Skip to content

Terminology

  • Broker: (also called a server or node) orchestrates the storage and passing of messages. These are the machines that store and service the data.

  • Consumer: the team, as well as the application, that subscribes to the topic and reads messages according to topic, partition and offset.

  • Domain: a broad classification of events that corresponds to an area of business within the VA. One can think of a domain as a radio station that plays a certain type of music.

    • For example, transition events, claims/benefits events, health events, life events, memorial events, and interaction events.

  • Event: the type of business action that has occurred.

    • For example, an appointment was created.

  • Event (instance): a specific instance of a business action that has occurred (note: event, message, and record can be seen interchangeably in various Kafka-related documentation).

    • For example, an appointment was created for Karen to see an orthopedic specialist on 6/1/2023 at 10:30 am.

  • MSK: Managed Streams for Kafka. The Enterprise Event Bus uses AWS Managed Streams for Kafka, a hosted version of Kafka that runs in the VA Enterprise Cloud.

  • Partitions: storage units within a topic. They hold a subset of the records owned by the topic. This is a logical concept in Kafka.

    • For example, the number of partitions will impact the distribution of your data. The Enterprise Event Bus team will provide guidance on allocating partitions for a topic during the onboarding process of a producer.

  • Producer: the team, as well as the application that appends messages to the end of the topic. Messages are written to partitions on a round robin basis, or to a specific partition based on the message key.

  • Topic: provides a destination for the storage of data. Each topic is split into one or more partitions. Topics are where events are durably stored; this is similar to how files are stored in a distributed file system. A topic can have many producers and many consumers. Continuing the music analogy from the definition of domain, a topic can be thought of as a radio channel that plays a single band.

    • For example, appointment events can be streamed from the appointments topic.

Find additional terms and abbreviations on the Event Bus terminology page in Github (must be part of VA GitHub organization to view).