Dashboard – Spectrum Analyzer component session issue

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Hi Dojo,

I'm configuring a spectrum analyzer in a dashboard but I'm getting the error "Failed to initialize spectrum session":

As described in the docs: Spectrum analyzer | DataMiner Docs, an element feed should be enough to get the visualization working but I'm not sure if an extra configuration is needed.

I'm testing this in 10.3.0.0-13537-CU9

Thank you!

Sebastian Ulloa [SLC] [DevOps Advocate] Selected answer as best 9th February 2024

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The dashboard visualization indeed only requires an element feed. The error message you see is not caused by an invalid dashboard configuration, but rather an unexpected issue when trying to open a spectrum analyzer session with the server.

How to investigate

  1. Open the browser DevTools
  2. Refresh the web page
  3. Search in the Network tab of the DevTools for WebSocket.ashx.
    WebSockets are required for Spectrum sessions in 10.3, so if the WebSocket connection is not supported or failed that could explain the error (although I would expect a different error message in that case).
  4. In the Messages tab of the WebSocket connection, find the message sent by the client with Method: "GetSpectrum"
    This is the message that initializes the spectrum analyzer session.
  5. Find the server response to this WebSocket message: the response will have the same ClientSubscriptionID as the client message from step 4.
  6. Find the error message contained in the server response. This should give us a clue for the underlying root cause.

Sebastian Ulloa [SLC] [DevOps Advocate] Posted new comment 9th February 2024
Sebastian Ulloa [SLC] [DevOps Advocate] commented

WebSocket is definitely what is failing here. I was able to see in the Network and the Console tab, that WebSocket communication was not completed.
I will review this documentation as per suggested by your team: https://docs.dataminer.services/user-guide/Advanced_Modules/Dashboards_and_Low_Code_Apps/FAQ/Dashboards_and_Low_Code_Apps_FAQ.html#what-should-i-do-if-i-get-websocket-errors-when-using-dashboards-or-low-code-apps

Thank you Ronald!