Transcript Document
Web Services Development in WebSphere v5
by Tapas Banerjee CEO, Web Age Solutions Inc.
What are Web Services?
Applications that can be published, located and invoked programmatically over the Web.
XML-based (XML-in, XML-out).
Self-contained functions that can be used individually to provide services.
Good applications: – – – Business Information.
Business Integration Business Process Externalization.
Service Oriented Architecture
A service-oriented architecture is created by services communicating with each other The SOA architecture allows – – Different systems and programming languages to talk to each other Describes the service interface clearly – Allows search for needed services It’s made up of - service provider, service broker and service requestor Web Services implement this architecture
Web Services Supporting Architecture Standards
Web Services rely on: – XML (eXtensible Markup Language).
– UDDI (Universal Description Discovery and Integration).
– ● Publish and discover.
SOAP (Simple Object Access Protocol).
– ● Query UDDI, binding and use of services.
WSDL (Web Services Description Language).
● Describe the interfaces of Web Services.
The Functions and Information Flow
Service Broker UDDI Registry 2. Assign a unique ID and populate the registry Service Provider Service Consumer 1. Publish 3. Discover Web Service 4. Request/Response via SOAP Client
Web Services Programming Model
RPC-based: Service-specific.
Synchronous model.
Similar to RMI and DCOM.
Message-based: Document-driven.
Asynchronous model.
Web Services Programming APIs
APIs for RPC-based Web Services: Sun’s JAX-RPC (Java API for XML-RPC) in WSDP.
Apache’s SOAP-RPC (Apache SOAP 2.3 ships with WAS5) APIs for Message-based Web Services: Sun’s JAXM (Java API for XML Messaging) in WSDP.
Apache’s SOAP-Message.
APIs for publishing and discovering Web Services: Sun’s JAXR(Java API for XML Registry) in WSDP.
IBM’s UDDI4J.
JAXR – Java API for XML Registry
Enables Java programs to access XML registries.
JAXR provider: – Accesses XML registry.
– A façade to a registry provider.
JAXR client: – A client program that accesses an XML registry using JAXR API.
– Perform queries and update UDDI registries.
Sun’s registry browser – – – Included in WSDP download.
Is a JAXR client with GUI.
Allows to publish and search XML registries.
Other Web Services Concepts
Several other important Web Services concepts: – Web Services Invocation Framework – Web Services Inspection Language (WS Inspection) – Workflows – Web Services Gateway – Web Services Security
Web Services Invocation Framework
Web Services Invocation Framework (WSIF) – A framework for the simple Services over a Java API.
invocation of Web – Allows for maximum flexibility and late (even runtime) binding for clients
Web Services Inspection Language (WS Inspection)
A complementary technology to UDDI A service discovery mechanism XML-based model for building a list of references to existing Web Service descriptors
Workflow and Web Services
A Workflow description allows a process to be described as a sequence of discrete events (e.g. service calls) A workflow engine can then parse the workflow description and execute the sequence automatically Defines a business process
Workflow Languages
There are three web services workflow languages: – Web Services Flow Language (WSFL) – ● XML-based Flow Definition Markup Language (FDML) – ● Similar to WSFL, but with extensions Business Process Execution Language For Web Services (BPEL4WS) ● A meeting of IBM's WSFL and Microsoft's XLANG
Web Services Gateway (WSGW)
The WSGW acts as an additional layer between a web service client, and a web service provider Server side Allows for better control over web service communication
The Gateway Administrative Console
Security Needs
Since web services are inherently network based (and typically Internet-based), security is crucial Additionally, web service communication can be compromised at many levels
SOAP HTTP Request Example
POST /SampleWebServiceWeb/servlet/rpcrouter HTTP/1.0
Host: localhost:9080 Content-Type: text/xml; charset=utf-8 Content-Length: 526 SOAPAction: ""
SOAP HTTP Response Example
HTTP/1.1 200 OK Server: WebSphere Application Server/5.0
Set-Cookie: JSESSIONID=000050K5KBO5DKK1CC4A2J2VKIY:-1;Path=/ Cache-Control: no-cache="set-cookie,set-cookie2" Expires: Thu, 01 Dec 1994 16:00:00 GMT Content-Type: text/xml; charset=utf-8 Content-Length: 659 Content-Language: en-US Connection: close
Different SOAP Implementations
SOAP4J - A Java reference implementation of the SOAP 1.1 specification. It now became the basis of the Apache SOAP 3.x project, also called Axis.
Apache SOAP 2.3
– – Ships with WebSphere V5 Important elements are ● ● ● Rpcrouter and messagerouter servlets The deployment descriptor Type mapping registry
What is WSDL?
WSDL is an XML-based language for defining available Web Services and describing how to access the services, including URL endpoint, message format, encoding and required protocol.
Similar to IDL (Interface Definition Language) for CORBA, describing the services and how to use the services WSDL 1.1 is the current standard.
Tools available to generate WSDL files.
UDDI Data Structure
Five data structure types: – – – – – businessEntity businessService bindingTemplat e publisherAsserti on tModel
UDDI4J
IBM’s UDDI4J is a Java-based UDDI client API.
It provides package/classes for accessing UDDI registry (publishing and discovering).
UDDIProxy object is the client side proxy of the registry.
Program the UDDIProxy for publishing/discovering services.
Developing Web Services
Generate deployable web service from – – – Java Bean DADX (XML/DB2 mapping documents) Enterprise Java Bean – URL Generate skeleton Java Bean and sample application from WSDL document Web Services Client wizard also creates – – Web Service Proxy as Java Bean Sample JSP-based client application
Overall Workflow
Typical development path 1.
2.
3.
4.
5.
Create a Web Project Create/Import a resource from which to create a web service (Java Bean, EJB, DADX document, …) Create a Web Service using Web Service Wizard Publish a Business Entity, if required Publish the Web Service
Creating a Web Service from a Java Bean
Typical steps: 1.
2.
Create/Import Java Bean into Web Project Generate binding WSDL document using Web Service Wizard 3.
4.
5.
Deploy Web Service to a Web Server Generate client proxy Generate sample client application Then publish, discover and use web service
… from an EJB
Typical steps: 1.
2.
Create a Web Project Create/Import EJBs into an EJB Project belonging to the same Enterprise Application Project as the Web Project 3.
Update project dependencies … then it’s “business as usual” WSAD only generates a Web Service from a Stateless Session EJB – … but that session bean can always use entity beans!
Web Service Development Phases
Build – May start from Java code, then we generate WSDL from that – Or start from WSDL and build/morph Java code to match Deployment – We can publish using UDDI, WSIL or E-mailing customers Run ● Management
Different web service creation paths
From an existing application – bottom-up – Most common. We like to expose existing back-end systems for enterprise integration (EAI) purposes.
From WSDL, generate a completely new application – top-down – This may be due to a new spec imposed by a governing body – The wizards can create skeleton code from WSDL, we then fill up the details Combine independent web services to provide new functionality. This route is similar to the façade design pattern.
Different WebSphere products – how do they fare?
There are three products in the WebSphere family that can be used – – WSAD WSAD IE – WebSphere SDK for web services (WSDK) family All three can do bottom-up and top-down from JavaBeans WSAD IE and WSDK can do bottom-up and top down from EJB’s – Regular WSAD cannot do top-down for EJB’s I.e. cannot create EJB’s from WSDL.
… from XML schema
Generate Java Bean from XML schema 1.
2.
Create any project that works with Java source code (Java, EJB, Web, …) Create/Import XML schema in the project 3.
4.
5.
Start Web Services Wizard Select Java beans for XML Schema.
Follow instructions to generate Java Beans Now generate the Web Service from the new Java Bean
WSDK 5.0
WebSphere SDK for Web Services – – – – – – Entry level developer kit, free for development But not for production or deployment Runs on Windows 2000/XP and Linux Based on Axis (Apache SOAP engine) Has embedded application server (mini WebSphere 5.0) and a private UDDI registry Supports SOAP 1.1, WSDL 1.1, UDDI 2.0, JAX_RPC 1.0, WSDL4J, UDDI4J and WS-Security
ETTK (previously called WSTK)
IBM Emerging Technologies Toolkit (previously called Web Services toolkit) An IBM alphaworks technology, showcases technologies to come Exposes the AXIS programming model WSTK version 3.2.2 includes – – – WS-C/WS-Tx for transaction flows between components Web Services matchmaking engine – Businesses submit advertisements. When a customers search matches an advertisement, a response is triggered WSXL – For better handshaking of web services with portal applications
Web Services Deployment in WebSphere
If you are using WSAD 5, it is same as deploying an EAR file If you are using WSAD 4 – Export the Web Service as a WAR – Use AAT to create an EAR – Use soapearenabler.bat to add SOAP services
Summary
We discussed – What are Web Services.
– Web Services programming model.
– How does a SOAP message look.
– Developing Web Services.
– Web Service Development Phases.