A Rationale-based Model for Architecture Design Reasoning

3.3. Existing methods for capturing and representing design rationale
3.3.6 Views and Beyond (V&B)
Views and Beyond is a collection of methods proposed by Clements et al. to document
software architecture [23]. It proposes a number of view types to represent software architecture:
Module Viewtype, Component-and-Connector Viewtype and the Allocation
Viewtype. Each viewtype gives a different perspective of the structure of the system. For
instance, the module viewtype has several representation styles such as decomposition of
code and layering of modules.
As well as documenting what the architecture is, they argue that it is important to
document why the architecture is what it is. Many decisions are made in a design and not
all decisions need to be justified. A number of principles to guide decision documentation
are suggested:
• Design team have spent significant time evaluating the options for the decision
• Decision is critical to the achievement of the requirement/goal
• Decision requires considerations of non-trivial background information
• Issues in a non trivial decision
• Decision has a widespread implication to the rest of the architecture design and will
be difficult to undo
• It is more cost-effective to document the decision now rather than later
Similar to ADDT, they take a pragmatic approach to documenting design rationale.
Instead of documenting the deliberation relationship, the following information, which is
centric to a decision, is documented:
• Decision - a summary of the decision
• Constraints - key constraints that rule out possibilities
• Alternatives - options that have been considered and the reasons of ruling them out
• Effects - the implications and ramifications of the decision
• Evidence - any confirmation that the decision was a good one
This list of design rationales can be easily mapped to the ADDT template. ADDT
provides a more comprehensive classification to assist designers to capture all the design
rationale. The V&B template is more general and easier to implement.
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