Basic Customization > Windchill Customization Basics > Managing Customizations > Best Practices for Customizing Files Supplied by PTC > Managing Client JAR Files
  
Managing Client JAR Files
Clients need to have the same versions of client JAR files as those located on the Windchill server in <Windchill>/codebase. Customizations to displayed text and properties can require that JAR files downloaded to clients are updated.
* 
When the client JAR files are updated, clients download them from the Windchill server as the applications detect the previously downloaded JAR files are out-of-date.
There are two times when you need to ensure that the client JAR files have been updated by rebuilding the files. Rebuild client JAR files:
As part of installing a maintenance release.
When customizations have been made that affect the client JAR files
* 
When updating for a maintenance release, running Windchill Service Pack installer with the Complete installation type rebuilds all client JAR files as needed. If you make new customizations or re-install existing customizations after running this installer, you must manually rebuild the client JAR files.
Most client JARs are maintained through the use of an Ant script, MakeJar.xml, provided with Windchill. To ensure that the JAR files maintained through the MakeJar.xml script are updated correctly, you should add the following to the <Windchill>/codebase/jarContents/Cust.bom:
Paths for the compiled resources (*.ser and/or *.class files) of the files you change
Paths of customized property files
To verify that all customized property files are listed in Cust.bom, you can compare targetFile entries in site.xconf with the files listed in Cust.bom. Any files listed in targetFile entries that are not in Cust.bom should be added to Cust.bom. For example, if the site.xconf file has an entry for the following:
targetFile="codebase/wt/change2/change2.properties"
Then, ensure that codebase/jarContents/Cust.bom contains the following entry:
wt/change2/change2.properties
To rebuild the client JAR files that are managed by jarContents and jarManifest specifications, execute the following command from a Windchill shell:
ant -f codebase/MakeJar.xml custUpdate
See Rebuilding Client JARs for more information.