What is a Producer?
A producer is an application that senses state changes (events) and publishes those events as messages. An event indicates a state change or update triggered by a user's/device's action.
The following are sample events:
- Placing an item in a shopping cart on an e-commerce website.
- Clicking the subscribe button on a YouTube channel.
- A temperature change in a sensor.
Why do we need Producers?
One of the core concepts of event-driven architecture is the publish/subscribe communication model. Producers are publishers in this model; they're the first logical layer responsible for distributing messages to the broker so that others can subscribe to receive messages.
The diagram above depicts the communication between a producer publishing events to a specific channel in a broker and a consumer subscribed to the same channel.
In some cases, an entity can be both a producer publishing messages to a specific channel in the broker and a consumer subscribing to messages from a different channel in the broker.
In the diagram above, we see a producer publishing messages to a specific channel and a consumer subscribing to messages from that channel. We also have a second producer who publishes to one channel, but subscribes to messages from another.
