Transcript BCS Teesside Web Services

BCS Teesside
Web Services
David Fuller
What I will cover
What are Web Services?
What is SOA?
What is BPEL?
Demonstrate the construction of a
web service
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
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
It’s what the world-wide-web does
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)
Web Service Architecture
Acronym Competition
WSDL
Web Service Description
Language
Acronym Competition
UDDI
Universal Description,
Discovery and Integration
Acronym Competition
SOAP
It doesn’t stand for
anything
It used to be ‘Simple
Object Access Protocol’
but no more
Acronym Competition
JAX-RPC
Java Api for Xml-based
Remote Procedure Call
– Now part of JAX-WS
Acronym Competition
JSR
Java Specification
Request
Acronym Competition
BPEL
Business Process
Execution Language
Acronym Competition
SOA
Service Oriented
Architecture
What is SOA?
A collection of loosely-coupled,
distributed services which
communicate and interoperate
via agreed standards
Source: Oxford University
SOA Principles
Reuseability
Service contract
loose coupling
Abstraction
Composability
Autonomous
Stateless
Discoverable
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
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
JSR 181
@WebService (
serviceName = "annotatedBank",
targetNamespace =
"http://service.annotatedBank"
)
public class BankServiceImpl {
….
JSR 181
@WebMethod (operationName=
"create-account")
public String createAccount(
@WebParam(name="accountName")
String acctName,float initBalance)
throws
RemoteException,AccountException {
return m_bank.addNewAccount(
acctName,initBalance);
}
WS-*
Set of 2nd generation Web Service
standards
They start with WS- prefix
WS-*
Include:
– Messaging Specifications
WS-Notification
WS-Addressing
WS-Transfer
WS-Eventing
WS-Enumeration
WS-*
– Metadata Exchange Specifications
WS-Policy
WS-PolicyAssertions
WS-PolicyAttachment
WS-Discovery
WS-*
– Security Specifications
WS-Security
WS-SecureConversation
WS-Trust
WS-Federation
WS-*
Include:
– Reliable Messaging Specifications
WS-ReliableMessaging
WS-Reliablility
WS-*
Include:
– Business Process Specifications
WS-BPEL
WS-Choreography
WS-CDL
WS-*
Include:
– Transaction Specifications
WS-AtomicTransaction
WS-Coordination
WS-CAF
WS-Transaction
WS-Context
WS-CF
WS-*
Include:
– Management Specifications
WS-Management
WS-ResourceTransfer
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”
Orchestration
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.
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
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?t
itle=JBossWS