It depends from the nature of the payload. If I have to send text, I'll use a text based protocol because I can debug it more easily, but if I have to send binary information, I'd rather send it using well defined structures after taking into account word sizes, alignment, endianess etc. on the involved hardware. Back in the day I had to do that with small agents on different achitectures (IBM Power and x86) with different languages (C and Object Pascal), and the correct textbook way to do that was to use xml, but that way everything had to be converted to text, interpreted and then translated back for replies. No way, hardware was slow and we aimed at speed, so we used plain C/Pascal structures and no other manipulation except for adjusting type sizes and endianess if the hardware or language required so to make all modules compatible no matter what they were written in and where they would run. I also built my own tools for testing and debugging which were nothing more than agents that sent predefined packets and echoed at screen the return values, so that any error in the data would be quickly spotted, while a xml translation of a corrupt buffer could have missed any error not comprised in the marked text, hence hiding there was a problem somewhere. A solution like that is highly debatable for sure, but I'm among the ones who want their software to crash loudly at the first problem, not try hiding it until it creates a bigger damage.