Transcript Intro to Apache Axis - Austin Java Users Group
Intro to Apache Axis
Siva Jagadeesan
About Me
I am a Java Consultant working in a project for Deloitte Consulting My fields of Expertise – J2EE Technologies – Java tools for Extreme Programming (Ant, JUnit etc) My fields of Interest – Web Services – J2ME – Aspect Oriented Programming
Agenda
Web Services Basics Intro to Apache Axis
Outline
Web Services Basics – What is Web Service?
– Web Services Architecture – XML Messaging XML-RPC SOAP – What is WSDL?
– Development plan for Service Requestor – Development plan for Service Provider
Outline
Intro to Apache Axis – What is Apache Axis?
– Architecture of Apache Axis – Features of Apache Axis – Installing Apache Axis – Publishing Web Service through Apache Axis – Walkthrough of deploying and accessing a simple web service using Apache Axis
What is Web Service?
A Web Service is any service that – is available over the web – uses standardized XML messaging – is OS and Programming language independent
Web Services Architecture
There are two ways we can view Web Services architecture 1. Web Service Roles 2. Web Service Protocol Stack
Web Service Roles
There are three major roles Logically Centralized directory of services Service Registry 2) Discover services 1) Register service Service Requestor Consumer of the Web Service 3) Invoke service Service Provider Provider of the Web Service
Web Service Protocol Stack
Discovery
UDDI Responsible for centralizing services
Description XML Messaging Transport
WSDL Responsible for describing the public interface to a specific web service XML-RPC,SOAP,XML Responsible for encoding messages in common XML format HTTP,SMTP,FTP,BEEP Responsible for transporting messages
XML Messaging
There are two ways of XML Messaging •
XML-RPC
•
SOAP
What is XML-RPC ?
is a simple protocol that uses XML messages to perform RPC Request are encoded in XML and send via HTTP Response are encoded in XML and received via HTTP is a easiest way to get started with web services
Sample XML-RPC Request
Sample XML-RPC Response
What is SOAP?
S imple O bject A ccess P rotocol SOAP is slightly more complicated than the XML-RPC SOAP extended XML-RPC It uses XML namespaces and XML Schemas.
SOAP Message
SOAP Message Envelope Header Body Envelope is like a wrapper for content Header is a optional element that could contain control information Body element includes requests and responses Body element will include a Fault element in the event of an error
Sample SOAP Request
Sample SOAP Response
What is WSDL?
W eb S ervices D escription L anguage
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Has 6 major elements
definitions
– defines the name of the web service
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types
– describes all the data types that will be transmitted
message
– defines the name of the message that will be transmitted
portType
– defines the operations
binding
– defines how the message will be transmitted
6.
service
– defines where the service is located
Development plan for Service Requestor
1) Find web service via UDDI 2) Retrieve service description file 3) Create XML-RPC or SOAP client 4) Invoke remote service
Development plan for Service Provider
1) Create the core functionality 2) Create XML-RPC or SOAP service wrapper 3) Create service description file 4) Deploy service 5) Register new service via UDDI
What is Apache Axis?
“Axis is essentially a SOAP engine – a framework for constructing SOAP processors such as clients , servers, gateways etc” - Axis Website
Architecture of Apache Axis
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Architecture of Apache Axis
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Admin Sub-system
handles administration and configuration of the server
Service Sub-system
implements the RPC exchange protocol
Provider Sub-system
is the interface between Axis server and the external component methods that are to be exposed as webservice
Transport Sub-system
receives and delivers the message from the service sub system
Encoding Sub-system
manages encoding/decoding and serilization/deserilization between XML data types and Java Classes
Message Sub-system
defines the structure of the different elements of a SOAP message and provides functionality for binding and parsing the different elements of these messages
Features of Apache Axis Successor to Apache SOAP It can run as a standalone server or as an a server that plugs into Servlet engine like Tomcat Automatic WSDL generation for deployed services Java2WSDL – to generate WSDL from Java interface WSDL2Java – to generate Java classes from WSDL Easy deployment Uses JAX-RPC API
Installing Apache Axis 1) Download Axis Distribution archive from http://xml.apache.org/axis/ - Axis distribution archive contains a web application ( webapps/axis/ directory) for hosting an Axis Server in a web container like Tomcat
Installing Apache Axis (Cont) 2) Deploy Axis Server in the Tomcat 4.X server a) Copy Axis Web application (webapps/axis directory) to $TOMCAT_HOME/webapps b) Copy jaxrpc.jar (that is provided with Axis distribution) and xerces.jar ( or any other XML parser) to $TOMCAT_HOME/common/lib
jaxrpc.jar and xerces.jar includes classes with “java” and “javax” packages and Tomcat does not authorize to load any classes in that package from WEB-INF/ lib directory of the web application.
Installing Apache Axis (Cont) 3) Configure the environment by including these libraries in the CLASSPATH - log4j-core.jar
- commons-logging.jar
- wsdl4j.jar
- jaxrpc.jar
- tt.bytecode.jar
- xerces.jar ( or any other XML Parser)
Validating the Installation 1) 2) 3) Start the Tomcat Web Server Goto http://localhost:8080/axis/ - you should be able to see Apache-Axis start page - if you did not , then the axis is not correctly installed or the web server is not running Goto http://localhost:8080/axis/happyaxis.jsp
- this test page verifies whether all the needed and optional libraries are present.
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Axis will not perform properly until all the needed libraries are present
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Publishing Web Service through Apache Axis The two ways we can publish a web service with Axis are,
1. Instant Deployment
– Java Web Service (JWS)
2. Custom Deployment
– Using Web Service Deployment Descriptor ( WSDD)
Walkthrough of deploying and accessing a simple web service using Apache Axis
The steps we will walkthrough
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Code
– code a simple HelloWorld java class that we want to expose as web service
Java2WSDL
– Generate the WSDL file for the given HelloWorld Interface
WSDL2Java
– Generate the Server side wrapper class and stubs for easy client access
Deploy
– deploy the service to apache axis
Client
– code a simple client that access our HelloWorld Web Service
Step 1: Code
HelloWorld.java
package helloworld; public interface HelloWorld { public String sayHello( String name); }
Step 1: Code (Cont)
HelloWorldImpl.java
package helloworld; public class HelloWorldImpl implements HelloWorld { public String sayHello( String name){ if(name == null) return “Hello Everyone”; else return “Hello “ + name; } }
Step 2: Java2WSDL
This command will generate the WSDL that Conforms to our interface
% java org.apache.axis.wsdl.Java2WSDL -o hello.wsdl -l http://localhost:8080/axis/services/helloworld -n urn:helloworld -p“helloworld" urn:helloworld helloworld.HelloWorld
Parameters description -o = Name of the output -l = URL of the web Service -n = Target Namespace for the WSDL -p = Map Java package to namespace Fully Qualified Class Name
Step 3: WSDL2Java
This command will generate the wrapper code for deploying the service, as well as client stubs for accessing it.
% java org.apache.axis.wsdl.WSDL2Java -o . -d Session -s -p helloworld.gen
hello.wsdl
Parameters description -o = Base output Directory -d = Scope of deployment -s = To generate Server-side code too -p = Package to place the code Name of the WSDL
Step 3: WSDL2Java
These are the codes that will get generated 1.
HelloWorldSoapBindingImpl.java
Service – This is the implementation code for the Web 2.
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HelloWorld.java
– This is the remote interface HelloWorldService.java
– This is the service interface HelloWorldServiceLocator.java
– Helper class to retrieve handler to service HelloWorldSoapBindingSkeleton.java
– Server-side skeleton code HelloWorldSoapBindingStub.java
– Client side stub deploy.wsdd
– axis deployment descriptor undeploy.wsdd
Axis System – deployment descriptor to undeploy the web services from the
Step 3: WSDL2Java
HelloWorldSoapBindingImpl
package helloworld.gen;
import helloworld.HelloWorldImpl;
public class HelloWorldSoapBindingImpl implements helloworld.gen.HelloWorld {
HelloWorldImpl helloWorld = new HelloWorldImpl();
public String sayHello(String str0) throws java.rmi.RemoteException {
return helloWorld.sayHello(str0);
} }
Step 4: Deploy
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Compile the Service Code % javac helloworld\gen\*.java
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Package the code for Axis % jar cvf hello.jar helloworld/*.class helloworld/gen/*.class
% mv hello.jar $TOMCAT_HOME/webapps/axis/WEB INF/lib 3.
Deploy the Service using WSDD % java org.apache.axis.client.AdminClient deploy.wsdd
Step 5: Client
package helloworld; Import helloworld.gen.*; public class HelloWorldTester { public static void main(String [] args) throws Exception { // Make a service HelloWorldService service = new HelloWorldServiceLocator(); // Now use the service to get a stub to the service helloworld.gen.HelloWorld hello = service.getHelloWorld(); // Make the actual call System.out.println( hello.sayHello(“Java Gurus”) ); } }
Summary Web Service – Roles in Web Services – Web Services Protocol Stack – Different ways of XML Messaging – Development plan for Service Requestor and Provider Axis – Architecture of Axis – Features of Apache Axis – Installing Apache Axis – Different ways of deploying Web Service with Axis – Deploying and accessing a simple web service using Apache Axis
Resources
JAX-RPC home http://java.sun.com/xml/jaxrpc/index.html
Web Services & Java home http://java.sun.com/j2ee/webservices/index.html
Java Web Services tutorial http://java.sun.com/xml/docs.html#tutorials Apache Axis http://xml.apache.org/axis/index.html
SOAP 1.1 http://www.w3.org/TR/SOAP WSDL 1.1 http://www.w3.org/TR/wsdl
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