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I want to update an application without any service interruption, the idea is to inform the first instance of the application (aka the old version) when the last (aka the new version) is ready to start.

Example:

  1. old version is running
  2. new version starts
  3. new version detects that old version is already running
  4. new version prepares to serve
  5. when ready, new version instructs old version to close
  6. when closed, old version informs new version
  7. new version starts serving

When the time comes, the procedure is repeated with a newer version.

This way the service is interrupted for the briefest possible time.

My idea was to use a system-wide mutex, unfortunately they are not available in mono, and it's probably not possible to do step 5 with this technique anyway.

Another approach whould be to use a pipe, this is not available on mono too.

My last idea was to use a socket bound to loopback address on a random (constant) port, do you think this is fine or there is a better way to handle situations like mine?

All the code must run on both linux Mono and .NET.

Thanks for reading, Fabio Iotti.

Fabio Iotti
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    It may be little bit overkilling. Which kind of application you're talking about? A service? Something with user interface? – Adriano Repetti Apr 16 '14 at 12:43
  • It's a web server, so a service, a console application whould be fine anyway. – Fabio Iotti Apr 16 '14 at 12:46
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    If there is not user interface (where a close request may wait indefinitely) then I'd simply ask process to terminate (`Process.Close()`) and start waiting (`Process.WaitForExit`). Old version will always serve pending requests before quitting and new version will be pending until done. No need for IPC. – Adriano Repetti Apr 16 '14 at 13:29

1 Answers1

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Kind of a hack, but could you just write to a known file

  1. Application Starts and checks file for other apps
  2. Writes "my id - running" if no app found otherwise write "my id - starting" if another running app is found
  3. running app checks file for any new apps marked as starting"
  4. If a starting app is found stop service and write "my id - shutdown", then terminate app
  5. Starting app will poll file until it finds there are no apps running, then it will start service and write "my id - running"

This looks like a link to a similar issue:

Simple cross-platform process to process communication in Mono?

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mmilleruva
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