Appendix 3Why Has SOA Failed So Often?




A.3.1. The need for flexibility

Facing competition that becomes tougher day after day, many large companies have struggled to improve the flexibility of their business processes and thereby gain an advantage over their competitors. Aligning the information system to business processes in order to decrease the “time to market” became the new motto. Service-oriented architecture (SOA) has been one of the most advocated solutions to meet this flexibility requirement. As a matter of fact, the various service-oriented approaches have attempted to solve two separate problems: the first is that of reusing existing components and the second is the flexibility of business processes. In Section 4.2, we presented various forms of reuse as solutions to the flexibility of requirements but obviously there are situations in which reuse is justified independently of any need for flexibility. Applying simplicity through reduction or simplicity through organization could indeed be legitimate enough reasons for reuse. Opening the system to the external world can also be considered a specific form of legitimate reuse.

As was discussed in Section 5.2, three layers are traditionally considered in software architecture: the data access layer, the service layer, and the user-interface layer.

Figure A3.1. SOA amounts to splitting the service layer into a business-process and a processing layer

Roughly speaking, introducing SOA into a classical three-tier ...

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