The use case Log in describes a login procedure that must be used by the users of the PM System.
Log in includes six steps listed in the section titled Steps. Each step refers to a use case step operation.
For instance step 1 references the User's operation 'insert card' and step 2 the PMSystem operation 'ask pin'. Step 5 includes a step condition 'User identification is valid'. The execution of step 5 (and that of the following step) is possible only under that condition. Step 6 operation is constrained by an after delay 'After 45 sec'. Means 45 seconds need to pass after the completion of step 5 before this step is possible.
Steps 1, 2 and 4 have step extensions described in the section titled Extensions. Each extension label starts with the corresponding step label. Extension 1a corresponds to step 1, 2a corresponds to step 2. Extensions 4a and 4b correspond to step 4.
Extensions 1a, 4a and 4b include conditions. For instance, after step 1 is completed the operation 1a1 followed by 1a2 are executed if the condition 'User Card is not regular' evaluates to true. Extension 2a includes an after delay, such that 60 seconds need to pass after step 2 operation completion for the extension to be possible.
All the extension actions in use case Log in are operation instances. The exception is extension 4a that includes a branching statement branching back to step 2.
Use case Log in includes one any extension. Any extension labels start with '*'. Log in any extension doesn't include a condition or a delay. Consequently, the extension is possible anytime during the execution of an instance of the use case.
Use case Log in includes the extension points labelled card inserted after step 1, and pin entered after step 3. An extension use case such as Log in secure can refer to these extension points.
A use case includes a primary scenario (or main course of events) and 0 or more secondary scenarios that are alternative courses of events to the primary scenario . The primary scenario is described in the section titled Steps while the secondary scenarios consist of interactions in the primary scenario followed by behaviors defined in the section titled Extensions. As an example, use case Log in primary scenario is defined by step 1 to 6 operation (sequence 1-2-3-4-5-6). Examples of secondary scenarios are defined by sequences 1-1a1-1a2 and 1-2-3-4-4b1-4b2.