What is this?

This is a proof of concept for a Schematron extension to the LemMinX XML language server.

It uses schxslt and Saxon-HE in order to validate an XML document against a schema.

Requirements

• Java 17+ (JRE or JDK) installed and set up on PATH.

Usage

VS Code (and forks/rebuilds of VS Code)

This project is available as an extension from the official marketplace and OpenVSX.

Other Clients

1. Download the LemMinX uber .jar from lemminx's maven repo. (If there is a newer version of lemminx than 0.30.0, replace the number in the URL to get it). Put it somewhere meaningful and memorable.
2. Build the LemMinX Schematron extension. Put the built .jar somewhere meaningful and memorable. See Building lemminx extension
3. Setup LemMinX according to the instructions of your editor. Note that you cannot use the binary build of LemMinX, since the binary cannot be extended dynamically. When you get to the part in the setup instructions where you specify the command to launch the language server, move on to step 4.
4. For the launch command, you need to use Java, specify both jars as classpath entries, and specify org.eclipse.lemminx.XMLServerLauncher as the main class. eg:

java -Xmx1G -cp /path/to/lemminx.jar:/path/to/lemminx-schematron.jar org.eclipse.lemminx.XMLServerLauncher

-Xmx1G configures the max memory Java can use; feel free to reduce or increase this number according to your needs. Note that the editor might want the arguments supplied as a list of strings, and may have separate fields for the command and the arguments.

Examples

Neovim

local lspconfig = require('lspconfig')
-- you should probably also specify `on_attach` and `capabilities` functions; I didn't here
lspconfig['lemminx'].setup {
  cmd = { 'java', '-cp', '/home/davthomp/Documents/lemminx-extensions/org.eclipse.lemminx-0.30.0-uber.jar:/home/davthomp/Documents/lemminx-extensions/lemminx-schematron-0.1.0-SNAPSHOT.jar', 'org.eclipse.lemminx.XMLServerLauncher' }
}

Helix (in languages.toml)

[[language]]
name = "xml"
file-types = [ "xml", "svg", "xsd", "xslt", "xsl", "sch" ]
auto-format = true
language-servers = [ "xml" ]

[language-server.xml]
command = "java"
args = ["-cp", "/home/davthomp/Documents/lemminx-extensions/lemminx-schematron-0.1.0-SNAPSHOT.jar:/home/davthomp/Documents/lemminx-extensions/org.eclipse.lemminx-0.30.0-uber.jar", "org.eclipse.lemminx.XMLServerLauncher"]

Building

lemminx extension

Prerequisites: git, Java 17 or newer

1. Clone this repo.
2. cd into lemminx-schematron
3. Run ./mvnw clean package (Linux, macOS) or .\mvnw.cmd clean package (Windows)
4. The .jar will be created in ./lemminx-schematron/target

vscode extension

Prerequisites: git, Java 17 or newer, NodeJS 20 or newer, macOS or Linux (the npm scripts I wrote are not cross platform)

1. Clone this repo.
2. cd into vscode-schematron
3. Install vsce globally if you don't have it installed already: npm i -g @vscode/vsce
4. Run vsce package
5. The .vsix will be created in ./vscode-schematron

Limitations

• You can only validate with local .sch files
• Not tested thoroughly
• The .jar is prohibitively large to include as a part of the standard LemMinX distribution