Labeler is a Java application which uses the PDS/PPI ruleset processor to generate PDS labels for files. It can be run from the command-line or may be embedded in Java servlets.
Here's what is available
Ruleset Language reference document
User's guide
Source code: labeler.java
Compiled Java Application: labeler.class
Installation instructions
1. Place the "labeler.class" file in $JAVA_HOME/jre/lib/pdsppi
2. Add "$JAVA_HOME/jre/lib/pdsppi" to your CLASSPATH environment variable.
Note: The application also uses the PDS Label parser, PDS/PPI Ruleset Processor, IGPP classes (iggp.jar) and Javax Servlet (javax.servlet.jar).
You will need to download these Jar files as well.
Some examples
Example ruleset to process a file.
Example ruleset for constants
Example template
A servlet that calls the Labeler to generate a response
<%@ page language="java" contentType="text/html" %>
<%@ page import="ruleset.Labeler" %>
<%
    ruleset.Labeler example = new ruleset.Labeler();
    example.setOutput(out);
    example.processItem("example.rul", "example.dat");
%>
Important additional information.Read This