Service Oriented Architecture


Total Cost of Ownership

Total Cost of Ownership (TCO) is a concept by which all costs associated with the purchase of a hardware or software product over a given time period are accounted for.
These costs include the purchasing, owning, operating and support costs. The TCO is useful in optimising and consolidating products.


A Services Based Architecture is a IT management and architectural approach that classifies services and the service components that implement them, with respect to how they support business and architecture objectives.
Service Based Architecture is an idea that focuses on delivering effective, reliable and flexible IT services as a way to controlling their costs and efficiency. It changes the IT department from running as a cost centre into one running as a mini business unit.
Service Based Architecture is not just a view of IT services seen from a technology perspective, but is a different business model for supporting the business users.
Instead of simply being seen as delivering off the shelf products and developing new bespoke applications, the IT department is now providing a complete service in the same way as an organisation may interact with a software product vendor.

Architecture Building Blocks

Architecture Building Blocks are large granularity pre-defined Service Components. TOGAF focuses on Architecture Building Blocks.

  • A Service Component a package of functionality defined to meet the Service needed by a System.
  • A Service Component has published interfaces to access the services it provides.
  • A Service Component may inter-operate with other, interdependent Service Components.
  • A Service Component has already been implemented and has a well defined context and guide to its usage and is already supported by technology and support staff.
  • A Service Component will be assembled from other Service Components and Infrastructure Service Components.

Ideally a Service Component is reusable in many different contexts.
A Service Component may have multiple implementations over time but will still provide the same Service.

Service Areas and Service Categories

The Service Areas and Service Categories enable the structured definition of standardised Service based applications and products.
They can be viewed as a set of layers (or 'Technology Stack') that structures the Application and Technical Architecture models from the presentation layer through the application services and application platform components to the underlying operating system, hardware and infrastructure.
The Service Areas and Service Categories are defined in the Technical Reference Model.

Service layers

Service Layers

Component Based Development

A system development process that places components and services at the heart of the development activities, with explicit reuse of services and components governed by the Enterprise Architecture.

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