I have two servers: Golang and Python (2.7). The Python (Bottle) server has a computation intensive task to perform and exposes a RESTful URI to start the execution of the process. That is, the Go server sends:
HTTP GET to myserver.com/data
The python server performs the computation and needs to inform the Go server of the completion of the processing. There are two ways in which I see this can be designed:
Go sends a callback URL/data to Python and python responds by hitting that URL. E.g:
HTTP GET | myserver.com/data | Data{callbackURI:goserver.com/process/results, Type: POST, response:"processComplete"}
Have a WebSocket based response be sent back from Python to Go.
What would be a more suitable design? Are there pros/cons of doing one over the other? Other than error conditions (server crashed etc.,) the only thing that the Python server needs to actually "inform" the client is about completing the computation. That's the only response.
The team working on the Go server is not very well versed with having a Go client based on websockets/ajax (nor do I. But I've never written a single line of Go :) #1 seems to be easier but am not aware of whether it is an accepted design approach or is it just a hack? What's the recommended way to proceed in this regard?
It depends on how often these signal are being sent. If it's many times per second, keeping a websocket open might make more sense. Otherwise, use option #1 since it will have less overhead and be more loosely coupled.
If you want to do it RESTful, then when the client requests HTTP GET myserver.com/data the server should return a 202 Accepted status code:
202 Accepted
The request has been accepted for processing, but the processing has not been completed. The request might or might not eventually be acted upon, as it might be disallowed when processing actually takes place. There is no facility for re-sending a status code from an asynchronous operation such as this.
The 202 response is intentionally non-committal. Its purpose is to allow a server to accept a request for some other process (perhaps a batch-oriented process that is only run once per day) without requiring that the user agent's connection to the server persist until the process is completed. The entity returned with this response SHOULD include an indication of the request's current status and either a pointer to a status monitor or some estimate of when the user can expect the request to be fulfilled.
The Python server could return an ETA and an URL to a temporary resource to request the current status of the operation (e.g.: myserver.com/temp_data?processing_status). Then it's up to the Go client to wait for the task to fulfill by requesting this resource and reading the ETA. Once the processing is done, the Python server could return a 410 Gone status with the definitive URL of the new resource.