jNetStream is a sniffer and a protocol analyzer. Includes applications and library. 100s of protocols are defined. Includes scripting. It is appropriate for custom protocol development, grad students, and network teachers/professors. Full SDK included.
ProtocolAnalyser provides an integrated develop environment for
generating a protocol-decoder. With a programable kernel, it can
support variety of protocols. Here is a framework of such a software,
hoping it will help you a lot.