Phoenix controller receiving messages

Phoenix Forum Questions / Help
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Hi, I have a scenario with the following components:

Controller (a Phoenix one) -> API (GenServer) -> EventBus (GenEvent) -> Worker (GenServer)

The applications are under an umbrella with the web layer, API and Messaging+Worker. For the web layer standpoint, I need to make sure of 2 things:

  1. API got my request
  2. job was done

But also for the web layer standpoint, the communication happens with the API only, how the API makes its work, it is an API concern.

One of my initial thoughts was having my API handle_call notifying the Messaging and listen to a message back, to then send the reply to the web layer. But I heard/read that is not good add a receive to listen general messages inside GenServer callbacks.

Other option is handling the worker messages in the API with handle_info, and send a message to the controller, but that will require having a receive to get the message in the controller side, what I don’t know if it is a good approach.

Any suggestions or comments?

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Why not? I mean, it could be a code smell in some situations, but every time you do a GenServer.call you drop into a receive block to listen for the response.

BUT, you could just not reply in the API.handle_call callback and have your Worker reply using the GenServer.reply function. It wouldn’t block your API GenServer waiting for a response, and still allows for a timeout using the GenServer.call semantics.

1 Like
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Thanks, I think I will return the handle_call with {:noreply, new_state} and inside handle_info use GenServer.reply/2.