Find Missing Custodial Requirements (Process Notes 7.1.5)


Custodial processing relates to the maintenance or housekeeping for the system's stored data. Most systems store data that must be able to be changed. For example, the addresses of customers change from time to time. The processing necessary to keep the address up-to-date has nothing to do with the fundamental activities of the systemthis is the custodial processing.

For each item of stored data, determine whether it has any custodial requirements. Should the user be able to change, or perhaps delete, it? Can the custodial activity be part of a fundamental process, or must you establish a new event/use case?

Also, examine the context model for data flows from the outside that indicate data to be changed. Look for flows that directly change stored data, such as "Customer Address Change." As some of these may be missing from the context, look for flows that bring data into the system that may need to be changed. For example, perhaps a flow establishes a new customer. The data stored by this activity would have to be changed at some point in the future. If it is missing, add the changing data flow to the context, and make it a requirement to change the stored data.

Consider all of the external entities for the system. If it is a service provider (e.g., if it manufactures goods handled by the system or transports goods), then there may be a need to create, change, and delete the information held about this external entity.

Similarly, inspect all of the data items stored by the system. Determine whether they need to be maintained in any way.

Finally, determine whether the maintenance must be a separate requirement or whether it can be included in the same events/use cases as other fundamental requirements.

Diagram 7.2. Evaluate Requirements Risk





Mastering the Requirements Process
Mastering the Requirements Process (2nd Edition)
ISBN: 0321419499
EAN: 2147483647
Year: 2006
Pages: 371

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