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Adding messages to channels

Added in eventcatalog@2.13.0

EventCatalog supports different types of messages (commands, events and queries).

Any message can be added to one or many channels.

Example

To add messages to a channel you first have to define your messages.

Once you define your message you can specify that channel/s it uses.

Adding messages to your channels​

To add a message to a channel, you need to add the channels information to your message.

Here is an example of adding channel information to an InventoryOutOfStockEvent.

/events/InventoryOutOfStockEvent/index.md (example)
---
id: InventoryOutOfStockEvent
... # other event frontmatter
channels:
  # The id of the channel to map to.
  - id: inventory.{env}.events
    # The version of the channel, this is optional and not required
    # EventCatalog will map to the latest channel version if not used.
    version: 0.0.1
    # optional list of params for this channel
    # this example means that this message is used on the inventory.dev.events channel
    parameters:
      env: dev
---

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The receives and sends fields in your service tell EventCatalog which messages this service either consumes or publishes.

Versioning your channels

Versioning for channels is optional. But if your message/channel relationship evolves over time, and you find value capturing this version/history then you can version your channels.

Using semver versioning​

You can use semver syntax when referencing your channels in your messages.

/events/InventoryOutOfStockEvent/index.md (example)
---
id: PaymentDomain
... # other domain frontmatter
channels:
    # Latest minor version of InventoryEvents (channel) will be added
    - id: InventoryEvents
      version: 0.x.1
    # Minor and patches of this version will be linked
    - id: NotificationsChannel
      version: ^1.0.1
    # Latest version of this service will be shown by default.
    - id: PaymentsChannel
---

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Visualizing messages with channels​

When messages get added to your channels EventCatalog will visualize this for you through the visualizer.

Example