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Erroneous string format using mosquitto_sub/_pub

See original GitHub issue

Steps to reproduce

Run the following *.ps1 script in a text file with UTF-8 ecoding:

while ($true)
{ 
  $date = Get-Date -Format "o"
  $rand = Get-Random -Minimum -10 -Maximum 40
  $message = '{"time":' + '"' + "$date" + '"' + ', "value":' + "$rand" + ', "label":"ºC"}'
  #echo "$message"
  mosquitto_pub -h test.mosquitto.org -t tofol/test -m "$message"
  Start-Sleep -s 1
}

Now in another terminal window, subscribe to the mosquitto topic:

mosquitto_sub -h test.mosquitto.org -t tofol/test

The output is unexpected:

{time:2021-03-30T12:30:24.0266957+02:00, value:3, label:║C}

Expected behavior

Expected behavior is seem by running the following script:

while ($true)
{ 
  $date = Get-Date -Format "o"
  $rand = Get-Random -Minimum -10 -Maximum 40
  $message = '{"time":' + '"' + "$date" + '"' + ', "value":' + "$rand" + ', "label":"ºC"}'
  echo "$message"
  #mosquitto_pub -h test.mosquitto.org -t tofol/test -m "$message"
  Start-Sleep -s 1
}

This outputs: {"time":"2021-03-30T12:31:48.2728626+02:00", "value":33, "label":"ºC"}

Environment data

Name                           Value
----                           -----
PSVersion                      7.1.3
PSEdition                      Core
GitCommitId                    7.1.3
OS                             Microsoft Windows 10.0.19041
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Issue Analytics

State:
Created 2 years ago
Comments:36 (20 by maintainers)

Top GitHub Comments

1reaction

mklement0commented, Apr 8, 2021

My pleasure, @chris-steema; I certainly learned a few things myself.

1reaction

chris-steemacommented, Apr 7, 2021

However, I wonder if these programs, like Python, offer an opt-in mechanism for specifying the desired encoding.

Good point. I’ll see if I can find anything. Thanks.

By contrast, character-encoding issues do come into play when PowerShell captures stdout output from mosquitto_sub, which invariably involves decoding (in order to convert the raw byte output to .NET strings), which PowerShell bases on [Console]::OutputEncoding

Yes, the conversion of byte streams to .NET strings I can imagine very clearly. Great stuff, thanks to your patient explanations I think I now have a pretty clear idea of what’s going on. Powershell’s inability to escape embedded quotes was a red herring for me, as I had imagined that that and what turned out to be an encoding issue were related, which they aren’t. As far as I’m concerned we can close this issue, but I won’t do so now just in case you’d prefer to keep it open for whatever reason.

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