This code snippet on the CA Wiki shows how you can retrieve the unique id for a composite application. Like Eclipse perspective Id’s, each application has a unique application idenitifier. This means you can use this in many ways to idenitify or link to an application. The CAI URL actually uses this id to resolve what application should be loaded. We have an article that is pretty popular that uses the CAI url, Passing context to components when opening composite applications.
The code snippet uses the current Eclipse perspective and finds what composite application the current page is in. Once you get the perspective Id you can query the Topology API’s for all kinds of application, page, and component properties. So a creative developer could put tickler data elements on applications, pages or components and look for them in special cases.