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...

Tapestry doesn't mandate that you use any build system, but we'll assume for the moment that you are using Maven 2. In that case, you'll have a pom.xml file something like the following:

Code Block

	XML	XML
title	pom.xml
	XML

<project>
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.example</groupId>
  <artifactId>happylib</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>jar</packaging>
  <name>happylib Tapestry 5 Library</name>

  <dependencies>
    <dependency>
      <groupId>org.apache.tapestry</groupId>
      <artifactId>tapestry-core</artifactId>
      <version>${tapestry-release-version}</version>
    </dependency>

    <dependency>
      <groupId>org.testng</groupId>
      <artifactId>testng</artifactId>
      <version>5.1</version>
      <classifier>jdk15</classifier>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <source>1.5</source>
          <target>1.5</target>
          <optimize>true</optimize>
        </configuration>
      </plugin>

      <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-jar-plugin</artifactId>
           <configuration>
           <archive>
             <manifestEntries>
               <Tapestry-Module-Classes>org.example.happylib.services.HappyModule</Tapestry-Module-Classes>
             </manifestEntries>
           </archive>
           </configuration>
       </plugin>

    </plugins>
  </build>

  <repositories>
    <repository>
      <id>codehaus.snapshots</id>
      <url>http://snapshots.repository.codehaus.org</url>
    </repository>
    <repository>
      <id>OpenQA_Release</id>
      <name>OpenQA Release Repository</name>
      <url>http://archiva.openqa.org/repository/releases/</url>
    </repository>
  </repositories>

  <properties>
    <tapestry-release-version>5.2.0</tapestry-release-version>
  </properties>
</project>

...

Our component is very simple:

Code Block

	java	java
title	HappyIcon.java
	java

package org.example.happylib.components;

import org.apache.tapestry5.Asset;
import org.apache.tapestry5.MarkupWriter;
import org.apache.tapestry5.annotations.Path;
import org.apache.tapestry5.ioc.annotations.Inject;

public class HappyIcon
{
    @Inject
    @Path("happy.jpg")
    private Asset happyIcon;

    boolean beginRender(MarkupWriter writer)
    {
        writer.element("img", "src", happyIcon);
        writer.end();

        return false;
    }
}

...

At application startup, Tapestry will read the library module along with all other modules and configure the ComponentClassResolver service using information in the module:

Code Block

	java	java
title	HappyModule.java
	java

package org.example.happylib.services;

import org.apache.tapestry5.ioc.Configuration;
import org.apache.tapestry5.services.LibraryMapping;

public class HappyModule
{
    public static void contributeComponentClassResolver(Configuration<LibraryMapping> configuration)
    {
        configuration.add(new LibraryMapping("happy", "org.example.happylib"));
    }
}

...

For Tapestry to load your module at application startup, it is necessary to put an entry in the JAR manifest. This is taken care of in the pom.xml above:

xml

Code Block

	xml
title	pom.xml (partial)
	xml

      <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-jar-plugin</artifactId>
           <configuration>
           <archive>
             <manifestEntries>
             <Tapestry-Module-Classes>org.example.happylib.services.HappyModule</Tapestry-Module-Classes>
             </manifestEntries>
           </archive>
           </configuration>
       </plugin>

...

With this in place, and the library and applications rebuilt and redeployed, the URL for happy.jpg becomes /happyapp/assets/happylib/1.0/components/happy.jpg. This is shorter, but also incorporates a version number ("1.0") that can be changed in a later release.

Since

since	5.2

In version 5.2 and later, Tapestry automatically creates a mapping for assets inside your JAR. In the above example, the icon image will be exposed as {{/assets/}}{_}application version{_}{{/happy/components/happy.jpg}} (the application version number is incorporated into the URL). The "happy" portion is a virtual folder that maps to the library's root package (as folder {{org/example/happylib}} on the Java classpath). The application version is a configurable value.

Conclusion

That's it! Autoloading plus the virtual folders for components and for assets takes care of all the issues related to components. Just build your JARs, setup the JAR Manifest, and drop them into your applications.

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