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

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: http://java.sun.com/webservices/ Dickson Chiu 2005

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

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

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

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

JAX-RPC Architecture Diagram Dickson Chiu 2005

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

What happen during an RPC? Dickson Chiu 2005

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

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

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

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

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

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

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

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

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="http://java.sun.com/xml/ns/jax-rpc/ri/config"> <service name="MyHelloService" targetNamespace="urn:Foo" typeNamespace="urn:Foo" packageName="helloservice"> <interface name="helloservice.HelloIF"/> </service> </configuration> Dickson Chiu 2005

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

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

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

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

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

WSDL Generated Dickson Chiu 2005 <?xml version="1.0" encoding="UTF-8"?> <definitions name="MyHelloService" targetNamespace="urn:Foo" xmlns:tns="urn:Foo" xmlns="http://schemas.xmlsoap.org/wsdl/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/wsdl/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="http://schemas.xmlsoap.org/soap/http" style="rpc"/> <operation name="sayHello"> <soap:operation soapAction=""/> <input> <soap:body encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" use="encoded" namespace="urn:Foo"/></input> <output> <soap:body encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" 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

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

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

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="http://java.sun.com/xml/ns/jax-rpc/ri/config">    <wsdl location="http://localhost:8080/hello-jaxrpc/hello?WSDL“ 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

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

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

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

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 = "http://www.w3.org/2001/XMLSchema"; private static String URI_ENCODING = "http://schemas.xmlsoap.org/soap/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

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

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

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

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

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

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

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: http://www.mindreef.net/tide/scopeit/start.do?referer=xmethods&url=http://services.xmethods.net/soap/urn:xmethods-delayed-quotes.wsdl Dickson Chiu 2005

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

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("http://64.124.140.30:9090/soap"); SOAPMessage response = connection.call(message, endpoint); connection.close(); response.writeTo(System.out); } catch (Exception ex) { ex.printStackTrace(); } <SOAP-ENV:Envelope xmlns:SOAP-ENV= "http://schemas.xmlsoap.org/soap/envelope/"> <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

SAAJ Result Message <soap:Envelope soap:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/"> <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

Adding Attachment with SAAJ // We're using a HTTP image repository here // to get the data for an image URL url = new URL ("http://images.wombats.com/w.jpg"); // 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

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