I decided to add some visualization to shed light on legacy applications' inner secrets. Here is a word cloud generated from the keywords found inside a legacy FOCUS 4GL application:
After scanning the legacy libraries, I used the R statistical programming language to create a word cloud.
Somebody with an understanding of the FOCUS language can decipher this word cloud and quickly see that this application runs on a mainframe computer (e.g., the DYNAM commands) using green-screen technologies (e.g., the -CRTFORM and PFKEY commands). It is primarily a mainframe reporting application (the TABLE command) using menu navigation screens.
What is unusual is the big CASE keyword, which is a MODIFY database maintenance feature to provide procedural branching.
In this word cloud, the MODIFY count is small, the CRTFORM count is slightly bigger, and the CASE count is relatively large. Without looking, my first hunch is that somebody used the old IBI MODIFYTALK facility to automatically generate an add/update/delete online transaction application. That 1980s tool was notorious for generating a lengthy routine with lots of CASE logic.
In addition to the keywords, I could also do a word cloud of the actual database tables being accessed. If I needed more detail, I could also do word clouds for the columns of particular tables.
Since I'm a visual guy, this seems much nicer to me than looking at a spreadsheet or tabular report of numbers.
Of course, this type of visual analysis is not limited to the FOCUS product from Information Builders. It could be done for the other 4GLs (NOMAD and RAMIS) or reporting tools such as SAS, QMF/SQL, Crystal Reports, etc.
There is no reason you should not understand your legacy reporting applications.
If you are interested in learning more, just contact me.