As part of the OGCE project, the Java CoG Kit developers have created a Grid abstraction layer (developed as part of the OGCE project) for performing common grid tasks. This layer's API and programming patterns are extensively documented on the Java CoG web site. The Grid abstraction layer hides the difference between different Grid toolkit providers and toolkit versions. For example, you can program to your Globus 2 and Globus 4 installations with identical portal clients.
The OGCE installation process places generally required Java CoG and supporting jars in Tomcat's /shared/lib directory. Because of jar incompatibilities between different toolkit versions, we place these in the directory apache-tomcat-5.5.x/cog-libs/$provider_name, where $provider_name is the toolkit name and version (such as "gt4_0_0"). These jars are not in Tomcat's classpath and are dynamically loaded by the CoG Kit instead. This allows you to connect to multiple Grid installations with the same portlet.