HTTP Request - handle failures

[fraczw...@gmail.com]

Now, when I use the HTTP Request block and it fails (because for example there is no internet connection at the moment), the fiber stops and there is nothing I can do about it.

If HTTP Request block had an alternative red failure path, I could retry the request after a specific delay or something like that.

I have a simple flow that cheks one URL periodically and when there is a connectoin problem, I have to restart the flow manually because it stops.

[meke...@gmail.com]

Prior to the HTTP request, use a Network Connected? block with immediate option. If no network is connected, use another Network Connected? block that's set to when changed. You can then have this block & the previous immediate check then flow to a ping block to ensure there's definitely a connection.

You'll also do well to use the failure catch block before your HTTP request, with the fail block going to a delay block before flowing back to the HTTP request block.

[fraczw...@gmail.com]

The HTTP Request may fail because of the server is down, too, so the Network Connected block does not solve the issue.

I have not found the Catch block (I was looking for Try). However, it does not seem to work with the HTTP Request block. I placed it directly before the HTTP Request, set the retry count to 5 and the fiber still stops immediately with a "Unknown host" error in log when I turn off the wifi.

CATCH FAILURE

(OK)     (FAIL) ---- DELAY (OK) -|

|                                |

HTTP <-------------------------- |

[meke...@gmail.com]

The Network Connected? block isn't a complete solution, but it will make your flow more robust because it will eliminate delay looping when there isn't a valid internet connection. The Failure Catch block should work for when the server is down.

[meke...@gmail.com]

The Failure Catch works for me as per the log:

2017-06-01 21:00:26.583 INFO 1936@3: HTTP request
2017-06-01 21:00:26.600 FAIL 1936@3: java.net.UnknownHostException: Unable to resolve host "www.google.co.uk": No address associated with hostname
2017-06-01 21:00:26.611 INFO 1936@5: Delay
2017-06-01 21:00:36.628 INFO 1936@3: HTTP request
2017-06-01 21:00:37.929 INFO 1936@4: Toast show
2017-06-01 21:00:37.959 INFO 1936@0: Stopped at end

The failure makes the flow delay for 10 seconds and retries. When I enable a data connection, the request is successful and then continues to the toast show message (showing the status code 200).

[fraczw...@gmail.com]

Yeah, it works. I put the catch on the wrong fiber and there was an earlier HTTP request that made me think the catch does not work.

Thank you!