Concepts

GBean

Geronimo is modular; it consists of a kernel and a set of components that implement the features needed to implement the J2EE specification. GBean (short for "Geronimo Bean") is the kernel-component interface. There's no GBean interface per se, but each GBean has a corresponding GBeanInfo object that describes the GBean and tells the kernel how to interact with it. Some GBeans implement GBeanLifecycle which allows them to get called when lifecycle events (start, stop, fail) happen. The source code for the GBeanTest class shows how a GBean is used.

GBeans are tracked using an MBeanServer (an MBean directory?).

According to mailing list traffic one advantage of GBeans over MBeans is that GBean method invocation is much faster.

Misc

GBeanMBean
Configuration
JMX, MBean
BootstrapContext
JSR-77 - a standard model for managing the J2EE Platform - home, overview
JSR-88 - J2EE Application Deployment - home,
DependencyManager
ConfigurationManager

Startup

Runs using a standalone application jar called target/bin/server.jar. The startup class specified in MANIFEST.MF is o.a.g.system.main.Daemon. The Daemon is a command-line wrapper around o.a.g.kernel.Kernel. The daemon first unserializes the META-INF/config.ser from server.jar using Configuration.loadGMBeanState(). The format of config.ser is a leading int that indicates how many attribute name/value pairs follow, then a leading int that indicates how many setReferencePatterns() parameter pairs follow:

        int attributeCount = ois.readInt();
        for (int i = 0; i < attributeCount; i++) {
            gbean.setAttribute((String) ois.readObject(), ois.readObject());
        }
        int endpointCount = ois.readInt();
        for (int i = 0; i < endpointCount; i++) {
            gbean.setReferencePatterns((String) ois.readObject(), (Set) ois.readObject());
        }

Deployment

Runs using a standalone application jar called target/bin/deployer.jar. The startup class specified in MANIFEST.MF is org.apache.geronimo.deployment.cli.DeployTool. DeployTool parses the command line parameters and delegates to org.apache.geronimo.deployment.cli.ServerConnection to do most of the work. ServerConnection starts up a small kernel and loads a configuration into that kernel. Among the gbeans loaded into that kernel is one that wraps the org.apache.geronimo.deployment.Deployer class. Deployer picks apart the jar file and builds the various bits and pieces.

If the thing being deployed is an ear file then Deployer will end up calling org.apache.geronimo.j2ee.deployment.EarConfigBuilder.

wiki page here: http://wiki.apache.org/geronimo/Deployment

j2ee xml descriptor files (and their geronimo counterparts) are unmarshalled into java classes using apache xmlbeans (http://xml.apache.org/xmlbeans).

For resource adapters, the ConnectorModuleBuilder class builds the configuration that gets deployed at run-time.

Stack trace at startup (setting a RA parameter), heavily edited to remove the gbean/mbean cruft:

        at skeleton.ra.spread.AdapterImpl.setConfigParameter(AdapterImpl.java:84)
        at org.apache.geronimo.connector.ResourceAdapterWrapper.setAttribute(ResourceAdapterWrapper.java:130)
        at mx4j.server.MX4JMBeanServer.registerMBean(MX4JMBeanServer.java:729)
        at org.apache.geronimo.kernel.Kernel.loadGBean(Kernel.java:255)
        at org.apache.geronimo.kernel.config.Configuration.doStart(Configuration.java:176)
        at org.apache.geronimo.gbean.jmx.GBeanMBean.doStart(GBeanMBean.java:593)
        at org.apache.geronimo.gbean.jmx.AbstractManagedObject.startRecursive(AbstractManagedObject.java:303)
        at mx4j.server.MX4JMBeanServer.invoke(MX4JMBeanServer.java:1079)
        at org.apache.geronimo.gbean.jmx.AbstractManagedObject.startRecursive(AbstractManagedObject.java:310)
        at org.apache.geronimo.kernel.Kernel.startRecursiveGBean(Kernel.java:275)
        at org.apache.geronimo.system.main.Daemon.main(Daemon.java:137)

In 1.2, the cli code is in the modules/geronimo-deploy-tool directory. It ends up in the lib/ directory and the repository, but the version in lib seems to take precedence. If you're making changes you can build in modules/geronimo-deploy-tool then copy the jar from the maven repo to the target lib directory, i.e.

$ cp ~/.m2/repository/org/apache/geronimo/modules/geronimo-deploy-tool/1.2-SNAPSHOT/geronimo-deploy-tool-1.2-SNAPSHOT.jar ~/target/lib/

EJB

Geronimo embeds OpenEJB as its EJB container, so there's a lot of good info at http://www.openejb.org/ that's also relevant to Geronimo, for example http://www.openejb.org/geronimo.html and http://openejb.codehaus.org/hello-world.html .

Geronimo's build process depends on downloading a copy of openejb from some site somewhere, and sometimes geronimo and openejb change simultaneously in ways that need to be closely coordinated. In that case you'll want to build openejb from source so that geronimo's build process can use your local openejb.

openejb's web site points to old source code, but according to http://hausmates.codehaus.org/projectinfo newer code seems to be located at:

  cvs -d :pserver:anonymous@cvs.openejb.codehaus.org:/home/projects/openejb/scm login
  (no password)
  cvs -d :pserver:anonymous@cvs.openejb.codehaus.org:/home/projects/openejb/scm cvs co openejb

Build openejb first, then geronimo.

Building

As of Oct 2006, the dev team has switched over to Maven2. A command-line build invocation that works for me is:

MAVEN_OPTS="-Xms256m -Xmx512m -XX:PermSize=64m -XX:MaxPermSize=256m" mvn -o

Command-line tools

For example, the deployer.

Code in modules/geronimo-deploy-tool/. This is referenced by configs/online-deployer/ that builds a "car" file.

Finally assembled in e.g. assemblies/geronimo-jetty-j2ee/. See src/main/assembly/bin.xml.