When you develop a SAP Java application (Portal, PI, WDJ, Neo) you do not have to take too much care into the Java classes used by your project. The Eclipse SDK is already handling this. Nevertheless, from time to time you may want to know more about the Java classes packaged in JAR files used by your applications. Alternatively, you even get charged in providing reports detailing the class references your project is using, or even tasked with creating reports that show the Java classes used in a NetWeaver installation.
One tool that helps you in getting reports out of the content of JAR files is tattletale.A look at the feature list shows that several of it are appealing:
- “Identify dependencies between JAR files
- Spot if a class/package is located in multiple JAR files
- Spot if the same JAR file is located in multiple locations
- With a list of what each JAR file requires and provides
- Locate a class in a JAR file” 
The most obvious use case where the reports tattletale provides helps you is finding “that CLASS” that is somehow missing (ex: JCA use cases). It reports the dependencies your application has as well as finding a duplicate (outdated) CLASS inside a JAR file.
Two directory that contain valuable JAR packages from SAP are:
SAP NetWeaver AS Java: 7.0x
SAP NetWeaver AS Java: 7.3x
To get a list of SAP jars you only have to run tattletale against these directories to get the reports.
It takes a time for tattletale to create the reports, but this is a one time task (per SP, EHP or even release). Still, in my case, the report generation took 30 minutes for the sap.com folder. The reports are rather large. For 7.0x it’s more than 320 MB.
The JAR files another JAR file depends on
Details about a JAR file
Tattletale can also be run against a single WAR or EAR file:
./java/bin/java -Xmx512m -jar tattletale.jar com.tobias.trn.test.war ./reports/
There can be many, many JAR files inside a directory like apps/sap.com. If this is the case, tattletale will exit with an OOME:
./java/bin/java -jar tattletale.jar /usr/sap/CTB/JC00/j2ee/cluster/server0/apps/sap.com/ ./reports/
Exception in thread “main” java.lang.OutOfMemoryError: Java heap space
Adjust the heap size to a value high enough like :
./java/bin/java -Xmx512m -jar tattletale.jar /usr/sap/CTB/JC00/j2ee/cluster/server0/apps/sap.com/ ./reports/
Tattletale needs Java 5 to run. In case your NetWeaver is <7.1, you’ll have to install Java 5.
 Tattletale home page http://www.jboss.org/tattletale