Developing SOA based solutions can be very complex and expensive. Apache Tuscany provides a lightweight infrastructure which enables users to easily implement SOA based solutions or to use
their existing assets and align them with SOA principles which would support a business model that can extend and expand as business needs change.
Apache Tuscany implements SCA specifications that is being standardized at OASIS. Tuscany provides the capabilities to construct, assemble and deploy composite applications using SCA.
This white paper explains how Tuscany integrates with Apache Geronimo, a fully certified Java EE 5 application server runtime, to provide added value to users wanting to develop SOA solutions using Geronimo as a platform. The added values include:
The following are a set of usage scenarios that both JEE and SCA developers could be interested in.
In this whitepaper, we will describe an initial step taken to integrate Tuscany and Geronimo. It is assumed that you are familiar with Geronimo and Tuscany SCA. Here is the link to SCA user doc .
We had proposed to stage the Tuscany/Geronimo integration on the Geronimo/Tuscany mailing lists. Here is a summary of the basic ideas that were discussed.
Stage 1 is now available in release 1.2 of Tuscany.
An initial prototype of stage 2 has been available in Tuscany since SCA Java 1.1-incubating release. Much more work is needed to re-align the plug-in to the latest release of Tuscany and to complete the work. Contributions are very welcome.
Put links to SCA and Geronimo download. Which versions are needed.
Here we will cover the first step in integrating Tuscany with Geronimo which is running Tuscany as a webapp on top of Geronimo. This is now available in release 1.2 of Tuscany that can be downloaded from put link.
In this scheme,an SCA composite crated with Tuscany is packaged into a web applications archive (WAR) while including application artifacts and tuscany jars and dependencies. The WAR can be deployed to Geronimo or to other web containers such as Tomcat, Jetty and WebSphere. Some container-specific deployment descriptor files may be added. PLEASE CLARIFY
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.
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Figure 1. Tuscany Webapp |
As illustrated in Figure 2, there are a few important files or folders in the WAR:
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Figure 2. Sample WAR |
As shown below, we configure the web.xml with a Tuscany servlet filter which is responsible to dispatch HTTP requests to corresponding SCA service binding listeners.
<?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>
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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).
<?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>
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We will use a Tuscany sample called calcualtor to demonstrate how the Geronimo/Tuscany integration using web application approach works. You can find the calculatr sample in Tuscany svn repo.
Below is the picture for the calculator sample and the description of SCA composite file.
The Calculator.composite is one such deployable sca composite and is defined as follows.
<?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>
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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.
<?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>
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You can expose a SCA service as a web service or access external web services using SCA.
You can acccess existing stateless session bean using binding.ejb. Here is an example of the composite file.
<binding.ejb uri="corbaname:iiop:1.2@localhost:1050#VegetablesCatalogEJB" /> |
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Make sure org.apache.geronimo.configs/openejb-corba-deployer/2.0.2/car is started. Look under System Modules in Geronimo admin console. |
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 |
In Eclipse, following the menu: File -> Import -> General --> Exising Projects into Workspace.
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>
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Tuscany has a suite of tests called itests. We have modified the tests to enable running of web applications as part of the test suite.
Automation of itests in web applications
Tuscany Geronimo Integration Next Steps