SOA principles

SOA principles

The following guiding principles define the ground rules for development, maintenance, and usage of the SOA^[8]

• Reuse, granularity, modularity, composability, componentization, and interoperability
• Compliance to standards (both common and industry-specific)
• Services identification and categorization, provisioning and delivery, and monitoring and tracking

The following specific architectural principles for design and service definition focus on specific themes that influence the intrinsic behaviour of a system and the style of its design:

• Service Encapsulation - A lot of existing web-services are consolidated to be used under the SOA Architecture. Many a times, such services have not been planned to be under SOA.
• Service Loose coupling - Services maintain a relationship that minimizes dependencies and only requires that they maintain an awareness of each other
• Service contract - Services adhere to a communications agreement, as defined collectively by one or more service description documents
• Service abstraction - Beyond what is described in the service contract, services hide logic from the outside world
• Service reusability - Logic is divided into services with the intention of promoting reuse
• Service composability - Collections of services can be coordinated and assembled to form composite services
• Service autonomy – Services have control over the logic they encapsulate
• Service optimization – All else equal, high-quality services are generally considered preferable to low-quality ones
• Service discoverability – Services are designed to be outwardly descriptive so that they can be found and assessed via available discovery mechanisms^[9]

In addition, the following factors should also be taken into account when defining a SOA implementation:

• SOA Reference Architecture covers the SOA Reference Architecture, which provides a worked design of an enterprise-wide SOA implementation with detailed architecture diagrams, component descriptions, detailed requirements, design patterns, opinions about standards, patterns on regulation compliance, standards templates etc.^[10]
• Life cycle management SOA Practitioners Guide Part 3: Introduction to Services Lifecycle introduces the Services Lifecycle and provides a detailed process for services management though the service lifecycle, from inception through to retirement or repurposing of the services. It also contains an appendix that includes organization and governance best practices, templates, comments on key SOA standards, and recommended links for more information.
• Efficient use of system resources
• Service maturity and performance
• EAI Enterprise Application Integration