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Version: Draft

Messaging Concepts

There are a number of terminologies used in the Async and Event driven architecture space which may have a different meaning in other contexts. This page is a glossary of terms used throughout this section.

ConceptDescription
MessageA packet of data that is transmitted over a channel, containing data such as an event
Message ProducerA software application which publishes messages to API Consumers using Asynchronous APIs
EventA message containing information about something that has occurred, such as an immunisation being administered, or a patient updating their address
Event ProducerA software application which publishes event messages to API Consumers using Asynchronous APIs
Unbounded eventAn event containing unbounded data, that is, data that is continuous, such as a heart rate reading sent from an IoT device
Discrete eventAn event containing discrete data - facts that have happened, such as an immunisation being administered
Message brokerSoftware which allows API Consumers and Provider to communicate. The message broker is responsible for distributing messages to the correct channels (routing), applying authorisation, managing subscriptions and applying transformations
TopicA destination where messages are published to by an API Provider
QueueA queue acts as both a destination that API Producers can publish messages to and as an endpoint that API Consumers can bind to and consume messages from
Event schemaA specification defining the data structure contained in a message
SubscriptionA unique relation to a topic by a subscriber that indicates it should receive updates for that topic
SubscriberThe API Consumer