Amin,
If you are going to develop a plug-in for the streaming server as you said, I guess Darwin is a good choice. Since it is open-sourced, you can even dig into Darwin's codes, if neccessary... In the case that you do need to develop a plug-in, I suggest you to consider an open-source one... Even if it is not Darwin, you might consider another open source one...
You will find easier to develop with open-source ones... Hope it helps...
Co-author of SCMAD Exam Guide, Author of JMADPlus
SCJP1.2, CCNA, SCWCD1.4, SCBCD1.3, SCMAD1.0, SCJA1.0, SCJP6.0