Service Oriented Architecture (SOA) - The Basics

SOA: the false, the ideal, the real

• False: SOA equals web services.
  SOA equals distributed services.
• Ideal: SOA cleanly partitions and consistently represent business services.
• Real: SOA is a fundamental change in the way we do business.

Real SOA

• Changed mindset: service-oriented context for business logic.
• Changed automation logic: service-oriented applications.
• Changed infrastructure: service-oriented technologies.
• A top-down organization transformation requiring real commitment.

SOA Characteristics

• Loosely coupled: minimizes dependencies between services.
• Contractual: adhere to agreement on service descriptions.
• Autonomous: control the business logic they encapsulate.
• Abstract: hide the business logic from the service consumers.
• Reusable: divide business logic into reusable services.
• Composable: facilitate the assembly of composite services.
• Stateless: minimize retained information specific to an activity.
• Discoverable: self-described so that they can be found and assessed.

Potential Benefits

• Based on open standards.
• Supports vendor diversity.
• Fosters intrinsic interoperability.
• Promotes discovery.
• Promotes federation.
• Fosters inherent reusability.
• Emphasizes extensibility.
• Promotes organizational agility.
• Supports incremental implementation.
• Technical architecture that adheres to and supports the principles of service orientation.

Common Misperceptions

• SOA is just Web services.
• SOA is just a marketing term.
• SOA is just distributed computing.
• SOA is a magic global solution to general interoperability.

Common Pitfalls

• Not basing SOA on standards.
• Not creating a transition plan.
• Not starting with a solid XML foundation architecture and skill set.
• Not understanding SOA performance requirements.
• Not understanding web services security.

Summing Up SOA

• Not a magic trick.
• Not a magic solution.
• Not an easy thing to do correctly.
• The wavelet of the present.
• The wave of the future.
• A useful architectural concept.
• A potential business facilitator.

Resources

• Douglas K. Barry, Web Services and Service-Oriented Architectures: the savvy manager’s guide.
• Thomas Erl, Service-Oriented Architecture: concepts, technology and design.
• Thomas Erl, Service-Oriented Architecture: a field guide to integrating XML and web services.