Tools for experimental Protocol Design & Development?

Question

Are there any open source, high level tools that would facilitate and simplify development of experimental network protocols (TCP/UDP) using a GUI?

Basically, something

Answer 1

Give up the GUI for a text editor and enter the world of protocol specification languages. Most of these tools take a description of some protocol, try to prove it's not broken, and generate an implementation and tests. Here's a few to get you started, but there's many more:

• Ragel
• APC
• SPIN