Support for IPC via STDIO using JSON-RPC

[amol-mandhane]

Based on the README, you need a host and port to do json-rpc in elisp. There are many programs which use STDIO for communication (LSP servers, for example). I'm working on a pull request for this. Is it okay to add STDIO support to this library?

[skeeto]

I'm not opposed to this so long as it doesn't interfere with the current functionality. Though I wonder how you plan to pull it off, since access to stdin and stdout from Emacs Lisp is, unfortunately, very limited.

[phst]

A typical approach would be to use HTTP-like framing, like the language server protocol (https://github.com/Microsoft/language-server-protocol/blob/master/protocol.md#base-protocol). From Emacs you'd start an asynchronous process with make-process. It needs a custom process filter. The filter would insert the new stdout into a temporary buffer and check for completed responses (i.e. where there's enough JSON content to read). Completed responses would be dispatched according to their IDs and removed from the temporary buffer.

[conao3]

Yes, I also want to communicate clangd via stdio/stdout interface.

[lambdadog]

You can see an example of this kind of implementation in jorgenschaefer/elpy, although as it notes at the top, it uses a limited JSON-RPC implementation itself.