is there a way to transfer file between two pc connected to the same apphost? I was wondering if using the PostFile method of JsonServiceClient I could send that file directly to a kind of "listener".
Not sure what you mean by connected to the same AppHost? How are they "connected" are they just calling the same Web Services of an external server? Are they both running a copy of the same self-hosting AppHost?
If the PC's know each other's IP and can start their own self-host AppHost, you could have them post the file directly to the other's IP where the client can use
JsonServiceClient PostFile to upload a file to the others Service.
If they're not running self-hosted Services, you'd instead have 1 upload a file to a central file server and msg the other a link to the file which you can notify them using Server Events if they're both connected to the same channel, or just a "msg inbox" that the other PC polls.
Yes, they are not running their own self-host. I will use server events as your suggestion.