Refactor and streamline API and IPC protocol.

This patch removes the obsolete API support to send raw messages using
a QWebChannel. Instead, it is encouraged to directly use WebSockets or
navigator.qt.

By doing so, we can cleanup the code considerably. While at it, the
transport API is adapted to work on QJsonObject messages, instead of
QStrings. This will allow us to use more efficient formats in e.g.
QtWebKit or QtWebEngine. One could also implement a JSONRPC interface
using a custom transport then.

Change-Id: Ia8c125a5558507b3cbecf128a46b19fdb013f47b
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@digia.com>

1 files changed, 59 insertions, 81 deletions

diff --git a/src/webchannel/qmetaobjectpublisher.cpp b/src/webchannel/qmetaobjectpublisher.cpp
index 646398d..d9aa548 100644
--- a/src/webchannel/qmetaobjectpublisher.cpp
+++ b/src/webchannel/qmetaobjectpublisher.cpp
@@ -59,30 +59,11 @@ QT_BEGIN_NAMESPACE
 
 namespace {
 
-// NOTE: keep in sync with corresponding maps in qwebchannel.js and WebChannelTest.qml
-enum Type {
-    TypeInvalid = 0,
-
-    TYPES_FIRST_VALUE = 1,
-
-    TypeSignal = 1,
-    TypePropertyUpdate = 2,
-    TypeInit = 3,
-    TypeIdle = 4,
-    TypeDebug = 5,
-    TypeInvokeMethod = 6,
-    TypeConnectToSignal = 7,
-    TypeDisconnectFromSignal = 8,
-    TypeSetProperty = 9,
-
-    TYPES_LAST_VALUE = 9
-};
-
-Type toType(const QJsonValue &value)
+MessageType toType(const QJsonValue &value)
 {
     int i = value.toInt(-1);
     if (i >= TYPES_FIRST_VALUE && i <= TYPES_LAST_VALUE) {
-        return static_cast<Type>(i);
+        return static_cast<MessageType>(i);
     } else {
         return TypeInvalid;
     }
@@ -99,13 +80,11 @@ const QString KEY_OBJECT = QStringLiteral("object");
 const QString KEY_DESTROYED = QStringLiteral("destroyed");
 const QString KEY_SIGNAL = QStringLiteral("signal");
 const QString KEY_TYPE = QStringLiteral("type");
-const QString KEY_MESSAGE = QStringLiteral("message");
 const QString KEY_METHOD = QStringLiteral("method");
 const QString KEY_ARGS = QStringLiteral("args");
 const QString KEY_PROPERTY = QStringLiteral("property");
 const QString KEY_VALUE = QStringLiteral("value");
 
-
 QString objectId(const QObject *object)
 {
     return QString::number(quintptr(object), 16);
@@ -261,7 +240,10 @@ void QMetaObjectPublisher::initializeClients()
             objectInfos[it.key()] = info;
         }
     }
-    webChannel->sendMessage(TypeInit, objectInfos);
+    QJsonObject message;
+    message[KEY_TYPE] = TypeInit;
+    message[KEY_DATA] = objectInfos;
+    broadcastMessage(message);
     propertyUpdatesInitialized = true;
     pendingInit = false;
 }
@@ -334,31 +316,34 @@ void QMetaObjectPublisher::sendPendingPropertyUpdates()
     }
 
     pendingPropertyUpdates.clear();
-    webChannel->sendMessage(TypePropertyUpdate, data);
+    QJsonObject message;
+    message[KEY_TYPE] = TypePropertyUpdate;
+    message[KEY_DATA] = data;
+    broadcastMessage(message);
     setClientIsIdle(false);
 }
 
-QByteArray QMetaObjectPublisher::invokeMethod(QObject *const object, const int methodIndex,
-                                              const QJsonArray &args, const QJsonValue &id)
+QJsonValue QMetaObjectPublisher::invokeMethod(QObject *const object, const int methodIndex,
+                                              const QJsonArray &args)
 {
     const QMetaMethod &method = object->metaObject()->method(methodIndex);
 
     if (method.name() == QByteArrayLiteral("deleteLater")) {
         // invoke `deleteLater` on wrapped QObject indirectly
         deleteWrappedObject(object);
-        return QByteArray();
+        return QJsonValue();
     } else if (!method.isValid()) {
         qWarning() << "Cannot invoke unknown method of index" << methodIndex << "on object" << object << '.';
-        return QByteArray();
+        return QJsonValue();
     } else if (method.access() != QMetaMethod::Public) {
         qWarning() << "Cannot invoke non-public method" << method.name() << "on object" << object << '.';
-        return QByteArray();
+        return QJsonValue();
     } else if (method.methodType() != QMetaMethod::Method && method.methodType() != QMetaMethod::Slot) {
         qWarning() << "Cannot invoke non-public method" << method.name() << "on object" << object << '.';
-        return QByteArray();
+        return QJsonValue();
     } else if (args.size() > 10) {
         qWarning() << "Cannot invoke method" << method.name() << "on object" << object << "with more than 10 arguments, as that is not supported by QMetaMethod::invoke.";
-        return QByteArray();
+        return QJsonValue();
     } else if (args.size() > method.parameterCount()) {
         qWarning() << "Ignoring additional arguments while invoking method" << method.name() << "on object" << object << ':'
                    << args.size() << "arguments given, but method only takes" << method.parameterCount() << '.';
@@ -389,8 +374,7 @@ QByteArray QMetaObjectPublisher::invokeMethod(QObject *const object, const int m
                   arguments[0], arguments[1], arguments[2], arguments[3], arguments[4],
                   arguments[5], arguments[6], arguments[7], arguments[8], arguments[9]);
 
-    // and send the return value to the client
-    return generateJSONMessage(id, wrapResult(returnValue), true);
+    return wrapResult(returnValue);
 }
 
 void QMetaObjectPublisher::signalEmitted(const QObject *object, const int signalIndex, const QVariantList &arguments)
@@ -399,11 +383,11 @@ void QMetaObjectPublisher::signalEmitted(const QObject *object, const int signal
         return;
     }
     if (!signalToPropertyMap.value(object).contains(signalIndex)) {
-        QJsonObject data;
+        QJsonObject message;
         const QString &objectName = registeredObjectIds.value(object);
         Q_ASSERT(!objectName.isEmpty());
-        data[KEY_OBJECT] = objectName;
-        data[KEY_SIGNAL] = signalIndex;
+        message[KEY_OBJECT] = objectName;
+        message[KEY_SIGNAL] = signalIndex;
         if (!arguments.isEmpty()) {
             // TODO: wrap (new) objects on the fly
             QJsonArray args;
@@ -419,9 +403,10 @@ void QMetaObjectPublisher::signalEmitted(const QObject *object, const int signal
 #else
             args = QJsonArray::fromVariantList(arguments);
 #endif
-            data[KEY_ARGS] = args;
+            message[KEY_ARGS] = args;
         }
-        webChannel->sendMessage(TypeSignal, data);
+        message[KEY_TYPE] = TypeSignal;
+        broadcastMessage(message);
 
         if (signalIndex == s_destroyedSignalIndex) {
             objectDestroyed(object);
@@ -486,78 +471,71 @@ void QMetaObjectPublisher::deleteWrappedObject(QObject *object) const
     object->deleteLater();
 }
 
-QByteArray QMetaObjectPublisher::handleRequest(const QJsonObject &message)
+void QMetaObjectPublisher::broadcastMessage(const QJsonObject &message) const
 {
-    if (!message.contains(KEY_DATA)) {
-        return QByteArray();
+    if (webChannel->d_func()->transports.isEmpty()) {
+        qWarning("QWebChannel is not connected to any transports, cannot send messages.");
+        return;
+    }
+
+    foreach (QWebChannelAbstractTransport *transport, webChannel->d_func()->transports) {
+        transport->sendMessage(message);
     }
+}
 
-    const QJsonObject &payload = message.value(KEY_DATA).toObject();
-    if (!payload.contains(KEY_TYPE)) {
-        return QByteArray();
+void QMetaObjectPublisher::handleMessage(const QJsonObject &message, QWebChannelAbstractTransport *transport)
+{
+    if (!message.contains(KEY_TYPE)) {
+        qWarning("JSON message object is missing the type property: %s", QJsonDocument(message).toJson().constData());
+        return;
     }
 
-    const Type type = toType(payload.value(KEY_TYPE));
+    const MessageType type = toType(message.value(KEY_TYPE));
     if (type == TypeIdle) {
         setClientIsIdle(true);
-        return QByteArray();
     } else if (type == TypeInit) {
         if (!blockUpdates) {
             initializeClients();
         } else {
             pendingInit = true;
         }
-        return QByteArray();
     } else if (type == TypeDebug) {
         static QTextStream out(stdout);
-        out << "DEBUG: " << payload.value(KEY_MESSAGE).toString() << endl;
-        return QByteArray();
-    } else if (payload.contains(KEY_OBJECT)) {
-        const QString &objectName = payload.value(KEY_OBJECT).toString();
+        out << "DEBUG: " << message.value(KEY_DATA).toString() << endl;
+    } else if (message.contains(KEY_OBJECT)) {
+        const QString &objectName = message.value(KEY_OBJECT).toString();
         QObject *object = registeredObjects.value(objectName);
         if (!object) {
             qWarning() << "Unknown object encountered" << objectName;
-            return QByteArray();
+            return;
         }
 
         if (type == TypeInvokeMethod) {
-            return invokeMethod(object, payload.value(KEY_METHOD).toInt(-1), payload.value(KEY_ARGS).toArray(), message.value(KEY_ID));
+            if (!message.contains(KEY_ID)) {
+                qWarning("JSON message object is missing the id property: %s",
+                          QJsonDocument(message).toJson().constData());
+                return;
+            }
+            QJsonObject response;
+            response[KEY_TYPE] = TypeResponse;
+            response[KEY_ID] = message.value(KEY_ID);
+            response[KEY_DATA] = invokeMethod(object, message.value(KEY_METHOD).toInt(-1), message.value(KEY_ARGS).toArray());
+            transport->sendMessage(response);
         } else if (type == TypeConnectToSignal) {
-            signalHandler.connectTo(object, payload.value(KEY_SIGNAL).toInt(-1));
-            return QByteArray();
+            signalHandler.connectTo(object, message.value(KEY_SIGNAL).toInt(-1));
         } else if (type == TypeDisconnectFromSignal) {
-            signalHandler.disconnectFrom(object, payload.value(KEY_SIGNAL).toInt(-1));
-            return QByteArray();
+            signalHandler.disconnectFrom(object, message.value(KEY_SIGNAL).toInt(-1));
         } else if (type == TypeSetProperty) {
-            const int propertyIdx = payload.value(KEY_PROPERTY).toInt(-1);
+            const int propertyIdx = message.value(KEY_PROPERTY).toInt(-1);
             QMetaProperty property = object->metaObject()->property(propertyIdx);
             if (!property.isValid()) {
-                qWarning() << "Cannot set unknown property" << payload.value(KEY_PROPERTY) << "of object" << objectName;
-                return QByteArray();
-            } else if (!object->metaObject()->property(propertyIdx).write(object, payload.value(KEY_VALUE).toVariant())) {
-                qWarning() << "Could not write value " << payload.value(KEY_VALUE)
+                qWarning() << "Cannot set unknown property" << message.value(KEY_PROPERTY) << "of object" << objectName;
+            } else if (!object->metaObject()->property(propertyIdx).write(object, message.value(KEY_VALUE).toVariant())) {
+                qWarning() << "Could not write value " << message.value(KEY_VALUE)
                            << "to property" << property.name() << "of object" << objectName;
-                return QByteArray();
             }
-            return QByteArray();
         }
     }
-    return QByteArray();
-}
-
-void QMetaObjectPublisher::handleMessage(const QString &message)
-{
-    QWebChannelAbstractTransport *transport = qobject_cast<QWebChannelAbstractTransport*>(sender());
-    Q_ASSERT(transport);
-
-    const QJsonDocument doc = QJsonDocument::fromJson(message.toUtf8());
-    if (!doc.isObject()) {
-        return;
-    }
-    const QByteArray &response = handleRequest(doc.object());
-    if (!response.isEmpty()) {
-        transport->sendTextMessage(QString::fromUtf8(response));
-    }
 }
 
 void QMetaObjectPublisher::setBlockUpdates(bool block)