According to Jonathan Mack, SOA adoption is "not nearly as ubiquitous as many of the analyst organizations and webinar publishers would suggest" today. The reason for that is very simple: successful SOA implementation is extremely challenging. The three main challenges, outlined by Jonathan, are:

• Dealing with the Pre-SOA Architecture - incorporating existing enterprise assets into SOA implementation
• Selling SOA to the Business - convincing business stakeholders, using concrete facts (not the general statements) of how SOA will yield benefits that justify its costs.
• Developing the most effective roadmap to SOA - defining the process of achieving SOA vision.

While the majority of SOA practitioners advocate building services as a thin layer on top of the existing enterprise applications, reusing functionality already in place as much as possible, such implementation is often more challenging than usually acknowledged. As Jonathan points out: