I am complete beginner in uml and need to make diagrams to show use and structure of current information system in organization. They use one system for manufacturing and one for accounting, warehousing and HR. First I want to do use cases with description. First question is should i do it by module (each area of business they cover)?
Then i need a diagram to view connections between the systems. Is it okay to use component diagram or which diagram is more appropriate? If company uses Office 365 does it show in diagram? Also if system supports EDI should i also include it?
Thanks for help.
As always: It depends.
Use cases are about added value. If you are going to document a complex system it's a good idea to group things. For a company a grouping by organizations would be reasonable. Though there are often horizontal (single focus) and vertical (needed in multiple area) departments. If the focus is to "re-invent" you should probably decouple your view. Anyhow, finding real use cases is a difficult task. So during synthesizing them you will likely find out how to group them logically.
Starting with components is also a good idea. You can use component instances showing concrete uses (with locations shown via packages). These concrete components can be abstracted to general components so you known which different basic components are used (package them centrally). Interfaces between components can be shown by assembly connectors (those with socket/lollipop). Later you can detail important components using ports and interfaces. Other components can be left peripherally without more details. Whether EDI/Office are "important" depends. Include them generally and find out in discussions during analysis whether details are needed.