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Document Sample
Web Services with
JAX-RPC and Apache Axis
Sep. 18, 2002
Pankaj Kumar (pankaj_kumar@hp.com),
Software Architect,
Web Services Management Organization,
Hewlett Packard Co.
Session Objectives
• Web Services in Perspective
• Learn about Web Services, wire-level interoperability
standards and portable Java APIs.
• Get to know JAX-RPC and Apache Axis to consume and
produce Web Services.
Monday, June 25,
2012
Speaker Introduction
• More than 12 years of development and project
management experience
• Worked on Web Services product development at HP
• Expert Group Member of JAX-RPC and JSR109
• Contributor to Apache Axis and Cocoon projects
• Author of open source project XPB4J (http://xpb4j.sf.net)
• Frequent speaker at developer conferences
• Authoring a book on J2EE and Web Services Security
• Architect with HP Web Services Mgmt. Operation
• Home Page: http://www.pankaj-k.net
Monday, June 25,
2012
Outline of the Session
• Introduction to Web Services
• Web Services Standards
• Java support for Web Services
• Apache Axis
– Installing Apache Axis
– Invoking a service
– Deploying a service
– Handlers
– Serializers and Deserializers
• Where to find more information
Monday, June 25,
2012
Web Services Infrastructure
Language and platform independent infrastructure for
loosely-coupled, inter-operable, app2app
communication over the Internet.
Monday, June 25,
2012
Web Services (Contd.)
Language and platform independent =>
separation of specification and implementation
Loosely coupled =>
message based, synchronous and asynchronous
interactions.
Over the Internet =>
No centralized control, use of established
protocols, security considerations.
Inter-operable =>
Standards based.
Monday, June 25,
2012
Early (Internet) Technologies
• SMTP/MIME
– e-mail is still the killer app
• FTP, NNTP
• HTTP/HTTPS, HTML
– the protocol behind Internet’s popularity
Most of these facilitated app to human interaction
over the Internet/intranet
Monday, June 25,
2012
Early (intranet) Technologies
• DCE from OSF -- RPC based, procedural
• ORB -- object oriented, mostly synchronous
– CORBA, COM/DCOM from Microsoft, Java RMI/EJBs
• MOM -- message oriented, synchronous as well as
asynchronous
– JMS ( Java API standard )
– Many proprietary implementations
Most of these facilitated app2app interaction within a
trusted intranet and without much consideration to
interoperability across different implementations.
Monday, June 25,
2012
App2App Interaction -- the Web
Services Way
• Transport protocol
– HTTP/HTTPS
• Data Encoding
– SOAP (Simple Object Access Protocol), XML Schema
• Interface Description
– WSDL (Web Services Description Language)
• Service Description and Discovery
– UDDI (Universal Description, Discovery and
Integration)
• Security
– WS-Security, XML-Signature, XML-Encryption, ...
Monday, June 25,
2012
The Web Services Way
Web Services standards (SOAP, WSDL, … ): based
on widely accepted Internet friendly technologies
(HTTP/HTTPS, XML, …), are mostly orthogonal to
each other and enjoy broad support from vendors
Web Services: Network accessible programs, expose
functionality by receiving/sending SOAP messages
over HTTP/HTTPS, and describe this interface as
WSDL descriptions.
Monday, June 25,
2012
Additional Web Services
Infrastructure Components
• Key Management (Security)
– XKMS
• Web Services Management
– OMI (Open Management Interface)
• ...
Interesting thing to note is that these
are Web Services in themselves
Monday, June 25,
2012
SOAP In One Slide
SOAP1.1 Message
• XML based protocol for
Structure
exchange of information SOAP
– Encoding rules for datatype Envelope
instances
Header
– Convention for representing Entries
RPC invocations
• Designed for loosely-coupled [Header
distributed computing Element]
– No remote references
Body
• Used with XML Schema Element
• Transport independent
• SOAP with Attachments [Fault
allow arbitrary data to be Element]
packaged.
Monday, June 25,
2012
WSDL in One Slide
WSDL1.1 Document
Structure
• A WSDL document describes WSDL
– What the service can do Document
– Where it resides [Types]
– How to invoke it
{Messages}
• WSDL are like IDL but lot
more flexible and extensible
{Port Types}
• Defines binding for SOAP1.1,
HTTP GET/POST and MIME {Bindings}
• WSDL descriptions can be
made available from an {Services}
UDDI registry
Monday, June 25,
2012
Java APIs for Web Services
• SOAP messages as Java objects
– SAAJ ( SOAP with Attachments API for Java)
• Programming Model
– JAX-RPC ( JSR101), JSR109, EJB2.1
• Accessing WSDL descriptions
– JWSDL (JSR110)
• Accessing Web Services Registries
– JAXR (Java API for XML Registries)
Monday, June 25,
2012
SAAJ Object Model
SOAPPart SOAPMessage AttachmentPart
Node
SOAPFault
SOAPElement
SOAPFaultElement
*
SOAPBody SOAPHeader
* SOAPBodyElement SOAPHeaderElement *
SOAPEnvelope
Monday, June 25,
2012
JAX-RPC
• WSDL/XML to Java Mapping
• Java to WSDL/XML Mapping
• SOAP Message with Attachments
• Client API
– Classes generated from WSDL
– Dynamic Proxy
– DII call Interface
• SOAP Message Handler
• Extensible Type Mapping
Monday, June 25,
2012
JAX-RPC Physical Architecture
WSDL description
Service Client Service Endpoint
Stub
WSDL<->Java Mapping Container
Dispatch
JAX-RPC API JAX-RPC API
Client Side JAX-RPC Server Side JAX-RPC
Runtime System Runtime System
Protocol (SOAP)
Transport
Monday, June 25,
2012
Interoperability and JAX-RPC
WSDL description
Client Service
JAX-RPC impl. Vendor prod.
<Vendor A> <Vendor C>
Client Service
Vendor prod. J2EE Container
<Vendor B> WSDL description <Vendor D>
Monday, June 25,
2012
Apache Axis
• A SOAP Processing Engine
– JAX-RPC Client System
– JAX-RPC Server System ( Servlet based )
– SAAJ implementation
– Flexible and extensible architecture
– Tools, Examples, Documentation, …
– A great place to learn about Web Services !!
• Open-source, hosted by Apache Software
Foundation
• Ready for use ( RC1 released on Sep. 6)
Monday, June 25,
2012
Install & Deploy Apache Axis
• Make sure that you have
– J2SE SDK 1.3 or 1.4: We will use 1.4 Direcotry Structure:
– A Servlet Container: We will use
Tomcat4.0.1 axis-1_0
• Download xml-axis-rc1-bin.zip
from http://xml.apache.org/axis webapps lib docs samples
• Unzip it and look at the dir. tree. Note
that Axis runs as a Servlet. axis
• Deploy Axis. WEB-INF
– Copy webapps\axis tree to webapps
directory of Tomcat. lib
– Alternatively, modify server.xml of classes
Tomcat.
web.xml
• Run Tomcat: issue bin\startup from
Tomcat home. ……
Monday, June 25,
2012
Test the Deployment
• Point your browser to http://localhost:8080/axis
Monday, June 25,
2012
A Simple Example
•AddFunction: A simple Java
class with method to add two
integers. Notice the filename
extension – it is .jws ( for Java
// File: AddFunction.jws
Web Service). public class AddFunction {
int addInt(int a, int b){
•Deploy it. Just copy the return(a+b);
AddFunction.jws file to }
webapps/axis directory. }
•Examine its WSDL description.
Point your browser to Note: All sources with instructions
http://localhost:8080/axis/AddFu to run are available at my web-site:
nction.jws?wsdl http://www.pankaj-k.net
Monday, June 25,
2012
Writing the Client Program
• There are many ways to write a Client program
– Using Dynamic Invocation Interface ( DII)
– Using generated Stubs from Service WSDL description
– Using Dynamic Proxy
• We will look at each of these
Writing the client requires more work
than writing the service
Monday, June 25,
2012
AddFunctionClient – using DII
// File: lesson1\client\dii\AddFunctionClient.java, edited for presentation
import javax.xml.rpc.Call;
import javax.xml.rpc.Service;
import javax.xml.namespace.QName;
public class AddFunctionClient {
public static void main(String [] args) {
try {
String endpoint = "http://localhost:8080/axis/AddFunction.jws";
Service service = new Service();
Call call = (Call) service.createCall();
call.setOperationName(new QName(endpoint, "addInt"));
call.setTargetEndpointAddress( new java.net.URL(endpoint) );
Integer ret = (Integer)call.invoke(new Object[]{new Integer(5), new Integer(6)});
System.out.println("addInt(5, 6) = " + ret);
} catch (Exception e) {
System.err.println("Execution failed. Exception: " + e);
}
}
}
Monday, June 25,
2012
Compiling and Running the
DII Client
Monday, June 25,
2012
AddFunctionClient – using
Dynamic Proxy
// File: lesson1\client\dproxy\AddFunctionClient.java, edited for presentation
import javax.xml.namespace.QName;
import javax.xml.rpc.*;
public class AddFunctionClient {
public static void main(String [] args) {
try {
String wsdlUrl = "http://localhost:8080/axis/AddFunction.jws?wsdl";
String nameSpaceUri = "http://localhost:8080/axis/AddFunction.jws";
String serviceName = "AddFunctionService";
String portName = "AddFunction";
ServiceFactory serviceFactory = ServiceFactory.newInstance();
Service afs = serviceFactory.createService(new java.net.URL(wsdlUrl),
new QName(nameSpaceUri, serviceName));
AddFunctionServiceIntf afsIntf = (AddFunctionServiceIntf)afs.getPort(
new QName(nameSpaceUri, portName), AddFunctionServiceIntf.class);
System.out.println("addInt(5, 3) = " + afsIntf.addInt(5, 3));
} catch (Exception e) {
System.err.println("Execution failed. Exception: " + e);
}
}
} Monday, June 25,
2012
Compiling and Running the
Dynamic Proxy Client
Monday, June 25,
2012
AddFunctionClient – using
Generated Stubs
Generate the stubs:
java org.apache.axis.wsdl.WSDL2Java \
http://localhost:8080/axis/AddFunction.jws?wsdl
// File: lesson1\client\stub\AddFunctionClient.java, edited for
presentation
Import localhost.*;
public class AddFunctionClient{
public static void main(String [] args) {
try {
AddFunctionService afs = new AddFunctionServiceLocator();
AddFunction af = afs.getAddFunction();
System.out.println("addInt(5, 3) = " + af.addInt(5, 3));
} catch (Exception e) {
System.err.println("Execution failed. Exception: " + e);
}
}
}
Monday, June 25,
2012
Generating Stubs, Compiling
and Running the Stub Client
Monday, June 25,
2012
Deployment Descriptors
• JWS deployment is simple, but has limitations:
– You must have the source code
– Can’t specify custom type mappings, handlers etc.
• WSDD (Web Services Deployment Descriptors)
allow more flexible deployments
– Handlers in request or response path
– Custom type mappings
– Different transports – HTTP/S, TCP/IP, DIME
– Different Dispatchers – Java Class, EJB, Servlet
– …
Monday, June 25,
2012
Adding complexitiy to the Simple
Example
•AddFunction1: A simple
// File: Complex.java
Java class with method to add public class Complex {
two Complex numbers. public Complex(){}
public double getR(){ … }
Complex is user defined Java public void setR(double r){ … }
class. …
public Complex add(Complex c){ … }
•Deploy it.
•Compile sources
•Copy .class files. // File: AddFunction1.java
•Write deployment descriptor public class AddFunction1 {
•Run AdminClient. public Complex addComplex
(Complex a, Complex b){
•Examine its WSDL description. return a.add(b);
Point your browser to }
}
http://localhost:8080/axis/servic
es/AddFunction1Service?wsdl
Monday, June 25,
2012
The Deployment Descriptor
// File: lesson2\service\deploy.wsdd
<deployment xmlns="http://xml.apache.org/axis/wsdd/"
xmlns:java="http://xml.apache.org/axis/wsdd/providers/java">
<handler name="print" type="java:LogHandler"/>
<service name="AddFunction1Service" provider="java:RPC">
<requestFlow>
<handler type="print"/>
</requestFlow>
<parameter name="className" value="AddFunction1"/>
<parameter name="allowedMethods" value="*"/>
<beanMapping qname="myNS:Complex" xmlns:myNS="urn:BeanService"
languageSpecificType="java:Complex"/>
</service>
</deployment>
Note:
(1) xmlns:java
(2) A handler in the request path
(3) Dispatch to RPC provider
(4) Bean type mapping Monday, June 25,
2012
Deploying the Service
Monday, June 25,
2012
AddFunction1Client – using
Generated Stubs
Generate the stubs:
java org.apache.axis.wsdlWSDL2Java \
http://localhost:8080/axis/services/AddFunction1Service?wsdl
// File: lesson2\client\stub\AddFunction1Client.java, edited
import localhost.*;
import BeanService.*;
public class AddFunction1Client {
public static void main(String [] args) throws Exception {
Complex a = new Complex();
Complex b = new Complex();
Generated
a.setR(10.0); a.setI(5.0);
class
b.setR(3.0); b.setI(2.0);
AddFunction1Service afs = new AddFunction1ServiceLocator();
AddFunction1 af = afs.getAddFunction1Service();
Complex ret = af.addComplex(a, b);
System.out.println("addComplex(a + b) = ("
+ ret.getR() + ", " + ret.getI() + ")");
}
}
Monday, June 25,
2012
Running the Client
Monday, June 25,
2012
Additional (Advanced!) Features
• SOAP with Attachments
• Custom type mappings (Pluggable Serializers)
• One-way invocations
• Document exchange
• Dispatch to EJBs
• HTTPS transport and mutual authentication
• Username and password based authentication
• …
Monday, June 25,
2012
Where to find more information?
• Apache Axis Home: http://xml.apache.org/axis
• Sun’s Web Services Developer Pack Home:
http://java.sun.com/webservices/webservicespack.
html
• W3C’s Web Services Activity Home Page:
http://www.w3.org/2002/ws/
• My Home Page: http://www.pankaj-k.net
Monday, June 25,
2012
Thank
You
Monday, June 25,
2012
