How to run the LSP Server (newbie)

[ianh9999]

I have a Windows text editor that currently uses the Gold parser to process my DSL. I want to replace this with the LSP functionality in Langium (with the Langium running as a server and my client communicating via http or stdio)

I'm a newbie to Javascript and NodeJS, so struggling to follow the examples. I thought the closest example to what I'm trying to do is the "Monaco Editor". I tried to observe the JSON messages being passed between the client and the server, but without success. I think the LSP server is actually running within the browser, so there is no LSP traffic on the network.

I feel like the answer will be obvious, but I just can't see how to run the "Hello-Word" example as a LSP server that my client can connect to.

Thanks in advance for any help, and apologies if the answer is staring at me in the help files.

[msujew]

Hey @ianh9999,

I would recommend you to start with the yeoman generator for Langium (requires yeoman) and select the vscode extension option. That will generate you some setup that produces a .js bundle that contains the whole language server. You can start this file with node <file> --stdio to start the language server in stdio mode. The vscode-languageclient library used by the generated extension automatically does under the hood to start the language server.

Now you just need a language client that is capable of connecting to this language server. Note that not every editor library is automatically capable of communication within the language server protocol.

[ianh9999]

Hi @msujew

Thank you so much for your reply! It was this bit of info that I needed to know "You can start this file with node --stdio to start the language server in stdio mode".

For anyone reading this experiencing the same problem, I did originally assume would be /out/cli/main.js (because I'm starting the server from the command line), however, the file /out/language/main.js is the one to use.