How to quickly and effectively learn a large and complex application with a long history and many interconnected and interdependent application systems

Ying Ding • I like this tools and test based approach. I can add ITADDM (IBM Tivoli Application Discovery Dependency Manager). This tool gives you a visualized presentation of the whole system and its interdependency as well as configuration details. http://www-01.ibm.com/software/tivoli/products/taddm/. Along with the Wily Introscope transaction monitoring capability ("Provides end-to-end transaction visibility from browser to back-end systems"), we should gain a lot insight into the application. http://www-304.ibm.com/partnerworld/gsd/solutiondetails.do?solution=23517&lc=en&stateCd=P&page=&expand=true

In my mind, ITADDM's visualization of the complete end-to-end application is highly valuable in understanding the holistic picture of the interconnected application suite and the transacation monitoring capability will reveal the dynamics of the applications.

Many large companes have unlimited license to ITADDM, but are not using it at all. I am not sure what is the driver behind the reluctance. Maybe skills level or the lack of strategic insight or both? Introscope is widely used, but need long years focused use to gain useful expertise - no easy buttons at all.