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Building a Simple Metro Application

The intent of this article is to demonstrate the steps required to build a web service starting both from Java code and from a WSDL document, to deploy that application into a web container, and to build a corresponding web service client application. In this example, the resulting application is portable across JAX-WS 2.0 implementations and do not use any Metro-specific technologies. It is intended as a baseline from which to develop your understanding of the larger Metro stack.


1. Overview

Supporting code samples are included to demonstrate building a JAX-WS web service in the Metro environment. The examples show how to develop a web service both starting from Java source code and starting from an existing WSDL document. For both scenarios, it shows how to develop a corresponding client application from the web service's WSDL document. Additional example shows how to use external web service metadata feature, which is necessary in case we are unable to use java annotations. The examples can be found below:

As mentioned above, these examples do not enable any Metro-specific technologies. However, the following article in this series, Enabling Advanced Features in a Web Service Application, builds on the information presented in this document. It explains configuring a web service and its client to enable advanced features available in Metro.

2. Environment Configuration Settings

2.1. Prerequisites

These series of articles require the following software to be installed on your system:

2.2. Adding WSIT (Metro) libraries into your web container

The following steps are required only if using Apache Tomcat as a web container (Glassfish v3 already contains Metro libraries): Unzip downloaded Metro Standalone Bundle and copy all .jar files from the lib/ directory into <tomcat-install-directory>/endorsed (where <tomcat-install-directory> points to your Apache Tomcat installation directory). Also put a copy of the servlet-api.jar library (<tomcat-install-directory>/lib) into endorsed/ libs.

2.3. Web Container "Listen" Port

The Java code and configuration files for the examples used in this document presume that the web container is listening on port 8080. Port 8080 is the default "listen" port for both GlassFish (domain1) and Tomcat. If you have changed the "listen" port, you will need to edit the example source files to account for that. The following is a list of the files which contain references to the "listen" port:

  1. wsit-jaxws-fromjava/src/fromjava/server/AddWebservice.java

  2. wsit-jaxws-fromjava/etc/custom-schema.xml

  3. wsit-jaxws-fromjava/etc/custom-client.xml

  4. wsit-jaxws-fromjava/etc/build.properties

  5. wsit-jaxws-fromwsdl/etc/custom-client.xml

  6. wsit-jaxws-fromwsdl/etc/build.properties

2.4. Web Container Home Directory

Before building and deploying the web service and its client, the home directory of the web container must be set either as an environment variable or as a property in the respective build.xml file.

Environment Variables

Assuming that you are running from the command-line, it is probably simplest to set the appropriate environment variable indicating the web container's "home" directory. For GlassFish, AS_HOME should be set to the top-level directory of the GlassFish installation. For Tomcat, CATALINA_HOME needs to be set to the Tomcat top-level directory.

Ant build.xml File

If you would rather not have to set the environment variable for each new terminal session, you can edit the build.xml file located at the top-level directory of each of the examples. There are two commented lines, one each for GlassFish (as.home) and Tomcat (catalina.home). Simply uncomment the appropriate line and edit the value for the directory name.

3. Building a JAX-WS Web Service

3.1. Starting from Java

One way to create a web service application is to start by coding the endpoint in Java. If you are developing your Java web service from scratch or have an existing Java class you wish to expose as a web service, this is the most direct path.

The web service is written as a normal Java class. Then the class and its methods that are to be exposed are annotated with specific web service annotations, @WebService and @WebMethod. The following code snippet shows an example:

@WebService
public class AddNumbersImpl {
    @WebMethod
    public int addNumbers(int a, int b) throws AddNumbersException {
        if (a < 0 || b < 0) {
            throw new AddNumbersException("Negative number cant be added!",
                    "Numbers: " + a + ", " + b);
        }
        return a + b;
    }
}

If you are using GlassFish, the web service in the wsit-jaxws-fromjava example can be compiled and bundled simply by invoking:

ant server

If using Tomcat, the command-line would be:

ant -Duse.tomcat=true server

The server target in build.xml in turn invokes the tools necessary to process the annotations and compile the sources, and to bundle the Java class files and configuration files into a deployable web archive (WAR file). The WAR file will be build/war/wsit-jaxws-fromjava.war. The tools that were called by ant during this step are briefly described next.

The JAX-WS tool apt (annotation processing tool) processes the annotated source code and invokes the compiler itself, resulting in the class files for each of the Java source files. In the accompanying fromjava example, the ant target build-server-java in build.xml handles this portion of the process. Then the individual class files are bundled together along with the web service's supporting configuration files into the application's WAR file. It is this file that will be deployed to the web container in the next step. The create-war target takes care of this.

3.2. Starting from WSDL

Typically, you would start from WSDL to build your web service if you want to implement a web service that is already defined either by a standard or an existing instance of the service. In either case, the WSDL already exists. The JAX-WS wsimport tool will process the existing WSDL document, either from a local copy on disk or by retrieving it from a network address. An example of manually accessing a service's WSDL using a web browser is shown below as part of the section on verifying deployment.

As in the previous example, to build the wsit-jaxws-fromwsdl service for GlassFish, you can simply invoke:

ant server

Otherwise for Tomcat use:

ant -Duse.tomcat=true server

wsimport will take the WSDL description and generate a corresponding Java interface and other supporting classes. Then the Java compiler needs to be called to compile both the user's code and the generated code. Finally, the class files are bundled together into the WAR file. The details can be seen in the wsit-jaxws-fromwsdl build.xml file as the build-server-wsdl and create-war targets.

4. Deploying the Web Service to a Web Container

As a convenience, invoking each sample's server target will build that web service's WAR file and immediately deploy it to the web container. However, in some situations, such as after undeploying a web service from its container, it may be useful to deploy the web service without rebuilding it.

For both the from Java and from WSDL scenarios described above, the resulting application is deployed in the same manner. However, the details of the deployment process differ slightly between the GlassFish and Tomcat web containers.

4.1. Deploying to GlassFish

For development purposes, it is simplest to use the "autodeploy" facility of GlassFish. To do so, copy your application's WAR file to the autodeploy directory for the domain to which you want to deploy. If you are using the default domain, domain1, set up by the GlassFish installation process, then the appropriate directory path would be <glassfish-install-home>/domains/domain1/autodeploy.

The build.xml file which accompanies this example has a deploy target for GlassFish. Invoke that target by running ant in the top-level directory of the respective examples, either fromjava or fromwsdl, as follows.

ant deploy

4.2. Deploying to Tomcat

Tomcat also has an "autodeploy" feature. That feature can be turned off but is enabled by Tomcat’s "out of the box" configuration settings. Look in <tomcat-install-directory>/conf/server.xml for the value of "autoDeploy" if you are unsure. Assuming "autoDeploy" is enabled, then copying your application to <tomcat-install-home>/webapps is all that is necessary. Again, there is a target in the ant build.xml file which accompanies this sample. The deploy target can be invoked by running the following command in the example's top-level directory.

ant -Duse.tomcat=true deploy

4.3. Verifying Successful Deployment

One basic test to verify that the application has deployed properly is to use a web browser to retrieve the application's WSDL from its hosting web container. The following URLs would retrieve the WSDL from each of the two example services. If you are running your web browser and web container on different machines, you will need to replace "localhost" with the name of the machine hosting your web service. It is also worth ensuring that your web container is actually running at this point.

If the browser displays a pageful of XML, things are working. If not, check the web container logs for any error messages related to the the sample WAR you have just deployed. For GlassFish, the appropriate log can be found at <glassfish-install-directory>/domains/<your-domain>/logs/server.log. For Tomcat, the appropriate log file will be <tomcat-install-directory>/logs/catalina.out.

5. Building a JAX-WS Web Service Client

Unlike developing a web service provider, the process for creating a web service client application will always start with an existing WSDL document. This process is similar to the steps taken when building a service from an existing WSDL. Typically, the WSDL will be retrieved directly from a web service provider by the wsimport tool . Wsimport then generates the corresponding Java source code for the described interface. javac, the Java compiler, is then called to compile the source into class files. The programmer's code uses the generated classes to access the web service. Here is an example code snippet:

AddNumbersPortType port = new AddNumbersService().getAddNumbersPort();
int a = 10;
int b = 20;
int result = port.addNumbers(a,b);

For both of the associated examples, invoking

ant client

or

ant -Duse.tomcat=true client

will run wsimport to retrieve the service's WSDL and compile the source.

6. Running the Web Service Client

For both examples, execute the resulting command-line clients via

ant run

or

ant -Duse.tomcat=true run

That target simply runs Java with the name of the client's class, such as java fromwsdl.client.AddNumbersClient. However, for convenience the run target takes care of passing a list of jar files via Java's -classpath option. When you invoke the run target, you can expect to see output from the client similar to the following:

[java] May 4, 2006 2:45:50 PM [com.sun.xml.ws.policy.jaxws.PolicyWSDLParserExten
       sion]  addClientConfigToMap
[java] WARNING: Optional client configuration file URL is missing. No client con
       figuration is processed.
[java] Invoking addNumbers(10, 20)
[java] The result of adding 10 and 20 is 30.

[java] Invoking addNumbers(-10, 20)
[java] Caught AddNumbersFault_Exception: Numbers: -10, 20

The WARNING line above is expected for both of these examples. Given that no Metro technologies are enabled, a configuration file is unnecessary. More information will be provided on Metro configuration files in the following article.

7. Undeploying a JAX-WS Web Service

Undeploying a web service means to disable & remove it from the web container. Clients will no longer be able to use the web service nor will the web service restart without explicit redeployment by the user. During the development process, it is often useful to undeploy a web service. This section explains the necessary steps for both GlassFish and Tomcat.

7.1. Undeploying from GlassFish

The asadmin command provides the simplest method of undeploying a web service from GlassFish.

asadmin undeploy --user admin wsit-jaxws-fromjava
asadmin undeploy --user admin wsit-jaxws-fromwsdl

7.2. Undeploying from Tomcat

Undeploying a given web service from Tomcat requires deleting its WAR file from the Tomcat webapps directory. For a typical UNIX scenario the commands below would delete the sample WAR files. Tomcat then automatically undeploys the web service within a few seconds.

rm $CATALINA_HOME/webapps/wsit-jaxws-fromjava.war
rm $CATALINA_HOME/webapps/wsit-jaxws-fromwsdl.war
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