Databases Reference
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around the lifecycle of your data. You might have one use case for adding new
records, one for listing records, one for searching, and one for exporting data,
for example.
Estimate effort level for each use case for each architecture
—For each use case, you'll
determine a rough estimate of the level of effort that's required and apply a
scoring system, such as 1 for difficult and 5 for easy. As you determine your
effort, you'll place the appropriate number for each use case into a spread-
sheet, as shown in figure 12.3.
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Use weighted scores to rank each architecture
—In this stage, you'll combine the effort
level with some type of weight to create a single score for each architecture.
Items that are critical to the success of the project and that are easy to imple-
ment will get the highest scores. Items that are lower in priority and not easy to
implement will get lower scores. By adding up the weighted scores, as shown in
figure 12.4, you'll generate a composite score that can be used to compare each
architecture.
In the first pass at weighting, effort and estimation may be rough. You can
start with a simple scale of High, Medium, and Low. As you become more com-
fortable with the results, you can add a finer scale of 1-5, using a higher num-
ber for lower effort.
How each use case is weighted against the others should also help your
group build consensus on the relative importance of each feature. Use cases
can also be used to understand risk factors of the project. Features marked
as critical will need special attention by project managers doing project risk
assessment.
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Document results
—Each step in the architecture trade-off process creates a set of
documents that can be combined into a report and distributed to your stake-
holders. The report will contain starting points for the information you need to
communicate to your stakeholders. These documents can be shared in many
forms, such as a report-driven website,
MS
Word documents, spreadsheets and
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Figure 12.3
A sample architecture trade-off score card for a specific project with categorized
use cases. For simplicity, all of the use cases have the same weighted value.
