Extensibility of lsp features

[angelozerr]

@tsmaeder I create the issue even if you answered me #1 (comment)

That's a definite no

But I think if Java-LS is the right mean to manage Java Language Server, I think it will important to support this extensiblity mechanism.

For instance in our case, our Quarkus support which manages Quarkus / MicroProfile validation does that with JDT.LS

I understand your point of view with API break, but in LemMinX XML Language Server we can customize for instance validation with particpant registered via Java SPI

[tsmaeder]

I'm interested to know how you interact with the Java language server in your XML LS? Runtime in-process extensions are problematic for various reasons, but maybe there is a different way to address the requirements.

[tsmaeder]

In Theia, we have a mix of run-time extensibility and compile time extensibility: some things can be extended by unknown third parties, whereas if you want to alter the main-line behavior of the framework, you have to compile your own distribution. I think that's a sensible approach.

[angelozerr]

I'm interested to know how you interact with the Java language server in your XML LS?

I don't do that, even if it should be possible I think.

By extensibility I mean add custom validation, custom completion etc.

The idea is very simple. When XML Language Server is started, the start command add custom JARs which registers custom validation, completion etc with Java SPI (see for instance for vscode https://github.com/redhat-developer/vscode-xml/blob/442471559bcf2b7b7cd5e2c73dad114775222d2a/src/server/java/javaServerStarter.ts#L96)

In vscode side, see doc at https://github.com/redhat-developer/vscode-xml/blob/main/docs/Extensions.md#custom-xml-extensions-written-in-java

It is managed with https://github.com/redhat-developer/vscode-xml/blob/442471559bcf2b7b7cd5e2c73dad114775222d2a/src/plugin.ts#L10

[angelozerr]

@tsmaeder if you are opened with this idea, I could try to provide this Java SPI extensiblity with diagnostics and a sample with Quarkus or Qute.

[tsmaeder]

I'm interested to know how you interact with the Java language server in your XML LS?

I don't do that, even if it should be possible I think.

By extensibility I mean add custom validation, custom completion etc.

The idea is very simple. When XML Language Server is started, the start command add custom JARs which registers custom validation, completion etc with Java SPI (see for instance for vscode https://github.com/redhat-developer/vscode-xml/blob/442471559bcf2b7b7cd5e2c73dad114775222d2a/src/server/java/javaServerStarter.ts#L96)

Well, then the question becomes how the custom jar and commands interacts with the language server. What information does it consume or provide?

[angelozerr]

Let me explore more java-ls to give you a relevant answer and try to do something.

When you will have time, please review #3