Though this post is about dotnet, it is likely to be also applicable to non-dotnet apps.
You can create/delete custom event logs. The 3 built-in event logs (app, security and sys) can’t be deleted. All of the above are viewable on eventvwr.exe
Except security log, all other event logs are writable – including app, sys and custom event logs. I feel this is a simple way to implement basic application logging in dotnet. The EntryWritten event firing feature looks neat.
Further, it looks like multiple (Local) processes can subscribe to the same EntryWritten event, so you could perhaps coordinate 2 processes using EntryWritten — IPC
You can even access remote event logs.
Perf counter is Another simple IPC mechanism. You can create custom perf counters, visible to other processes + perfmon.exe.
Since one process can update the counter and another process can see it in real time, it’s IPC.
I have yet to implement IPC this way.