I am pleased to announce that HK Airport Authority has awarded the Event Broker contract to E Tag to deliver Solace Event Broker for HK Smart Airport's Event Driven Architecture (EDA).
What is Event Broker?
The primary purpose of a broker is to take incoming messages from applications and perform some action on them. Message brokers can decouple end-points, meet specific non-functional requirements, and facilitate reuse of intermediary functions. For example, an event broker may be used to manage a workload queue or message queue for multiple receivers.
Using Event Broker for Microservices Communication
You can use events to implement business transactions that span multiple services, which gives you eventual consistency between those services. An eventually consistent transaction consists of a series of distributed actions. At each action, the microservice updates a business entity and publishes an event that triggers the next action. The below figure shows a PriceUpdated event published through and event bus, so the price update is propagated to the Basket and other microservices.
Event Broker == MiddleMan?
How do you achieve anonymity between publisher and subscriber? An easy way is let a middleman take care of all the communication. An event bus is one such middleman. In the below figure you can see how, from an application point of view, the event bus is nothing more than a Pub/Sub channel. The way you implement this asynchronous communication can vary.