Developing Web Services Developing Web Services with the Eclipse Web with the Eclipse Web

Tools PlatformTools PlatformBoris MinkinBoris Minkin

Web Services? What and why? Web Services? What and why?

• Companies need to integrate existing systems – achieve interoperability among disparate implementations

• Web Services and XML came along with the ability to provide standard communication interface between these systems

• They are essentially language/platform-neutral remote procedure calls built on HTTP infrastructure

Fundamental standards and Fundamental standards and technologiestechnologies

• XML – eXtensible Markup Language: The syntax used for Web Service messages, configuration files, description files, etc.

• HTTP – Hypertext Transfer Protocol: The standard transport used to communicate between Web Service servers and clients

• RPC – Remote Procedure Call: The technique of executing a method call remotely—here, the client calling a web service’s operation.

Web Service standards and Web Service standards and technologiestechnologies

• SOAP – Simple Object Access Protocol. An XML-based standard for sending messages (in a SOAP envelope) between web services and clients.

• WSDL—Web Service Definition Language XML-based description of a web services public interface. (Similar to CORBA IDL.)

• UDDI—Universal Description, Discovery and Integration. And XML-based registry for web service. Interrogated with SOAP messages, returns WSDL documents.

Locating and Using Web ServicesLocating and Using Web Services

Web Service

UDDI Registry

Publish WSDL

Client Application

Query registry

Obtain WSDL

Call web serviceoperation

Get result back

Java Web Service related Java Web Service related standards and protocolsstandards and protocols

• Web Services are Part of J2EE 1.4– Web Services for Java: JSR 101/109 standard– One can generate web service from Java Bean or

Stateless Session EJB

• Various Protocols and Standards:– JAXP—Java API for XML Processing– JAX-RPC—Java API for XML-based RPC– JAXR—Java API for XML registries– SAAJ—SOAP with Attachments API for Java– SAX—Simple API for XML processing– DOM API—Document Object Model API

What is Eclipse?What is Eclipse?• Open-Source Java Integrated Development Environment

(IDE)• Initially donated by IBM to the Open-Source foundation• Includes:

– Java Development Tools (JDT)– Integrated Testing and Debugging Support– Incremental compilation and build– Team development support

• CVS support comes out of the box

• Pluggable – major advantage – can develop custom plug-ins – variety is available at sites such as:

• http://www.eclipseplugincentral.com/• http://eclipse-plugins.2y.net/eclipse/index.jsp

Eclipse main conceptsEclipse main concepts• Workspace

– A workspace is a place where Eclipse stores the user’s data.– It’s a tree with projects, folders and files.– A workspace can contains many projects– You can have several workspaces but only one workspace can be

activated at a time.• Project

– Collection of folders and files• Workbench

– The workbench is the development environment window contains one or more perspectives

• Perspective– A layout with a set of editors and views– Some Perspectives include: Java, CVS, Debug, Resource, etc.

• Editor/View– Editors allow to edit content of a particular type (e.g., Java code editor)– Views present information in non-editable way (some views include Ant,

Console, Declaration, Error log, Hierarchy, Javadoc, Navigator, Outline, Package Explorer, Problems, Search

Eclipse Web Tools Project (WTP) Eclipse Web Tools Project (WTP) PlatformPlatform

• One of the top Eclipse projects• Adds Web/J2EE/Web Services development facilities

– J2EE and Web perspectives– Web, EJB and Enterprise Application projects– Variety of editors and views for editing JSP/HTML, XML, other files

• Provides tools for:– Web applications using JSP / Servlets

• Provides editors for XML, HTML, JSP, JavaScript– Enterprise Java Beans (EJB)– Web Service (based on Apache AXIS)– Database exploration– Support for servers such as Tomcat, JBoss, etc.

• WTP Roadmap:– WTP 0.7, July 2005 – End User Tools– WTP 1.0, December 2005 – Platform APIs– WTP 1.5, June 2006 – Java EE 5.0

Two ways to create Web Two ways to create Web Service with Eclipse WTPService with Eclipse WTP

• Bottom up:– You create the web service Java Bean or Stateless

Session EJB– Eclipse creates the glue classes and the WSDL

• Top down:– You write the WSDL– Eclipse creates the necessary glue classes and the

service’s method stubs in a Java Bean– You implement the operations

Eclipse WTP – Web Services ToolsEclipse WTP – Web Services Tools• Wizard to create Web service

top-down (from WSDL) and bottom-up (from Java).

• Wizard creates a Java stub that binds to a Web service.

• Wizard can optionally configure test client and deployment of your Web service

• You can also specify to monitor your web service once its launched

Eclipse WTP – Web Services ToolsEclipse WTP – Web Services Tools• Graphical WSDL/XSD Editor

– Edit your WSDL file without wrestling with the syntax

Containers for data type definitions using XML schema type system

Abstract, typed definitions of the data being communicated. A message can have one or more typed parts, for example the highlighted message getLatestDateTimeResponse has just one part which is its return parameter of xsd:date (XML Schema date type).

Abstract sets of one or more operations supported by one or more ports.

Concrete protocol and data format specifications for a particular port type

Collections of related ports

Eclipse WTP – Web Services ToolsEclipse WTP – Web Services Tools

• XML Schema, WSDL, and WS-I validators– Ensure your documents conform to standards

(WSDL, XSD) and standard extensions (WS-I)

Eclipse WTP – Web Services ToolsEclipse WTP – Web Services Tools

• Web Service Explorer– Publish/Discover Web

services.– Invoke Web services

dynamically. No code generation required for testing.

– One can go ahead and specify method parameters to invoke them

Eclipse WTP – Web Services ToolsEclipse WTP – Web Services ToolsTCP/IP Monitor is a powerful facility to show data sent through

the wire and to simplify analysis of any possible problems

Shows the list of interactions (request/response) that have been performed in the chronological order.

Displays the contents of SOAP envelope generated by web services request.

Displays the SOAP response envelope

A First Web Tools Project – Step 1A First Web Tools Project – Step 1

• Before we can make any web services we have to create a Dynamic Web Project in Eclipse.

• However, before we can make a dynamic Web Project, we need to configure a target server.

A First Web Tools Project – Step 2A First Web Tools Project – Step 2

• Now, we are ready to create our Dynamic Web Project.

• Since Tomcat is just a Web Container provider, Web project is enough for it.

• For servers such as JBoss or WebSphere, you will need to create Enterprise Application Project.

J2EE Scenario – Typical Web J2EE Scenario – Typical Web Services Application ArchitectureServices Application Architecture

• Java class accesses data from a database or another source

• Java class exposed as a Web service

Our Sample Application DescriptionOur Sample Application Description

stockNamestockSymbol

StockService

getLatestPrice getLatestVolume

getLatestDateTime getStockName

getStockSymbolsetStockName

setStockSymbolgetStockHistory

StockData

• Just two Java classes – one for exposing the methods to be called through the service, – another for data gathering

pricevolume

dateTime

get/setPriceget/setVolume

get/setDateTime

1 1..N

Free stuff !!!Free stuff !!!• You can go ahead and download yourself all

the software I’ll use in the demo:– J2SE 5.0 JRE: http://java.sun.com/j2se– Eclipse 3.1.2: http://www.eclipse.org– Eclipse Web Tools Project (WTP) 1.0:

http://ww.eclipse.org/webtools• You can download the complete set (including Eclipse itself

and all required components)• You can also install it using Eclipse Install/Update facility –

from Help menu select Software Updates – Find and Install, New Features to Install, then: New Remote Site with any name and URL: http://download.eclipse.org/webtools/updates/

– Tomcat 5.0/5.5: http://jakarta.apache.org/tomcat/

Demo – Building Bottom-Up Web Demo – Building Bottom-Up Web ServiceService

• Create a web service, bottom-up• Exploring a Web Service using the Web

Services Explorer • Exploring generated WSDL using WSDL file

editor• Creating a simple client to invoke our web

service• Writing our own client• Create a web service, top down

Invoke our Web Service from Java Invoke our Web Service from Java command line applicationcommand line application

• package services;• /**• * Creating a simple Java client to invoke Web Service through the generated service locator

and • * service end point interface.• */• public class StockServiceClient {• /**• * To invoke stock service• */• public static void main(String[] args) {• try{• StockServiceServiceLocator wsl = new StockServiceServiceLocator();• StockService ws = (StockService) wsl.getStockService();• String name = ws.getStockName();• System.out.println("Stock name: " + name);• double price = ws.getLatestPrice();• System.out.println("Stock price: " + price);• long volume = ws.getLatestVolume();• System.out.println("Stock volume: " + volume);• } catch (Exception e) {• e.printStackTrace();• }• }• }

Invoke our Web Service from Invoke our Web Service from Microsoft .NET clientMicrosoft .NET client

• Demonstrates Web Services Interoperability

• Using Microsoft .NET 1.1 framework generation and compilation tools

• Sample program I’ve written in C#

To get more information…To get more information…

• WTP websitehttp://www.eclipse.org/webtools

• WTP newsgroupnews://news.eclipse.org/eclipse.webtools

• WTP Community Resources (articles, tutorials, events)

http://www.eclipse.org/webtools/community/community.html

• Article in Eclipse Developer Journal – Developing Web Services with Eclipse WTP:

http://eclipse.sys-con.com/read/180402.htm