Download Web Services Development in WebSphere Application Server v5

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).
●
–
SOAP (Simple Object Access Protocol).
●
–
Publish and discover.
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
Web Service
3. Discover
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:



APIs for Message-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)
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 (WSInspection)
–
Workflows
–
Web Services Gateway
–
Web Services Security
Web Services Invocation
Framework
Web Services Invocation Framework (WSIF)
–
A framework for the simple invocation of Web
Services over a Java API.
–
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)
●
–
Flow Definition Markup Language (FDML)
●
–
XML-based
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: ""
<?xml version='1.0' encoding='UTF-8'?>
<SOAP-ENV:Envelope xmlns:SOAPENV="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<SOAP-ENV:Body>
<ns1:findDepartmentByName
xmlns:ns1="http://tempuri.org/webservice.ejb.EmployeeDirectory"
SOAPENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
<departmentName xsi:type="xsd:string">Sales</departmentName>
</ns1:findDepartmentByName>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
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
<?xml version='1.0' encoding='UTF-8'?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<SOAP-ENV:Body>
<ns1:findDepartmentByNameResponse
xmlns:ns1="http://tempuri.org/webservice.ejb.EmployeeDirectory" SOAPENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
<return xmlns:ns2="http://bean.webservice/" xsi:type="ns2:Department">
<location xsi:type="xsd:string">Toronto</location>
<name xsi:type="xsd:string">Sales</name>
</return>
</ns1:findDepartmentByNameResponse>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
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
<businessEntity>
<businessEntity>
name, contact, identification
name,
contact,category
identification
description,
description, category
<businessService>
(1..n)
<businessService>
name
(1..n)
description
name
description
<publisherAssertion>
Name
description
reference
<bindingTemplate>
<bindingTemplate>
<tModel>
Name
Description
URL pointer
to specification
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.
Create a Web Project
2.
Create/Import a resource from which to create a
web service (Java Bean, EJB, DADX document,
…)
3.
Create a Web Service using Web Service Wizard
4.
Publish a Business Entity, if required
5.
Publish the Web Service
Creating a Web Service from a Java
Bean
 Typical steps:
1.
Create/Import Java Bean into Web Project
2.
Generate binding WSDL document using Web
Service Wizard
3.
Deploy Web Service to a Web Server
4.
Generate client proxy
5.
Generate sample client application
 Then publish, discover and use web service
… from an EJB
 Typical steps:
1.
Create a Web Project
2.
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.
3.
4.
5.
Create any project that works with Java source
code (Java, EJB, Web, …)
Create/Import XML schema in the project
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.