Documentation for usage for libnfc-llcp is as far as i can see quite scarce
Yes it is. But keep in mind that the code is under development and that the "public" API is not yet in place (well we have low level functions for transmitting LLC PDUs, but nothing "high-level"). This public API will hopefully has it's sibling man pages at the end. ATM, I am trying to fix LLC disconnections before working on this user-level public API. Stay tuned!
i couldnt get Cutter Testing tool and log4c (again both with very little help for usage) for the log messages to work.
ATM the log messages are really a plus, so you will definitively need them for hacking. Note that cutter only provide unit tests so it is not required to have cutter to use the logging feature. For log4c, once you have the headers / lib available (if your system has different packages for header files double-check they are installed) the autotools should automatically detect and use it (don't forget to run autoreconf again if you where missing the log4c developpment files). Check the ./configure output to see if the script has been looking for log4c and evetually found it.
And i am clueless what you mean by creating that service. I tried to run the llcp-test-server, and it hang somewhere in the initialisation, tracked it down with my own printfs to nfc_target_init.
Right now there is no convenient API to do so. I am planning to "port" pynfc's client test application in C in the tools/llcp-test-client directory but for now, the disconnection is not robust enough so I am focussing on this point. When the client will provide some real tests, you will probably easierly figure-out how to proceed for chatting with another LLC device.
And in nfcpy i had a strange error regarding an unexpected return value (an array instead of a string ..) in a python library.
I got dozens of errors of this kind when testing the libnfc-llcp with the test-client of pynfc. It seems that error checking is sparce, so instead of reporting the problems as soon as they occured, python fails a few lines later with some unrelated error message.
So to sum-up, for the moment, if you want to see the libnfc-llcp in action, you can try to compile it against log4c and use the test-server with a NFC device and pynfc's test-client with aonther device. FYI, I work with a SCL3711 and microbuilder's PN532 NFC Breakout Board. I pluged-in an arygon in place of the microbuilder board and it seems to be okay too. All the rest is untested :-)