Developing Solutions for Microsoft Azure (AZ-204) Practice Exam

Which event schema property requires a value?

1. Topic

2. Data

3. Subject

4. Event type

The correct answer is: Subject

The subject property in an event schema is crucial because it provides a context-specific identifier for the event being described. This allows event subscribers to filter and determine which events they are interested in processing based on their subject matter. Essentially, the subject acts as a categorization mechanism, enhancing the event's usability by enabling more defined routing and handling. In contrast, while the other properties such as Topic, Data, and Event type also play important roles in the structure and functioning of events, they don't have the same rigidity in needing a value. For example, Topic can sometimes be more general or hierarchical, whereas the Data property is usually optional and can be left empty if there is no associated payload. Event type indicates the nature of the event but doesn't guarantee a unique identifier like the subject does. This distinction is key in understanding the components of event schemas and their roles within an event-driven architecture.