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Tuscany Web Application based Integration with Geronimo

1. Introduction

Apache Tuscany is a java implementation of the emerging SCA specifications. Tuscany provides the infrastructure to construct, assmble and deploy composite applications with SCA. Apache Geronimo is a fully certified Java EE 5 application server runtime. The ability to deploy and run SCA composite applications with Geronimo will bring great value to both projects and communities. In this whitepaper, we will describe a simple web application based integration between Tuscany and Geronimo and walk through how to develop a web application using Apache Tuscany and deploy it to Apache Geronimo.

2. Staged Approaches for Tuscany/Geronimo Integration

3. Web Application based Tuscany/Geronimo Shadow Integration

In this scheme, we simply package the application artifcts together with the required tuscany jars and dependencies into standard web application archive (WAR). The WAR can be deployed to the most popular web containers such as Geronimo, Tomcat, Jetty and WebSphere. Some container-specific deployment descriptor files may be added.

A tuscany provided servlet filter (org.apache.tuscany.sca.host.webapp.TuscanyServletFilter) is configured to startup/shutdown the Tuscany runtime when the web application is started or stopped. The tuscany filter is also responsible to dispatch HTTP requests to HTTP-based bindings such as Web Services, JSONRPC and Atom/RSS Feed. Figure 1 below shows how the tuscany servlet filter bridges web application to SCA.

As illustrated in Figure 2, there are a few important files or folders in the WAR:

2.1 web.xml

Sample WEB-INF/web.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>

  <display-name>Apache Tuscany Calculator Web Service Sample</display-name>
    <filter>
        <filter-name>tuscany</filter-name>
        <filter-class>org.apache.tuscany.sca.host.webapp.TuscanyServletFilter</filter-class>
    </filter>

    <filter-mapping>
        <filter-name>tuscany</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

</web-app>

2.2 geronimo-web.xml

The most important setting in the geronimo-web.xml is inverse-classloading which ensures the tuscany and its dependency classes will be loaded from the WEB-INF/lib. It creates an isolated environment for the tuscany runtime without being interfered by other jars shipped by Geronimo (such as axis2).

Sample WEB-INF/geronimo-web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://geronimo.apache.org/xml/ns/j2ee/web-2.0"
    xmlns:d="http://geronimo.apache.org/xml/ns/deployment-1.2">
    <d:environment>
        <d:moduleId>
            <d:groupId>org.apache.tuscany.sca</d:groupId>
            <d:artifactId>sample-calculator-ws-webapp</d:artifactId>
            <d:version>1.2-incubating-SNAPSHOT</d:version>
            <d:type>war</d:type>
        </d:moduleId>
        <d:inverse-classloading />
    </d:environment>
</web-app>

2.3 sca-contribution.xml

META-INF/sca-contribution.xml defines the deployable composites for the given SCA contribution (the WAR in the webapp case). Tuscany servlet filter will bootstrap the SCA domain and deploy these composites.

META-INF/calculator.composite
<?xml version="1.0" encoding="UTF-8"?>
<contribution xmlns="http://www.osoa.org/xmlns/sca/1.0"
              targetNamespace="http://sample"
              xmlns:sample="http://sample">
   <deployable composite="sample:Calculator"/>
</contribution>

2.4 SCA composites

2.4.1 binding.ws

 
The  Calculator.composite is one such deployable sca composite and is defined as follows.

Calculator.composite
<?xml version="1.0" encoding="UTF-8"?>
<composite xmlns="http://www.osoa.org/xmlns/sca/1.0"
           targetNamespace="http://sample"
           xmlns:sample="http://sample"
           name="Calculator">

    <component name="CalculatorServiceComponent">
		<implementation.java class="calculator.CalculatorServiceImpl"/>
        <reference name="addService" >
           <interface.java interface="calculator.AddService" />
            <binding.ws uri="http://localhost:8080/sample-calculator-ws-webapp/AddServiceComponent"/>
        </reference>
        <reference name="subtractService" target="SubtractServiceComponent"></reference>
        <reference name="multiplyService" target="MultiplyServiceComponent"></reference>
        <reference name="divideService" target="DivideServiceComponent"></reference>
    </component>

    <component name="AddServiceComponent">
        <implementation.java class="calculator.AddServiceImpl"/>
        <service name="AddService">
             <interface.java interface="calculator.AddService" />
            <binding.ws/>
        </service>
    </component>

    <component name="SubtractServiceComponent">
        <implementation.java class="calculator.SubtractServiceImpl"/>
    </component>

    <component name="MultiplyServiceComponent">
        <implementation.java class="calculator.MultiplyServiceImpl"/>
    </component>

    <component name="DivideServiceComponent">
        <implementation.java class="calculator.DivideServiceImpl"/>
    </component>

</composite>

3. Devloping a Tuscany web application for Geronimo using Maven and Eclipse

3.1 Create an empty maven project for your web application

mvn archetype:generate

Select 18: internal -> maven-archetype-webapp (A simple Java web application) and provide the groupId/artifactId/version and package name.

You can use the calculator-ws-webapp sample as a template to configure the pom.xml.

mvn eclipse:eclipse

3.2 Import the project into Eclipse

In Eclipse, following the menu: File -> Import -> General --> Exising Projects into Workspace.

4. Configure the maven pom.xml to generate web.xml and geronimo-web.xml automatically

Tuscany provides a maven which can generate the WEB-INF/web.xml and WEB-IN/geronimo-web.xml automatically as part of the maven build. The following xml snippet shows
the usage.

<build>
    <plugins>
    <!-- Generate web-xml and geronimo deployment descriptor -->
        <plugin>
            <groupId>org.apache.tuscany.sca</groupId>
            <artifactId>tuscany-maven-web-junit</artifactId>
            <version>1.2-incubating-SNAPSHOT</version>
            <executions>
                <execution>
                    <id>generate-web-xml</id>
                    <configuration>
                        <geronimo>true</geronimo>
                    </configuration>
                    <phase>process-resources</phase>
                    <goals>
                        <goal>generate</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

5. Test automation with maven

Automation of itests in web applications

6. Next steps

Tuscany Geronimo Integration Next Steps

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