Push

According to the architecture, from the standpoint of the Pidgeon, there are multiple points from which errors can occur. Starting from the gateways and going to the server, we can expect to see errors in these areas:

• Gateway -> Pidgeon: Gateways are responsible to transmit measurements from meters to Pidgeon via a pull mechanism. There are a little million ways that this could go wrong, but from the standpoint of Pidgeon, only two categories of scenarios are relevant, the gateway is not sending data or the gateway is sending incorrect data.

• Pidgeon: Pidgeon itself could stop working or have a bug that causes it to stop pulling data from gateways.

• Pidgeon -> Server: Pidgeon sends measurements to the server. If the server is down or there is no connection to the server or there are request problems, the server will not be able to store the data.

Failures

Here is a list of failures that can occur in the push process divided into areas:

• Gateway -> Pidgeon:

  • Gateway is not sending data
  • Gateway is sending incorrect data

• Pidgeon:

  • Pidgeon is not connected to the network
  • Pidgeon throws an exception (software bug)

• Pidgeon -> Server:

  • Server is not connected to the network
  • Server throws an exception (software bug)

Testing

To test resiliency in the push process, we can simulate failures in the following ways:

• Gateway is not sending data: Stop the gateway and start it back up. The Pidgeon should be unaffected.

• Gateway is sending incorrect data: Change the data that the gateway is sending. The Pidgeon should be able to detect the incorrect data and ignore it.

• Pidgeon is not connected to the network: Disconnect the Pidgeon from the network and reconnect it. The Pidgeon should be able to detect the network failure and retry sending the data.

• Pidgeon throws an exception: Introduce a bug in the Pidgeon that causes it to throw an exception. The Pidgeon should be able to catch the exception, log it and continue working.

• Server is not connected to the network: Disconnect the server from the network and reconnect it. The Pidgeon should be able to detect the network failure and retry sending the data.

• Server throws an exception: Introduce a bug in the server that causes it to throw an exception. The Pidgeon should be able to catch the exception, log it and continue working.