An evaluation of four patterns of interaction for integrating disparate ESBs effectively and easily

Organisations use Enterprise Service Busses (ESBs) to support enterprise application integration. For a variety of reasons – mergers and acquisitions, geographically distributed enterprise units, distributed governance, scalability – enterprises sometimes need to acquire multiple, disparate ESBs and enable the applications that each one supports to interoperate. However, currently, no standard architecture exists for integrating multiple, disparate ESBs. To begin to address this problem, four candidate disparate ESB integration patterns – directly connected, web services, homogeneous messaging middleware, and message bridge – were identified from the enterprise application integration literature and tested for their effectiveness in integrating multiple, disparate ESBs. Each pattern was applied in two different scenarios: loan broker request, and inter-divisional messaging. In each scenario a number of enterprise applications were integrated using three disparate ESBs: Oracle Service Bus, Apache ServiceMix, and Mule ESB. The experiments were designed to test how well the different patterns supported effective integration of different ESBs. The results indicate that the web services and homogeneous messaging middleware patterns are the best for integrating disparate EBS effectively and with minimal difficulty. In addition, it was discovered that the degree to which ESB integration could be achieved depended upon the number of ESBs being integrated, the relevant skills of the integration team, and the types of the ESBs. The results may be of practical benefit to the communities engaged in enterprise application integration research and practice.