while doing research for my own platform (C#) I'm developing right now (still being in the first steps) there is also the issue to connect to a broker for datafeed (especially L2-Data), trades and my own DOM. At the moment my application is requesting it's data from Multicharts because that program is continuous collecting data from IB. Beside the existing CSV-Import its far better to have a direct broker API addressed to send the data and watch/handle trades. As I'm using IB for myself I come upon this thread and wondering what you've done in the end.
Thanks for the information regarding the frequent API-Changes on IB side but is there a real experience regarding a custom IB-Connector needing changes ... is it really that often that the custom connector needs to be changed due to the IB-API-Changes? In this case it shouldn't matter whether the connector is in C++ or Java.