Initial commit

Lts/Common/LtsWebSocket/CMakeLists.txt

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+#
+# $Id$
+# $HeadURL$
+# $Author$
+# Created by Philipp Dassow, SLST, 2017-11-28
+
+#
+# --- Library LtsWebSocketCommon --------------------------------------------------------------------------------
+#
+SET(LtsWebSocketCommon_SRCS
+  client_message_factory.cpp
+  client_message_factory.h
+  client_message.cpp
+  client_message.h
+  reply_message.cpp
+  reply_message.h
+  data_manager_base_dl.h
+  json_keys.h
+
+  logger.cpp
+  logger.h
+)
+
+NGL_ADD_LIBRARY2(WS AAR SV LtsWebSocketCommon SHARED ${LtsWebSocketCommon_SRCS})
+
+NGL_TARGET_INCLUDE_DIRECTORIES(LtsWebSocketCommon
+  PUBLIC
+    ${CMAKE_CURRENT_SOURCE_DIR}/../
+)
+
+NGL_TARGET_LINK_LIBRARIES(LtsWebSocketCommon
+  Qt5::Core
+  Qt5::WebSockets
+  NGLLogger
+)
+
+#
+# --- Library ltsWebSocketServer --------------------------------------------------------------------------------
+#
+SET(LtsWebSocketServer_SRCS
+  client_connection.cpp
+  client_connection.h
+  connection_handler.cpp
+  connection_handler.h
+  lts_web_socket_server.cpp
+  lts_web_socket_server.h
+)
+
+NGL_ADD_LIBRARY2(WS AAR SV LtsWebSocketServer SHARED ${LtsWebSocketServer_SRCS})
+
+NGL_TARGET_INCLUDE_DIRECTORIES(LtsWebSocketServer
+  PUBLIC
+    ${CMAKE_CURRENT_SOURCE_DIR}/../
+)
+
+NGL_TARGET_LINK_LIBRARIES(LtsWebSocketServer
+  Qt5::Core
+  LtsWebSocketCommon
+)
+
+#
+# --- Library ltsWebSocketClient --------------------------------------------------------------------------------
+#
+SET(LtsWebSocketClient_SRCS
+  lts_web_socket_client.cpp
+  lts_web_socket_client.h
+)
+
+NGL_ADD_LIBRARY2(WS AAR SV LtsWebSocketClient SHARED ${LtsWebSocketClient_SRCS})
+
+NGL_TARGET_INCLUDE_DIRECTORIES(LtsWebSocketClient
+  PUBLIC
+    ${CMAKE_CURRENT_SOURCE_DIR}/../
+)
+
+NGL_TARGET_LINK_LIBRARIES(LtsWebSocketClient
+  Qt5::Core
+  LtsWebSocketCommon
+)

Lts/Common/LtsWebSocket/client_connection.cpp

@@ -0,0 +1,90 @@
+/**
+  * @RDE_HEADER@
+  * The ClientConnection class represents a connection to a single client.
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Hannes Baeuerle, SLSE, 2016-08-25
+  */
+#include "client_connection.h"
+
+#include <QWebSocket>
+
+namespace LtsWebSocket
+{
+
+ClientConnection::ClientConnection(QWebSocket *socket, QObject *parent)
+  : QThread(parent)
+  , m_socket(socket ? socket : new QWebSocket)
+  , m_logger(getLogger("ClientConnection"))
+{
+}
+
+ClientConnection::~ClientConnection()
+{
+  DEBUG_LOG(m_logger) << "Thread closed" << this;
+  delete m_socket;
+  qDeleteAll(m_messageQueue);
+}
+
+bool ClientConnection::init()
+{
+  if (m_socket == nullptr)
+  {
+    ERROR_LOG(m_logger) << "Initialisation failed due to an invalid socket";
+    return false;
+  }
+
+  DEBUG_LOG(m_logger) << "Started new thread" << this;
+  connect(m_socket, &QWebSocket::textMessageReceived, this, &ClientConnection::onNewTextMessageFromSocket, Qt::DirectConnection);
+  connect(m_socket, &QWebSocket::connected, this, &ClientConnection::sendMessagesFromQueue);
+  connect(m_socket, &QWebSocket::disconnected, this, &ClientConnection::onSocketDisconnect);
+
+  return true;
+}
+
+void ClientConnection::addReply(ReplyMessage *message)
+{
+  if (!m_socket || m_socket->state() != QAbstractSocket::ConnectedState)
+  {
+    m_messageQueue.enqueue(message);
+    DEBUG_LOG(m_logger) << "Adding message to queue, size: " << m_messageQueue.size();
+    return;
+  }
+  const QString msg(message->toJsonString());
+  DEBUG_LOG(m_logger) << "Sending message: " << msg ;//<< msg;
+  m_socket->sendTextMessage(msg);
+  delete message;
+}
+
+void ClientConnection::onNewTextMessageFromSocket(const QString &message)
+{
+  DEBUG_LOG(m_logger) << "Recv msg: " << message << this;
+  emit newTextMessage(this, message);
+}
+
+void ClientConnection::sendMessagesFromQueue()
+{
+  INFO_LOG(m_logger) << "Client connected ip: " << m_socket->peerAddress().toString() << ":" << m_socket->peerPort();
+
+  if (m_socket->state() != QAbstractSocket::ConnectedState)
+    return;
+  while (!m_messageQueue.isEmpty())
+  {
+    ReplyMessage *message = m_messageQueue.dequeue();
+    const QString msg(message->toJsonString());
+    TRACE_LOG(m_logger) << "Send msg: " << msg;
+    m_socket->sendTextMessage(msg);
+    delete message;
+    DEBUG_LOG(m_logger) << "Sent message from queue, new size: " << m_messageQueue.size();
+  }
+}
+
+void ClientConnection::onSocketDisconnect()
+{
+  DEBUG_LOG(m_logger) << "Client disconnected ip: " << m_socket->peerAddress().toString() << ":" << m_socket->peerPort();
+  exit(0);
+  emit disconnected(this);
+}
+
+} // namespace LtsWebSocket

Lts/Common/LtsWebSocket/client_connection.h

@@ -0,0 +1,91 @@
+/**
+  * @RDE_HEADER@
+  * The ClientConnection class represents a connection to a single client.
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Hannes Baeuerle, SLSE, 2016-08-25
+  */
+#pragma once
+
+#include <QtCore/QThread>
+#include <QtCore/QQueue>
+
+#include "reply_message.h"
+#include "logger.h"
+#include <LtsWebSocket/ltswebsocketserver_export.h>
+
+class QWebSocket;
+
+namespace LtsWebSocket
+{
+
+/**
+ * @brief The ClientConnection class represents a connection to a single client
+ */
+class LTSWEBSOCKETSERVER_EXPORT ClientConnection
+  : public QThread
+  , public ReplyHandler
+{
+  Q_OBJECT
+public:
+  /**
+   * @brief ClientConnection Constructor
+   * @param socket Pointer to a QWebSocket Object. Should be QWebSocketServer::nextPendingConnection()
+   * @param parent QObject parent
+   */
+  explicit ClientConnection(QWebSocket *socket, QObject *parent = nullptr);
+
+
+  /**
+   * @brief ~ClientConnection Destructor
+   */
+  ~ClientConnection();
+
+  /**
+   * @brief init Initialises the ClientConnection
+   * @return True on success, otherwise false
+   */
+  bool init();
+
+  /**
+   * @brief writeTextMessage Add a message to a queue to be sent to the client
+   * @param message Message which is queued
+   */
+  void addReply(ReplyMessage *message) override;
+
+  QWebSocket *webSocket() { return m_socket; }
+signals:
+  /**
+   * @brief newTextMessage Emitted when a new text message arrives at the associated socket
+   * @param message The new message
+   */
+  void newTextMessage(ClientConnection *client, const QString &message);
+
+  /**
+   * @brief disconnected Emitted when a client disconnects
+   * @param client The client
+   */
+  void disconnected(ClientConnection *client);
+
+
+private slots:
+  void onNewTextMessageFromSocket(const QString &message);
+  void sendMessagesFromQueue();
+  void onSocketDisconnect();
+private: // methods
+  /**
+   * @brief sendMessages Runs in an own thread and constantly tries to send
+   * queued messages
+   */
+  void sendMessages();
+
+private: // attributes
+  QWebSocket *m_socket;
+  QQueue<ReplyMessage *> m_messageQueue;
+
+  LOGGER_T m_logger;
+
+
+}; // class ClientConnection
+} // namespace LtsWebSocket

Lts/Common/LtsWebSocket/client_message.cpp

@@ -0,0 +1,44 @@
+/**
+  * @RDE_HEADER@
+  * LTS web socket server - Abstract Client Message
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Philipp Dassow, SLST, 2017-11-28
+  */
+#include "client_message.h"
+
+#include "json_keys.h"
+
+#include <QJsonDocument>
+
+namespace LtsWebSocket
+{
+
+// ######## AbstractClientMessage end ########
+
+// ######## InvalidMessage begin ########
+InvalidMessage::InvalidMessage(ReplyHandler *client, const QString &uuid, const QString &errorText)
+  : AbstractClientMessage(client, QString(), 1, uuid) // Check if 1 is feasible - or if it needs to be a part of InvalidMessage
+  , m_errorText(errorText)
+{}
+
+void InvalidMessage::process()
+{
+  ErrorMessage::ErrorData errorData;
+
+  errorData.errorClass    = 1; // ??????????
+  errorData.errorMessage  = m_errorText;
+  errorData.uuid          = m_uuid;
+
+  m_client->addReply(new ErrorMessage(errorData));
+}
+
+bool InvalidMessage::hasValidData() const
+{
+  // always true because there is no data part
+  return true;
+}
+// ######## InvalidMessage end ########
+
+} // namespace LtsWebSocketServer

Lts/Common/LtsWebSocket/client_message.h

@@ -0,0 +1,84 @@
+/**
+  * @RDE_HEADER@
+  * LTS web socket server - Abstract Client Message
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Philipp Dassow, SLST, 2017-11-28
+  */
+#pragma once
+
+#include <LtsWebSocket/ltswebsocketcommon_export.h>
+#include "reply_message.h"
+
+#include <QString>
+#include <QJsonValue>
+
+namespace LtsWebSocket
+{
+
+/**
+ * @brief API for client message implementations that are needed by the LtsWebSocketServer
+ */
+class LTSWEBSOCKETCOMMON_EXPORT AbstractClientMessage
+{
+public:
+  AbstractClientMessage(ReplyHandler *client, const QString &type, const int typeId, const QString &uuid, const QJsonValue &data = QJsonValue())
+    : m_type(type)
+    , m_typeId(typeId)
+    , m_uuid(uuid)
+    , m_data(data)
+    , m_client(client)
+  {}
+
+  virtual ~AbstractClientMessage() = default;
+
+  /**
+   * @brief process Processes the messages data
+   */
+  virtual void process() = 0;
+
+  /**
+   * @brief hasValidData Validates the content of the message
+   * @return True if the message is ICD conform, otherwise false
+   */
+  virtual bool hasValidData() const = 0;
+
+  /**
+   * @brief reply Send a Reply to the client that has send this message
+   * @param reply
+   */
+  void reply(ReplyMessage *reply)
+  {
+    m_client->addReply(reply);
+  }
+
+protected: // attributes
+  const QString     m_type;
+  const int         m_typeId;
+  const QString     m_uuid;
+  const QJsonValue  m_data;
+  ReplyHandler *m_client;
+
+}; // class AbstractClientMessage
+
+// #################### basic error messages ####################
+
+/**
+ * @brief The InvalidMessage class represents any message from the client which either could
+ * not be validated, is not JSON conform or has no type or uuid
+ */
+class LTSWEBSOCKETCOMMON_EXPORT InvalidMessage final : public AbstractClientMessage
+{
+public:
+  explicit InvalidMessage(ReplyHandler *client, const QString &uuid, const QString &errorText);
+
+  void process() override;
+  bool hasValidData() const override;
+
+private: // attributes
+  QString m_errorText;
+
+}; // class InvalidMessage
+
+} // namespace LtsWebSocket

Lts/Common/LtsWebSocket/client_message_factory.cpp

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+/**
+  * @RDE_HEADER@
+  * LTS web socket server - Abstract Client Message Factory
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Philipp Dassow, SLST, 2017-11-28
+  */
+
+#include "client_message_factory.h"
+
+#include "client_connection.h"
+#include "json_keys.h"
+
+#include <QJsonDocument>
+
+namespace LtsWebSocket
+{
+
+// ######## AbstractClientMessageFactory begin ########
+QJsonParseError AbstractClientMessageFactory::parseMessage(const QString &message)
+{
+  QJsonParseError error;
+  QJsonDocument doc = QJsonDocument::fromJson(message.toUtf8(), &error);
+
+  if (error.error != QJsonParseError::NoError)
+    return error;
+
+  QJsonObject obj = doc.object();
+
+  m_data   = obj.value(JsonKeys::DATA());
+  m_type   = obj.value(JsonKeys::TYPE()).toString();
+  m_typeId = obj.value(JsonKeys::TYPEID()).toInt();
+  m_uuid   = obj.value(JsonKeys::UUID_()).toString();
+
+  return error;
+}
+
+AbstractClientMessage *AbstractClientMessageFactory::checkAttributes(ReplyHandler *client,
+                                                                     const QString &message) const
+{
+  if (!m_uuid.isEmpty() && !m_type.isEmpty())
+    return nullptr;
+  if (m_uuid.isEmpty())
+  {
+    WARNING_LOG(m_logger) << "Got message without uuid: " << message << "'";
+    return new LtsWebSocket::InvalidMessage(client, QString(), QStringLiteral("Got message without uuid"));
+  }
+  WARNING_LOG(m_logger) << "Got message no type: " << message << "'";
+  return new LtsWebSocket::InvalidMessage(client, m_uuid, QStringLiteral("Message has no type"));
+}
+
+AbstractClientMessage *AbstractClientMessageFactory::checkResult(ReplyHandler *client,
+                                                                 const QString &message,
+                                                                 AbstractClientMessage *result) const
+{
+  if (result == nullptr)
+  {
+    WARNING_LOG(m_logger) << "Could not parse message: " << message;
+    result = new LtsWebSocket::InvalidMessage(client, m_uuid, QStringLiteral("Invalid type"));
+  }
+
+  if (!result->hasValidData())
+  {
+    WARNING_LOG(m_logger) << "Resulting JSon message has invalid data... " << message;
+    delete result;
+    result = new LtsWebSocket::InvalidMessage(client, m_uuid, QStringLiteral("Has invalid data part"));
+  }
+
+  return result;
+}
+
+// ######## AbstractClientMessageFactory end ########
+
+} // namespace LtsWebSocketServer

Lts/Common/LtsWebSocket/client_message_factory.h

@@ -0,0 +1,85 @@
+/**
+  * @RDE_HEADER@
+  * LTS web socket server - Abstract Client Message Factory
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Philipp Dassow, SLST, 2017-11-28
+  */
+#pragma once
+
+#include "client_message.h"
+#include "reply_message.h"
+#include <LtsWebSocket/ltswebsocketcommon_export.h>
+
+#include <QString>
+#include <QJsonParseError>
+
+namespace NGL
+{
+class INGLLogger;
+}
+namespace LtsWebSocket
+{
+
+/**
+ * @brief API for the client message factory that has to be provided to the LtsWebSocketServer
+ * */
+class LTSWEBSOCKETCOMMON_EXPORT AbstractClientMessageFactory
+{
+public:
+  explicit AbstractClientMessageFactory(NGL::INGLLogger &logger)
+    : m_logger(logger)
+  {}
+
+  virtual ~AbstractClientMessageFactory() {}
+
+  /**
+   * @brief parseMessage parses the message for TYPE, UUID and DATA
+   * @param message to be parsed
+   * @return QJsonParseError
+   */
+  QJsonParseError parseMessage(const QString &message);
+
+  /**
+   * @brief createMessage Creates the ClientMessage which will process the message
+   * Since the message is not created in the main thread, nothing should be done here!
+   * @param client Handler for replys
+   * @return new client message processor
+   */
+  virtual AbstractClientMessage *createMessage(ReplyHandler *client, const QString &message) = 0;
+
+protected:
+  AbstractClientMessage *checkAttributes(ReplyHandler *client,
+                                         const QString &message) const;
+  AbstractClientMessage *checkResult(ReplyHandler *client,
+                                     const QString &message,
+                                     AbstractClientMessage *result) const;
+protected: // attributes of currently processed message
+  QString     m_type;
+  int         m_typeId;
+  QString     m_uuid;
+  QJsonValue  m_data;
+  NGL::INGLLogger &m_logger;
+
+}; // class AbstractClientMessageFactory
+
+class PongMessage final : public ReplyMessage
+{
+public:
+  static QString strPong() { return QStringLiteral("pong"); }
+  static int idPong() { return 2; }
+  explicit PongMessage(const QString &payload)
+    : ReplyMessage(strPong(), idPong(), QString())
+    , m_payload(payload)
+  {}
+
+  QString toJsonString() const override
+  {
+    return m_payload.isEmpty() ? strPong() : QStringLiteral("%1 %2").arg(strPong(), m_payload);
+  }
+private:
+  QString m_payload;
+};
+
+} // namespace LtsWebSocket

Lts/Common/LtsWebSocket/connection_handler.cpp

@@ -0,0 +1,95 @@
+/**
+  * @RDE_HEADER@
+  * The ConnectionHandler class functions as a WebSocket server and manages incoming client connections.
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Hannes Baeuerle, SLSE, 2016-08-25
+  */
+#include "connection_handler.h"
+
+#include "client_connection.h"
+
+#include <QtWebSockets/QWebSocket>
+
+using namespace LtsWebSocket;
+
+ConnectionHandler::ConnectionHandler(QObject *parent)
+  : QObject(parent)
+  , m_server(nullptr)
+  , m_logger(getLogger("ConnectionHandler"))
+{}
+
+ConnectionHandler::~ConnectionHandler()
+{
+  for (auto connection : qAsConst(m_connections))
+    connection->disconnect(this);
+}
+
+bool ConnectionHandler::init(const QString &serviceName, unsigned short port)
+{
+  if (m_server != nullptr)
+  {
+    m_server->disconnect();
+    delete m_server;
+  }
+  // TODO: get the SslMode from config ?
+  m_server = new QWebSocketServer(QStringLiteral("RME-") + serviceName, QWebSocketServer::NonSecureMode, this);
+
+  connect(m_server, &QWebSocketServer::newConnection, this, &ConnectionHandler::onNewConnection);
+  connect(m_server, &QWebSocketServer::serverError, this, &ConnectionHandler::onServerError);
+
+  DEBUG_LOG(m_logger) << "Trying to listen ";
+  if (!m_server->listen(QHostAddress::Any, port))
+  {
+    ERROR_LOG(m_logger) << "Not possible to listen to port " << port;
+    return false;
+  }
+  DEBUG_LOG(m_logger) << "... ok, port " << m_server->serverPort();
+
+  return true;
+}
+
+void ConnectionHandler::sendToAllClients(ReplyMessage *message)
+{
+  for (auto connection : qAsConst(m_connections))
+    connection->addReply(new ReplyMessage(*message));
+
+  delete message;
+}
+
+void ConnectionHandler::onServerError(QWebSocketProtocol::CloseCode closeCode)
+{
+  ERROR_LOG(m_logger) << "Got server error with close code " << closeCode;
+}
+
+void ConnectionHandler::onNewConnection()
+{
+  while (m_server->hasPendingConnections())
+  {
+    QWebSocket *socket = m_server->nextPendingConnection();
+
+    ClientConnection *newConnection = new ClientConnection(socket, this);
+    connect(newConnection, &ClientConnection::destroyed, this, [this](QObject* o)
+    {
+      m_connections.remove(static_cast<ClientConnection*>(o));
+    });
+
+    if (!newConnection->init())
+    {
+      ERROR_LOG(m_logger) << "Failed to initialise new client";
+      delete newConnection;
+      newConnection = nullptr;
+      continue;
+    }
+    newConnection->start();
+
+    connect(newConnection, &ClientConnection::newTextMessage, this, &ConnectionHandler::newTextMessageFromClient);
+    connect(newConnection, &ClientConnection::disconnected, this, &ConnectionHandler::clientDisconnected);
+    connect(newConnection, &ClientConnection::finished, newConnection, &ClientConnection::deleteLater);
+
+    m_connections.insert(newConnection);
+    emit clientConnected(newConnection);
+    INFO_LOG(m_logger) << "New client connected ip: " << socket->localAddress().toString() << ":" << socket->localPort();
+  }
+}

Lts/Common/LtsWebSocket/connection_handler.h

@@ -0,0 +1,88 @@
+/**
+  * @RDE_HEADER@
+  * The ConnectionHandler class functions as a WebSocket server and manages incoming client connections.
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Hannes Baeuerle, SLSE, 2016-08-25
+  */
+#pragma once
+
+#include <QtNetwork/QHostAddress>
+#include <QtWebSockets/qwebsocketprotocol.h>
+#include <QtWebSockets/QWebSocketServer>
+
+#include "logger.h"
+
+namespace LtsWebSocket
+{
+class MessageHandler;
+class ClientConnection;
+class ReplyMessage;
+
+/**
+ * @brief The ConnectionHandler class functions as a WebSocket server and manages incoming client connections
+ */
+class ConnectionHandler
+  : public QObject
+{
+  Q_OBJECT
+public:
+  /**
+   * @brief ConnectionHandler
+   * @param parent
+   */
+  explicit ConnectionHandler(QObject *parent = nullptr);
+  ~ConnectionHandler();
+
+  /**
+   * @brief init Starts listening for incoming connections and connects internal signals and slots
+   * @param serviceName Is Used to name the server (RDE-"servicename")
+   * @param port Port the server is listening, if 0 the port number will be random
+   * @return True on success, otherwise false
+   */
+  bool init(const QString &serviceName, unsigned short port);
+
+  /**
+   * @brief sendToAll Sends the given msg to all connected Clients
+   * @param message Message to be send
+   */
+  void sendToAllClients(ReplyMessage *message);
+
+  /**
+   * @brief webSocketPort returns the listen port
+   * @return listen port
+   */
+  unsigned short webSocketPort() { return m_server->serverPort(); }
+
+signals:
+  /**
+   * @brief newTextMessageFromClient Emitted when a message from any client is received
+   * @param client Client where replies are written to
+   * @param message Message from the client
+   */
+  void newTextMessageFromClient(ClientConnection *client, const QString &message);
+
+  /**
+   * @brief clientDisconnected Emitted when a client disconnects
+   * @param client The client
+   */
+  void clientDisconnected(ClientConnection *client);
+
+  /**
+   * @brief clientConnected Emitted when a client connects
+   * @param client The client
+   */
+  void clientConnected(ClientConnection *client);
+
+private slots:
+  void onServerError(QWebSocketProtocol::CloseCode closeCode);
+  void onNewConnection();
+
+private: // attributes
+  QWebSocketServer *m_server;
+  QSet<ClientConnection *> m_connections;
+  LOGGER_T m_logger;
+
+};
+} // namespace LtsWebSocket

Lts/Common/LtsWebSocket/data_manager_base_dl.h

@@ -0,0 +1,61 @@
+/**
+  * @RDE_HEADER@
+  * The DataManager class is a convenience class for managing structure data
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Philipp Dassow, SLST, 2017-12-12
+  */
+#pragma once
+#include <memory>
+#include <NGLLogger/INGLLogger.h>
+
+#include "reply_message.h"
+
+namespace LtsWebSocket
+{
+/**
+ * @brief The DataManager class is a convenience class for managing structure data from db
+ *        T needs to be of namspace::DatabaseInterface
+ */
+template<typename T>
+class DataManagerBaseDl
+{
+protected: // methods
+  /**
+   * @brief DataManager Constructor
+   * @param dbInterface Interface for requesting db-structs data
+   */
+  explicit DataManagerBaseDl(const std::shared_ptr<T> &dbInterface, NGL::INGLLogger &logger)
+    : m_logger(logger)
+    , m_dbInterface(dbInterface)
+  {}
+
+  /**
+   * @brief toBaseDataMessageFromDb selects the DbType data from the db and converts it to JSON
+   * @param uuid of the base DL request
+   * @return message send to the requester
+   */
+  template<typename DbType, typename MessageType>
+  ReplyMessage *toBaseDataMessageFromDb(const QString &uuid) const
+  {
+    QVector<DbType> dataVec;
+    // read all data from database
+    if (!m_dbInterface->select(dataVec))
+    {
+      const QString errorMessage = QStringLiteral("Error reading data from database!");
+      ERROR_LOG(m_logger) << errorMessage;
+      ErrorMessage::ErrorData errData;
+      errData.errorMessage = errorMessage;
+      errData.uuid = uuid;
+      return new ErrorMessage(errData);
+    }
+
+    return new MessageType (m_dbInterface->template toJson<DbType>(dataVec), uuid);
+  }
+
+protected: // attributes
+  NGL::INGLLogger &m_logger;
+  std::shared_ptr<T> m_dbInterface;
+}; // class DataManagerBaseDl
+} // namespace LtsWebSocket

Lts/Common/LtsWebSocket/json_keys.h

@@ -0,0 +1,33 @@
+/**
+  * @RDE_HEADER@
+  * Header file which holds basic JSON keys
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Philipp Dassow, SLSt, 2017-11-28
+  */
+#pragma once
+
+#include <QtCore/QString>
+
+namespace LtsWebSocket
+{
+/**
+ * @brief Namespace which holds all occuring JSON keys as const QString objects
+ */
+namespace JsonKeys
+{
+  // root keys
+  inline QString DATA()                     { return QStringLiteral("data"); }
+  inline QString UUID_()                    { return QStringLiteral("uuid"); }  // Windows: typedef GUID UUUID; ...
+  inline QString TYPE()                     { return QStringLiteral("type"); }
+  inline QString TYPEID()                   { return QStringLiteral("typeId"); }
+
+  // types for server --> client messages
+  inline QString ERROR_()                   { return QStringLiteral("error"); }
+
+  // data keys
+  inline QString ERROR_MESSAGE()            { return QStringLiteral("errorMessage"); }
+  inline QString ERROR_CLASS()              { return QStringLiteral("errorClass"); }
+} // namespace JsonKeys
+} // namespace LtsWebSocket

Lts/Common/LtsWebSocket/logger.cpp

@@ -0,0 +1,38 @@
+/**
+  * @RDE_HEADER@
+  * LTS web socket server - logging facility
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Philipp Dassow, SLST, 2017-11-28
+  */
+
+#include "logger.h"
+
+#include <NGLLogger/NGLLoggerBootstrap.h>
+
+namespace LtsWebSocket
+{
+
+LOGGER_T getLogger(const char *name)
+{
+  static const char ns[] = "Lts.WebSocket.";
+  std::string loggerName;
+  const size_t len = strlen(name);
+  loggerName.reserve(sizeof(ns) + len);
+  loggerName.append(ns, sizeof(ns) - 1);
+  loggerName.append(name, len);
+
+  try
+  {
+    return NGL::NGLLoggerBootstrap::getNGLRootLogger().
+           getNGLLogger(loggerName);
+  }
+  catch (const std::exception &ex)
+  {
+    fprintf(stderr, "Error retrieving logger: %s", ex.what());
+    abort();
+  }
+}
+
+} // namespace LtsWebSocketServer

Lts/Common/LtsWebSocket/logger.h

@@ -0,0 +1,24 @@
+/**
+  * @RDE_HEADER@
+  * LTS web socket server - logging facility
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Philipp Dassow, SLST, 2017-11-28
+  */
+
+#pragma once
+
+#include <LtsWebSocket/ltswebsocketcommon_export.h>
+#include <NGLLogger/INGLLogger.h>
+
+namespace LtsWebSocket
+{
+typedef NGL::INGLLogger &LOGGER_T;
+
+LTSWEBSOCKETCOMMON_EXPORT LOGGER_T getLogger(const char *name);
+inline LOGGER_T getLogger(const QString &loggerName)
+{
+  return getLogger(loggerName.toUtf8().constData());
+}
+} // namespace LtsWebSocket

Lts/Common/LtsWebSocket/lts_web_socket_client.cpp

@@ -0,0 +1,208 @@
+/**
+  * @RDE_HEADER@
+  * The LtsWebSocketClient handles a websocket connection to a server
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Philipp Dassow, NLST, 2018-03-19
+  */
+#include "lts_web_socket_client.h"
+
+#include <QThread>
+#include <QUrl>
+#include <QWebSocket>
+
+#include "client_connection.h"
+
+namespace LtsWebSocket
+{
+class WebSocketHelper : public QObject
+{
+  Q_OBJECT
+public:
+  WebSocketHelper(AbstractClientMessageFactory *messageFactory,
+                  LtsWebSocketClient *webSocketClient,
+                  NGL::INGLLogger &logger);
+  ~WebSocketHelper();
+
+public Q_SLOTS:
+  void doOpen(const QString &hostname, const unsigned short port);
+  void doClose();
+  void doSendTextMessage(const QString &msg);
+  void onConnected();
+  void onDisconnected();
+  void onError(QAbstractSocket::SocketError error);
+  void parseMessage(const QString &message);
+Q_SIGNALS:
+  void messageParsed(AbstractClientMessage *clientMessage);
+  void connected();
+  void disconnected();
+  void dataReceived();
+  void error(QAbstractSocket::SocketError);
+private:
+  AbstractClientMessageFactory *m_messageFactory;
+  LtsWebSocketClient *m_webSocketClient;
+  QWebSocket *m_socket;
+  NGL::INGLLogger &m_logger;
+};
+
+WebSocketHelper::WebSocketHelper(AbstractClientMessageFactory *messageFactory,
+                                 LtsWebSocketClient *webSocketClient,
+                                 NGL::INGLLogger &logger)
+  : QObject() // no parent, is moved to another thread
+  , m_messageFactory(messageFactory)
+  , m_webSocketClient(webSocketClient)
+  , m_socket(new QWebSocket(QString(), QWebSocketProtocol::VersionLatest, this))
+  , m_logger(logger)
+{
+  connect(m_socket, &QWebSocket::textMessageReceived, this, &WebSocketHelper::parseMessage);
+  connect(m_socket, &QWebSocket::textFrameReceived, this, &WebSocketHelper::dataReceived);
+  connect(m_socket, &QWebSocket::connected, this, &WebSocketHelper::onConnected);
+  connect(m_socket, &QWebSocket::disconnected, this, &WebSocketHelper::onDisconnected);
+  connect(m_socket, QOverload<QAbstractSocket::SocketError>::of(&QWebSocket::error), this, &WebSocketHelper::error);
+}
+
+WebSocketHelper::~WebSocketHelper()
+{
+  m_socket->close();
+  delete m_socket;
+}
+
+void WebSocketHelper::doOpen(const QString &hostname, const unsigned short port)
+{
+  const QUrl url(QStringLiteral("ws://%1:%2/").arg(hostname).arg(port));
+
+  if (m_socket->state() == QAbstractSocket::SocketState::ConnectedState)
+  {
+    if (m_socket->requestUrl() != url)
+      doClose();
+    else
+    {
+      INFO_LOG(m_logger) << "Web socket to url: " <<  url.toDisplayString() << " is already open.";
+      return;
+    }
+  }
+
+  INFO_LOG(m_logger) << "Opening web socket to url: " << url.toDisplayString();
+  m_socket->open(url);
+}
+
+void WebSocketHelper::doClose()
+{
+  INFO_LOG(m_logger) << "Closing web socket to url:" << m_socket->requestUrl().toDisplayString();
+  m_socket->close();
+}
+
+void WebSocketHelper::doSendTextMessage(const QString &msg)
+{
+  if (!m_socket || m_socket->state() != QAbstractSocket::ConnectedState)
+  {
+    ERROR_LOG(m_logger) << "Message could not be send, socket is not connected.";
+    return;
+  }
+  DEBUG_LOG(m_logger) << "Sending message: " << msg;
+  m_socket->sendTextMessage(msg);
+}
+
+void WebSocketHelper::onConnected()
+{
+  INFO_LOG(m_logger) << "Connected to server url: " << m_socket->requestUrl().toDisplayString()
+                     << " using local port: " << m_socket->localPort();
+  emit connected();
+}
+
+void WebSocketHelper::onDisconnected()
+{
+  INFO_LOG(m_logger) << "Disconnected from server url: " << m_socket->requestUrl().toDisplayString();
+  emit disconnected();
+}
+
+void WebSocketHelper::onError(QAbstractSocket::SocketError error)
+{
+  ERROR_LOG(m_logger) << "Error occured: " << error << " closing socket.";
+  m_socket->close();
+}
+
+void WebSocketHelper::parseMessage(const QString &message)
+{
+  const QString pingMsg(QStringLiteral("ping"));
+  if (message.startsWith(pingMsg))
+  {
+    doSendTextMessage(PongMessage(message.mid(pingMsg.size())).toJsonString());
+    return;
+  }
+
+  AbstractClientMessage *clientMessage = nullptr;
+  auto result = m_messageFactory->parseMessage(message);
+  if (QJsonParseError::NoError == result.error)
+    clientMessage = m_messageFactory->createMessage(m_webSocketClient, message);
+  else
+  {
+    WARNING_LOG(m_logger) << "Could not parse incoming message: '" << message
+                          << "', error: " << result.errorString();
+    clientMessage = new InvalidMessage(m_webSocketClient, QString(),
+                                       QStringLiteral("Got message which is not JSON conform (%1)").arg(result.errorString()));
+  }
+  if (clientMessage)
+    emit messageParsed(clientMessage);
+}
+
+//
+// LtsWebSocketClient
+//
+LtsWebSocketClient::LtsWebSocketClient(AbstractClientMessageFactory *messageFactory, QObject *parent)
+  : QObject(parent)
+  , m_messageFactory(messageFactory)
+  , m_webSocketHelperThread(new QThread(this))
+  , m_logger(getLogger("LtsWebSocketClient"))
+{
+  m_webSocketHelper = new WebSocketHelper(m_messageFactory, this, m_logger);
+  m_webSocketHelper->moveToThread(m_webSocketHelperThread);
+  m_webSocketHelperThread->start();
+
+  connect(m_webSocketHelper, &WebSocketHelper::connected, this, &LtsWebSocketClient::connected);
+  connect(m_webSocketHelper, &WebSocketHelper::disconnected, this, &LtsWebSocketClient::disconnected);
+  connect(m_webSocketHelper, &WebSocketHelper::dataReceived, this, &LtsWebSocketClient::dataReceived);
+  connect(m_webSocketHelper, &WebSocketHelper::messageParsed, this, &LtsWebSocketClient::onNewClientMessage);
+
+  connect(this, &LtsWebSocketClient::onOpen, m_webSocketHelper, &WebSocketHelper::doOpen);
+  connect(this, &LtsWebSocketClient::onClose, m_webSocketHelper, &WebSocketHelper::doClose);
+  connect(this, &LtsWebSocketClient::onSendTextMessage, m_webSocketHelper, &WebSocketHelper::doSendTextMessage);
+}
+
+LtsWebSocketClient::~LtsWebSocketClient()
+{
+  m_webSocketHelper->disconnect(this);
+  m_webSocketHelperThread->quit();
+  m_webSocketHelperThread->wait();
+  delete m_webSocketHelper;
+}
+
+void LtsWebSocketClient::open(const QString &hostname, const unsigned short port)
+{
+  emit onOpen(hostname, port);
+}
+
+void LtsWebSocketClient::close()
+{
+  emit onClose();
+}
+
+void LtsWebSocketClient::addReply(ReplyMessage *message)
+{
+  const QString msg(message->toJsonString());
+  emit onSendTextMessage(msg);
+  delete message;
+}
+
+void LtsWebSocketClient::onNewClientMessage(AbstractClientMessage *clientMessage)
+{
+  if (!clientMessage)
+    return;
+  clientMessage->process();
+  delete clientMessage;
+}
+
+}
+
+#include "lts_web_socket_client.moc"

Lts/Common/LtsWebSocket/lts_web_socket_client.h

@@ -0,0 +1,84 @@
+/**
+  * @RDE_HEADER@
+  * The LtsWebSocketClient handles a websocket connection to a server
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Philipp Dassow, NLST, 2018-03-19
+  */
+#pragma once
+
+#include <QObject>
+#include <QAbstractSocket>
+
+#include <LtsWebSocket/ltswebsocketclient_export.h>
+#include "client_message_factory.h"
+#include "logger.h"
+
+
+class QThread;
+namespace LtsWebSocket
+{
+class WebSocketHelper;
+
+/**
+ * @brief The LtsWebSocketClient class processes messages from a client connection and starts the parsing of them
+ */
+class LTSWEBSOCKETCLIENT_EXPORT LtsWebSocketClient
+  : public QObject
+  , public ReplyHandler
+{
+  Q_OBJECT
+public:
+  /**
+   * @brief LtsWebSocketClient Constructor
+   * @param messageFactory Convenience class for creating ClientMessage
+   * @param parent QObject parent
+   */
+  explicit LtsWebSocketClient(AbstractClientMessageFactory *messageFactory, QObject *parent = nullptr);
+  ~LtsWebSocketClient();
+
+  /**
+   * @brief open Opens a websocket with the given hostname and port
+   * @param hostname Hostname
+   * @param port Port of the server
+   */
+  void open(const QString &hostname, const unsigned short port);
+
+  /**
+   * @brief close
+   */
+  void close();
+
+  /**
+   * @brief addReply Sends the message to the server
+   * @param message Message to be send
+   */
+  void addReply(ReplyMessage *message) override;
+
+signals:
+  void connected();
+  void disconnected();
+  void dataReceived();
+
+private slots:
+  /**
+   * @brief called when the thread finsihed parsing the message so it can be processed by the main thread
+   */
+  void onNewClientMessage(AbstractClientMessage *clientMessage);
+
+signals:
+  void onOpen(const QString &hostname, const unsigned short port);
+  void onClose();
+  void onSendTextMessage(const QString &msg);
+
+private:
+  AbstractClientMessageFactory *m_messageFactory;
+
+  QThread          *m_webSocketHelperThread;
+  WebSocketHelper  *m_webSocketHelper;
+
+
+  LOGGER_T m_logger;
+};
+} // namespace LtsWebSocketClient

Lts/Common/LtsWebSocket/lts_web_socket_server.cpp

@@ -0,0 +1,125 @@
+/**
+  * @RDE_HEADER@
+  * The LtsWebSocketServer class processes messages from the client
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Hannes Baeuerle, SLSE, 2016-08-25
+  */
+#include "lts_web_socket_server.h"
+
+#include "connection_handler.h"
+#include "client_connection.h"
+#include <QTimer>
+
+namespace LtsWebSocket
+{
+
+LtsWebSocketServer::LtsWebSocketServer(AbstractClientMessageFactory *messageFactory, QObject *parent)
+  : QObject(parent)
+  , m_queueTimer(new QTimer(this))
+  , m_messageFactory(messageFactory)
+  , m_connectionHandler(nullptr)
+  , m_logger(getLogger("LtsWebSocketServer"))
+{
+  connect(m_queueTimer, &QTimer::timeout,
+          this, &LtsWebSocketServer::onQueueTimerTimeout);
+
+  m_queueTimer->setSingleShot(true);
+}
+
+LtsWebSocketServer::~LtsWebSocketServer() = default;
+
+bool LtsWebSocketServer::init(const QString &serviceName, const unsigned short port)
+{
+  m_connectionHandler.reset(new ConnectionHandler(this));
+
+  if (!m_connectionHandler->init(serviceName, port))
+  {
+    ERROR_LOG(m_logger) << "Could not init m_connectionHandler with servicename: " << serviceName << ((port == 0) ? QStringLiteral(" random port") : QStringLiteral(" port: ") + QString::number(port));
+    m_connectionHandler.reset();
+    return false;
+  }
+
+  connect(m_connectionHandler.get(), &ConnectionHandler::newTextMessageFromClient, this, &LtsWebSocketServer::onNewTextMessage);
+  connect(m_connectionHandler.get(), &ConnectionHandler::clientDisconnected, this, &LtsWebSocketServer::clientDisconnected);
+  connect(m_connectionHandler.get(), &ConnectionHandler::clientConnected, this, &LtsWebSocketServer::clientConnected);
+
+  m_queueTimer->start(m_messageDelay);
+
+  return true;
+}
+
+bool LtsWebSocketServer::init(const QString &serviceName, const QPair<quint16, quint16> &portRange)
+{
+  if (portRange.first < 1025 || portRange.first > portRange.second) // "portRange.second > 65535" check is superfluous since 65535 ist max quint16
+    return init(serviceName);
+
+  for (quint16 currentPort = portRange.first; currentPort <= portRange.second; ++ currentPort)
+  {
+    if (init(serviceName, currentPort))
+      return true;
+  }
+
+  return init(serviceName);
+}
+
+void LtsWebSocketServer::sendToAllClients(ReplyMessage *message)
+{
+  DEBUG_LOG(m_logger) << "Sending message to all clients: " << message->toJsonString();
+  m_connectionHandler->sendToAllClients(message);
+}
+
+unsigned short LtsWebSocketServer::webSocketPort() const
+{
+  return m_connectionHandler->webSocketPort();
+}
+
+void LtsWebSocketServer::setMessageDelay(qint32 delay)
+{
+  m_messageDelay = delay;
+}
+
+void LtsWebSocketServer::onNewTextMessage(ReplyHandler *client, const QString &message)
+{
+  const QString pingMsg(QStringLiteral("ping"));
+  if (message.startsWith(pingMsg))
+  {
+    client->addReply(new PongMessage(message.mid(pingMsg.size())));
+    return;
+  }
+  DEBUG_LOG(m_logger) << "Got new message: " << message;
+
+  m_messageQueue.append({client, message});
+
+  if (!m_queueTimer->isActive())
+    m_queueTimer->start(m_messageDelay);
+}
+
+void LtsWebSocketServer::onQueueTimerTimeout()
+{
+  if (m_messageQueue.isEmpty())
+    return;
+
+  MessageCredentials credentials = m_messageQueue.takeFirst();
+  AbstractClientMessage *clientMessage = nullptr;
+  auto result = m_messageFactory->parseMessage(credentials.message);
+
+  if (QJsonParseError::NoError == result.error)
+    clientMessage = m_messageFactory->createMessage(credentials.client, credentials.message);
+  else
+  {
+    WARNING_LOG(m_logger) << "Could not parse incoming message: '" << credentials.message << "', error: " << result.errorString();
+
+    clientMessage = new InvalidMessage(credentials.client, QString(), QStringLiteral("Got message which is not JSON conform"));
+  }
+
+  if (clientMessage)
+    clientMessage->process();
+
+  delete clientMessage;
+
+  m_queueTimer->start(m_messageDelay);
+}
+
+}

Lts/Common/LtsWebSocket/lts_web_socket_server.h

@@ -0,0 +1,120 @@
+/**
+  * @RDE_HEADER@
+  * The LtsWebSocketServer class processes messages from the client
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Hannes Baeuerle, SLSE, 2016-08-25
+  */
+#pragma once
+
+#include <QtCore/QObject>
+
+#include <LtsWebSocket/ltswebsocketserver_export.h>
+#include "client_message_factory.h"
+#include "logger.h"
+#include <memory>
+#include <QQueue>
+
+class QTimer;
+
+namespace LtsWebSocket
+{
+class ConnectionHandler;
+class ClientConnection;
+
+/**
+ * @brief The LtsWebSocketServer class processes messages from a client connection and starts the parsing of them
+ */
+class LTSWEBSOCKETSERVER_EXPORT LtsWebSocketServer
+  : public QObject
+{
+  Q_OBJECT
+public:
+  /**
+   * @brief LtsWebSocketServer Constructor
+   * @param messageFactory Convenience class for creating ClientMessage
+   * @param parent QObject parent
+   */
+  explicit LtsWebSocketServer(AbstractClientMessageFactory *messageFactory, QObject *parent = nullptr);
+  virtual ~LtsWebSocketServer();
+
+  /**
+   * @brief init Initialises the LtsWebSocketServer to work properly
+   * @param serviceName Is Used to name the server (RDE-servicename)
+   * @param port Port the server is listening, if 0 the port number will be random
+   * @return True on success, otherwise false
+   */
+  bool init(const QString &serviceName, const unsigned short port = 0);
+
+  /**
+   * @brief init Initialises the LtsWebSocketServer to work properly
+   * @param serviceName Is Used to name the server (RDE-servicename)
+   * @param portRange Range where to look at for a port. If invalid (valid range is 1025-65535) a random port is chosen
+   * @return True on success, otherwise false
+   */
+  bool init(const QString &serviceName, const QPair<quint16, quint16> &portRange);
+
+  /**
+   * @brief sendToAll Sends the given msg to all connected Clients
+   * @param message Message to be send
+   */
+  void sendToAllClients(ReplyMessage *message);
+
+  /**
+   * @brief webSocketPort returns the listen port
+   * @return listen port
+   */
+  unsigned short webSocketPort() const;
+
+  /**
+   * @brief setMessageDelay Sets the delay between two messages to be processed
+   * @param delay Delay in milliseconds
+   */
+  void setMessageDelay(qint32 delay);
+signals:
+  /**
+   * @brief disconnected Emitted when a client disconnects
+   * @param client The client
+   */
+  void clientDisconnected(ClientConnection *client);
+
+  /**
+   * @brief clientConnected Emitted when a client connects
+   * @param client The client
+   */
+  void clientConnected(ClientConnection *client);
+
+private slots:
+  /**
+   * @brief onNewTextMessage Slot to react to new messages from clients
+   * @param client Client to handle a reply
+   * @param message Message from a client
+   */
+  void onNewTextMessage(ReplyHandler *client, const QString &message);
+
+  /**
+   * @brief onQueueTimerTimeout Timeout for messageprocessing
+   */
+  void onQueueTimerTimeout();
+
+private:
+  struct MessageCredentials
+  {
+    ReplyHandler *client {nullptr};
+    QString message;
+
+    MessageCredentials(ReplyHandler *client, const QString &message)
+      : client(client)
+      , message(message)
+    {}
+  };
+
+  QQueue<MessageCredentials>          m_messageQueue;
+  QTimer                             *m_queueTimer { nullptr };
+  AbstractClientMessageFactory       *m_messageFactory { nullptr };
+  std::unique_ptr<ConnectionHandler>  m_connectionHandler;
+  qint32                              m_messageDelay { 0 };
+  LOGGER_T                            m_logger;
+};
+} // namespace LtsWebSocket

Lts/Common/LtsWebSocket/message_transmitter.h

@@ -0,0 +1,26 @@
+/**
+  * @RDE_HEADER@
+  * The MessageTransmitter Interface offers an extremely lightweight API for a class to just write textmessages to
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Hannes Baeuerle, SLSE, 2016-08-25
+  */
+
+namespace LtsWebSocketServer
+{
+class ReplyMessage;
+
+/**
+ * @brief The MessageHandler Interface offers an extremely lightweight API for a class to just write textmessages to
+ */
+class MessageHandler
+{
+public:
+  /**
+   * @brief writeTextMessage Method to write a textmessage via this MessageHandler
+   * @param message Message to send
+   */
+  virtual void addMessage(ReplyMessage *message) = 0;
+};
+} // namespace LtsWebSocket

Lts/Common/LtsWebSocket/reply_message.cpp

@@ -0,0 +1,47 @@
+/**
+  * @RDE_HEADER@
+  * LTS web socket server - Abstract Reply Message and Reply Handler
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Philipp Dassow, SLST, 2017-11-28
+  */
+
+#include "reply_message.h"
+
+#include "json_keys.h"
+
+#include <QUuid>
+
+namespace LtsWebSocket
+{
+
+// ######## ReplyMessage begin ########
+QString ReplyMessage::toJsonString() const
+{
+  return QString::fromUtf8(QJsonDocument(m_jsonRepresentation).toJson(QJsonDocument::Compact));
+}
+
+ReplyMessage::ReplyMessage(const QString &type, const int typeId, const QString &uuid)
+{
+  m_jsonRepresentation.insert(JsonKeys::TYPE(), type);
+  m_jsonRepresentation.insert(JsonKeys::TYPEID(), typeId);
+
+  if (!uuid.isEmpty())
+    m_jsonRepresentation.insert(JsonKeys::UUID_(), uuid);
+}
+// ######## ReplyMessage end ########
+
+// ######## ErrorMessage begin ########
+ErrorMessage::ErrorMessage(const ErrorMessage::ErrorData &data)
+  : ReplyMessage(JsonKeys::ERROR_(), -1, QUuid::createUuid().toString())
+{
+  m_jsonRepresentation.insert(JsonKeys::DATA(),
+  QJsonObject({{JsonKeys::UUID_(), data.uuid},
+    {JsonKeys::ERROR_CLASS(), data.errorClass},
+    {JsonKeys::ERROR_MESSAGE(), data.errorMessage}
+  }));
+}
+// ######## ErrorMessage end ########
+
+} // namespace LtsWebSocketServer

Lts/Common/LtsWebSocket/reply_message.h

@@ -0,0 +1,87 @@
+/**
+  * @RDE_HEADER@
+  * LTS web socket server - Abstract Reply Message and Reply Handler
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Philipp Dassow, SLST, 2017-11-28
+  */
+#pragma once
+
+#include <LtsWebSocket/ltswebsocketcommon_export.h>
+
+#include <QString>
+#include <QJsonObject>
+#include <QJsonParseError>
+
+namespace LtsWebSocket
+{
+
+/**
+ * @brief Base class for reply messages
+ */
+class LTSWEBSOCKETCOMMON_EXPORT ReplyMessage
+{
+public:
+  /**
+   * @brief ~ReplyMessage Destructor
+   */
+  virtual ~ReplyMessage() = default;
+
+  /**
+   * @brief toJsonString Converts this message into a valid JSON string
+   * @return QString JSON representation of this class
+   */
+  virtual QString toJsonString() const;
+
+  QJsonObject json() const { return m_jsonRepresentation; }
+
+protected: // methods
+  ReplyMessage() = default;
+  ReplyMessage(const QString &type, const int typeId, const QString &uuid);
+
+protected: // attributes
+  QJsonObject m_jsonRepresentation;
+}; // class ReplyMessage
+
+/**
+ * @brief The ReplyHandler Interface offers an extremely lightweight API for a class to just write textmessages to
+ */
+class LTSWEBSOCKETCOMMON_EXPORT ReplyHandler
+{
+public:
+  virtual ~ReplyHandler() = default;
+  /**
+   * @brief addReply Method to write a textmessage via this MessageTransmitter
+   * @param message Message to send
+   */
+  virtual void addReply(ReplyMessage *message) = 0;
+}; // class ReplyHandler
+
+// #################### basic error messages ####################
+
+/**
+ * @brief The ErrorMessage class is sent when any data from a client could not be processed
+ */
+class LTSWEBSOCKETCOMMON_EXPORT ErrorMessage final
+  : public ReplyMessage
+{
+public:
+  /**
+   * @brief The ErrorData struct represents the data part of an ErrorMessage object
+   */
+  struct ErrorData
+  {
+    int errorClass = 0;
+    QString uuid;
+    QString errorMessage;
+  };
+
+  /**
+   * @brief ErrorMessage Constructor
+   * @param data Data part of an ErrorMessage object
+   */
+  explicit ErrorMessage(const ErrorData &data);
+}; // class ErrorMessage
+
+} // namespace LtsWebSocket