Transaction
• WS-Context
• WS-CF

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WS-

• Include
• Management Specifications
• WS-Management
• WS-ResourceTransfer

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Orchestration

• Web Service Orchestration enables web services to
  be strung together in predefined patterns and
  executed via orchestration scripts
• Typically owned by a business
• The heart of SOA

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Orchestration
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Choreography
Specification by the W3C defining a XML-based
business process modeling language that
describes collaboration protocols of cooperating
Web Service participants, in which services act
as peers, and interactions may be long-lived
and stateful.
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BPEL

• Consortium originally made up of BEA (now
  Oracle), IBM and Microsoft
• Provides a language defining process flow
• Supports asynchronous operations and correlations
• Supports long-running workflows

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Reference Sites

• www.WhatIsSOA.com
• www.SOAPrinciples.com
• www.WS-Standards.com
• www.w3.org and www.ws-i.org
• www.w3schools.com/webservices/default.asp
• http//java.sun.com/webservices/
• http//www.oracle.com/technology/index.html
• http//jbossws.jboss.org/mediawiki/index.php?title
  JBossWS