Section 9.2. Building a Timing Diagram from a Sequence Diagram

9.2. Building a Timing Diagram from a Sequence Diagram

Let's assemble a timing diagram from scratch. We're going to work from the same example used in the communication and sequence diagram chapters, the Create a new Regular Blog Account interaction, shown in Figure 9-3.

Figure 9-3. A sequence diagram contains very little, if any, information about timing, and its main focus is the order of events within an interaction

9.2.1. Timing Constraints in System Requirements

The interaction shown in Figure 9-3 was originally the result of a requirement such as the one described in Requirement A.2.

Requirement A.2

The content management system shall allow an administrator to create a new regular blog account, provided the personal details of the author are verified using the Author Credentials Database.

Now, let's extend the original requirement with some timing considerations so that we've got something to add by modeling the interaction in a timing diagram.

Requirement A.2 (Updated)

The content management system shall allow an administrator to create a new regular blog account within five seconds of the information being entered, provided the personal details of the author are verified using the Author Credentials Database.

Requirement A.2 has been modified to include a timing constraint that dictates how long it should take for the system to accept, verify, and create a new account. Now that there is more information about the timing of Requirement A.2, there is enough justification to model the interaction that implements the requirement using a timing diagram.