Analyzing Activities › Event Analysis › Analyzing Events

Analyzing Events

Event analysis involves these steps:

Step 1 Identify Events

Events are often encountered during information gathering, and they can be found in the operational documentation for current systems. The external events can be identified by examining the interactions from external objects to activities, which is identified during dependency analysis.

You can define a list of events:

• Event
• Corporation opens new store
• Corporation closes store
• Distributor sends a catalog to corporation
• Corporation selects films of interest
• Store decides to purchase tapes from a distributor
• Distributor ships tapes to store
• Store manager changes daily rate for store catalog item
• Customer applies for club membership
• Customer applies for store membership
• Customer reserves tape
• Customer asks to make rental
• Customer returns tape
• Reservations department checks item availability
• It is time to notify overdue customer

You can begin with a preliminary list of the principle events to which the business must respond. Progressively extend and refine this list as you discover further events, compare events with the processes that are involved in responding to events, and find events that are associated with state transitions in the life-cycles of entities. Entity type life-cycle analysis is described in the chapter "Analyzing Interactions."

Step 2 Define Event Response

You can describe the actions that are involved in the response using one of the following techniques:

• Use the names of processes where these are already identified
• Use an ordered list of actions such as the one shown in the following table.

A number of elementary processes participate in the response to an event. Processes are added to an event list as shown in the following table.

New processes that are identified are added to the Activity Hierarchy Diagram. Previously identified activities are grouped as candidate actions of a process; these actions are added to the process description. Common actions are identified. They represent processes that respond to more than one event, or possibly common business logic that uses more than one elementary process. See also the discussion of process logic analysis in the chapter "Analyzing Interactions."

Step 3 Specify Dependencies in Event Response

You draw a dependency diagram to show how processes together participate in the response to a single event.

If all the processes are siblings, the event can be shown on a single diagram for the parent activity.

However, it is possible that the responding processes are subordinate to more than parent activity. Several dependency diagrams are required to show separate representations of the event.

If several activities are found that respond to the same event, it is worth asking whether these activities are separate processes, or whether they overlap. This can lead to simplifying the set of processes.

To help understand the complete response to an event, a separate dependency diagram for which the event is the subject is needed. Such a diagram is known as an event consequence diagram and is shown in the following illustration.

Where these processes are coordinated, a single elementary process is enabled by the occurrence of the event and then initiate the response of business.

Step 4 Specify Conditions in Event Response

So that the response of each process to the event can be recorded as part of the process definition, you need to define the circumstances in which each process can be executed. These circumstances are defined as preconditions (described in Dependency Analysis) and can be annotated on an event consequence diagram and defined as part of the dependency. This ensures that the event is taken into account when the process logic is specified. See the chapter "Analyzing Interactions" for a description of how each event contributes to the process definition.