My supervisor has asked me to start doing some research about different middleware packages. I have collected a lot of information about a few different packages and I was wondering what other people out there were actually working with.

My first question, does anybody have expereince working with any middleware packages, if so what packages? What do you prefer? What don't you like?

If you could compare the above mentioned middlware packages do so. Don't leave out complaints or opinions.

Finally is there anything you would suggest when looking for a middleware package?