The following shows an example of how to capture information for Architectural Mechanism. The attributes of two possible mechanisms are shown: Persistence and Communication.

Persistence

For all classes with instances that may become persistent, you need to identify:

• Granularity: What is the range of size of the objects to keep persistent?

• Volume: How many objects (number) do you need to keep persistent?

• Duration: How long does the object typically need to be kept?

• Retrieval mechanism: How is a given object uniquely identified and retrieved?

• Update frequency: Are the objects more or less constant? Are they permanently updated?

• Reliability: Do the objects need to survive a crash of the process, the processor, or the whole system?

Communication

For all model elements that need to communicate with components or services that are running in other processes or threads, you need to identify:

• Latency: How fast must processes communicate with another?

• Synchronicity: Asynchronous communication

• Size of message: A spectrum might be more appropriate than a single number

• Protocol: Flow control, buffering, and so on

Notice that there is no design-level information or specification here. Instead, this is more about collating and refining architecturally significant requirements.