The appeal of open source has always been the cost, or lack thereof. But because open source products are often of relatively narrow scope, several products would be needed to create a complete technology stack. That presents an integration challenge not found with more comprehensive commercial offerings.
In the book Open Source SOA, software architect Jeff Davis designs a complete SOA technology stack made entirely of open source products. Davis provides a detailed analysis of why each product was chosen, and gives thorough walkthroughs on how to use each of them. Specific products covered include JBoss jBPM software, the Apache Synapse ESB, and the WSO2 Registry metadata repository, among others.
Though each product is covered in fine detail, throughout the book Davis retains a focus on the greater challenge: Integrating the products together to create a capable SOA stack. In chapter two, available as a free excerpt, Davis explains why he chose each tool for each task, and presents some alternative choices. The remainder of the book contains the detailed integration and implementation instructions for each tool selected in order to compose an open source SOA.