Even though it does not show when activities are supposed to take place, the system context diagram has all actors and all possible activities performed on the system on one diagram, whereas the event sequence diagram has to be done from each individual actor’s perspective in order to be effective.A Sequence diagram is a structured representation of behavior as a series of sequential steps over time.
One drawback to consider when representing time in a diagram is that a single diagram will, for the most part, contend with the viewpoint of a single actor/stakeholder. In comparison to the system context diagram, the event sequence diagram clearly shows when each step in a process occurs and when and why each user is interacting with the system. Lets explore the last perspective of the customer service rep. Similarly, for the customer, the event sequence diagram would look something like this: In the sample event sequence diagram below, you can see the sequential execution of each activity as the system admin interacts with the system. Each step in the process flow is accounted for and its occurrence within the sequence is known. Since event sequence diagrams are typically done from one user perspective at a time, we will start with the system admin.
To illustrate, we will use the event sequence diagram. In this example, we can show how rendering services is represented when a time sequence is added to a diagram. However this does not mean you are adding hours and minutes, but rather you are adding a sequence to the activities. Using event sequence diagrams to show timeĪdding a time dimension to diagrams allows for a three-dimensional view of a model. As mentioned above, if we wanted to depict a time perspective, then a system context diagram will not work.Īs you can see, a system context diagram is two-dimensional it shows the system artifacts and relationships of the artifacts to the system but makes no reference to the timing of events. To represent this diagrammatically, we have several options depending on the goal. To expand on this example, assume that there is also a customer service rep who logs into the system to provide services to customers.
For the customer to successfully log in, a system administrator must provide login credentials by logging in and manually provisioning the customer. ABC Corp provides services to a customer who needs to log into a system and provide personal information to complete their customer profile. In a previous article, we created use case examples for a fictitious company called ABC Corp. 2-D versus 3-D diagramsĮvent sequence diagrams, collaboration diagrams, and activity diagrams stand in contrast to static diagrams such as the system context diagram. But first, let’s differentiate between 2-D and 3-D diagrams.
In this article, we’ll take a look at how to capture time in event sequence diagrams. There are many diagrams or modeling options to chose from to illustrate timing of events within a system or process.Ī few favorites that are helpful in capturing the dynamic artifact-time relationship are: Including the time dimension in Enterprise Architecture models enables the modeler to depict the interaction of the events, tasks, and actors depicted in the model in a way that indicates the order of the interactions.