An Enterprise Service Bus, or ESB, can provide many advantages and efficiencies for a business: Process and services can be centralized and streamlined; reliability and scalability can be provided for core business activity; and a cutting-edge service-oriented architecture can connect you, your partners and all core data systems.
All of this comes at a cost, however—most serious ESB implementations will set your business back by six figures, and that doesnt include support and possible consultant fees.
But there is another avenue to a robust ESB implementation, one thats making all manner of enterprise applications more widely accessible: open source.
Celtix is backed by and uses code provided by Iona, though it is completely unrelated to Ionas Artix ESB. Celtix is licensed under both the standard GNU LGPL (Lesser General Public License) and the Eclipse Public License.
Mule doesnt appear to use any public open-source license; it seems to have an open-source-inspired license from SymphonySoft, the company that provides and supports Mule.
Our tests show that these open-source applications provide solid core ESB functionality, from JMS (Java Message System)- and IP-based connectivity to strong support for SOA (service-oriented architecture) standards such as SOAP (Simple Object Access Protocol).
However, both Celtix and Mule are mainly engines, and organizations looking for advanced interfaces such as those provided by commercial ESBs will probably be disappointed. Both products offer plug-in options for the Eclipse development environment, but we found the plug-ins fairly basic in form, serving mostly to assist in accessing the ESB during services development.
Mule looked to be more mature than Celtix, with broader transport and Web standards support. We also liked that Mule integrates with the J2EE Spring framework, which should make it easier to integrate Mule with complex J2EE applications.
For open-source projects—especially relatively new ones—both of these products have pretty good support options. As part of the ObjectWeb Consortium, Celtix has some of the top middleware companies behind it, and several high-level training options are offered. SymphonySoft, the company behind Mule, offers standard corporate support options.
Companies hoping to build a complete open-source SOA stack can combine these ESB engines with a host of other Java-based open-source projects, including the Tomcat application server, the ActiveMQ messaging service and software project management tools such as Apache Maven.
Labs Director Jim Rapoza can be reached at firstname.lastname@example.org.