phoenix-api-channels

Build real-time chat features with Phoenix Channels by establishing WebSocket connections and routing messages through PubSub. This enables clients to join topic rooms, broadcast events, and receive instant updates across the BEAM virtual machine.

Track connected users in Elixir Phoenix using the Presence module. It leverages CRDTs on the BEAM to efficiently monitor online clients, sync join and leave events, and broadcast presence state across distributed nodes.

Create a versioned JSON API using Phoenix controllers by defining custom plug pipelines. Plugs authenticate requests and parse parameters, while controllers leverage Ecto contexts to fetch, format, and render JSON responses.

You can use Ecto contexts for data management in Phoenix Channels. Contexts encapsulate database logic, allowing channel handlers to validate incoming WebSocket events and persist data before broadcasting updates via PubSub.

Authenticate WebSocket connections in Phoenix by assigning authentication logic to plugs in the pipeline. Plugs verify tokens or session data before allowing clients to establish a channel connection and subscribe to PubSub topics.

Phoenix Presence works across distributed BEAM nodes. It uses a Conflict-Free Replicated Data Type (CRDT) protocol to automatically synchronize presence information and track connected processes without a single point of failure.