JServ module

Java Servlet Support

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Overview
The JServ module interfaces Zeus with the Apache JServ Servlet Server. JServ is an 'Open Source' Servlet engine that is freely downloadable.

For more information look at:

• The step-by-step installation guide
• JServ homepage
• Information about servlets
• Servlet tutorial

Zeus can also interface with Live Software's JRun Servlet engine, see the support website for details.

Configuration
Zeus is configured to access a JServ servlet engine by specifying a 'mount point', under which any accesses are sent to the JServ engine. The JServ process can run on the same machine as the webserver, or on a remote machine, or multiple remote machines to provide load-balancing and fault tolerance.

A single mount point requires four pieces of information. The hostname of the machine running the JServ program, ('localhost' if you are running it locally), the port number the JServ program is bound to (JServ defaults to 8007), the JServ 'zone' to use, and the protocol to use for the communication between the webserver and the JServ engine.

Zones

For more information on zones, check the JServ documentation. Basically each zone has its own 'CLASSPATH' to determine where Java classes should be found, and also allows for automatic reloading of classes upon servlet re-compilation.

Protocols

The protocol chosen for a mount-point defines how the webserver 'talks' to the JServ engine. The original versions of JServ, upto and including version 1.0 talked a protocol called ajpv11. More recent versions of JServ (>= 1.1), talk a different protocol called ajpv12. These two protocols are incompatible with each other, however Zeus supports both on a per mount basis, so you can simultaneously run both JServ 1.0 and JServ 1.1 engines with Zeus if you desire.

In summary, choose the protocol to use from the following table:

JServ version	Protocol
<= 1.0	AJPv11
>= 1.1	AJPv12

Usage
Once a mount point is setup, servlets are accessed via '<mountpoint>/<servletname>', e.g. http:://www.mysite.com/jserv/HelloWorld.

Servlets that are in 'subdirectories', can be accessed by putting a '.' between directories, e.g. /jserv/org.mysite.HelloWorld.

JServ itself provides a default servlet that generates information about itself, this can be accessed via a servlet called 'org.apache.jserv.JServ'. Thus if you mounted JServ on '/jserv', you can access this servlet via http://www.mysite.com/jserv/org.apache.jserv.JServ