Open source ESB tools have been getting a lot of press lately with the availability of Apache ServiceMix, Mule,
and Progress Software's FUSE. Jess Thompson, Research Vice President at Gartner, said that Open Source ESBs make sense if you are careful during the development process to be standards conformant. This involves using XML over HTTP or a Web services based approach and constraining development to the base WS stack. But when you contemplate moving to production, the risk of encountering a bug is too much for all but leading-edge organizations, which are willing to trade risks for the competitive advantage they obtain.
Over 90% of open source ESB software is only downloaded to test it out. Thompson said the main problem is that it is not supported. While he acknowledges that organizations like MuleSource and Progress Software provide some support, it is not of the same caliber as that provided by IBM and Oracle. "The use of the technology does not go into products. The reason is that most CIOs are terribly reluctant to put into production anything that depends on technology that is not supported," said Thompson.
Open source software can theoretically be acquired for free, and Thompson said that CIOs are attracted to products where they don't have to show a capital expense. However, an open source ESB can still have costs. "If the operational expenses are high in terms of staffing, the overall cost of ownership for open source can be higher than for licensed technology," said Thompson. "Then there are the higher risks the CIO takes with a technology that is less proven than a commercial product."