Currently I am working on a project which has two sub system: a web application and a web API (consumed by android app) and both being developed as separate project since the API system need to deploy on different server but will access same database. After gathering requirements and producing Use cases, I have designed all the system functionalities as a single system (as a single use case diagram and I have not explicitly designed separate diagrams e.g. communication diagram, state diagram etc. for web application and API). So, my problem lies here. For instance, while producing the class diagram, I found the functions getProductDetails() (a function called from android/web api) and addNewProduct() (function called from web application) belongs to same class Product. In this case, how would I transform class diagram into coding considering the fact that function will implemented in two distinct sub-system?
Do I have to produce the same class in both system? In this case, addNewProduct() function for API system would be useless and vice versa.
Or do I have to design separate design for both system?
Any ideas on designing the class diagram would be very appreciated. PS. I am newbie in system design, so I am eager to have any good guidance from you guys.