Pretty simple

Init

• First of all you make connection to it - server is listening on /debuginp and outputs on /debugout
• Then you init debugger by sending program and input params(for sending input params more detailed - see Rest api page in wiki) to debugger. Send this stuff on /coffeedebugger/debuginp (everything in json obliviously) with "command" param as "init", "app" param as your brainfuck code, and "args" param as your input.
• Use it!

Running

• To make a step forward send "command" parameter as "next" to /coffeedebugger/debuginp
• To make a step backward send "command" param as "prev" to /coffeedebugger/debuginp