npace writes "I've been noticing more and more mid-sized companies leaning towards open-source solutions for the past few years. The current economy certainly makes the companies tighter when it comes to budget. I've recently been tasked with exploring open-source solutions that can replace our existing expensive, commercial middleware appliance. Since there are no sales people telling me that they have the perfect product that fits my needs, I've been installing different ESBs like Apache ServiceMix, SUN's Glassfish OpenESB and others. What I'm looking for is it being able to connect to various different databases, execute RFCs in the SAP ERP system, send emails, transform XML files, and solve the world's energy problem. Most of the open-source ESBs support these requirements but what I'm also looking for are standards. I'm leaning towards an Eclipse development environment and (hopefully) BPEL I'd also prefer that there is commercial 24/7 support available for cheap. Really, my question is "Which one do I pick?" but I'd settle with your opinions and feedback on Middlewares/ESBs you have used and like or don't like."