The following FMC diagram shows the interaction between the identified subsystems and the data types. (If you're unfamiliar with FMC: rectangles are actors, rounded boxes and circles are memories of all types, arrows to actors are read accesses, arrows from actors are write accesses, dashed arrows are pointers)
Note that the networking actor could also be used to read from local (but frequently updated) files or even command pipes. So maybe the name is not as perfect as possible.
When we abstract feed data to all the possibilities of the current syndicating standards (RSS, CDF, Atom, OCS and OPML) and define that each feed should be updated only once at a time we get the following data relations.
The next step is to refine the analysis of the subsystems. See GUIAnalysis , BackendAnalysis and NetworkingAnalysis
Please post comments, suggestions, errors...