| By Jinsong Yang | Article Rating: |
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| January 14, 2009 09:59 PM EST | Reads: |
49,714 |
The core part of this snippet is the java task with the classname attribute set to org.apache.cxf.tools.wsdlto.WSDLToJava. Include this macro in your build file and then you can call it as shown in Listing 7.
Successfully running the tool will generate all necessary software artifacts, which include a service interface, a service endpoint interface (SEI), Java classes that implement all types defined in the WSDL document, and APIs that are used to obtain instances of these types.
Service Implementation Class
Now it's time to provide an implementation for the service. We do so by creating a Java class called MovieServiceImpl. There are some requirements that this class has to fulfill to become a service implementation class. It must be annotated with the JAX-WS @WebService annotation, and the endpointInterface member attribute of the annotation must refer to the generated SEI, i.e., org.example.movieservice.MovieService in our example. The service implementation bean may implement the SEI, but it's not required to do so. The service implementation bean must implement all method signatures defined in the SEI.
Listing 8 shows a code snippet of the implementation class.
Server Development and Service Publishing
We now need to create a server that hosts our service. XML-based Java Web Services can be hosted either in a managed or in non-managed environment.
Non-Managed Environment
JAX-WS provides functionality for creating and publishing Web Service endpoints dynamically using javax.xml.ws.Endpoint API running in a non-managed environment. CXF is JAX-WS-compliant and so supports JAX-WS dynamic Web Service publishing. Listing 9 is a code snippet of dynamic publishing.
This code is not CXF-specific and is portable among all JAX-WS-compliant runtimes. The complete server code is straightforward and sp omitted here. Start the server and you can then test the server by pointing your browser to the location: http://localhost:8080/MyMovieService?wsdl.
Managed Environment
Implementing Enterprise Web Services (JSR 109) defines ways of implementing Web Services and publishing endpoints in a managed environment. The use of dynamic publishing is considered non-portable in a managed environment. So JSR 109 requires that both the servlet and EJB container disallow publishing the endpoint dynamically by not granting the publishEndpoint security permission.
There are two means of implementing Web Services that run in a managed Java EE environment. The first is a container-based extension of the JAX-RPC or JAX-WS programming model, which defines a Web Service as a Java class running in Web container. The second one defines the use of a stateless enterprise session bean to run in the EJB container.
Due to the fact that CXF doesn't come with any Java EE container, neither is it specifically designed to support a particular vendor's Java EE container, it's quite different to implement Web Services in a managed environment using CXF. First, CXF doesn't support deploying Web Services in an EJB container. Second, the way of deploying Web Services in a web container is different from the one defined by JSR 109. While JSR 109 requires the container runtime to embed each endpoint implementation class in one servlet, CXF provides a generic servlet for all endpoint implementation classes.
Let's see this in action by deploying our example service to a Web container. The whole process involves 1.) configuring the Spring runtime to be aware of the service implementation class, 2.) registering the CXF servlet with the Web container and lastly, 3.) providing a configuration file that glues the last two together.
Configuring Spring is ;ole configuring a Spring project. A Spring context loader listener is added to the Web container via web.xml. Also added is the Spring configuration file, cxf-bean.xml, which is passed to the container as a context parameter. We'll cover this file momentarily. Listing 10 is a fragment of the web.xml file.
Registering CXF servlet is also straightforward. See Listing 11. Note that only one servlet is needed, and it acts as the entry point of all service endpoints.
We now need to somehow let the servlet know how to dispatch requests to the corresponding service implementation beans. This is the exact purpose of cxf-bean.xml, which is listed in Listing 12.
Using this file, we guide the servlet to forward all requests at the address /MovieService to MovieServiceImpl bean. Note that you'd better make sure that the value of the address attribute matches the one you advertised in the WSDL document.
After packaging the application and deploying it to a Web container (say, Tomcat), we can test the service by pointing the browser to the address http://localhost:8080/MovieService/cxf/MovieService?wsdl.
This concludes the server development. Now we move on to client development.
Client Development
In general, JAX-WS defines the Web Service client programming model, while JSR 109 defines the Web Service client programming model in a Java EE environment.
As mentioned, CXF doesn't have any Java EE runtime, so the primary way of creating a client is through JAX-WS. Listing 13 shows a simple client that consumes the MovieService Web Service.
RESTful Web Services Support
CXF supports RESTful Web Services by annotations. It uses four annotations for specifying the HTTP verb that will be used for a method:
- org.codehaus.jra.Delete specifies that the method maps to a DELETE.
- org.codehaus.jra.Get specifies that the method maps to a GET.
- org.codehaus.jra.Post specifies that the method maps to a POST.
- org.codehaus.jra.Put specifies that the method maps to a PUT.
Listing 14 is a code snippet that shows how annotations are used to implement RESTful services. Four services are defined that let clients book tickets, get ticket information, modify the booking, and cancel the booking, respectively. The code itself is fairly self-explanatory.
Assuming that these services are deployed and running, a client system can modify booking information by sending an HTTP request to an URL similar to the following, with the METHOD attribute of the request set to PUT. Note the bold portion of the URL:
http://www.mymovieticket.com/ticketbooking/tickets/9182
Published January 14, 2009 Reads 49,714
Copyright © 2009 SYS-CON Media, Inc. — All Rights Reserved.
Syndicated stories and blog feeds, all rights reserved by the author.
More Stories By Jinsong Yang
Jinsong Yang is a senior application engineer at Warnerbros. Advanced Digital Services, and is a Sun Certified Enterprise Architect. He has devoted the last six-plus years to designing and integrating large-scale Java EE applications. He holds an MS in computer science from UCLA.
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kuldeep_saini83 08/29/09 08:33:00 PM EDT | |||
Hi, Thaanks...!!! |
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yogesh 10/06/08 02:27:38 PM EDT | |||
Hey Yang, |
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