University Domain
In this tutorial, we’ll be working with a Axon University domain. Our initial examples will focus on the Faculty Bounded Context, where we’ll implement features related to course management and student registrations.
Within this context, the business capabilities are:
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The faculty can create courses with assigned capacity (the maximum number of students allowed).
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Course capacity can be modified after creation.
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Course name can be changed after creation.
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Students can enroll in the faculty.
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Students can subscribe to courses (within capacity limits), there is also a limit of course subscriptions per student.
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Students can unsubscribe from courses.
Event modeling
Before diving into code, let’s take a moment to design our system using Event Modeling. This approach helps us identify the messages that will flow through our application and ensures our flow of information is complete, and we are ready to go into implementation.
We conducted an Event Modeling session to identify the command and events that will be used in our system.
After an Event Modeling (which you can see above) session we have identified the following events:
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StudentEnrolledInFaculty- A fact that a student has enrolled faculty. -
CourseCreated- A fact that a course has been created with assigned capacity. -
CourseCapacityChanged- A fact that a course’s capacity has been modified. -
StudentSubscribedToCourse- A fact that the student has subscribed to a course. -
StudentUnsubscribedFromCourse- A fact that the student has unsubscribed from a course.
These events form the backbone of our system and serve as the contract between different slices of our application. By focusing on the events first, we can clearly define how information flows through our system.
With this domain understanding established, we’re ready to start building our Axon University application following the Vertical Slice Architecture pattern that Axon Framework 5 supports so well.