Developing a real-time terminology plug-in

I am considering having a plug-in developed like IATE Real-Time TerminologySince I do not want to reinvent the wheel, I wonder what would be the best way to go ahead.

For example, would the content need to be in JSON or XML, would any processing for the proper handling of synonyms in Studio take place in the plug in, or should it have a specific format in the source?