core: improve rpc protocol

- Ensure that pending requests are properly rejected when the underlying service channel is closed.
- Remove obsolete id-property from `NotificationMessage`s. Ids are only required fro matching request-response pairs.
- Rename `JsonRpcProxyFactory` and related types to `RpcProxyFactory` (Rpc*). The naming scheme was a remainder of the old vscode jsonr-rpc based protocol.
  By simply using the `Rpc` suffix the class names are less misleading and protocol agnostic.
- Keep deprecated declarations of the old `JsonRpc*` namespace. The components are heavily used by adopters so we should maintain this deprecated symbols for a while to enable graceful migration without hard API breaks.
- Use a deferred in the `RpcProxyFactory` for protocol initialization

Fixes #12581

packages/core/src/common/message-rpc/rpc-message-encoder.ts

@@ -51,7 +51,6 @@ export interface RequestMessage {
 
 export interface NotificationMessage {
     type: RpcMessageType.Notification;
-    id: number;
     method: string;
     args: any[];
 }
@@ -111,7 +110,7 @@ export interface RpcMessageDecoder {
 export interface RpcMessageEncoder {
     cancel(buf: WriteBuffer, requestId: number): void;
 
-    notification(buf: WriteBuffer, requestId: number, method: string, args: any[]): void
+    notification(buf: WriteBuffer, method: string, args: any[]): void
 
     request(buf: WriteBuffer, requestId: number, method: string, args: any[]): void
 
@@ -130,8 +129,8 @@ export class MsgPackMessageEncoder implements RpcMessageEncoder {
     cancel(buf: WriteBuffer, requestId: number): void {
         this.encode<CancelMessage>(buf, { type: RpcMessageType.Cancel, id: requestId });
     }
-    notification(buf: WriteBuffer, requestId: number, method: string, args: any[]): void {
-        this.encode<NotificationMessage>(buf, { type: RpcMessageType.Notification, id: requestId, method, args });
+    notification(buf: WriteBuffer, method: string, args: any[]): void {
+        this.encode<NotificationMessage>(buf, { type: RpcMessageType.Notification, method, args });
     }
     request(buf: WriteBuffer, requestId: number, method: string, args: any[]): void {
         this.encode<RequestMessage>(buf, { type: RpcMessageType.Request, id: requestId, method, args });

packages/core/src/common/message-rpc/rpc-protocol.ts

@@ -77,7 +77,11 @@ export class RpcProtocol {
         this.encoder = options.encoder ?? new MsgPackMessageEncoder();
         this.decoder = options.decoder ?? new MsgPackMessageDecoder();
         this.toDispose.push(this.onNotificationEmitter);
-        channel.onClose(() => this.toDispose.dispose());
+        channel.onClose(event => {
+            this.pendingRequests.forEach(pending => pending.reject(new Error(event.reason)));
+            this.pendingRequests.clear();
+            this.toDispose.dispose();
+        });
         this.toDispose.push(channel.onMessage(readBuffer => this.handleMessage(this.decoder.parse(readBuffer()))));
         this.mode = options.mode ?? 'default';
 
@@ -98,7 +102,7 @@ export class RpcProtocol {
                     return;
                 }
                 case RpcMessageType.Notification: {
-                    this.handleNotify(message.id, message.method, message.args);
+                    this.handleNotify(message.method, message.args);
                     return;
                 }
             }
@@ -116,7 +120,7 @@ export class RpcProtocol {
             }
         }
         // If the message was not handled until here, it is incompatible with the mode.
-        console.warn(`Received message incompatible with this RPCProtocol's mode '${this.mode}'. Type: ${message.type}. ID: ${message.id}.`);
+        console.warn(`Received message incompatible with this RPCProtocol's mode '${this.mode}'. Type: ${message.type}`);
     }
 
     protected handleReply(id: number, value: any): void {
@@ -179,7 +183,7 @@ export class RpcProtocol {
         }
 
         const output = this.channel.getWriteBuffer();
-        this.encoder.notification(output, this.nextMessageId++, method, args);
+        this.encoder.notification(output, method, args);
         output.commit();
     }
 
@@ -226,7 +230,7 @@ export class RpcProtocol {
         }
     }
 
-    protected async handleNotify(id: number, method: string, args: any[]): Promise<void> {
+    protected async handleNotify(method: string, args: any[]): Promise<void> {
         if (this.toDispose.disposed) {
             return;
         }

packages/core/src/common/messaging/proxy-factory.ts

@@ -23,28 +23,30 @@ import { Emitter, Event } from '../event';
 import { Channel } from '../message-rpc/channel';
 import { RequestHandler, RpcProtocol } from '../message-rpc/rpc-protocol';
 import { ConnectionHandler } from './handler';
+import { Deferred } from '../promise-util';
 
-export type JsonRpcServer<Client> = Disposable & {
+export type RpcServer<Client> = Disposable & {
     /**
      * If this server is a proxy to a remote server then
      * a client is used as a local object
-     * to handle JSON-RPC messages from the remote server.
+     * to handle RPC messages from the remote server.
      */
     setClient(client: Client | undefined): void;
     getClient?(): Client | undefined;
 };
 
-export interface JsonRpcConnectionEventEmitter {
+export interface RpcConnectionEventEmitter {
     readonly onDidOpenConnection: Event<void>;
     readonly onDidCloseConnection: Event<void>;
 }
-export type JsonRpcProxy<T> = T & JsonRpcConnectionEventEmitter;
 
-export class JsonRpcConnectionHandler<T extends object> implements ConnectionHandler {
+export type RpcProxy<T> = T & RpcConnectionEventEmitter;
+
+export class RpcConnectionHandler<T extends object> implements ConnectionHandler {
     constructor(
         readonly path: string,
-        readonly targetFactory: (proxy: JsonRpcProxy<T>) => any,
-        readonly factoryConstructor: new () => JsonRpcProxyFactory<T> = JsonRpcProxyFactory
+        readonly targetFactory: (proxy: RpcProxy<T>) => any,
+        readonly factoryConstructor: new () => RpcProxyFactory<T> = RpcProxyFactory
     ) { }
 
     onConnection(connection: Channel): void {
@@ -54,20 +56,30 @@ export class JsonRpcConnectionHandler<T extends object> implements ConnectionHan
         factory.listen(connection);
     }
 }
+
 /**
- * Factory for creating a new {@link RpcConnection} for a given chanel and {@link RequestHandler}.
+ * Factory for creating a new {@link RpcProtocol} for a given chanel and {@link RequestHandler}.
  */
-export type RpcConnectionFactory = (channel: Channel, requestHandler: RequestHandler) => RpcProtocol;
+export type RpcProtocolFactory = (channel: Channel, requestHandler: RequestHandler) => RpcProtocol;
 
-const defaultRPCConnectionFactory: RpcConnectionFactory = (channel, requestHandler) => new RpcProtocol(channel, requestHandler);
+const defaultRpcProtocolFactory: RpcProtocolFactory = (channel, requestHandler) => new RpcProtocol(channel, requestHandler);
+
+export interface RpcProxyFactoryOptions {
+    rpcProtocolFactory?: RpcProtocolFactory,
+    /**
+     * Used to identify proxy calls that should be sent as notification. If method starts with one of the given
+     * keys it is treated as a notification
+     */
+    notificationKeys?: string[]
+}
 
 /**
- * Factory for JSON-RPC proxy objects.
+ * Factory for RPC proxy objects.
  *
- * A JSON-RPC proxy exposes the programmatic interface of an object through
- * JSON-RPC.  This allows remote programs to call methods of this objects by
- * sending JSON-RPC requests.  This takes place over a bi-directional stream,
- * where both ends can expose an object and both can call methods each other's
+ * A RPC proxy exposes the programmatic interface of an object through
+ * Theia's RPC protocol. This allows remote programs to call methods of this objects by
+ * sending RPC requests. This takes place over a bi-directional stream,
+ * where both ends can expose an object and both can call methods on each other's
  * exposed object.
  *
  * For example, assuming we have an object of the following type on one end:
@@ -76,87 +88,87 @@ const defaultRPCConnectionFactory: RpcConnectionFactory = (channel, requestHandl
  *         bar(baz: number): number { return baz + 1 }
  *     }
  *
- * which we want to expose through a JSON-RPC interface.  We would do:
+ * which we want to expose through a JSON interface.  We would do:
  *
  *     let target = new Foo()
- *     let factory = new JsonRpcProxyFactory<Foo>('/foo', target)
+ *     let factory = new RpcProxyFactory<Foo>('/foo', target)
  *     factory.onConnection(connection)
  *
  * The party at the other end of the `connection`, in order to remotely call
  * methods on this object would do:
  *
- *     let factory = new JsonRpcProxyFactory<Foo>('/foo')
+ *     let factory = new RpcProxyFactory<Foo>('/foo')
  *     factory.onConnection(connection)
  *     let proxy = factory.createProxy();
  *     let result = proxy.bar(42)
  *     // result is equal to 43
  *
  * One the wire, it would look like this:
- *
- *     --> {"jsonrpc": "2.0", "id": 0, "method": "bar", "params": {"baz": 42}}
- *     <-- {"jsonrpc": "2.0", "id": 0, "result": 43}
+ *     --> { "type":"1", "id": 1, "method": "bar", "args": [42]}
+ *     <-- { "type":"3", "id": 1, "res": 43}
  *
  * Note that in the code of the caller, we didn't pass a target object to
- * JsonRpcProxyFactory, because we don't want/need to expose an object.
+ * RpcProxyFactory, because we don't want/need to expose an object.
  * If we had passed a target object, the other side could've called methods on
  * it.
  *
- * @param <T> - The type of the object to expose to JSON-RPC.
+ * @param <T> - The type of the object to expose to RPC.
  */
 
-export class JsonRpcProxyFactory<T extends object> implements ProxyHandler<T> {
+export class RpcProxyFactory<T extends object> implements ProxyHandler<T> {
 
     protected readonly onDidOpenConnectionEmitter = new Emitter<void>();
     protected readonly onDidCloseConnectionEmitter = new Emitter<void>();
 
-    protected connectionPromiseResolve: (connection: RpcProtocol) => void;
-    protected connectionPromise: Promise<RpcProtocol>;
+    protected rpcDeferred = new Deferred<RpcProtocol>();
 
     /**
-     * Build a new JsonRpcProxyFactory.
+     * Build a new RpcProxyFactory.
      *
-     * @param target - The object to expose to JSON-RPC methods calls.  If this
+     * @param target - The object to expose to RPC methods calls.  If this
      *   is omitted, the proxy won't be able to handle requests, only send them.
      */
-    constructor(public target?: any, protected rpcConnectionFactory = defaultRPCConnectionFactory) {
+    constructor(public target?: any, protected rpcProtocolFactory = defaultRpcProtocolFactory) {
         this.waitForConnection();
     }
 
     protected waitForConnection(): void {
-        this.connectionPromise = new Promise(resolve =>
-            this.connectionPromiseResolve = resolve
-        );
-        this.connectionPromise.then(connection => {
-            connection.channel.onClose(() => {
+        this.rpcDeferred.promise.then(protocol => {
+            protocol.channel.onClose(() => {
                 this.onDidCloseConnectionEmitter.fire(undefined);
                 // Wait for connection in case the backend reconnects
                 this.waitForConnection();
             });
+            protocol.channel.onError(err => {
+                if (this.rpcDeferred.state !== 'resolved') {
+                    this.rpcDeferred.reject(err);
+                }
+            });
             this.onDidOpenConnectionEmitter.fire(undefined);
         });
     }
 
     /**
-     * Connect a MessageConnection to the factory.
+     * Connect a {@link Channel} to the factory by creating an {@link RpcProtocol} on top of it.
      *
-     * This connection will be used to send/receive JSON-RPC requests and
+     * This protocol will be used to send/receive RPC requests and
      * response.
      */
     listen(channel: Channel): void {
-        const connection = this.rpcConnectionFactory(channel, (meth, args) => this.onRequest(meth, ...args));
-        connection.onNotification(event => this.onNotification(event.method, ...event.args));
+        const protocol = this.rpcProtocolFactory(channel, (meth, args) => this.onRequest(meth, ...args));
+        protocol.onNotification(event => this.onNotification(event.method, ...event.args));
 
-        this.connectionPromiseResolve(connection);
+        this.rpcDeferred.resolve(protocol);
     }
 
     /**
-     * Process an incoming JSON-RPC method call.
+     * Process an incoming RPC method call.
      *
-     * onRequest is called when the JSON-RPC connection received a method call
-     * request.  It calls the corresponding method on [[target]].
+     * onRequest is called when the RPC connection received a method call
+     * request. It calls the corresponding method on [[target]].
      *
      * The return value is a Promise object that is resolved with the return
-     * value of the method call, if it is successful.  The promise is rejected
+     * value of the method call, if it is successful. The promise is rejected
      * if the called method does not exist or if it throws.
      *
      * @returns A promise of the method call completion.
@@ -181,7 +193,7 @@ export class JsonRpcProxyFactory<T extends object> implements ProxyHandler<T> {
     }
 
     /**
-     * Process an incoming JSON-RPC notification.
+     * Process an incoming RPC notification.
      *
      * Same as [[onRequest]], but called on incoming notifications rather than
      * methods calls.
@@ -194,37 +206,37 @@ export class JsonRpcProxyFactory<T extends object> implements ProxyHandler<T> {
 
     /**
      * Create a Proxy exposing the interface of an object of type T.  This Proxy
-     * can be used to do JSON-RPC method calls on the remote target object as
+     * can be used to do RPC method calls on the remote target object as
      * if it was local.
      *
-     * If `T` implements `JsonRpcServer` then a client is used as a target object for a remote target object.
+     * If `T` implements `RpcServer` then a client is used as a target object for a remote target object.
      */
-    createProxy(): JsonRpcProxy<T> {
+    createProxy(): RpcProxy<T> {
         const result = new Proxy<T>(this as any, this);
         return result as any;
     }
 
     /**
-     * Get a callable object that executes a JSON-RPC method call.
+     * Get a callable object that executes a RPC method call.
      *
      * Getting a property on the Proxy object returns a callable that, when
-     * called, executes a JSON-RPC call.  The name of the property defines the
+     * called, executes a RPC call.  The name of the property defines the
      * method to be called.  The callable takes a variable number of arguments,
-     * which are passed in the JSON-RPC method call.
+     * which are passed in the RPC method call.
      *
      * For example, if you have a Proxy object:
      *
-     *     let fooProxyFactory = JsonRpcProxyFactory<Foo>('/foo')
+     *     let fooProxyFactory = RpcProxyFactory<Foo>('/foo')
      *     let fooProxy = fooProxyFactory.createProxy()
      *
      * accessing `fooProxy.bar` will return a callable that, when called,
-     * executes a JSON-RPC method call to method `bar`.  Therefore, doing
+     * executes a RPC method call to method `bar`.  Therefore, doing
      * `fooProxy.bar()` will call the `bar` method on the remote Foo object.
      *
      * @param target - unused.
      * @param p - The property accessed on the Proxy object.
      * @param receiver - unused.
-     * @returns A callable that executes the JSON-RPC call.
+     * @returns A callable that executes the RPC call.
      */
     get(target: T, p: PropertyKey, receiver: any): any {
         if (p === 'setClient') {
@@ -249,7 +261,7 @@ export class JsonRpcProxyFactory<T extends object> implements ProxyHandler<T> {
         return (...args: any[]) => {
             const method = p.toString();
             const capturedError = new Error(`Request '${method}' failed`);
-            return this.connectionPromise.then(connection =>
+            return this.rpcDeferred.promise.then(connection =>
                 new Promise<void>((resolve, reject) => {
                     try {
                         if (isNotify) {
@@ -308,3 +320,32 @@ export class JsonRpcProxyFactory<T extends object> implements ProxyHandler<T> {
 
 }
 
+/**
+ * @deprecated since 1.39.0 use `RpcConnectionEventEmitter` instead
+ */
+export type JsonRpcConnectionEventEmitter = RpcConnectionEventEmitter;
+
+/**
+ * @deprecated since 1.39.0 use `RpcServer` instead
+ */
+export type JsonRpcServer<Client> = RpcServer<Client>;
+
+/**
+ * @deprecated since 1.39.0 use `RpcProxy` instead
+ */
+export type JsonRpcProxy<T> = RpcProxy<T>;
+
+/**
+ * @deprecated since 1.39.0 use `RpcConnectionHandler` instead
+ */
+export class JsonRpcConnectionHandler<T extends object> extends RpcConnectionHandler<T> {
+
+}
+
+/**
+ * @deprecated since 1.39.0 use `JsonRpcProxyFactory` instead
+ */
+export class JsonRpcProxyFactory<T extends object> extends RpcProxyFactory<T> {
+
+}
+