J2EE Web Services. J2EE Web Services , Richard Monson-Haefel, Addison-Wesley, 2004 Enterprise Java Beans, 4 th Edition , Richard Monson-Haefel, O’Reilly, 2004. J2EE/JAX-RPC Web Services. Two main interfaces Service interface acts as a factory for endpoint stub extends javax.xml.rpc.Service
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J2EE Web Services J2EE Web Services, Richard Monson-Haefel, Addison-Wesley, 2004 Enterprise Java Beans, 4th Edition, Richard Monson-Haefel, O’Reilly, 2004 J2EE Web Services
J2EE/JAX-RPC Web Services • Two main interfaces • Service interface • acts as a factory for endpoint stub • extends javax.xml.rpc.Service • Endpoint interface • provides operations • Two types of endpoints • Java Service/Servlet Endpoints (JSE) • deployed within a J2EE Web Container • implemented as a normal class, but operates within a Servlet • EJB Endpoints • deployed within an J2EE EJB Container • implemented as a Stateless Session EJB J2EE Web Services
Major J2EE/JAX-RPC Elements • WSDL • implementation/platform neutral definition of Service/Endpoint interface • Service/Endpoint Java Interfaces • client or server-specific Java classes that are used by client or server implementation • can be statically defined during development or dynamically generated at runtime • J2EE Containers • provides a standard deployment structure • deploy Web Service/Endpoint implementations and/or their clients • generate server-side skeletons and client-side stubs for participants • provide normal WEB and/or EJB environment for client/server participants to operate • Deployment Descriptors • define the web service to either the client or server J2EE Container • identify the WSDL and Java classes relevant to a service • provide a mapping between the WSDL and Java elemments J2EE Web Services
J2EE/JAX-RPC Environment WSDL Document defines the schema for XML-based messages Web Container JAX-RPC Servlet JSE Endpoint HTTP 1.1/SOAP Web Service Client Web Container EJB Container HTTP 1.1/SOAP JAX-RPC Servlet EJB Endpoint JAX-RPC Servlet is notional/probable for EJB Endpoints, but not required J2EE Web Services
WSDL The Web Services Description Language J2EE Web Services
WSDL Overview • Web Services Description Language (WSDL) • Uses XMLSchema to describe a web service • Describes service • Input/output • Message encoding • Transport required • Address information • Initially developed by IBM, Ariba, Microsoft • Given a WSDL description, automated tools can generate stubs to call the service J2EE Web Services
WSDL (Cont) • WSDL is a generic mechanism that can describe web services that are implemented in any protocol i.e. it is abstract • The WS-I basic Profile 1.0 endorses SOAP 1.1 over HTTP J2EE Web Services
WSDL and JAX/RPC • Generated Stubs • Network Stubs are generated at deployment time by a JAX-RPC compiler • WSDL portType => Endpoint Interface • WSDL binding and port => Stub • Endpoint Interface • Java RMI Remote interface (extends java.rmi.Remote) • Interface Name comes from portType name attribute J2EE Web Services
WSDL Structure <?xml version="1.0" encoding="UTF-8"?> <wsdl:definitions targetNamespace="http://wsj2ee.corej2ee/SimplePingJSE" xmlns:impl=http://wsj2ee.corej2ee/SimplePingJSE xmlns:intf="http://wsj2ee.corej2ee/SimplePingJSE …….. <types> ……… <xsd:complexType name=“….” Generated code using ‘impl’ Namespace will be in package corej2ee.wsj2ee Declare XML Namespaces Used Custom XML Schema types used ……. <wsdl:message name="echoResponse"> <wsdl:part name="echoReturn" type="xsd:string"/> </wsdl:message> ……………….. Describe structure of messages that will be passed in method calls. Could be custom/complex XML Schema types J2EE Web Services
WSDL Structure (Cont) <wsdl:binding name="SimplePingJSEEndpointSoapBinding" type="impl:SimplePingJSEEndpoint"> <wsdlsoap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/> <wsdl:operation name="ping"> <wsdlsoap:operation soapAction=""/> <wsdl:input name="pingRequest"> <wsdlsoap:body use="literal" namespace="http://wsj2ee.corej2ee/SimplePingJSE"/> Defines protocols and Encoding style used <wsdl:service name="SimplePingJSEEndpointService"> <wsdl:port name="SimplePingJSEEndpoint" binding="impl:SimplePingJSEEndpointSoapBinding"> <wsdlsoap:address location="http://localhost:8080/wsj2eeSimplePing/SimplePing"/> </wsdl:port> </wsdl:service> Internet address of SOAP service J2EE Web Services
Sample WSDL Document (SimplePing.wsdl) ………… <wsdl:message name="echoResponse"> <wsdl:part name="echoReturn" type="xsd:string"/> Defines method that returns a string </wsdl:message> <wsdl:message name="echoRequest"> <wsdl:part name="in0" type="xsd:string"/> Defines method that takes in a string </wsdl:message> …………….. <wsdl:portType name="SimplePingEndpoint"> public interface SimplePingEndpoint ……………… <wsdl:operation name="echo" parameterOrder="in0"> <wsdl:input name="echoRequest" message="impl:echoRequest"/> <wsdl:output name="echoResponse" message="impl:echoResponse"/> </wsdl:operation> …………………… J2EE Web Services
SimplePingEndpoint.java(Endpoint Interface) public interface SimplePingEndpoint extends java.rmi.Remote { /** simple test method to call without args or return value */ void ping() throws RemoteException; /** simple test method that returns the string arcgument that is passed */ String echo(String message) throws RemoteException; /** simple test method that returns a string based on internal & inputs */ String speak(String message) throws RemoteException; } J2EE Web Services
WSDL document for Stub Generation • <wsdl:binding name="SimplePingEndpointSoapBinding" type="impl:SimplePingEndpoint"> • <wsdlsoap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/> • <wsdl:operation name="echo"> • <wsdlsoap:operation soapAction=""/> • <wsdl:input name="echoRequest"> • <wsdlsoap:body use="literal" namespace="http://wsj2ee.corej2ee/SimplePing"/> • </wsdl:input> • <wsdl:output name="echoResponse"> • <wsdlsoap:body use="literal" namespace="http://wsj2ee.corej2ee/SimplePing"/> • </wsdl:output> • </wsdl:operation> • </wsdl:binding> • Binding states that the messages passed in the echo method are encoded using rpc/literal encoding. • Generated sub implements the Endpoint interface and contains code to generate the correctly-formatted SOAP messages. J2EE Web Services
Service Interface (SimplePingEndpointService.java) • Serves as a factory for the stub • Used to get an instance at run-time • getSimplePingEndpoint() returns a stub implementation • J2EE components obtain reference to Service via jndi java:comp/env lookup public interface SimplePingEndpointService extends javax.xml.rpc.Service { public java.lang.String getSimplePingEndpointAddress(); public corej2ee.examples.wsj2ee.simple.wsimpl.SimplePingEndpoint getSimplePingEndpoint() throws javax.xml.rpc.ServiceException; public corej2ee.examples.wsj2ee.simple.wsimpl.SimplePingEndpoint getSimplePingEndpoint(java.net.URL portAddress) throws javax.xml.rpc.ServiceException; } J2EE Web Services
J2EE Web Service Client public class SimplePingClientServlet extends HttpServlet { ………………….. Context jndi = new InitialContext(); jseService_ = (SimplePingEndpointService)jndi.lookup("java:comp/env/service/SimplePingJSE"); ………………… protected void invokeService(SimplePingEndpointService service, String message, PrintWriter out) throws ServletException { SimplePingEndpoint stub = service.getSimplePingEndpoint(); out.println("<pre>"); out.println("executing echo(" + message + ")"); String reply = stub.echo(message); out.println("result=" + reply); out.println("</pre>"); J2EE Web Services
Build System Targets • Converting Java to WSDL • Converting WSDL to Java (endpoint and stub) J2EE Web Services
Service Interface • only necessary in clients • may be statically defined/compiled into client • may be dynamically created when service referenced • used to get a handle/stub (“Port”) to remote service • extends javax.xml.rpc.Service package corej2ee.examples.wsj2ee.simple.wsclient; import corej2ee.examples.wsj2ee.simple.wsclient.SimplePingJSEPort; public interface SimplePingJSEService extends javax.xml.rpc.Service { public java.lang.String getSimplePingJSEPortAddress(); public SimplePingJSEPort getSimplePingJSEPort() throws javax.xml.rpc.ServiceException; public SimplePingJSEPort getSimplePingJSEPort( java.net.URL portAddress) throws javax.xml.rpc.ServiceException; } J2EE Web Services
Endpoint/Port Interface • Defines WS operations that will be publicly available • Referred to as an “Endpoint” on server side and “Port” on client side • Interface required to extend java.rmi.Remote • Methods required to throw java.rmi.RemoteException //server-side hand-authored endpoint interface package corej2ee.examples.wsj2ee.simple.ws; import java.rmi.Remote; import java.rmi.RemoteException; public interface SimplePingEndpoint extends Remote { void ping() throws RemoteException; String echo(String message) throws RemoteException; String speak(String message) throws RemoteException; } J2EE Web Services
Endpoint/Port Interface (cont.) //client-side wsdl-generated port interface package corej2ee.examples.wsj2ee.simple.wsclient; public interface SimplePingJSEPort extends java.rmi.Remote { public void ping() throws java.rmi.RemoteException; public java.lang.String echo( java.lang.String in0) throws java.rmi.RemoteException; public java.lang.String speak(java.lang.String in0) throws java.rmi.RemoteException; } J2EE Web Services
JSE Endpoint Implement • Provides implementation for public operations • Extends Endpoint interface package corej2ee.examples.wsj2ee.simple.impl; import java.rmi.RemoteException; import java.util.Date; import javax.xml.rpc.ServiceException; import javax.xml.rpc.server.ServletEndpointContext; import corej2ee.examples.wsj2ee.simple.ws.SimplePingEndpoint; public class SimplePingImpl implements SimplePingEndpoint { public void ping() {} public String echo(String message) { return message; } public String speak(String message) { return new Date() + ":hello from JSE Web Service"; } } J2EE Web Services
JSE Optionally Implements ServiceLifecycle • Provides • getHttpSession() • getServletContext() • getMessageContext() • getUserPrincipal() • isUserInRole() import javax.xml.rpc.server.ServiceLifecycle; public class SimplePingImpl implements … , ServiceLifecycle { public void destroy() {} /** @param context is a javax.xml.rpc.ServletEndpointContext */ public void init(Object context) throws ServiceException { ServletEndpointContext ctx = (ServletEndpointContext) context; ctx.getServletContext().log( "SimplePingImpl.init(context=" + context + ")"); } } J2EE Web Services
EJB Endpoint Implementation • Provides the implementation of public operations • Optionally extends Endpoint interface • this example uses a wsdl-generated port interface for the endpoint interface package corej2ee.examples.wsj2ee.simple.ejb; import java.util.Date; import javax.ejb.SessionBean; import javax.ejb.SessionContext; import corej2ee.examples.wsj2ee.simple.ws.SimplePingEJBPort; public class SimplePingEJB implements SessionBean, SimpleEJBPingPort { public void ping() {} public String echo(String message) { return message; } public String speak(String message) { return new Date() + ":hello from EJB Web Service"; } public void ejbCreate() {} public void ejbActivate() {} public void ejbPassivate() {} public void ejbRemove() {} public void setSessionContext(SessionContext ctx) {} } J2EE Web Services
Component Deployment Descriptor • Web Services are deployed within pre-existing J2EE container types • Java Service/Servlet Endpoints (JSE) are deployed within a WEB/Servlet Container • EJB Endpoints are deployed within an EJB container • Web Services enjoy the same resources made available to their predecessors • JSE Endpoints may make use of HttpSessions, etc. • EJB Endpoints may make use of transactions, etc. • Pre-existing deployment descriptors (web.xml and ejb-jar.xml) have been modified to handle some Web Service properties • ex. adding <service-endpoint> to ejb-jar.xml • Some Web Service concepts have been made to fit within pre-existing deployment descriptors • ex. registering endpoint classes within <servlet> elements • New deployment descriptors have been added • ex. webservices.xml and <jaxrpc-mapping>.xml J2EE Web Services
Server web.xml • web-app • servlet • a re-used/morphed web.xml element that defines a JSE versus a Servlet/JSP • servlet-name • normal servlet element that assigns a unique name within the component/application • servlet-class • class which implements JSE • servlet-mapping • a re-used/morphed web.xml element that defines the mapping from a URL to the specific JSE • servlet-name • identifies JSE/Servlet from above • url-pattern • standard does not allow wildcards or multiple url-patterns for JSEs. • is directly related to the WSDL port endpoint address J2EE Web Services
Server web.xml Example <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd"> <web-app> <servlet> <servlet-name>SimplePing</servlet-name> <servlet-class>corej2ee.examples.wsj2ee.simple.impl.SimplePingImpl </servlet-class> </servlet> <servlet-mapping> <servlet-name>SimplePing</servlet-name> <url-pattern>/SimplePing</url-pattern> </servlet-mapping> </web-app> J2EE Web Services
Server ejb-jar.xml • enterprise-beans • session • ejb-name • normal EJB element that uniquely identifies the EJB within the component/application • used by webservices.xml to link service with the EJB • service-endpoint • unique to J2EE Web Services • identifies the interface class that implements the endpoint interface • extends javax.rmi.Remote • value entered here is duplicated in webservices.xml service-endpoint-interface element • ejb-class • normal EJB element that identifies the EJB implementation class • … J2EE Web Services
Server ejb-jar.xml example <?xml version="1.0" encoding="UTF-8"?> <ejb-jar xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/ejb-jar_2_1.xsd“ version="2.1"> <enterprise-beans> <session> <ejb-name>SimplePingEJB</ejb-name> <service-endpoint> corej2ee.examples.wsj2ee.simple.wsimpl.SimplePingEJBPort </service-endpoint> <ejb-class>corej2ee.examples.wsj2ee.simple.ejb.SimplePingEJB </ejb-class> <session-type>Stateless</session-type> <transaction-type>Container</transaction-type> </session> </enterprise-beans> </ejb-jar> J2EE Web Services
Server Web Service Descriptor (webservices.xml) • Required by all J2EE Components serving Web Service Endpoints • WEB-INF/webservices.xml for JSE • META-INF/webservices.xml for EJB • Binds J2EE Endpoints to their • WSDL port definition, • implementation deployment descriptor, • JAX-RPC mapping, and • endpoint interface • Binding used to generate skeleton code for the Web Service within the component • XML Elements • webservice-description • one element per WSDL file J2EE Web Services
Server webservice-description (webservices.xml) • wsdl-file • path within the component to the WSDL file • jaxrpc-mapping-file • path within the component to the JAXRPC Mapping file • port-component • maps a specific Endpoint to a specific port with the WSDL • port-component-name • unique name within webservices.xml • wsdl-port • provides qualified name of specific WSDL port being mapped • service-endpoint-interface • specify the endpoint interface class here • needed/first time specified for JSE • duplicate information (still required!) specified for EJB service-endpoint • service-impl-bean • ejb-link – points to ejb-name within the ejb-jar.xml declaration • servlet-link – points to the servlet-name within the web.xml declaration • handler • structure defines SOAP message handlers J2EE Web Services
Web Service Handler Description(server webservice-definition and client service-ref sub-element) • handler • optionally used by both server and client to add SOAP message handlers to handle issues like encryption, identification, etc. • handler-name • provides a unique name to the handler for internal use • handler-class • must implemenet javax.xml.rpc.handler.Handler interface • init-param (param-name, param-value) • obtained by handler through HandlerInfo.getHandlerConfig() • soap-header • names specific SOAP header for handler to process • soap-role • role that the handler is playing (ex. Security) • this will be matched with SOAP message actor attribute • port-name • identifies the WSDL port for which this handler applies • services can implement multiple ports J2EE Web Services
JAX-RPC Mapping File • Describes the relationship between Java Endpoint and Service classes and the WSDL document • maps Java endpoint interfaces, methods, and parameters to WSDL portTypes, operations, and messages • associates the Java endpoint with a specific WSDL port • maps Java service interfaces to WSDL service definitions • Allows specific Java and WSDL elements to be developed independently and mapped together within the application • when one is generated from or consistent with the other, this mapping is trivial • when the two are independently created, this mapping can get complex • example: map MyException.class <-> BankTellerFault • 1:1 relationship between the mapping and WSDL files • No standard name for the mapping file • Much of the details can be defaulted, resulting in a “lightweight” mapping file • unfortunately the lightweight form can only be used by RPC-encoded messages, which is not compliant with Basic (Interoperability) Profile 1.0 J2EE Web Services
JAX-RPC Mapping Elements • package-mapping • one or more mapping of WSDL namespaces to Java packages • package-type • Java package name • namespaceURI • WSDL namespace • Heavyweight mapping is very complex • see J2EE Web Services text for a detailed coverage of this topic J2EE Web Services
Client ejb-jar.xml and web.xml Service Reference • JNDI Environment References (j2ee_1_4.xsd) • env-entry • ejb-ref • ejb-local-ref • service-ref • Used to describe an external Web Service that will made available to the client J2EE component • Client container uses this as a starting point to locate the required definitions/mappings to generate the required stubs • Obtained through its java:comp/env JNDI context XXXService service = (XXXService)jndi.lookup(“service/XXXService”); XXXStub stub = service.getXXXPort(); stub.method(); • resource-ref • resource-env-ref • message-destination-ref J2EE Web Services
Primary Client Service Reference (service-ref) Elements • service-ref-name • defines the java:comp/env name the service will be registered • service-interface • the class type in which the JNDI lookup should return • type known at deployment time for statically generated stubs • type known at runtime for dynamically generated stubs • use javax.xml.rpc.Service in this case • wsdl-file • specifies a path within the component for the service’s WSDL file • WEB-INF/wsdl/<name>.wsdl for JSE deployments • META-INF/wsdl/<name>.wsdl for EJB deployments • jaxrpc-mapping-file • specifies a path within the component for the service’s jaxrpc mapping file • WEB-INF/<name>.xml for JSE deployments • META-INF/<name>.xml for EJB deployments • service-qname • identifies a specific service within the WSDL file J2EE Web Services
Other Service Reference Elements • port-component-ref • used by services who make use of Service.getPort(Stub.class) method • required only when using dynamically generated proxy classes • service-endpoint-interface • names the specific endpoint class returned for the stub • port-component-link • if service is deployed within same application, this can directly link the reference to the internally deployed service • handler • used, in this case, to add SOAP handlers on the client side • same structure used as server side webservices.xml J2EE Web Services
