Skip to end of metadata
Go to start of metadata

You are viewing an old version of this page. View the current version.

Compare with Current View Page History

« Previous Version 3 Next »


Developing a LS extension

We use java ServiceLoader to register stuff. Here is a small example how a LanguageServerExtension is registered via a ServiceLoader and how it is used:

Register LanguageServerExtensions (ServiceLoader Example)

This is a LanguageServerExtension. It has to be used in the de.cau.cs.kieler.language.server plugin. Since the language-server-plugin should not have dependencies to all plugins that define a language server extension dependency inversion is used to prevent that. A ServiceLoader does exactly that.

Here is such an example extension, the KiCoolLanguageServerExtension:

package de.cau.cs.kieler.kicool.ide.language.server


/**
 * @author really fancy name
 *
 */
@Singleton
class KiCoolLanguageServerExtension implements ILanguageServerExtension, CommandExtension, ILanguageClientProvider {
	// fancy extension stuff

	var KeithLanguageClient client
	// A language server extension must implement the initialize method,
	// it is however only called if the extension is registered via a language.
	// This should never be the case, so this is never called.
    override initialize(ILanguageServerAccess access) {
        this.languageServerAccess = access
    }
    
	// implement ILanguageClientProvider
    override setLanguageClient(LanguageClient client) {
        this.client = client as KeithLanguageClient
    }
    
	// implement ILanguageClientProvider
    override getLanguageClient() {
        return this.client
    }

}

The CommandExtension defines all commands (requests or notifications) that are send from client to server. An example how this looks like can be seen in the code snippet Example CommandExtension is an example how to define a server side extension interface.

The ILanguageClientProvider should be implemented by an extension that plans to send messages from the server to the client.

This language server extension is provided by a corresponding contribution, which is later used to access it:

package de.cau.cs.kieler.kicool.ide.language.server

import com.google.inject.Injector
import de.cau.cs.kieler.language.server.ILanguageServerContribution

/**
 * @author really fancy name
 *
 */
class KiCoolLanguageServerContribution implements ILanguageServerContribution {
    
    override getLanguageServerExtension(Injector injector) {
        return injector.getInstance(KiCoolLanguageServerExtension)
    }
}

Create a file called de.cau.cs.kieler.language.server.ILanguageServerContribution in <plugin>/META-INF/services/ (in this example this is de.cau.cs.kieler.kicool.ide). The name of the file refers to the contribution interface that should be used to provide the contribution. The content of the file is the following:

de.cau.cs.kieler.kicool.ide.language.server.KiCoolLanguageServerContribution

This is the fully qualified name of the contribution written earlier.

The language server uses all LanguageServerExtensions like this:

var iLanguageServerExtensions = <Object>newArrayList(languageServer) // list of all language server extensions
for (lse : KielerServiceLoader.load(ILanguageServerContribution)) { // load all contributions
	iLanguageServerExtensions.add(lse.getLanguageServerExtension(injector))
}

The resulting list of implementions is used to add the extensions to the language server.

Register an extension (on server side)

See example above for ServiceLoader and initial stuff.

What is still missing are the contents of the CommandExtension implemented by the KiCoolLanguageServerExtension. This is an interface defining all additional commands. The CommandExtension looks like this.

Example CommandExtension
package de.cau.cs.kieler.kicool.ide.language.server

import java.util.concurrent.CompletableFuture
import org.eclipse.lsp4j.jsonrpc.services.JsonRequest
import org.eclipse.lsp4j.jsonrpc.services.JsonSegment

/**
 * Interface to the LSP extension commands
 * 
 * @author really fancy name
 *
 */
@JsonSegment('keith/kicool')
interface CommandExtension {
    
    /**
     * Compiles file given by uri with compilationsystem given by command.
     */
    @JsonRequest('compile')
    def CompletableFuture<CompilationResults> compile(String uri, String clientId, String command, boolean inplace);
    
    /**
     * Build diagram for snapshot with id index for file given by uri. Only works, if the file was already compiled.
     */
    @JsonRequest('show')
    def CompletableFuture<String> show(String uri, String clientId, int index)
    
    /**
     * Returns all compilation systems which are applicable for the file at given uri.
     * 
     * @param uri URI as string to get compilation systems for
     * @param filter boolean indicating whether compilation systems should be filtered
     */
    @JsonRequest('get-systems')
    def CompletableFuture<Object> getSystems(String uri, boolean filterSystems)
}

This defines three json-rpc commands: "keith/kicool/compile", "keith/kicool/show", "keith/kicool/get-systems". These are implemented in KiCoolLanguageServerExtension.


Server Client communication interface

Not only messages from client to server but rather messages from server client might be needed.

Messages that can be send from server to client are defined in the KeithLanguageClient:

Example KeithLanguageLCient
/**
 * LanguageClient that implements additional methods necessary for server client communication in KEITH.
 * 
 * @author really fancy name
 *
 */
 @JsonSegment("keith")
interface KeithLanguageClient extends LanguageClient {
    
    @JsonNotification("kicool/compile")
    def void compile(Object results, String uri, boolean finished);
    
    @JsonNotification("kicool/cancel-compilation")
    def void cancelCompilation(boolean success);
    
	// Not only notifications, but also server client requests should be possible, but currently there is no use case for that.
}

These messages can be caught on the client side by defining the message that is caught like this:

Client side message definition
export const snapshotDescriptionMessageType = new NotificationType<CodeContainer, void>('keith/kicool/compile');

This message type is bound to a method that should be called whenever the client receives such a message.

Client side message registration
const lClient: ILanguageClient = await this.client.languageClient
lClient.onNotification(snapshotDescriptionMessageType, this.handleNewSnapshotDescriptions.bind(this))

The method should receive all parameters specific in the KeithLanguageClient interface on the serevr side.

Such a notification from server to client is send like this:

Server side message sending
future.thenAccept([
	// client is the KeithLanguageClient registered in a LanguageServerExtension that implements a ILanguageClientProvider
	// compile is the command defined in the KeithLanguageClientInterface
	client.compile(new CompilationResults(this.snapshotMap.get(uri)), uri, finished)
])


Register and calling an extension (on client side)

Language server extension do not have to be registered on the client side. It is just called.

You can send a request or a notification to the language server like this:

Client side message sending
const lclient = await this.client.languageClient
const snapshotsDescriptions: CodeContainer = await lclient.sendRequest("keith/kicool/compile", [uri, KeithDiagramManager.DIAGRAM_TYPE + '_sprotty', command,
	this.compilerWidget.compileInplace]) as CodeContainer
// or via a thenable
client.languageClient.then(lClient => {
lClient.sendRequest("keith/kicool/compile").then((snapshotsDescriptions: CodeContainer) => {
	// very important stuff
}
// await is preferred, since it is shorter. 

In this example client is an instance of a language client. It is usually injected like this:

Client side LanguageClientContribution injection
@inject(KeithLanguageClientContribution) public readonly client: KeithLanguageClientContribution
constructor(
	// other injected classes that are relevant for the constructor
    ) {
	// constructor stuff
}


How to make a new package for KEITH

Clone the KEITH repository.

Open the keith folder in VSCode. You are know in the keith directory in VSCode.

You see something like this: TODO picture

Create a new folder called keith-<your extension name>.

Copy a package.json, a tslint.json, a tsconfig.json, and a src folder into the folder.

Add keith-<your extension name> to workspaces in the top level package.json.

Add "keith-<your extension name>": "0.1.0" to the dependencies in the top level package.json and the product package.json files (e.g. the package.json in keith-app).

What is in the src directory?

The source directory has three optional subfolders.

  • node: Holds all backend related classes. This does currently only exist in the keith-language package.
  • common: Holds general helper methods, string constants and some data classes
  • browser: Holds all widgets, contribution for commands, menus, and widgets, and the frontend-extension.

The frontend-extension

This binds all necessary classes. Look at existing frontend extension in KEITH or Theia to see how this is done.

More examples for stuff

See Theia examples.

How to write a widget

There are different kinds of widgets that are commonly used in KEITH or in existing Theia packages.

  • BaseWidget: Very basic
  • ReactWidget: A render method has to be implemented that redraws the widget on demand. Additionally several on* event methods can beimplemented.
  • TreeWidget: Extends the ReactWidget and draws the contents of the widget in a tree view.

If a widget has a state it should implement the StatefulWidget interface, which allows to imlement a store and restore method.

Look at examples in KEITH or Theia to see how this is done.

How to make a new module for sprotty (see actionModule, ...)

WIP

  • No labels