Java
Startup and Control Framework 
The Java startup
and control framework is used to start, stop, and monitor a 
Java Instance. The
framework comprises the JControl and JLaunch programs. JLaunch is started by JControl and itself starts the bootstrap Java program or an
element of the Java cluster (dispatcher or server process).
The Java startup and control framework is called in different ways depending on the operating system and installation type:
· Under Windows the SAP Management Console is used. If you choose an instance containing a J2EE Engine Action ® Start, the JControl program is called.
· Under UNIX platforms and OS/400 the scripts startsap and stopsap are used, which call the program.
· If you start the Java instance using the SAP NetWeaver Developer Studio, the Studio calls this JControl.
The framework consists of the following components:
Component |
Description |
JControl |
Starts, stops, and monitors the processes of a Java instance (usually a dispatcher and several server processes). The program implements the SAP signal handling to stop the instance. JControl starts the JLaunch processes. |
JLaunch |
Starts a Java program. It loads the JVM into its own address space and then represents the required cluster element. The program can receive from notification from the JControl process via named pipes to stop the cluster element, and terminates, if the JControl stops running (fork emulation under Windows). |
Bootstrap JAVA |
Synchronizes the binary data from the Java database with the local file system and creates a property file describing the processes of the Java instance, which is used by the Jlaunch processes. |
The process is
described in Startup, Operation and
Shutdown of a Java Instance.
Important Processes
The processes involved are started and controlled using the Java startup and control framework. The JControl program starts a JLaunch process for each Java process that loads the JVM and then represents the dispatcher or server process.
The following processes must be running for the simplest installation (one dispatcher, one server):
· Message Server (msg_server or msg_server.exe)
· Enqueue Server (enserver or enserver.exe)
· Dispatcher and server process (two jlaunch.exe)
· Software Deployment Manager (SDM, jlaunch.exe)
Under Windows you can use the SAP Management Console to monitor the processes.
Under UNIX you can view the processes with the command: ps -ef | grep jlaunch
At least three processes should be displayed: dispatcher, server, and SDM.
With the command
ps -ef | grep java | grep <SID>adm
you can filter the processes by user.
Since under Linux each thread runs in a separate process, the command
ps ef | grep java | wc l
results in about 300 processes alone for the dispatcher/server of the J2EE Engine. So this method can only be used here to see if the J2EE Engine is running at all.
See also: