Remember that programs in the real world get modified constantly. We must prepare for this. Therefore , don't give too much responsibility to any one object unless it can use other objects to help it with its tasks. Each object should have one major responsibility . If an object has more than one responsibility, they must be closely related.
Clients are also objects.
Each client needs to know which objects provide it services. Therefore , when you write down a client object, list the server objects that it must communicate with. Connect clients to servers . You may want to do this with pictures as well, but each object needs a listing of its servers. In the picture, an arrow from a client to each of its servers is standard documentation practice.