1. Java Web Services Programming
Dickson K.W. Chiu
PhD, SMIEEE
Deitel et al., Java Web Services for Experienced Programmers

2. Java Web Services Development Pack (JWSDP)
Now integrated into J2EE 1.4
Provides a convenient all-in-one package
Geared for developers
Contains
JAXP (Java API for XML Processing)
JAX-RPC (Java API for XML-based RPC)
SAAJ (SOAP with Attachments API for Java)
JAXR (Java API for XML Registries) …
JAXM (Java API for XML Messaging)
See:
Dickson Chiu 2005

3. JAX-RPC and JAXM Both based on SOAP with Attachments
For web service programming
Sun recommends JAX-RPC – easier to program
SAAJ / JAXM
Interoperability (e.g. calling other clients)
Non-blocking option
Dickson Chiu 2005

4. JAX-RPC Java™ API for XML-based RPC
RPC requests and responses represented using SOAP
Both Web service endpoints and clients use JAX-RPC
Services are described using WSDL
Key technology for Web Services in the upcoming J2EE 1.4 platform
Dickson Chiu 2005

5. Remote Procedure Call (RPC)
RPC, COM, CORBA, RMI:
Synchronous communication - calling process blocks until there is a response
Tightly coupled - client must find recipients and know method arguments
Non persistent
Dickson Chiu 2005

6. JAX-RPC Design Goal Easy to use programming model
Defining a service
Using a service
Hides all the plumbing – complexity of SOAP messaging
SOAP and WSDL-based interoperability
Interoperate with any SOAP compliant peers
Extensibility and Modularity
Support future versions of XML specification, i.e., XMLP (SOAP 1.2 and beyond)
Message handler architecture
Dickson Chiu 2005

7. JAX-RPC Architecture Diagram
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8. What happen during an RPC?
To call a remote procedure, the HelloClient program invokes a method on a stub, a local object that represents the remote service.
The stub invokes routines in the JAX-RPC runtime system.
The runtime system converts the remote method call into a SOAP message and then transmits the message as an HTTP request.
When the server receives the HTTP request, the JAX-RPC runtime system extracts the SOAP message from the request and translates it into a method call.
The JAX-RPC runtime system invokes the method on the tie object.
The tie object invokes the method on the implementation of the HelloWorld service.
The runtime system on the server converts the method's response into a SOAP message and then transmits the message back to the client as an HTTP response.
On the client, the JAX-RPC runtime system extracts the SOAP message from the HTTP response and then translates it into a method response for the HelloClient program.
Dickson Chiu 2005

9. What happen during an RPC?
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10. Service Description and WSDL
JAX-RPC describes a Web Service as a collection
of remote interfaces and methods
Tools are used to convert between WSDL documents and sets of Java remote interfaces
WSDL describes a Web Service as a
collection of ports and operations
JAX-RPC service endpoint mapped to WSDL service description
WSDL enables export of a JAX-RPC service endpoint across heterogeneous environments
JAX-RPC specifies the standard WSDL<-> Java mapping:
Mapping between service endpoint interface and WSDL definitions
Binding to specific protocol and transport
XML <-> Java data types
Dickson Chiu 2005

11. WSDL Mapping
wsdl:portType mapped into a Java Interface (Service Definition Interface) that extends java.rmi.Remote
wsdl:operation mapped into a method of the Service definition interface
wsdl:message's are mapped into parameters of the method
wsdl:type's of wsdl:message's are mapped into the types of the parameters
Dickson Chiu 2005

12. WSDL Mapping Example
<! WSDL Document >
<message name=”GetLastTradePriceInput”>
<part name=”tickerSymbol” type=”xsd:string”/>
</message>
<message name=”GetLastTradePriceOutput”?
<part name=”result” type=”xsd:float”/>
<portType name=”StockQuoteProvider”>
<operation name=”GetLastTradePrice” parameterOrder=”tickerSymbol”>
<input message=”tns:GetLastTradePriceInput”/>
<output message=”tns:GetLastTradePriceOutput”/>
</operation>
</portType>
public interface StockQuoteProvider extends java.rmi.Remote {
float getLastTradePrice(String tickerSymbol)
throws java.rmi.RemoteException; }
Dickson Chiu 2005

13. Supported Java Type See J2EE tutorial
Note: all objects are passed by copy
Java primitive types
String, Date, Calendar, BigInteger, BigDecimal
Multi-dimensional Java arrays
JAX-RPC value type – classes you’ve written for your applications, based on the above
JavaBean Components – also based on the above
Dickson Chiu 2005

14. Developing a JAX-RPC Web Service
Define service endpoint
Implement Service endpoint
Compile code and generate WSDL
Packaging WAR and deploy
Dickson Chiu 2005

15. 0. Setting the Port If you do not use the default port 8080, edit:
<INSTALL>/j2eetutorial14/examples/common/build.properties
<INSTALL>/j2eetutorial14/examples/jaxrpc/staticstub/ config-wsdl.xml
<INSTALL>/j2eetutorial14/examples/jaxrpc/ dynamicproxy/config-wsdl.xml
<INSTALL>/j2eetutorial14/examples/jaxrpc/appclient/ config-wsdl.xml
<INSTALL>/j2eetutorial14/examples/jaxrpc/webclient/ config-wsdl.xml
<INSTALL>/j2eetutorial14/examples/jaxrpc/ webclient/web/response.jsp
<INSTALL>/j2eetutorial14/examples/security/ basicauthclient/SecureHello.wsdl
<INSTALL>/j2eetutorial14/examples/security/ mutualauthclient/SecureHello.wsdl
Dickson Chiu 2005

16. 1. Service Endpoint Definition
Specified in Service Definition Interface
Could be generated from WSDL document using a tool or
Could be written in Java programming language directly
No assumption about type of client that would use this service definition interface
package hello;
import java.rmi.Remote;
import java.rmi.RemoteException;
public interface HelloIF extends Remote {
public String sayHello(String s) throws RemoteException; }
Dickson Chiu 2005

17. 2. Service Implementation
Service implementation class is an ordinary Java class
Invocation done inside the servlet container
JAX-RPC defines Servlet-based Endpoint model
Other endpoint models (e.g., stateless session beans) will be defined in J2EE 1.4 / EJB 2.1
Optional ServiceLifecycle interface for initialization and destruction callbacks
package hello;
public class HelloImpl implements HelloIF {
public String message = new String("Hello ");
public String sayHello(String s) {
return new String(message + s); }
package hello;
import java.rmi.Remote;
import java.rmi.RemoteException;
public interface HelloIF extends Remote {
public String sayHello(String s)
throws RemoteException; }
Dickson Chiu 2005

18. 3. Compiling / WSDL generation
Use the ant tool simplifies the job
Compile HelloIF.java and HelloImpl.java, go to the <INSTALL>/j2eetutorial14/examples/jaxrpc/helloservice/ directory and type the following: ant build
compile-service: compiles HelloIF.java and HelloImpl.java, writing the class files to the build subdirectory
generate-wsdl: runs wscompile, creating MyHelloService.wsdl and mapping.xml
Customize wsdl generation with config-interface.xml
<?xml version="1.0" encoding="UTF-8"?>
<configuration xmlns="
<service name="MyHelloService" targetNamespace="urn:Foo"
typeNamespace="urn:Foo" packageName="helloservice">
<interface name="helloservice.HelloIF"/>
</service>
</configuration>
Dickson Chiu 2005

19. 4. Packaging the WAR file (i)
Use Deploytool to create a standalone WAR module
Dickson Chiu 2005

20. 4. Packaging the WAR file (ii)
Use Deploytool to create a standalone WAR module
Dickson Chiu 2005

21. 4. Packaging the WAR file (iii)
Enter context root
Add alias “hello”
Update the endpoint address to hello (see previous slide)
Save and Deploy
Dickson Chiu 2005

22. 4’. Another way to deploy the WAR file
To create the WAR file that contains the service code:
asant create-war
Set your admin port, username, and password in <INSTALL>/j2eetutorial14/examples/common/build.properties.
To deploy the WAR file:
asant deploy-war
Note this may create different
naming
Dickson Chiu 2005

23. JAX-RPC Clients
Independent of how an XML based RPC service (service endpoint) is implemented on the server side
Generates a Java based client side representation for a service from WSDL document
Not tied to a specific XML based protocol, transport or any JAX-RPC implementation specific mechanism
Can use either J2SE or J2EE
3 programming modes:
Static stub-based – least dynamic, easiest to program - you know everything about the services and pre-generate the stub
Dynamic proxy - call location dynamic (URL/service/name), information about the service by looking up WSDL document at run time (but signature of method fixed)
Dynamic invocation interface (DII) – everything dynamic, but more tedious and more time to set up a call
Dickson Chiu 2005

24. WSDL Generated Dickson Chiu 2005
<?xml version="1.0" encoding="UTF-8"?>
<definitions name="MyHelloService" targetNamespace="urn:Foo" xmlns:tns="urn:Foo" xmlns=" xmlns:xsd=" xmlns:soap="
<types/>
<message name="HelloIF_sayHello">
<part name="String_1" type="xsd:string"/></message>
<message name="HelloIF_sayHelloResponse">
<part name="result" type="xsd:string"/></message>
<portType name="HelloIF">
<operation name="sayHello" parameterOrder="String_1">
<input message="tns:HelloIF_sayHello"/>
<output message="tns:HelloIF_sayHelloResponse"/></operation></portType>
<binding name="HelloIFBinding" type="tns:HelloIF">
<soap:binding transport=" style="rpc"/>
<operation name="sayHello">
<soap:operation soapAction=""/>
<input>
<soap:body encodingStyle=" use="encoded" namespace="urn:Foo"/></input>
<output>
<soap:body encodingStyle=" use="encoded" namespace="urn:Foo"/></output></operation></binding>
<service name="MyHelloService">
<port name="HelloIFPort" binding="tns:HelloIFBinding">
<soap:address location="REPLACE_WITH_ACTUAL_URL"/></port></service></definitions>
Dickson Chiu 2005

25. WSDL Mapping - binding, port, service
wsdl:service is mapped into an implementation of javax.xml.rpc.Service interface
JAX-RPC runtime provides the implementation
A javax.xml.rpc.Service class acts as a factory of either
Instance of a generated stub class
Dynamic proxy for a service port
Instance of the object javax.xml.rpc.Call for the dynamic invocation of a remote operation on a service port
Dickson Chiu 2005

26. Static Stub - Client Code
package staticstub;
import javax.xml.rpc.Stub;
public class HelloClient {
private String endpointAddress;
public static void main(String[] args) {
System.out.println("Endpoint address = " + args[0]);
try {
Stub stub = (Stub) (new MyHelloService_Impl().getHelloIFPort());
stub._setProperty(javax.xml.rpc.Stub.ENDPOINT_ADDRESS_PROPERTY, args[0]);
HelloIF hello = (HelloIF) stub;
System.out.println(hello.sayHello("Duke!"));
} catch (Exception ex) {
ex.printStackTrace(); }
// output – “Hello Duke!”
Generated by wscompile before writing this program (i.e., static and implementation-specific)
Dickson Chiu 2005

27. Static Stub – build and run
To automate the rest of the steps, go to the <INSTALL>/j2eetutorial14/examples/jaxrpc/staticstub/ directory and type the following: asant build
generate-stubs: wscompile -gen:client -d build -classpath build config-wsdl.xml
<configuration xmlns="   
<wsdl location="
packageName="staticstub"/>
</configuration>
compile-client: compiles src/HelloClient.java and writes the class file to the build subdirectory.
package-client: packages the files created by the generate-stubs and compile-client tasks into the dist/client.jar file.
Run the client - asant run
Dickson Chiu 2005

28. Dynamic Proxy-based Client
Client calls a remote procedure through a dynamic proxy
Client gets information about the service by looking up its WSDL document at runtime - call location (URL/service/name)
But the signature (parameters and their types) of the method is fixed
The Service class that is created during runtime
Similar usage of asant
However, only the service endpoint interface class of the sample target is used but not the generated stub
Dickson Chiu 2005

29. Example Dynamic Proxy-based Client
package dynamicproxy;
import java.net.URL;
import javax.xml.rpc.Service;
import javax.xml.rpc.JAXRPCException;
import javax.xml.namespace.QName;
import javax.xml.rpc.ServiceFactory;
import dynamicproxy.HelloIF;
public class HelloClient {
public static void main(String[] args) {
try {
String UrlString = args[0] + "?WSDL";
String nameSpaceUri = "urn:Foo";
String serviceName = "MyHelloService";
String portName = "HelloIFPort";
System.out.println("UrlString = " + UrlString);
URL helloWsdlUrl = new URL(UrlString);
ServiceFactory serviceFactory = ServiceFactory.newInstance();
Service helloService =
serviceFactory.createService(helloWsdlUrl,
new QName(nameSpaceUri, serviceName));
dynamicproxy.HelloIF myProxy =
(dynamicproxy.HelloIF) helloService.getPort
(new QName(nameSpaceUri,portName),
dynamicproxy.HelloIF.class);
System.out.println(myProxy.sayHello(“Buzz”));
} catch (Exception ex) {
ex.printStackTrace(); }
Dickson Chiu 2005

30. Dynamic Invocation Interface (DII) Client
Dynamic invocation of an operation on the target service endpoint
Enables broker model
Client finds (through search criteria) from a UDDI directory and invokes a service during runtime through a broker
Note: the code in the following example does not show the lookup and simply hardcode the services in strings
Used when service definition interface is not known until runtime
Set all operation and parameters during runtime
From the Service object create Call object first
Similar usage of asant
Dickson Chiu 2005

31. DII Client Example Dickson Chiu 2005 package dii;
import javax.xml.rpc.Call;
import javax.xml.rpc.Service;
import javax.xml.rpc.JAXRPCException;
import javax.xml.namespace.QName;
import javax.xml.rpc.ServiceFactory;
import javax.xml.rpc.ParameterMode;
public class HelloClient {
private static String qnameService = "MyHelloService";
private static String qnamePort = "HelloIF";
private static String BODY_NAMESPACE_VALUE = "urn:Foo";
private static String ENCODING_STYLE_PROPERTY =
"javax.xml.rpc.encodingstyle.namespace.uri";
private static String NS_XSD = "
private static String URI_ENCODING =
"
public static void main(String[] args) {
System.out.println("Endpoint address = " + args[0]);
try {
ServiceFactory factory = ServiceFactory.newInstance();
Service service = factory.createService(new QName(qnameService));
QName port = new QName(qnamePort);
Call call = service.createCall(port);
call.setTargetEndpointAddress(args[0]);
call.setProperty(Call.SOAPACTION_USE_PROPERTY, new Boolean(true));
call.setProperty(Call.SOAPACTION_URI_PROPERTY, "");
call.setProperty(ENCODING_STYLE_PROPERTY, URI_ENCODING);
QName QNAME_TYPE_STRING = new QName(NS_XSD, "string");
call.setReturnType(QNAME_TYPE_STRING);
call.setOperationName(new QName(BODY_NAMESPACE_VALUE, "sayHello"));
call.addParameter(“String_1”, QNAME_TYPE_STRING,
ParameterMode.IN);
String[] params = { "Murph!" };
String result = (String) call.invoke(params);
System.out.println(result);
} catch (Exception ex) {
ex.printStackTrace();
} } }
Dickson Chiu 2005

32. JAXM Java API for XML Messaging
Java support for sending and receiving SOAP XML document oriented messages
Two JAXM API Programming Models
Point-to-point model – simpler
JAXM Provider-based" (like a "messaging server") model - supports Asynchronous messaging
Design Goals
Build on SOAP with Attachments
Add support to plug higher-level messaging protocols (e.g., ebXML)
Design for easy porting of applications from one container to another – specifically from web containers to that of J2EE
Don’t attempt to build a full-fledged messaging API (e.g., JMS)
Dickson Chiu 2005

33. JAXM Point-to-Point Model
Synchronous Request-response interaction
Calling process blocks until there is a response
Connection established directly to the ultimate recipient
No persistence
can be difficult to scale
Dickson Chiu 2005

34. JAXM Provider Model Asynchronous (or Synchronous you choose)
Sender is not blocked, Receiver does not have to be available
Reliable - Message can be stored and forwarded (routed) until it can be delivered
JAXM Provider works behind the scene
Dickson Chiu 2005

35. JAXM Provider
Offers message routing and reliable messaging as all messages go through it
Assign message identifiers and keeping track of messages
JAXM client makes JAXM method calls, and the provider (working with container) makes everything happen
JAXM providers are responsible for producing an error message and sending it to the offending JAXM client when receiving a malformed message
Responsibility of JAXM application to consume error messages and take corrective actions
Dickson Chiu 2005

36. JAXM client Not using JAXM provider Just a standalone J2SE application
Point to point operation
Establishes a connection directly with the service (using a URL)
Synchronous only
Request/response interaction
Using JAXM provider
Maintains a connection with JAXM provider, and all messages go through the provider
JAXM client deployed in a web or EJB container
MessageDrivenBean
JAXMServlet
Send and receive messages synchronously or asynchronously
Dickson Chiu 2005

37. JAXM vs. JMS Similarities Differences
Both supports Messaging Provider model
Reliable, secure message delivery
Routing
Both supports asynchronous message delivery
Differences
JAXM provider could be lightweight while JMS provider is usually heavyweight
JAXM supports standalone mode while JMS does not
JAXM client is interoperable over any SOAP compatible client while JMS client is interoperable only with other JMS client over the same messaging system
Delivery endpoint model is different
Dickson Chiu 2005

38. Using SAAJ API to call a Web Service
Steps
Create SOAP message
Populate SOAP message
Add attachments (optional)
Initialize SOAP connection
Send SOAP message
Analyze response message
Code based on J2EE tutorial p.398 request.java
Library files required:
H:/Sun/Appserver/lib/j2ee.jar;H:/Sun/Appserver/lib/saaj-impl.jar;H:\Sun\AppServer\lib\endorsed\xercesImpl.jar;H:\Sun\AppServer\lib\endorsed\dom.jar;.
Example based on URL:
Dickson Chiu 2005

39. SAAJ Example Code import javax.xml.soap.*; import java.util.*;
import java.net.URL;
public class Request {
public static void main(String[] args) {
try {
SOAPConnectionFactory soapConnectionFactory = SOAPConnectionFactory.newInstance();
SOAPConnection connection = soapConnectionFactory.createConnection();
SOAPFactory soapFactory = SOAPFactory.newInstance();
MessageFactory factory = MessageFactory.newInstance();
SOAPMessage message = factory.createMessage();
SOAPHeader header = message.getSOAPHeader();
SOAPBody body = message.getSOAPBody();
header.detachNode();
Dickson Chiu 2005

40. SAAJ Example Code (2)
Name bodyName = soapFactory.createName( "getQuote", "m",
"urn:xmethods-delayed-quotes");
SOAPBodyElement bodyElement = body.addBodyElement(bodyName);
Name name = soapFactory.createName("symbol");
SOAPElement symbol = bodyElement.addChildElement(name);
symbol.addTextNode(args[0]);
URL endpoint = new URL("
SOAPMessage response = connection.call(message, endpoint);
connection.close();
response.writeTo(System.out);
} catch (Exception ex) {
ex.printStackTrace(); }
<SOAP-ENV:Envelope xmlns:SOAP-ENV=
"
<SOAP-ENV:Body>
<m:getQuote xmlns:m=" urn:xmethods-delayed-quotes">
<symbol>XXXX</symbol>
</m:getQuote>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
Dickson Chiu 2005

41. SAAJ Result Message <soap:Envelope
soap:encodingStyle="
xmlns:soap=" xmlns:xsi=" xmlns:xsd=" xmlns:soapenc="
<soap:Body>
<n:getQuoteResponse xmlns:n="urn:xmethods-delayed-quotes">
<Result xsi:type="xsd:float">4.15</Result>
</n:getQuoteResponse>
</soap:Body>
</soap:Envelope>
Dickson Chiu 2005

42. Adding Attachment with SAAJ
// We're using a HTTP image repository here
// to get the data for an image
URL url = new URL ("
// Create a JAF DataHandler with this URL
DataHandler dh = new DataHandler(url);
// Create and Add an AttachmentPart
message.addAttachmentPart(
message.createAttachmentPart(dh));
Dickson Chiu 2005

43. Summary – Calling Web Services in Java
Use JAX-RPC
Static Stub – you know everything about the services and pre-generate the stub
Dynamic Proxy – call location dynamic (URL/service/name), information about the service by looking up WSDL document at run time (but signature of method fixed)
DII – everything lookup at run time, i.e., call and parameters prepared at runtime
Send SOAP messages with SAAJ
for most flexibility
target is not RPC
Dickson Chiu 2005