Re-Implement 3rd party TCP Java client

Question

I need to know if there are any tools to figure out the interface to a TCP client. My Company has purchased a 3rd party tool and we really like the Server side and most of the client side.

I would like to see if I can figure out the calls that the client side makes to the server so I can create the client side functionality we want.

I have been able to figure out what the port number and protocol that the client communicates with the server on. Since we host the server, I have full access to that too.

Any ideas on how to get hold of and execute the methods that the client app is calling on the server?

I am not that good at java, so I would like to use C#.NET if at all possible. Does that sound feasible?

NOTE: I have done something like this before (connect to a 3rd party Java Based Server with a custom .NET client) but that time I had a bit of documentation to get me started. This time I have nothing.

Any Help will be greatly appreciated.

Also, if you know better tags for this please post them as comments (or just re-tag if you have the permissions)

Answer 1

If you're trying to reverse engineer the protocol so you can write your own client to the server, get Wireshark. You can use it to follow the conversation between client and server.

Answer 2

You could attempt to decompile the library. That should give you all of the low-level info that you need.

Answer 3

You could also use TCPMon to grab the exact message text passed between client and server.