6. Determine criteria for specification selection

Objective    Approach     Inputs     Activities    Outputs

Objective

The objective of this step is to develop a set of criteria for choosing specifications and portfolios of specifications.

Approach

Choosing the right criteria is vital if the final architecture is to meet its objectives. These criteria will depend on the existing system and the overall objectives for the new architecture. The overall objectives should be developed from the organization's business goals, so it is hard to give specific advice here, but some example objectives are listed in Part IV, Business Scenarios.

Here are some example criteria, selected by a large government organization with the intention of building a stable and widely applicable architecture:

A standard or specification:

• Must meet the organization's requirements
• Must meet legal requirements
• Should be a publicly available specification
• Should have been developed by a process which sought a high level of consensus from a wide variety of sources
• Should be supported by a range of readily available products
• Should be complete
• Should be well understood, mature technology
• Should be testable, so that components or products can be checked for conformance
• Should support internationalization
• Should have no serious implications for ongoing support of legacy systems
• Should be stable
• Should be in wide use
• Should have few, if any problems or limitations

A high level of consensus is often considered the most important factor by large organizations because standards and specifications chosen have to accommodate a wide range of user needs. For example, in determining the level of consensus for standards in their architecture, the Application Portability Profile or APP, the US National Institute for Standards and Technology prefers to use international standards for the basis of specifications. The process through which these international standards have evolved requires a very high level of consensus. A number of US Federal Information Processing Standards (FIPS) specified in the APP are based on approved international standards. The use of international standards has significant benefits for any organization which works or trades with organizations in other countries.

Inputs

The inputs to this step are:

• Business Architecture Version 2
• Technical Architecture Version 0.5
• Standards Information Base

Activities

Key activities in this step include:

1. Brainstorm criteria for choosing specifications and portfolios of specifications relying on previously used criteria for existing system and extrapolating for new architectural elements.
2. Meet with sponsors and present current state to negotiate a continue request from sponsors.

Outputs

The outputs of this step are:

• Technical Architecture Version 0.6
  • Technical Architecture - Requirements Traceability (standards selection criteria)

Step 7: Complete architecture definition

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