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Faye - real time messaging

Sends realtime messages to the logged in users. Generally reports things like notifications.

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What is Faye?

Faye is a websockets implementation that we run on notifications.pixwel.com. The UI subscribes to endpoints - e.g. a user’s browser may subscribe to notifications.pixwel.com/staging/faye/{my user id} to get notifications for a given user. This endpoint does not have to exist at the time of subscription, but if any messages get pushed to that endpoint, the user’s browser will pick them up.

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Where does Faye run?

  • On development, it runs locally
  • On all other environments, it runs on notifications.pixwel.com with endpoints for the various environments.

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Testing Faye

  • Open Chrome and open the web sockets tab of Chrome tools
  • Log in as User A
  • Assert that a web sockets connection is made to Faye
  • In an incognito tab, log in as User A and then find User B and click the ‘impersonate’ button for that user
  • As User B, share some assets to User A
  • As User A, click Notifications in the grey bar and assert that the new share is in there

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Infrastructure

Faye is deployed as a containerized service on AWS ECS (Fargate) — see faye/ecs-faye.service.yml and faye/Dockerfile, deployed with fargate-deploy.sh. notifications.pixwel.com is a reverse proxy in front of the Faye container, with per-environment paths (for example notifications.pixwel.com/production/faye).
Historically Faye ran on a hand-provisioned EC2 node via Ansible/Upstart; that approach (and its WebSocket-vs-load-balancer caveat) is no longer current — modern AWS load balancers support WebSockets.
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