You can develop Web services clients based on the Web Services for Java 2 Platform, Enterprise Edition (J2EE) specification and the supported Web services development programming models.
Web services clients that can both access and invoke a JAX-WS Web service are developed based on the Web Services for Java 2 Platform, Enterprise Edition (J2EE) specification. The Feature Pack for Web Services supports Enterprise JavaBeans (EJB) clients, J2EE application clients, JavaServer Pages (JSP) files and servlets. Web services clients based on the JAX-RPC specification can invoke JAX-WS-based Web services if the Web Services Description Language (WSDL) file complies with the Web Services-Interoperability (WS-I) Basic Profile. The Feature Pack for Web Services only supports unmanaged clients even when the unmanaged clients are running in a Java 2 Platform, Enterprise Edition (J2EE) container. Unmanaged clients are clients that do not use container managed services. These clients are packaged as Java archive (JAR) files which do not contain any JSR-109 Web Service client deployment information. Web services unmanaged clients that run in a J2EE container are responsible for the instantiation of services rather than the J2EE container managing the instantiation of services.
The JAX-WS Web service client programming model supports both the Dispatch client API and the dynamic proxy client API. The Dispatch client API is a dynamic client programming model, whereas the static client programming model for JAX-WS is the dynamic proxy client. The Dispatch and dynamic proxy clients enable both synchronous and asynchronous invocation of JAX-WS Web services. The Dispatch client API, javax.xml.ws.Dispatch, is an XML messaging-oriented client that is intended for advanced XML developers who prefer using XML constructs. The Dispatch API can send data in either PAYLOAD or MESSAGE mode. When using the PAYLOAD mode, the Dispatch client is only responsible for providing the contents of the soap:Body and JAX-WS includes the payload in a soap:Envelope element. When using the MESSAGE mode, the Dispatch client is responsible for providing the entire SOAP envelope. The dynamic proxy client invokes a Web service based on a service endpoint interface (SEI) that is provided. The JAX-WS dynamic proxy instances leverage the dynamic proxy function in the base Java Runtime Environment Version 5.
To develop Web services clients based on the JAX-WS programming model, you must determine the client model that best suits the needs of your Web service application. If you want to work directly with XML rather than a Java abstraction and work with either the message structure or the message payload structure, use the Dispatch API to develop a dynamic Web service client. If you want the Web services client to invoke the service based on service endpoint interfaces with a dynamic proxy, use the Dynamic Proxy API to develop a static Web service client. After the proxies are created, the client application can invoke methods on these proxies just like a standard implementation of the service endpoint interfaces. The remainder of this article describes how to develop a static Web services client starting with a WSDL file.
To invoke Web services asynchronously using a static or dynamic JAX-WS client, determine if you will implement the callback or the polling model. Read about invoking JAX-WS Web services asynchronously for more information regarding implementing asynchronous callback or polling for Web service clients. The JAX-WS programming model for the service and client uses annotations to represent the same information that was provided in JAX-RPC client binding in a vendor-neutral manner.
Web services for J2EE clients are defined by Java Specification Requirements (JSR) 109 and are known as managed clients because they run in a J2EE container. These clients are packaged as enterprise archive (EAR) files and contain components that act as service requesters. These components can be a J2EE client application, a Web component such as a servlet or JavaServer Pages (JSP), or a session Enterprise JavaBeans (EJB). Web services managed clients use JSR 109 APIs and deployment information to look up and invoke a Web service.
For the managed clients, the service lookup is through Java Naming and Directory Interface (JNDI) lookup. Read about setting up UserName token Web services security, digital signature Web services security and Lightweight Third-Party Authentication (LTPA) token Web services security. The following is an example of a context lookup that is JSR 109 compliant:
InitialContext ctx = new InitialContext(); FredsBankServiceLocator locator =(FredsBankService)ctx.lookup("java:comp/env/service/FredsBankService"); FredsBank fb = locator.getFredsBank(url); long balance = fb.getBalance();
When you are instantiating a context lookup for a managed client, do not use new() for the service locator. Here is an example that is not JSR 109 compliant (new ServiceLocator):
Properties prop = new Properties(); InitialContext ctx = new InitialContext(prop); FredsBankServiceLocator locator = new FredsBankServiceLocator(); FredsBank fb = locator.getFredsBank(url); long balance = fb.getBalance();
Without the lookup() call, the client has no access to the deployment descriptor. The Web services security configuration is in the Web services deployment descriptor.
J2SE clients that use the JAX-RPC run time to invoke Web services and do not run in any J2EE container are known as unmanaged clients. A Web services unmanaged client is a stand-alone Java client that can directly inspect a WSDL file and formulate the calls to the Web service by using the JAX-RPC APIs directly. These clients are packaged as JAR files which do not contain any deployment information.
For a Java application to act as a Web service client, a mapping between the WSDL file and the Java application must exist. For JAX-RPC Web services, the mapping is defined by the Java API for XML-based RPC (JAX-RPC) specification. You can use a Java component to implement a Web service by specifying the component interface and binding information in the WSDL file and designing the application server infrastructure to accept the service request. This entire process is based on the Web Services for J2EE specification. The JAX-RPC specification defines the mapping between a WSDL file, Java code and XML Schema types.
After you develop a Web services application client, and the client is statically bound, the service endpoint used by the implementation is the one that is identified in the WSDL file that you used during the development process. During or after installation of the Web services application, you might want to change the service endpoint. For managed clients, you can change the endpoint with the administrative console or the wsadmin scripting tool. For unmanaged JAX-WS Web services clients, you can change the endpoint from within the client application.
In this information ...Subtopics
Related tasks
Related reference
| IBM Redbooks, demos, education, and more |