Middle-ware

Hello Guys!!!
i know this might not be the right place to put this thread, but this is the most appropirate i could find.

i was interested in getting information about the middleware as i am doing software middleware couce, and i really do not know any thing about:
1. what is middleware.
2. what are the middleware technologies.
3. how do we identify the middleware.
4. how can we design and implement middleware.

i did try to find some of the information on google, but it was not much.
i wonder if someone can help me by directing me to some resources.
Thanks for your time and patience.
Regards
Harbir