approaches to organise event handling with increasing software complexity

Question

I am trying to use the Model View Presenter (MVP) pattern for a software that I am writing. I am using C# and Windows Forms, althought that should not matter for answering my question.

I have multiple "MVP-structures". One, for example, is handling retained mode graphics where I can draw geometric shapes on a canvas. Another one is taking these shapes, doing some analysis on them and putting the result somewhere else. There are potentially many events that cause controllers to manipulate data somewhere which then causes cascading manipulation of data in yet another place and so forth.

My fear is that I will eventually loose track of what is changing what if I do not organise my software properly. I can think of two ways to organise the interactions between programm parts occuring in my software: either hierarchical or switch board-like.

My question is: Are there any well known approaches or patterns, that I should look up to organise my software? I would need a starting point for my web search.

Answer 1

I think your intuition is right. If you create many events that cascade you are going to end in trouble. I've seen many times over-complex applications due to out of control eventing. This makes the code very difficult to debug and improve.

First thing it came to my mind was the mediator pattern. Elaborating a bit more I would have central classes that manage parts of the business logic. I would have the model in each of the MVP lightweight , basically being a client that asks the server (one of this controller classes) for more complicated business logic. The idea is to have every model of the MVP classes interacting with as few classes as possible (core business logic) and avoid interacting with other MVPs (which will have more specific business logic)

In any case I would limit as much as possible the classes that throw and listen to events and would centralize this in as few places as possible. The observer pattern can help here. Also having a client-server architecture with a service layer containing the heavy business logic can help making this decoupled and maintanable in the future.

The pattern service layer from the fowler classic "patterns of enterprise application architecture" could be good reading too.