How to build a cluster with Jetty / OSGi

How to build a cluster with Jetty / OSGi

In this blog post I describe how to set up a cluster node with an embedded Jetty Server inside Equinox.

Basically I followed the instructions available at the Jetty Wiki page Session Clustering Using a Database [1].

There are two Jetty configuration files involved:

  • /etc/jetty.xml defining a JDBCSessionIdManager
  • /WEB-INF/jetty-web.xml defining a JDBCSessionManager

The main jetty.xml resides in the folder etc of the jetty.home.bundle which itself is a fragment of org.eclipse.jetty.osgi.boot. The jetty.osgi.boot bundle is provided by the Jetty team and is responsible for bootstrapping Jetty in an OSGi environment.

The main configuration file contains the JDBCSessionIdManager definition using a H2 database:

 
  
    
      
    
    
      
    
    
      org.h2.Driver
      jdbc:h2:tcp://localhost:9101/sessions
    
    60
  


  jdbcIdMgr
  
    
  

Note: To reuse the configuration in multiple cluster nodes I use a SystemProperty tag to give every node a unique “worker.name”. The database configuration is hardwired to a local H2 database.

With additional system properties I can tell the Jetty bootstrapper where to look for the global Jetty configuration and which port the Jetty instance should bind to:

-Dworker.name=primary
-Djetty.port=18081
-Djetty.home.bundle=com.eclipsesource.cluster.jetty.home.bundle

To enable the Jetty server to load the H2 database drivers I added a dynamic import directive via the fragment org.eclipse.jetty.serverdynamic.import:

Fragment-Host: org.eclipse.jetty.server;bundle-version="7.4.2"
DynamicImport-Package: *

The web application specific configuration /WEB-INF/jetty-web.xml is located in the web bundle, com.eclipsesource.cluster.jetty.demo.webbundle. This configuration file contains the JDBCSessionManager definition.


  
    
  
  
    
      
        
          
            
          
        
      
    
  

Note: “jdbcIdMgr” is a Reference to the jetty.xml from jetty.home.bundle.

If you want to try it out yourself, the code is available at GitHUB [2].

Note: The bundle com.eclipsesource.cluster.h2 contains an Eclipse launch configuration to start a local H2 database which is needed to run the example.

[1] http://wiki.eclipse.org/Jetty/Feature/Session_Clustering_Using_a_Database
[2] https://github.com/eclipsesource/com.eclipsesource.cluster

No Comments

Post a Comment

Comment
Name
Email
Website