Communicator 3000 MPE/iX Release 6.0 (Platform Software Release C.60.00) (30216-90269)

246 Chapter 10
Technical Articles
Developer’s Kit for Java/iX
users probably won't need the AWT on the HP 3000; user-interface code
is usually downloaded to a Web browser or run in some other
client-server type of configuration. We certainly recommend this for
your own development:
• Design the user interface as a separable module that can be
executed on a client, and leave application logic and database access
modules on the server.
You may, however, encounter Java applications that aren't designed
this way, and the MPE AWT implementation will allow you to execute
these applications, if you can provide an X-Windows capable display
device accessible from the HP 3000.
Java Directory Structure
Java is installed in MPE's hierarchical file system under the path
/usr/local/java. There are several additional directory levels
beyond this point.
The next level down specifies the Java version. For example, Version
1.1.5 of Java is installed under /usr/local/java/jdk1.1.5. There
is also a symbolic link called latest that you can use to access the
most recent version of Java, so that you do not need to change shell
scripts, jobstreams, and command files every time you install a new
version of Java. Thus, you can use /usr/local/java/latest/… as
the path to any Java components to use the latest installed version.
When you install new versions, you can remove this link and create a
new one. If you have software that must be run with a particular
version of Java, you can always specify a specific version directory
rather than latest.
Two major hierarchies, lib and bin, are under
/usr/local/java/latest, as well as the optional hierarchies, demo
and doc, and a number of files such as the latest README file.
The bin hierarchy contains Java program files and shell scripts used to
run those programs. Under /usr/local/java/latest/bin are shell
scripts used to run each of the Java components (described in the next
section). So, for example, /usr/local/java/latest/bin/java is
the script to run the latest version of the Java interpreter. If the PATH
(or HPPATH) variable is set correctly, it is not necessary to specify this
entire path; java MyClass would be sufficient.
The actual program binaries are two levels further down in the
hierarchy. Under /usr/local/java/latest/bin is the directory
PA-RISC. In the future, an additional subdirectory may be created at
this level to contain IA-64 binaries. Under the PA-RISC directory is the
directory green_threads. This directory holds the actual Java
programs. Green threads is a simulated threads library provided by
JavaSoft. If at some point we choose to create a version of Java that
uses MPE's kernel threads, a native_threads subdirectory will be