blob: 54ab0c251f2f52ba8a303905d1eb2e6c8a25c247 [file] [log] [blame]
// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'dart:async';
import 'dart:convert';
import 'package:fuchsia_logger/logger.dart';
/// ignore_for_file: avoid_annotating_with_dynamic
/// A callback for data sent by xi-core.
/// TODO(jasoncampbell): Allow typed structures to be sent instead of strings.
typedef XiClientListener = void Function(dynamic data);
/// An error received from core in response to an RPC.
class CoreError {
int code;
String message;
dynamic data;
CoreError(Map<String, dynamic> errorJson) {
code = errorJson['code'];
message = errorJson['message'];
data = errorJson['data'];
/// Handler, for handling requests (both notification and RPC) from core
abstract class XiRpcHandler {
/// Handle a json-rpc notification
void handleNotification(String method, dynamic params);
/// Handle a json-rpc request. Note: the signature is currently
/// synchronous (so that the handler must immediately return), but
/// this may change. Not currently exercised.
dynamic handleRpc(String method, dynamic params);
/// Generic abstract class for wrapping xi-core process/service
abstract class XiClient {
/// Flag marking wether the client has been initialized or not.
bool initialized = false;
int _id = 0;
final Map<int, Completer<dynamic>> _pending = <int, Completer<dynamic>>{};
XiRpcHandler _handler;
/// Callbacks fired whenever a message from xi-core is received. Add with
/// [onMessage].
List<XiClientListener> listeners = <XiClientListener>[];
/// A [StreamController] that handles the transformation of input from
/// either the xi-core FIDL service or the xi-core process. To send data
/// through the pipeline use the stream controller. For example, to connect
/// to a Process' stdout:
/// process.stdout.listen(streamController.add);
StreamController<List<int>> streamController =
/// [XiClient] constructor.
XiClient() {
// Adds a transformation pipeline for stream input into line separated
// strings.
// TODO(jasoncampbell): add a transformation for automatic JSON
// deserialization.
.transform(const LineSplitter())
onError: onError,
cancelOnError: true,
/// Override this method to control where/how messages are sent to the
/// xi-core process or service.
void send(String data);
/// Override this method and add any required initialization work.
Future<Null> init();
/// Register a handler. This causes incoming json-rpc requests to be
/// routed to that handler.
set handler(XiRpcHandler h) {
_handler = h;
/// Register an event listener.
void onMessage(XiClientListener callback) {
/// Classes that extend [XiClient] should use this method to trigger any
/// [listeners].
void handleData(String data) {
Map<String, dynamic> decoded = json.decode(data);
if (decoded.containsKey('error')) {
} else if (decoded.containsKey('result')) {
} else if (_handler == null) {
// not a response, so it must be a request
log.warning('no handler registered for request');
} else {
String method = decoded['method'];
dynamic params = decoded['params'];
// a request with an id must get a response
if (decoded.containsKey('id')) {
_handler.handleRpc(method, params).then((dynamic result) {
sendResponse(decoded['id'], result);
}).catchError((err) {
sendErrorResponse(decoded['id'], err);
} else {
_handler.handleNotification(method, params);
if (listeners.isNotEmpty) {
for (XiClientListener callback in listeners) {
void handleErrorResponse(Map<String, dynamic> error) {
log.warning('Received error response', error);
int id = error['id'];
Completer<dynamic> completer = _pending.remove(id);
CoreError coreError = CoreError(error['error']);
if (completer != null) {
void handleResponse(Map<String, dynamic> response) {
int id = response['id'];
Completer<dynamic> completer = _pending.remove(id);
if (completer != null) {
void sendResponse(int id, dynamic payload) {
Map<String, dynamic> response = <String, dynamic>{
'result': payload,
'id': id,
void sendErrorResponse(int id, dynamic payload) {
//TODO: have some real type for errors originating in the client
Map<String, dynamic> error = <String, dynamic>{
'code': 1,
'msg': '$payload',
Map<String, dynamic> response = <String, dynamic>{
'error': error,
'id': id,
void _sendJson(dynamic decoded) {
/// Send an asynchronous notification to the core.
void sendNotification(String method, dynamic params) {
Map<String, dynamic> json = <String, dynamic>{
'method': method,
'params': params
/// Send an RPC request to the core.
Future<dynamic> sendRpc(String method, dynamic params) {
Completer<dynamic> completer = Completer<dynamic>();
_pending[_id] = completer;
Map<String, dynamic> json = <String, dynamic>{
'method': method,
'params': params,
'id': _id
return completer.future;
/// Generic error handler that can be used or everyone by implementations of [XiClient].
void onError(Object error, StackTrace stackTrace) {
log.severe('[XiClient ERROR]:', error, stackTrace);