extensions/json-language-features/server/src/jsonServer.ts/startServer
export function startServer(connection: Connection, runtime: RuntimeEnvironment) {

	function getSchemaRequestService(handledSchemas: string[] = ['https', 'http', 'file']) {
		const builtInHandlers: { [protocol: string]: RequestService | undefined } = {};
		for (const protocol of handledSchemas) {
			if (protocol === 'file') {
				builtInHandlers[protocol] = runtime.file;
			} else if (protocol === 'http' || protocol === 'https') {
				builtInHandlers[protocol] = runtime.http;
			}
		}
		return (uri: string): Thenable<string> => {
			const protocol = uri.substr(0, uri.indexOf(':'));

			const builtInHandler = builtInHandlers[protocol];
			if (builtInHandler) {
				return builtInHandler.getContent(uri);
			}
			return connection.sendRequest(VSCodeContentRequest.type, uri).then(responseText => {
				return responseText;
			}, error => {
				return Promise.reject(error.message);
			});
		};
	}

	// create the JSON language service
	let languageService = getLanguageService({
		workspaceContext,
		contributions: [],
		clientCapabilities: ClientCapabilities.LATEST
	});

	// Create a text document manager.
	const documents = new TextDocuments(TextDocument);

	// Make the text document manager listen on the connection
	// for open, change and close text document events
	documents.listen(connection);

	let clientSnippetSupport = false;
	let dynamicFormatterRegistration = false;
	let hierarchicalDocumentSymbolSupport = false;

	let foldingRangeLimitDefault = Number.MAX_VALUE;
	let foldingRangeLimit = Number.MAX_VALUE;
	let resultLimit = Number.MAX_VALUE;
	let formatterMaxNumberOfEdits = Number.MAX_VALUE;

	let diagnosticsSupport: DiagnosticsSupport | undefined;


	// After the server has started the client sends an initialize request. The server receives
	// in the passed params the rootPath of the workspace plus the client capabilities.
	connection.onInitialize((params: InitializeParams): InitializeResult => {

		const initializationOptions = params.initializationOptions as any || {};

		const handledProtocols = initializationOptions?.handledSchemaProtocols;

		languageService = getLanguageService({
			schemaRequestService: getSchemaRequestService(handledProtocols),
			workspaceContext,
			contributions: [],
			clientCapabilities: params.capabilities
		});

		function getClientCapability<T>(name: string, def: T) {
			const keys = name.split('.');
			let c: any = params.capabilities;
			for (let i = 0; c && i < keys.length; i++) {
				if (!c.hasOwnProperty(keys[i])) {
					return def;
				}
				c = c[keys[i]];
			}
			return c;
		}

		clientSnippetSupport = getClientCapability('textDocument.completion.completionItem.snippetSupport', false);
		dynamicFormatterRegistration = getClientCapability('textDocument.rangeFormatting.dynamicRegistration', false) && (typeof initializationOptions.provideFormatter !== 'boolean');
		foldingRangeLimitDefault = getClientCapability('textDocument.foldingRange.rangeLimit', Number.MAX_VALUE);
		hierarchicalDocumentSymbolSupport = getClientCapability('textDocument.documentSymbol.hierarchicalDocumentSymbolSupport', false);
		formatterMaxNumberOfEdits = initializationOptions.customCapabilities?.rangeFormatting?.editLimit || Number.MAX_VALUE;

		const supportsDiagnosticPull = getClientCapability('textDocument.diagnostic', undefined);
		if (supportsDiagnosticPull === undefined) {
			diagnosticsSupport = registerDiagnosticsPushSupport(documents, connection, runtime, validateTextDocument);
		} else {
			diagnosticsSupport = registerDiagnosticsPullSupport(documents, connection, runtime, validateTextDocument);
		}

		const capabilities: ServerCapabilities = {
			textDocumentSync: TextDocumentSyncKind.Incremental,
			completionProvider: clientSnippetSupport ? {
				resolveProvider: false, // turn off resolving as the current language service doesn't do anything on resolve. Also fixes #91747
				triggerCharacters: ['"', ':']
			} : undefined,
			hoverProvider: true,
			documentSymbolProvider: true,
			documentRangeFormattingProvider: initializationOptions.provideFormatter === true,
			documentFormattingProvider: initializationOptions.provideFormatter === true,
			colorProvider: {},
			foldingRangeProvider: true,
			selectionRangeProvider: true,
			documentLinkProvider: {},
			diagnosticProvider: {
				documentSelector: null,
				interFileDependencies: false,
				workspaceDiagnostics: false
			}
		};

		return { capabilities };
	});



	// The settings interface describes the server relevant settings part
	interface Settings {
		json?: {
			schemas?: JSONSchemaSettings[];
			format?: { enable?: boolean };
			validate?: { enable?: boolean };
			resultLimit?: number;
		};
		http?: {
			proxy?: string;
			proxyStrictSSL?: boolean;
		};
	}

	interface JSONSchemaSettings {
		fileMatch?: string[];
		url?: string;
		schema?: JSONSchema;
	}



	let jsonConfigurationSettings: JSONSchemaSettings[] | undefined = undefined;
	let schemaAssociations: ISchemaAssociations | SchemaConfiguration[] | undefined = undefined;
	let formatterRegistrations: Thenable<Disposable>[] | null = null;
	let validateEnabled = true;

	// The settings have changed. Is send on server activation as well.
	connection.onDidChangeConfiguration((change) => {
		const settings = <Settings>change.settings;
		runtime.configureHttpRequests?.(settings?.http?.proxy, !!settings.http?.proxyStrictSSL);
		jsonConfigurationSettings = settings.json?.schemas;
		validateEnabled = !!settings.json?.validate?.enable;
		updateConfiguration();

		foldingRangeLimit = Math.trunc(Math.max(settings.json?.resultLimit || foldingRangeLimitDefault, 0));
		resultLimit = Math.trunc(Math.max(settings.json?.resultLimit || Number.MAX_VALUE, 0));

		// dynamically enable & disable the formatter
		if (dynamicFormatterRegistration) {
			const enableFormatter = settings.json?.format?.enable;
			if (enableFormatter) {
				if (!formatterRegistrations) {
					const documentSelector = [{ language: 'json' }, { language: 'jsonc' }];
					formatterRegistrations = [
						connection.client.register(DocumentRangeFormattingRequest.type, { documentSelector }),
						connection.client.register(DocumentFormattingRequest.type, { documentSelector })
					];
				}
			} else if (formatterRegistrations) {
				formatterRegistrations.forEach(p => p.then(r => r.dispose()));
				formatterRegistrations = null;
			}
		}
	});

	// The jsonValidation extension configuration has changed
	connection.onNotification(SchemaAssociationNotification.type, associations => {
		schemaAssociations = associations;
		updateConfiguration();
	});

	// A schema has changed
	connection.onNotification(SchemaContentChangeNotification.type, uriOrUris => {
		let needsRevalidation = false;
		if (Array.isArray(uriOrUris)) {
			for (const uri of uriOrUris) {
				if (languageService.resetSchema(uri)) {
					needsRevalidation = true;
				}
			}
		} else {
			needsRevalidation = languageService.resetSchema(uriOrUris);
		}
		if (needsRevalidation) {
			diagnosticsSupport?.requestRefresh();
		}
	});

	// Retry schema validation on all open documents
	connection.onRequest(ForceValidateRequest.type, async uri => {
		const document = documents.get(uri);
		if (document) {
			updateConfiguration();
			return await validateTextDocument(document);
		}
		return [];
	});

	connection.onRequest(LanguageStatusRequest.type, async uri => {
		const document = documents.get(uri);
		if (document) {
			const jsonDocument = getJSONDocument(document);
			return languageService.getLanguageStatus(document, jsonDocument);
		} else {
			return { schemas: [] };
		}
	});

	function updateConfiguration() {
		const languageSettings = {
			validate: validateEnabled,
			allowComments: true,
			schemas: new Array<SchemaConfiguration>()
		};
		if (schemaAssociations) {
			if (Array.isArray(schemaAssociations)) {
				Array.prototype.push.apply(languageSettings.schemas, schemaAssociations);
			} else {
				for (const pattern in schemaAssociations) {
					const association = schemaAssociations[pattern];
					if (Array.isArray(association)) {
						association.forEach(uri => {
							languageSettings.schemas.push({ uri, fileMatch: [pattern] });
						});
					}
				}
			}
		}
		if (jsonConfigurationSettings) {
			jsonConfigurationSettings.forEach((schema, index) => {
				let uri = schema.url;
				if (!uri && schema.schema) {
					uri = schema.schema.id || `vscode://schemas/custom/${index}`;
				}
				if (uri) {
					languageSettings.schemas.push({ uri, fileMatch: schema.fileMatch, schema: schema.schema });
				}
			});
		}
		languageService.configure(languageSettings);

		diagnosticsSupport?.requestRefresh();
	}

	async function validateTextDocument(textDocument: TextDocument): Promise<Diagnostic[]> {
		if (textDocument.getText().length === 0) {
			return []; // ignore empty documents
		}
		const jsonDocument = getJSONDocument(textDocument);
		const documentSettings: DocumentLanguageSettings = textDocument.languageId === 'jsonc' ? { comments: 'ignore', trailingCommas: 'warning' } : { comments: 'error', trailingCommas: 'error' };
		return await languageService.doValidation(textDocument, jsonDocument, documentSettings);
	}

	connection.onDidChangeWatchedFiles((change) => {
		// Monitored files have changed in VSCode
		let hasChanges = false;
		change.changes.forEach(c => {
			if (languageService.resetSchema(c.uri)) {
				hasChanges = true;
			}
		});
		if (hasChanges) {
			diagnosticsSupport?.requestRefresh();
		}
	});

	const jsonDocuments = getLanguageModelCache<JSONDocument>(10, 60, document => languageService.parseJSONDocument(document));
	documents.onDidClose(e => {
		jsonDocuments.onDocumentRemoved(e.document);
	});
	connection.onShutdown(() => {
		jsonDocuments.dispose();
	});

	function getJSONDocument(document: TextDocument): JSONDocument {
		return jsonDocuments.get(document);
	}

	connection.onCompletion((textDocumentPosition, token) => {
		return runSafeAsync(runtime, async () => {
			const document = documents.get(textDocumentPosition.textDocument.uri);
			if (document) {
				const jsonDocument = getJSONDocument(document);
				return languageService.doComplete(document, textDocumentPosition.position, jsonDocument);
			}
			return null;
		}, null, `Error while computing completions for ${textDocumentPosition.textDocument.uri}`, token);
	});

	connection.onHover((textDocumentPositionParams, token) => {
		return runSafeAsync(runtime, async () => {
			const document = documents.get(textDocumentPositionParams.textDocument.uri);
			if (document) {
				const jsonDocument = getJSONDocument(document);
				return languageService.doHover(document, textDocumentPositionParams.position, jsonDocument);
			}
			return null;
		}, null, `Error while computing hover for ${textDocumentPositionParams.textDocument.uri}`, token);
	});

	connection.onDocumentSymbol((documentSymbolParams, token) => {
		return runSafe(runtime, () => {
			const document = documents.get(documentSymbolParams.textDocument.uri);
			if (document) {
				const jsonDocument = getJSONDocument(document);
				if (hierarchicalDocumentSymbolSupport) {
					return languageService.findDocumentSymbols2(document, jsonDocument, { resultLimit });
				} else {
					return languageService.findDocumentSymbols(document, jsonDocument, { resultLimit });
				}
			}
			return [];
		}, [], `Error while computing document symbols for ${documentSymbolParams.textDocument.uri}`, token);
	});

	function onFormat(textDocument: TextDocumentIdentifier, range: Range | undefined, options: FormattingOptions): TextEdit[] {
		const document = documents.get(textDocument.uri);
		if (document) {
			const edits = languageService.format(document, range ?? getFullRange(document), options);
			if (edits.length > formatterMaxNumberOfEdits) {
				const newText = TextDocument.applyEdits(document, edits);
				return [TextEdit.replace(getFullRange(document), newText)];
			}
			return edits;
		}
		return [];
	}

	connection.onDocumentRangeFormatting((formatParams, token) => {
		return runSafe(runtime, () => onFormat(formatParams.textDocument, formatParams.range, formatParams.options), [], `Error while formatting range for ${formatParams.textDocument.uri}`, token);
	});

	connection.onDocumentFormatting((formatParams, token) => {
		return runSafe(runtime, () => onFormat(formatParams.textDocument, undefined, formatParams.options), [], `Error while formatting ${formatParams.textDocument.uri}`, token);
	});

	connection.onDocumentColor((params, token) => {
		return runSafeAsync(runtime, async () => {
			const document = documents.get(params.textDocument.uri);
			if (document) {

				const jsonDocument = getJSONDocument(document);
				return languageService.findDocumentColors(document, jsonDocument, { resultLimit });
			}
			return [];
		}, [], `Error while computing document colors for ${params.textDocument.uri}`, token);
	});

	connection.onColorPresentation((params, token) => {
		return runSafe(runtime, () => {
			const document = documents.get(params.textDocument.uri);
			if (document) {
				const jsonDocument = getJSONDocument(document);
				return languageService.getColorPresentations(document, jsonDocument, params.color, params.range);
			}
			return [];
		}, [], `Error while computing color presentations for ${params.textDocument.uri}`, token);
	});

	connection.onFoldingRanges((params, token) => {
		return runSafe(runtime, () => {
			const document = documents.get(params.textDocument.uri);
			if (document) {
				return languageService.getFoldingRanges(document, { rangeLimit: foldingRangeLimit });
			}
			return null;
		}, null, `Error while computing folding ranges for ${params.textDocument.uri}`, token);
	});


	connection.onSelectionRanges((params, token) => {
		return runSafe(runtime, () => {
			const document = documents.get(params.textDocument.uri);
			if (document) {
				const jsonDocument = getJSONDocument(document);
				return languageService.getSelectionRanges(document, params.positions, jsonDocument);
			}
			return [];
		}, [], `Error while computing selection ranges for ${params.textDocument.uri}`, token);
	});

	connection.onDocumentLinks((params, token) => {
		return runSafeAsync(runtime, async () => {
			const document = documents.get(params.textDocument.uri);
			if (document) {
				const jsonDocument = getJSONDocument(document);
				return languageService.findLinks(document, jsonDocument);
			}
			return [];
		}, [], `Error while computing links for ${params.textDocument.uri}`, token);
	});

	// Listen on the connection
	connection.listen();
}