2.2. Create a Publisher Client

Overview

This section describes how to create a publisher client of the notification broker. The publisher client is capable of sending messages on a specific topic to the notification broker.

Prerequisites

In order to access artifacts from the Maven repository, you need to add the fusesource repository to Maven's settings.xml file. Maven looks for your settings.xml file in the following standard location:

UNIX: home/User/.m2/settings.xml
Windows: Documents and Settings\User\.m2\settings.xml

If there is currently no settings.xml file at this location, you need to create a new settings.xml file. Modify the settings.xml file by adding the repository element for fusesource, as highlighted in the following example:

<settings>
    <profiles>
        <profile>
            <id>my-profile</id>
            <activation>
                <activeByDefault>true</activeByDefault>
            </activation>
            <repositories>
                <repository>
                    <id>fusesource</id>
                    <url>http://repo.fusesource.com/nexus/content/groups/public/</url>
                    <snapshots>
                        <enabled>false</enabled>
                    </snapshots>
                    <releases>
                        <enabled>true</enabled>
                    </releases>
                </repository>
                ...
            </repositories>
        </profile>
    </profiles>
    ...
</settings>

Sample publisher client code

Example 2.1, “Publisher Client Code” shows the code for a sample publisher client that pushes a simple Hello World! message to the MyTopic topic on the notification broker.

Example 2.1. Publisher Client Code

// Java
package org.jboss.fuse.example.wsn.publisher;

import javax.xml.bind.JAXBElement;
import javax.xml.namespace.QName;

import org.w3c.dom.Element;

import org.apache.cxf.wsn.client.Consumer;
import org.apache.cxf.wsn.client.NotificationBroker;
import org.apache.cxf.wsn.client.Subscription;
import org.oasis_open.docs.wsn.b_2.NotificationMessageHolderType;

/**
 * 
 */
public final class Client {
    private Client() {
        //not constructed
    }

    /**
     * @param args
     */
    public static void main(String[] args) throws Exception {
        String wsnPort = "8182";
        if (args.length > 0) {
            wsnPort = args[0];
        }
        
        // Create a NotificationBroker proxy
        NotificationBroker notificationBroker 
            = new NotificationBroker("http://localhost:" + wsnPort + "/wsn/NotificationBroker");


        for (int i=0; i<120; i++) {
            // Send notifications on the Topic
            notificationBroker.notify(
                "MyTopic", 
                new JAXBElement<String>(
                    new QName("urn:test:org", "foo"),
                    String.class,
                    "Hello World!"
                )
            );
        
            // Sleep for 1s between notifications
            Thread.sleep(1000);
        }
        
        // Cleanup and exit
        System.exit(0);
    }

}

NotificationBroker proxy class

The client code from Example 2.1, “Publisher Client Code” uses the NotificationBroker proxy class to connect to the remote notification broker and to publish notifications to the broker. In this example, the following NotificationBroker methods are invoked:

NotificationBroker(String address, Class<?>... cls): The NotificationBroker constructor normally takes a single argument, which is the URL of the remote notification broker Web service.
notify(String topic, Object msg): Sends a message, msg, on the topic, topic, to the notification broker, where the format of the msg argument is an XML document. For example, you can use the JAX-B API to create a single XML element containing a string for the message, as shown in Example 2.1, “Publisher Client Code”.

Note

This NotificationBroker proxy class belongs to the simplified client API provided by the Apache CXF implementation of WS-Notification; it is not an instance of the standard NotificationBroker SEI defined by JAX-WS (although the standard SEI is also available and could be used instead).

Steps to create a publisher client

Perform the following steps to create a publisher client:

You can create a Maven project directly from the command line, by invoking the archetype:generate goal. First of all, create a directory to hold the WS-Notification client projects. Open a command prompt, navigate to a convenient location in your file system, and create the wsn directory, as follows:
```
mkdir wsn
cd wsn
```
You can now use the archetype:generate goal to invoke the karaf-soap-archetype archetype, which generates a simple Apache CXF demonstration, as follows:
```
mvn archetype:generate \
  -DarchetypeGroupId=io.fabric8.archetypes \
  -DarchetypeArtifactId=karaf-soap-archetype \
  -DarchetypeVersion=1.2.0.redhat-621084 \
  -DgroupId=org.jboss.fuse.example \
  -DartifactId=wsn-publisher \
  -Dversion=1.0-SNAPSHOT \
  -Dpackage=org.jboss.fuse.example.wsn.publisher \
  -Dfabric8-profile=wsn-publisher-profile
```
Note
The backslash characters at the end of each line are effective as line-continuation characters on UNIX and LINUX platforms. If you are entering the command on a Windows platform, however, you must enter the entire command on a single line.
You will be prompted to confirm the project settings, with a message similar to this one:
```
Confirm properties configuration:
groupId: org.jboss.fuse.example
artifactId: wsn-publisher
version: 1.0-SNAPSHOT
package: org.jboss.fuse.example.wsn.publisher
fabric8-profile: wsn-publisher-profile
 Y: :
```
Type Return to accept the settings and generate the project. When the command finishes, you should find a new Maven project in the wsn/wsn-publisher directory.

Some of the generated project files are not needed for this tutorial. Under the wsn/wsn-publisher directory, delete the following files and directories:

src/main/resources/OSGI-INF/blueprint/blueprint.xml
src/main/java/org/jboss/fuse/example/wsn/publisher/HelloWorld.java
src/main/java/org/jboss/fuse/example/wsn/publisher/HelloWorldImpl.java

Edit the pom.xml file in the wsn-publisher directory, and add the dependency required for WS-Notification clients:

<?xml version="1.0" encoding="UTF-8"?>
<project ...>
    ...
    <dependencies>
        ...
        <!-- Needed for WS-Notification -->
        <dependency>
            <groupId>org.apache.cxf.services.wsn</groupId>
            <artifactId>cxf-services-wsn-api</artifactId>
        </dependency>
    </dependencies>
    ...
</project>

Note

There is no need to specify the version of this artifact, because the version is provided by the Fabric8 BOM, which uses Maven dependency management to specify the artifact versions.

Delete the cxf-java2ws-plugin plug-in configuration from the wsn-publisher/pom.xml file. That is, open the pom.xml file and delete the cxf-java2ws-plugin plug-in configuration as highlighted in the following example:

<?xml version="1.0" encoding="UTF-8"?>
<project ...>
    ...
    <build>
      <plugins>
        ...
       <!-- DELETE THE FOLLOWING LINES! -->
        <plugin>
          <groupId>org.apache.cxf</groupId>
          <artifactId>cxf-java2ws-plugin</artifactId>
          <version>${cxf-version}</version>
          <executions>
            <execution>
              <id>process-classes</id>
              <phase>process-classes</phase>
              <goals>
                <goal>java2ws</goal>
              </goals>
              <configuration>
                <className>org.jboss.fuse.example.wsn.publisher.HelloWorld</className>
                <genWsdl>true</genWsdl>
                <attachWsdl>false</attachWsdl>
                <verbose>true</verbose>
              </configuration>
            </execution>
          </executions>
        </plugin>
        ...
      </plugins>
    </build>
    ...
</project>

Add a client profile to the POM file, which provides an easy way to run the publisher client code. Edit the wsn-publisher/pom.xml file and add the new profile element, as highlighted in the following example:

<?xml version="1.0" encoding="UTF-8"?>
<project ...>
    ...
    <profiles>
        ...
        <profile>
            <id>client</id>
            <build>
                <defaultGoal>test</defaultGoal>
                <plugins>
                    <plugin>
                        <groupId>org.codehaus.mojo</groupId>
                        <artifactId>exec-maven-plugin</artifactId>
                        <executions>
                            <execution>
                                <phase>test</phase>
                                <goals>
                                    <goal>java</goal>
                                </goals>
                                <configuration>
                                    <mainClass>org.jboss.fuse.example.wsn.publisher.Client</mainClass>
                                </configuration>
                            </execution>
                        </executions>
                    </plugin>
                </plugins>
            </build>
        </profile>
    </profiles>
    ...
</project>

Create a new Client.java file in the wsn-publisher/src/main/java/org/jboss/fuse/example/wsn/publisher/ directory, and add the code from Example 2.1, “Publisher Client Code” to this file.
You can now run the publisher client from the wsn-publisher directory by entering the following command:
```
mvn -Pclient
```
In the command window, you should see some output like the following:
```
[INFO] --- exec-maven-plugin:1.4.0:java (default) @ wsn-publisher ---
```
Notification messages are now accumulating in the broker, but you will not be able to receive the messages until you create a consumer client.

2.2. Create a Publisher Client

Overview

Prerequisites

Sample publisher client code

NotificationBroker proxy class

Steps to create a publisher client

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