Step 2 is to consider different architecture reference models, viewpoints, and tools.
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The objective of this step is to perform an analysis of the Technology Architecture from a number of different concerns (requirements) or viewpoints and to document each relevant viewpoint. The purpose of considering these viewpoints is to ensure that all relevant stakeholder concerns will have been considered in the final Technology Architecture, so ensuring that the target system will meet all the requirements put on it.
The Business Architecture is used to select the most relevant viewpoints for the project. It is important to recognize that in practice it will be rarely possible to reach 100% coverage of stakeholder concerns.
Pertinent viewpoints are created first from the existing system to identify the salient elements of the current systems requirements that the stakeholders confirm must also be satisfied in the target system. A comprehensive set of stakeholder viewpoints must also be created for the target system. The corresponding views of the existing system will be compared with the views of the target system to identify elements of the existing system that are intended for replacement or improvement.
If a set of viewpoints is carefully chosen, it will expose the most important aspects of the existing architecture and the requirements of the target system.
Several different viewpoints may be useful. Architecture viewpoints and views are described in greater detail in Book 3: Developing Architecture Views. The viewpoints presented there should not be considered an exhaustive set, but simply a starting point. In developing a Technology Architecture, it is very likely that some of the viewpoints given there will not be useful, while others not given there will be essential. Again, use the Business Architecture as a guide in selecting the pertinent viewpoints.
The inputs to Step 2 are:
Request for Architecture Work (see Request for Architecture Work)
Statement of Architecture Work (see Major Output Descriptions)
Business Architecture V2
Technology Architecture V0.1
Key activities in Step 2 include:
Select relevant Technology Architecture resources (reference models, patterns, etc.) from the Architecture Continuum, on the basis of the business drivers, and the stakeholders and concerns.
Select relevant Technology Architecture viewpoints; i.e., those that will enable the architect to demonstrate how the stakeholder concerns are being addressed in the Technology Architecture. (See Book 3: Developing Architecture Views for examples).
Document the selected viewpoints, if not already documented.
Consider using ANSI/IEEE Std 1471-2000 as a guide for documenting a viewpoint.
A primary reference model will be the TOGAF TRM. Other reference models will be taken from the Architecture Continuum.
Consider developing at least the following views:
Networked Computing/Hardware view
Communications view
Processing view
Cost view
Standards view
Brainstorm and document technical constraints deriving from analysis of the concerns, and ensure they are covered by the viewpoints.
Identify appropriate tools and techniques to be used for capture, modeling, and analysis, in association with the selected viewpoints. Depending on the degree of sophistication warranted, these may comprise simple documents or spreadsheets, or more sophisticated modeling tools and techniques.
Perform trade-off analysis to resolve conflicts (if any) among the different viewpoints.
One method of doing this is CMU/SEI's Architecture Trade-off Analysis (ATA) Method (refer to www.sei.cmu.edu/ata/ata_method.html).
The outputs of Step 2 are:
Technology Architecture V0.2
Technology Architecture - architecture viewpoints:
Networked Computing/Hardware view
Communications view
Processing view
Cost view
Standards view
Technology Architecture - constraints