We are required to integrate WCI API with 3 different internal systems , which is the best way to integrate and what are the pros and cons.
1) Directly consume the web service into respective systems .
2) Is It require to access via proxy gateway way server .
Without any context, there's no easy answer to that question as it is not a generic product question but more an implementation question. Since you have an open case, let's take this off-line. You can route your question through your project team.