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Adding a servlet to Orion (Eclipse Cloud IDE) from a package built using maven.


Orion is an open source project and it is under the Eclipse Cloud Development top-level project. It’s an cloud IDE which is available online and also which can be hosted in on premise. [1] [2]. Orion can work with git repos, create git repos or work with local code same as Eclipse.

Orion has two repos. For the backend server code [2] and for the client / ui code [3]. Orion server is an osgi server based on eclipse equinox. But the problems are they have not implemented the dropins concept. Because of that adding an external bundle to Orion Server is not straightforward. We have to edit the bundles.info to add a bundle to Orion server. And Orion is using jetty for the servlets.

As mentioned Orion is working with Jetty and to add a servlet via a bundle is easy if we use eclipse itself to develop and bundle the package. But if we use maven to build it then the problems arises. What we have to do is add an entry to plugins.xml and package the plugins.xml to the bundle we are creating.

So to do this what has to be done is add a plugins.xml (You can copy an existing plugins.xml from orion code base) to the resources directory and edit it to have your servlets in it. And in the pom.xml under the build tag add following section. You can look into the sample code [4].

     <resources>  
       <resource>  
         <directory>src/main/resources</directory>  
         <filtering>true</filtering>  
         <includes>  
           <include>build.properties</include>  
           <include>bundle.properties</include>  
           <include>plugin.xml</include>  
         </includes>  
       </resource>  
     </resources>

Sample plugins.xml is as below.

 <?xml version="1.0" encoding="UTF-8"?>  
 <?eclipse version="3.4"?>  
 <plugin>  
   <extension  
      point="org.eclipse.equinox.http.registry.servlets">  
    <servlet  
       alias="/helloworld"  
       class="org.orion.sample.servlet.servlet.HelloWorldServlet">  
    </servlet>  
    <serviceSelector  
       filter="(other.info=org.eclipse.orion)">  
    </serviceSelector>  
   </extension>  
 </plugin>

Servlet code will be the following

 package org.orion.sample.servlet.servlet;  
 import org.eclipse.orion.server.servlets.OrionServlet;  
 import javax.servlet.ServletException;  
 import javax.servlet.http.HttpServletRequest;  
 import javax.servlet.http.HttpServletResponse;  
 import java.io.IOException;  
 public class HelloWorldServlet extends OrionServlet {  
      @Override  
      protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {  
           resp.getWriter().println("Hello JCG, Hello OSGi");  
      }  
      public HelloWorldServlet() {  
           super();  
      }  
 }

Since to deploy the bundle to Orion it has to be an osgi bundle you have add maven scr and maven bundle plugins to your project as well. So the build tag in the pom.xml should be like below.

   <build>  
     <resources>  
       <resource>  
         <directory>src/main/resources</directory>  
         <filtering>true</filtering>  
         <includes>  
           <include>build.properties</include>  
           <include>bundle.properties</include>  
           <include>plugin.xml</include>  
         </includes>  
       </resource>  
     </resources>  
     <plugins>  
       <plugin>  
         <groupId>org.apache.felix</groupId>  
         <artifactId>maven-scr-plugin</artifactId>  
         <version>1.7.2</version>  
         <executions>  
           <execution>  
             <id>generate-scr-scrdescriptor</id>  
             <goals>  
               <goal>scr</goal>  
             </goals>  
           </execution>  
         </executions>  
       </plugin>  
       <plugin>  
         <groupId>org.apache.felix</groupId>  
         <artifactId>maven-bundle-plugin</artifactId>  
         <version>2.3.5</version>  
         <extensions>true</extensions>  
         <configuration>  
           <instructions>  
             <Bundle-SymbolicName>${project.artifactId};singleton:=true</Bundle-SymbolicName>  
             <Bundle-Name>${project.artifactId}</Bundle-Name>  
             <Export-Package>  
               org.orion.sample.servlet.*,  
             </Export-Package>  
             <DynamicImport-Package>*</DynamicImport-Package>  
             <Require-Bundle>  
               org.eclipse.jetty.server,  
               org.eclipse.jetty.servlet,  
               org.eclipse.jetty.http,  
               org.eclipse.jetty.io,  
               org.eclipse.jetty.security,  
               org.eclipse.jetty.util,  
               org.eclipse.orion.server.core,  
               org.eclipse.orion.server.git,  
               org.eclipse.orion.server.servlets,  
               org.eclipse.equinox.http.registry  
             </Require-Bundle>  
           </instructions>  
         </configuration>  
       </plugin>  
     </plugins>  
   </build>

And you have to add the Service Component class to get it activated at the startup. Code would be like following.

 package org.orion.sample.servlet.internal;  
 import org.osgi.service.component.ComponentContext;  
 /**  
  * @scr.component name="org.orion.sample.servlet.internal.ServletSampleServiceComponent" immediate="true"  
  */  
 public class ServletSampleServiceComponent {  
      protected void activate(ComponentContext context) {  
           System.out.println("Registration Complete");  
      }  
 }

Now you can run mvn clean install on the package and build the jar file. Now go in to the Orion server folder and create a folder named dropins and copy your jar file in to dropins. Now edit

 $ORION_HOME/configuration/org.eclipse.equinox.simpleconfigurator/bundles.info

file and following in the end add following line.

org.orion.sample.servlet,1.0.0,dropins/org.orion.sample.servlet-1.0.0.jar,4,false

[1] https://wiki.eclipse.org/Orion
[2] https://github.com/eclipse/orion.server
[3] https://github.com/eclipse/orion.client
[4] https://drive.google.com/open?id=0ByTCb2KmTk76OVMtcnplQnpOajQ

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