Communicator e3000 MPE/iX Release 6.5 Express 2 (Software Release C.65.02) (30216-90322)

34 Chapter3
Technical Articles
Java Servlets for MPE/iX
Figure 3-1. Java Servlet model on HP e3000
Apache's mod_jserv and the servlet engine communicate through a special protocol,
Apache JServ Protocol (AJP), which runs on top of TCP. The TCP connection is usually
through the localhost, 127.0.0.1, but can also be via a remote host. For a remote host, the
Apache Web Server and the servlet engine are on separate machines.
A servlet is a body of server-side Java code that is loaded into and runs inside the servlet
engine. It receives and responds to requests from clients in a manner similar to CGI.
When making a request, the web browser acts as a client and sends its request to Apache
using the HTTP protocol. Apache's mod_jserv translates this HTTP request into AJP and
acts as the AJP client by sending the request over the network (local or remote) to the
servlet engine. The servlet engine acts as the AJP server and listens on a specific port
(8007 by default) for incoming requests. The servlet engine will process a request by
executing the requested servlet. When the servlet has completed processing its request,
the servlet engine responds back to Apache using AJP. Apache converts the AJP response
to HTTP and sends it back to the client browser.
Major Components
Java Servlets for MPE/iX installs and runs under directory /APACHE/PUB for Apache or
directory /APACHE/SECURE for WebWise Secure Web Server. Under one of these
directories will be the following files and subdirectories:
JSRV - The Apache job stream file for starting the JServ engine. It contains the necessary
Client Browser
Apache Web Server
JServ Servlet Engine