GF API has rich functionality, but isn't suitable for every task.
Some trading systems can benefit from using GAIN Futures FIX instead of GF API. GAIN Futures FIX can be better when:
Your application doesn't need post-processed chart data
Your application already has FIX gateways to other brokers
Your application is running on Linux or on Java platform
If you are not familiar with the FIX protocol, we would recommend QuickFIX Engine as a starting point.