One-LS Overview

This is a simple service that starts and stops language servers. It's intended to work with Emacs, but it will work with any client as long as you have the ability to prepend a small amount of data to the socket when it's first opened.

Windows Install

I will assume everything is installed in <root>. Set a global environment variable ONE_LS_PATH="<root>/one-ls". Put one-ls files in this directory. Install python if you don't have it already. If you want to run it as a Window's service, run the commands below as admin. Then you just need to find Language Server Service in services and set it to automatic.

python.exe -m pip install --upgrade pywin32
python.exe one-ls.py install

Environment variables need to be defined for the system. If they're only defined for your user, the service won't see them. Check the event viewer under Windows Logs -> Applications for diagnostic log messages.

Java

The language server may require a different version of the JDK than the one needed for your project. Download the version you need for the language server into <root>/ls-jdk and create <root>/ls-workspace. The log file will be <root>/ls-workspace/.metadata/.log. JAVA_HOME will point to the build JDK.

Node/Npm

Install the official .msi or better use NVM for Windows.

Create the following files.

<root>
  nodejs
    npm
      .npmrc
C:\Users\<username>\.npmrc

Add the following text to both .npmrc files.

prefix=<root>\\nodejs\\npm
cache="<root>\\nodejs\\npm-cache"

Set environment variable NODE_PATH="<root>\nodejs\npm".

Language Servers

Clients

Emacs

Check specific package's xxx-download-url for version number.

Servers

Java

Download and expand into <root>/eclipse.jdt.ls.

XML

Download uber jar to <root>/lemminx. Create <root>/.lsp4xml directory.

TypeScript

npm i -g typescript-language-server typescript

Bash

npm i bash-language-server -g

Workaround for punycode deprecation:

npm i punycode -g

Replace require("punycode") with require("punycode/").

Rust

Set environment variables:

RUSTUP_HOME=<root>/rustup
CARGO_HOME=<root>/cargo

Install rustup and run:

rustup install stable
rustup component add rust-analyzer
rustup component add rust-src

Configuration

There is an exec.conf file in <root>/one-ls so that the binaries are not hard coded into the run scripts. The format is <server id>=<binary>. For example:

jdtls=org.eclipse.equinox.launcher_1.6.400.v20210924-0641.jar
bashls=bash-language-server

This executable information gets passed to the relevant script under <root>/onel-ls/win to start the language server. The server.conf file tells one-ls which modes are available for each language server. All language servers seem to be able to communicate over stdio but may not be able to operate as a client or server.

P

The language server communicates over stdio and one-ls will forward IO back to the client. The opening string sent to one-ls:

language server name>::EONELS\n\n\n\n

S

The client connects to the language server on a given port.

<language server name>::<port #>EONELS\n\n\n\n

C

The language server connects back to the client on a given port.

<language server name>:<host name>:<port #>EONELS\n\n\n\n