[ question / xtext / lsp ] xtext accepting multiple clients

[genlike]

Good afternoon,

I want to implement client concurrency within a single xtext LS process.

I saw that someone tried to do a interface before the ls (1239), what I want to do is directly in the xtext server add the code necessary for the server to be able to handle multiple clients, and not spawn a ls process for each client.

Since the last post was a couple years old, I wanted to know if someone already did something like this.

Or give me some hints on where to start, thank you.

[kris7t]

(Not affiliated with the project, but I had similar challenges to solve.)

One way to achive this is to use the Xtext Web interface instead of LSP. Xtext web supports multiple clients out of the box: https://github.com/eclipse/xtext-web However, Xtext Web might lead to worse performance if used from a browser, because it uses separate REST calls for each editing operation instead of a single WebSocket connection.

Since my project was limited in scope, hacked around this issue by rewriting the Xtext Web client to send specific messages through a WebSocket connection instead of separate REST calls, and the corresponding servlet to accept WebSocket connections. But if you absolutely need full LSP functionality, this might be quite painful to rewrite.

[genlike]

Thanks for taking time in answering.

"But if you absolutely need full LSP functionality, this might be quite painful to rewrite." Unfortunately this is my situation.

But I wanted to know, what this work consists of, so that I can analyse if this is worth investigating, or that this is insensible to do and I should be creating a process of language server for each client connecting.

[kris7t]

You can take a look at how I rewrote the Xtext Web servlet for WebSocket in https://github.com/graphs4value/refinery/blob/43d098e61e546d696e03143d284cc820434ccf22/subprojects/language-web/src/main/java/tools/refinery/language/web/xtext/servlet/XtextWebSocketServlet.java but it's not full LSP. In particular, I only handle the highlighting, validation, content assist, and occurrences services, so no refactoring support at all (I'm not even sure Xtext Web supports refactoring).

Here's my attempt at a client but it's honestly a mess: https://github.com/graphs4value/refinery/blob/43d098e61e546d696e03143d284cc820434ccf22/subprojects/frontend/src/xtext/XtextWebSocketClient.ts It'd probably be better to just use Monaco on the client side with LSP, but that would mean running a full LSP backend for each user.

If you're building a language from scratch, Langium might be a simpler solution, because it lets you run the whole LSP server in a WebWorker on the client side. But naturally, that only applies if you don't need to do anything in Java on the server.

[genlike]

Ok the langium option seems the best for me, found some articles in converting a xtext grammar to langium, so I will close this question.

Thank you very much for pointing out for me.