Exemplo n.º 1
0
    def send_file(self):
        self._transaction.set_status(TransactionStatus.SENDING)
        file_to_byte_array = QByteArray()
        data = QByteArray()
        stream = QDataStream(data, QIODevice.WriteOnly)

        QFile.open(self._file, QIODevice.ReadOnly)
        stream.writeUInt32(0)
        stream.writeString(self._file_name)
        print("size of name ", getsizeof(self._file_name))
        file_to_byte_array = self._file.readAll()
        data.append(file_to_byte_array)
        self._file.close()

        stream.device().seek(0)
        stream.writeUInt32(data.size() - getsizeof(self._file_name))
        print("total  ", data.size() - getsizeof(self._file_name))

        x = 0
        while (x < data.size()):
            y = self._socket.write(data)
            print("poslato  ", y)
            x += y
            print("x  ", x)
        self._transaction.set_status(TransactionStatus.FINISHED)
Exemplo n.º 2
0
    def testVoidPtr(self):
        # Creating a VoidPtr object requires an address of
        # a C++ object, a wrapped Shiboken Object type,
        # an object implementing the Python Buffer interface,
        # or another VoidPtr object.

        # Original content
        b = b"Hello world"
        ba = QByteArray(b)
        vp = VoidPtr(ba, ba.size())
        self.assertIsInstance(vp, shiboken.VoidPtr)

        # Create QByteArray from voidptr byte interpretation
        nba = QByteArray.fromRawData(vp.toBytes())
        # Compare original bytes to toBytes()
        self.assertTrue(b, vp.toBytes())
        # Compare original with new QByteArray data
        self.assertTrue(b, nba.data())
        # Convert original and new to str
        self.assertTrue(str(b), str(nba))

        # Modify nba through a memoryview of vp
        mv = memoryview(vp)
        self.assertFalse(mv.readonly)
        mv[6:11] = b'void*'
        self.assertEqual(str(ba), str(b"Hello void*"))
Exemplo n.º 3
0
    def testIt(self):
        w = QGLWidget()
        w.makeCurrent()

        b = QGLBuffer()
        b.setUsagePattern(QGLBuffer.DynamicDraw)

        self.assertTrue(b.create())
        self.assertTrue(b.bufferId() != 0)
        self.assertTrue(b.bind())

        data = QByteArray(py3k.b("12345"))
        b.allocate(data)
        self.assertEqual(b.size(), data.size())

        m = b.map(QGLBuffer.ReadOnly)
        if m:
            self.assertEqual(m, py3k.buffer(py3k.b(data.data())))
            b.unmap()

            m = b.map(QGLBuffer.ReadWrite)
            m[3] = py3k.b('A')[0]
            b.unmap()
            result, rdata = b.read(3, 1)
            self.assertTrue(result)
            self.assertEqual(py3k.b('A'), rdata.data())
        else:
            print(" memory mapping is not possible in this OpenGL implementation.")
        b.release()
Exemplo n.º 4
0
    def testIt(self):
        w = QGLWidget()
        w.makeCurrent()

        b = QGLBuffer()
        b.setUsagePattern(QGLBuffer.DynamicDraw)

        self.assertTrue(b.create())
        self.assertTrue(b.bufferId() != 0)
        self.assertTrue(b.bind())

        data = QByteArray("12345")
        b.allocate(data)
        self.assertEqual(b.size(), data.size())

        m = b.map(QGLBuffer.ReadOnly)
        if m:
            self.assertEqual(m, py3k.buffer(py3k.b(data.data())))
            b.unmap()

            m = b.map(QGLBuffer.ReadWrite)
            m[3] = py3k.b('A')
            b.unmap()
            result, rdata = b.read(3, 1)
            self.assertTrue(result)
            self.assertEqual(py3k.b('A'), rdata.data())
        else:
            print(" memory mapping is not possible in this OpenGL implementation.")
        b.release()
Exemplo n.º 5
0
    def run(self):
        # Try to connect to an incomming tcp socket using its socket descriptor
        tcpSocket = QTcpSocket()
        if not tcpSocket.setSocketDescriptor(self.socketDescriptor):
            FreeCAD.Console.PrintError("Socket not accepted.\n")
            return

        # Wait for an incomming message
        if not tcpSocket.waitForReadyRead(msecs=WAIT_TIME_MS):
            FreeCAD.Console.PrintError("No request send.\n")
            return

        # Make an input data stream
        instr = QDataStream(tcpSocket)
        instr.setVersion(QDataStream.Qt_4_0)

        # Try to read the message size
        if self.blockSize == 0:
            if tcpSocket.bytesAvailable() < 2:
                return
            self.blockSize = instr.readUInt16()

        # Check message is sent complete
        if tcpSocket.bytesAvailable() < self.blockSize:
            return

        # Read message and inform about it
        instr = instr.readString()
        FreeCAD.Console.PrintLog("CommandServer received> " + str(instr) +
                                 "\n")

        # Try to execute the message string and prepare  a response
        try:
            exec(str(instr))
        except Exception as e:
            FreeCAD.Console.PrintError("Executing external command failed:" +
                                       str(e) + "\n")
            message = "Command failed - " + str(e)
        else:
            FreeCAD.Console.PrintLog("Executing external command succeded!\n")
            message = COMMAND_EXECUTED_CONFIRMATION_MESSAGE

        # Prepare the data block to send back and inform about it
        FreeCAD.Console.PrintLog("CommandServer sending> " + message + " \n")
        block = QByteArray()
        outstr = QDataStream(block, QIODevice.WriteOnly)
        outstr.setVersion(QDataStream.Qt_4_0)
        outstr.writeUInt16(0)
        outstr.writeQString(message)
        outstr.device().seek(0)
        outstr.writeUInt16(block.size() - 2)

        # Send the block, disconnect from the socket and terminate the QThread
        tcpSocket.write(block)
        tcpSocket.disconnectFromHost()
        tcpSocket.waitForDisconnected()
    def run(self):
        self.mutex.lock()
        serverName = self.hostName
        serverPort = self.port
        self.mutex.unlock()

        while not self.quit:
            Timeout = 5 * 1000

            socket = QTcpSocket()
            socket.connectToHost(serverName, serverPort)

            if not socket.waitForConnected(Timeout):
                self.error.emit(socket.error(), socket.errorString())
                return

            while socket.bytesAvailable() < 2:
                if not socket.waitForReadyRead(Timeout):
                    self.error.emit(socket.error(), socket.errorString())
                    return

            instr = QDataStream(socket)
            instr.setVersion(QDataStream.Qt_4_0)
            blockSize = instr.readUInt16()

            block = QByteArray()
            outstr = QDataStream(block, QIODevice.WriteOnly)
            outstr.setVersion(QDataStream.Qt_4_0)

            

            while socket.bytesAvailable() < blockSize:
                if not socket.waitForReadyRead(Timeout):
                    self.error.emit(socket.error(), socket.errorString())
                    return

            self.mutex.lock()
            outstr.writeUInt16(0)
            outstr.writeQString("Message to Server")
            outstr.device().seek(0)
            outstr.writeUInt16(block.size() - 2)
            socket.write(block)
#            socket.write(block)
            fortune = instr.readQString()
            self.newFortune.emit(fortune)

            self.cond.wait(self.mutex)
            serverName = self.hostName
            serverPort = self.port
            self.mutex.unlock()
    def run(self):
        tcpSocket = QTcpSocket()
        if not tcpSocket.setSocketDescriptor(self.socketDescriptor):
            self.error.emit(tcpSocket.error())
            return

        block = QByteArray()
        outstr = QDataStream(block, QIODevice.WriteOnly)
        outstr.setVersion(QDataStream.Qt_4_0)
        outstr.writeUInt16(0)
        outstr.writeQString(self.text)
        outstr.device().seek(0)
        outstr.writeUInt16(block.size() - 2)

        tcpSocket.write(block)
        tcpSocket.disconnectFromHost()
        tcpSocket.waitForDisconnected()
    def run(self):
        tcpSocket = QTcpSocket()
        if not tcpSocket.setSocketDescriptor(self.socketDescriptor):
            self.error.emit(tcpSocket.error())
            return

        block = QByteArray()
        outstr = QDataStream(block, QIODevice.WriteOnly)
        outstr.setVersion(QDataStream.Qt_4_0)
        outstr.writeUInt16(0)
        outstr.writeQString(self.text)
        outstr.device().seek(0)
        outstr.writeUInt16(block.size() - 2)

        tcpSocket.write(block)
        tcpSocket.disconnectFromHost()
        tcpSocket.waitForDisconnected()
Exemplo n.º 9
0
def sendClientCommand(host, port, cmd, wait_time=WAIT_TIME_MS):
    # Try to connect to a host server
    tcpSocket = QTcpSocket()
    tcpSocket.connectToHost(host, port, QIODevice.ReadWrite)
    if not tcpSocket.waitForConnected(msecs=wait_time):
        return CLIENT_ERROR_NO_CONNECTION

    # Prepare a command message to be sent
    block = QByteArray()
    outstr = QDataStream(block, QIODevice.WriteOnly)
    outstr.setVersion(QDataStream.Qt_4_0)
    outstr.writeUInt16(0)
    outstr.writeQString(cmd)
    outstr.device().seek(0)
    outstr.writeUInt16(block.size() - 2)
    tcpSocket.write(block)

    # Try to send the message
    if not tcpSocket.waitForBytesWritten(msecs=wait_time):
        return CLIENT_ERROR_BLOCK_NOT_WRITTEN

    # Wait for a response from the host server
    if not tcpSocket.waitForReadyRead(msecs=10000):
        return CLIENT_ERROR_NO_RESPONSE

    # Try to read the response
    instr = QDataStream(tcpSocket)
    instr.setVersion(QDataStream.Qt_4_0)
    blockSize = 0
    if blockSize == 0:
        if tcpSocket.bytesAvailable() < 2:
            return CLIENT_ERROR_RESPONSE_NOT_COMPLETE
        blockSize = instr.readUInt16()
    if tcpSocket.bytesAvailable() < blockSize:
        return CLIENT_ERROR_RESPONSE_NOT_COMPLETE

    # Wait until the host server terminates the connection
    tcpSocket.waitForDisconnected()

    # Return value representing a command execution status
    if instr.readString() == COMMAND_EXECUTED_CONFIRMATION_MESSAGE:
        return CLIENT_COMMAND_EXECUTED
    else:
        return CLIENT_COMMAND_FAILED
Exemplo n.º 10
0
    def run(self):
        """
Thread's functionality method.

The starting point for the thread. After calling start(), the newly created
thread calls this function. This function then tries to make QTcpSocket.
It waits `WAIT_TIME_MS` for an incomming message. If message is received
it checks its a whole message using blockSize sent in the first word as
an UINT16 number. If a whole message is received, the thread tries to execute
the message string and sends back an appropriate response. The response is
*Command failed - "error string"* if the execution failed, or *Commmand
executed successfully* otherwise. Then the thread is terminated.
        """
        # Try to connect to an incomming tcp socket using its socket descriptor
        tcpSocket = QTcpSocket()
        if not tcpSocket.setSocketDescriptor(self.socketDescriptor):
            FreeCAD.Console.PrintError("Socket not accepted.\n")
            return

        # Wait for an incomming message
        if not tcpSocket.waitForReadyRead(msecs=WAIT_TIME_MS):
            FreeCAD.Console.PrintError("No request send.\n")
            return

        # Make an input data stream
        instr = QDataStream(tcpSocket)
        instr.setVersion(QDataStream.Qt_4_0)

        # Try to read the message size
        if self.blockSize == 0:
            if tcpSocket.bytesAvailable() < 2:
                return
            self.blockSize = instr.readUInt16()

        # Check message is sent complete
        if tcpSocket.bytesAvailable() < self.blockSize:
            return

        # Read message and inform about it
        instr = instr.readString()
        FreeCAD.Console.PrintLog("CommandServer received> " + str(instr) +
                                 "\n")

        # Try to execute the message string and prepare  a response
        try:
            exec(str(instr))
        except Exception as e:
            FreeCAD.Console.PrintError("Executing external command failed:" +
                                       str(e) + "\n")
            message = "Command failed - " + str(e)
        else:
            FreeCAD.Console.PrintLog("Executing external command succeded!\n")
            message = COMMAND_EXECUTED_CONFIRMATION_MESSAGE

        # Prepare the data block to send back and inform about it
        FreeCAD.Console.PrintLog("CommandServer sending> " + message + " \n")
        block = QByteArray()
        outstr = QDataStream(block, QIODevice.WriteOnly)
        outstr.setVersion(QDataStream.Qt_4_0)
        outstr.writeUInt16(0)
        outstr.writeQString(message)
        outstr.device().seek(0)
        outstr.writeUInt16(block.size() - 2)

        # Send the block, disconnect from the socket and terminate the QThread
        tcpSocket.write(block)
        tcpSocket.disconnectFromHost()
        tcpSocket.waitForDisconnected()
Exemplo n.º 11
0
def sendClientCommand(host, port, cmd, wait_time=WAIT_TIME_MS):
    """
Method to be used for sending commands.

This method is an alternative to using `CommandClient`. It does not print any
logs, just returns a value saying how the execution went.

Args:
    cmd: A str command to be executed.
    host: A QtHostAddress to the `CommandServer`.
    port: An int of port at which `CommandServer` is listening.

Kwargs:
    wait_time: An int setting miliseconds to wait for connection or message.

Returns:
    `CLIENT_COMMAND_EXECUTED` if all went great and command was executed.
    `CLIENT_COMMAND_FAILED` if `cmd` execution failed.
    `CLIENT_ERROR_RESPONSE_NOT_COMPLETE` if a response received was incomplete.
    `CLIENT_ERROR_NO_RESPONSE` if there was no response within `WAIT_TIME_MS`.
    `CLIENT_ERROR_BLOCK_NOT_WRITTEN` if communication failed during sending.
    `CLIENT_ERROR_NO_CONNECTION` if no connection to a host was established.
    """
    # Try to connect to a host server
    tcpSocket = QTcpSocket()
    tcpSocket.connectToHost(host, port, QIODevice.ReadWrite)
    if not tcpSocket.waitForConnected(msecs=wait_time):
        return CLIENT_ERROR_NO_CONNECTION

    # Prepare a command message to be sent
    block = QByteArray()
    outstr = QDataStream(block, QIODevice.WriteOnly)
    outstr.setVersion(QDataStream.Qt_4_0)
    outstr.writeUInt16(0)
    outstr.writeQString(cmd)
    outstr.device().seek(0)
    outstr.writeUInt16(block.size() - 2)
    tcpSocket.write(block)

    # Try to send the message
    if not tcpSocket.waitForBytesWritten(msecs=wait_time):
        return CLIENT_ERROR_BLOCK_NOT_WRITTEN

    # Wait for a response from the host server
    if not tcpSocket.waitForReadyRead(msecs=10000):
        return CLIENT_ERROR_NO_RESPONSE

    # Try to read the response
    instr = QDataStream(tcpSocket)
    instr.setVersion(QDataStream.Qt_4_0)
    blockSize = 0
    if blockSize == 0:
        if tcpSocket.bytesAvailable() < 2:
            return CLIENT_ERROR_RESPONSE_NOT_COMPLETE
        blockSize = instr.readUInt16()
    if tcpSocket.bytesAvailable() < blockSize:
        return CLIENT_ERROR_RESPONSE_NOT_COMPLETE

    # Wait until the host server terminates the connection
    tcpSocket.waitForDisconnected()

    # Return value representing a command execution status
    if instr.readString() == COMMAND_EXECUTED_CONFIRMATION_MESSAGE:
        return CLIENT_COMMAND_EXECUTED
    else:
        return CLIENT_COMMAND_FAILED
Exemplo n.º 12
0
class Generator(QIODevice):
    def __init__(self, format, durationUs, sampleRate, parent):
        super(Generator, self).__init__(parent)

        self.m_pos = 0
        self.m_buffer = QByteArray()

        self.generateData(format, durationUs, sampleRate)

    def start(self):
        self.open(QIODevice.ReadOnly)

    def stop(self):
        self.m_pos = 0
        self.close()

    def generateData(self, format, durationUs, sampleRate):
        pack_format = ''

        if format.sampleSize() == 8:
            if format.sampleType() == QAudioFormat.UnSignedInt:
                scaler = lambda x: ((1.0 + x) / 2 * 255)
                pack_format = 'B'
            elif format.sampleType() == QAudioFormat.SignedInt:
                scaler = lambda x: x * 127
                pack_format = 'b'
        elif format.sampleSize() == 16:
            if format.sampleType() == QAudioFormat.UnSignedInt:
                scaler = lambda x: (1.0 + x) / 2 * 65535
                pack_format = '<H' if format.byteOrder(
                ) == QAudioFormat.LittleEndian else '>H'
            elif format.sampleType() == QAudioFormat.SignedInt:
                scaler = lambda x: x * 32767
                pack_format = '<h' if format.byteOrder(
                ) == QAudioFormat.LittleEndian else '>h'

        assert (pack_format != '')

        channelBytes = format.sampleSize() // 8
        sampleBytes = format.channelCount() * channelBytes

        length = (format.sampleRate() * format.channelCount() *
                  (format.sampleSize() // 8)) * durationUs // 100000

        self.m_buffer.clear()
        sampleIndex = 0
        factor = 2 * pi * sampleRate / format.sampleRate()

        while length != 0:
            x = sin((sampleIndex % format.sampleRate()) * factor)
            packed = pack(pack_format, int(scaler(x)))

            for _ in range(format.channelCount()):
                self.m_buffer.append(packed)
                length -= channelBytes

            sampleIndex += 1

    def readData(self, maxlen):
        data = QByteArray()
        total = 0

        while maxlen > total:
            chunk = min(self.m_buffer.size() - self.m_pos, maxlen - total)
            data.append(self.m_buffer.mid(self.m_pos, chunk))
            self.m_pos = (self.m_pos + chunk) % self.m_buffer.size()
            total += chunk

        return data.data()

    def writeData(self, data):
        return 0

    def bytesAvailable(self):
        return self.m_buffer.size() + super(Generator, self).bytesAvailable()
Exemplo n.º 13
0
    def sendCommand(self, cmd):

        # connect a Qt slot to receive and print errors
        self.tcpSocket.error.connect(self.displayError)

        # Try to connect to a host server
        self.tcpSocket.connectToHost(self.host, self.port, QIODevice.ReadWrite)
        if not self.tcpSocket.waitForConnected(msecs=WAIT_TIME_MS):
            if "FreeCAD" in sys.modules:
                FreeCAD.Console.PrintError(
                    "CommandClient.sendCommand error: " + "No connection\n")
            else:
                print("CommandClient.sendCommand error: No connection\n")
            return CLIENT_ERROR_NO_CONNECTION

        # Prepare a command message to be sent
        block = QByteArray()
        outstr = QDataStream(block, QIODevice.WriteOnly)
        outstr.setVersion(QDataStream.Qt_4_0)
        outstr.writeUInt16(0)
        outstr.writeQString(cmd)
        outstr.device().seek(0)
        outstr.writeUInt16(block.size() - 2)

        # Try to send the message
        if "FreeCAD" in sys.modules:
            FreeCAD.Console.PrintMessage("CommandClient sending> " + cmd +
                                         "\n")
        else:
            print("CommandClient sending> " + cmd + "\n")
        self.tcpSocket.write(block)
        if not self.tcpSocket.waitForBytesWritten(msecs=WAIT_TIME_MS):
            if "FreeCAD" in sys.modules:
                FreeCAD.Console.PrintError(
                    "CommandClient.sendCommand error: " +
                    "Block not written\n")
            else:
                print("CommandClient.sendCommand error: Block not written\n")
            return CLIENT_ERROR_BLOCK_NOT_WRITTEN

        # Wait for a response from the host server
        if not self.tcpSocket.waitForReadyRead(msecs=WAIT_TIME_MS):
            if "FreeCAD" in sys.modules:
                FreeCAD.Console.PrintError(
                    "CommandClient.sendCommand error: " +
                    "No response received.\n")
            else:
                print("CommandClient.sendCommand error: " +
                      "No response received.\n")
            return CLIENT_ERROR_NO_RESPONSE

        # Try to read the response
        instr = QDataStream(self.tcpSocket)
        instr.setVersion(QDataStream.Qt_4_0)
        if self.blockSize == 0:
            if self.tcpSocket.bytesAvailable() < 2:
                return CLIENT_ERROR_RESPONSE_NOT_COMPLETE
            self.blockSize = instr.readUInt16()

        if self.tcpSocket.bytesAvailable() < self.blockSize:
            return CLIENT_ERROR_RESPONSE_NOT_COMPLETE
        response = instr.readString()
        if "FreeCAD" in sys.modules:
            FreeCAD.Console.PrintMessage("CommandClient received> " +
                                         response + "\n")
        else:
            print("CommandClient received> " + response + "\n")

        # Wait until the host server terminates the connection
        self.tcpSocket.waitForDisconnected()
        # Reset blockSize to prepare for sending next command
        self.blockSize = 0

        # Return value representing a command execution status
        if response == COMMAND_EXECUTED_CONFIRMATION_MESSAGE:
            return CLIENT_COMMAND_EXECUTED
        else:
            return CLIENT_COMMAND_FAILED
Exemplo n.º 14
0
class Generator(QIODevice):

    def __init__(self, format, durationUs, sampleRate, parent):
        super(Generator, self).__init__(parent)

        self.m_pos = 0
        self.m_buffer = QByteArray()

        self.generateData(format, durationUs, sampleRate)

    def start(self):
        self.open(QIODevice.ReadOnly)

    def stop(self):
        self.m_pos = 0
        self.close()

    def generateData(self, format, durationUs, sampleRate):
        pack_format = ''

        if format.sampleSize() == 8:
            if format.sampleType() == QAudioFormat.UnSignedInt:
                scaler = lambda x: ((1.0 + x) / 2 * 255)
                pack_format = 'B'
            elif format.sampleType() == QAudioFormat.SignedInt:
                scaler = lambda x: x * 127
                pack_format = 'b'
        elif format.sampleSize() == 16:
            if format.sampleType() == QAudioFormat.UnSignedInt:
                scaler = lambda x: (1.0 + x) / 2 * 65535
                pack_format = '<H' if format.byteOrder() == QAudioFormat.LittleEndian else '>H'
            elif format.sampleType() == QAudioFormat.SignedInt:
                scaler = lambda x: x * 32767
                pack_format = '<h' if format.byteOrder() == QAudioFormat.LittleEndian else '>h'

        assert(pack_format != '')

        channelBytes = format.sampleSize() // 8
        sampleBytes = format.channelCount() * channelBytes

        length = (format.sampleRate() * format.channelCount() * (format.sampleSize() // 8)) * durationUs // 100000

        self.m_buffer.clear()
        sampleIndex = 0
        factor = 2 * pi * sampleRate / format.sampleRate()

        while length != 0:
            x = sin((sampleIndex % format.sampleRate()) * factor)
            packed = pack(pack_format, int(scaler(x)))

            for _ in range(format.channelCount()):
                self.m_buffer.append(packed)
                length -= channelBytes

            sampleIndex += 1

    def readData(self, maxlen):
        data = QByteArray()
        total = 0

        while maxlen > total:
            chunk = min(self.m_buffer.size() - self.m_pos, maxlen - total)
            data.append(self.m_buffer.mid(self.m_pos, chunk))
            self.m_pos = (self.m_pos + chunk) % self.m_buffer.size()
            total += chunk

        return data.data()

    def writeData(self, data):
        return 0

    def bytesAvailable(self):
        return self.m_buffer.size() + super(Generator, self).bytesAvailable()
Exemplo n.º 15
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 def testAppend(self):
     b = QByteArray()
     b.append("A")
     self.assertEqual(b.size(), 1)
     b.append("AB")
     self.assertEqual(b.size(), 3)
Exemplo n.º 16
0
 def testAppend(self):
     b = QByteArray()
     b.append("A")
     self.assertEqual(b.size(), 1)
     b.append("AB")
     self.assertEqual(b.size(), 3)
Exemplo n.º 17
0
    def sendCommand(self, cmd):
        """
Method used to send commands from client to `CommandServer`.

This method tries to connect to a specified host `CommandServer` via
`tcpSocket`. If connection was successfull, the command `cmd` is sent.
Then the response is expected. If the response is equal to
COMMAND_EXECUTED_CONFIRMATION_MESSAGE, then the execution was successfull.
The progress and result of `sendCommand` can be obtained from printed logs and
return value.

Args:
    cmd: A str command to be executed.

Returns:
    `CLIENT_COMMAND_EXECUTED` if all went great and command was executed.
    `CLIENT_COMMAND_FAILED` if `cmd` execution failed.
    `CLIENT_ERROR_RESPONSE_NOT_COMPLETE` if a response received was incomplete.
    `CLIENT_ERROR_NO_RESPONSE` if there was no response within `WAIT_TIME_MS`.
    `CLIENT_ERROR_BLOCK_NOT_WRITTEN` if communication failed during sending.
    `CLIENT_ERROR_NO_CONNECTION` if no connection to a host was established.
        """

        # connect a Qt slot to receive and print errors
        self.tcpSocket.error.connect(self.displayError)

        # Try to connect to a host server
        self.tcpSocket.connectToHost(self.host, self.port, QIODevice.ReadWrite)
        if not self.tcpSocket.waitForConnected(msecs=WAIT_TIME_MS):
            if "FreeCAD" in sys.modules:
                FreeCAD.Console.PrintError(
                    "CommandClient.sendCommand error: " + "No connection\n")
            else:
                print("CommandClient.sendCommand error: No connection\n")
            return CLIENT_ERROR_NO_CONNECTION

        # Prepare a command message to be sent
        block = QByteArray()
        outstr = QDataStream(block, QIODevice.WriteOnly)
        outstr.setVersion(QDataStream.Qt_4_0)
        outstr.writeUInt16(0)
        outstr.writeQString(cmd)
        outstr.device().seek(0)
        outstr.writeUInt16(block.size() - 2)

        # Try to send the message
        if "FreeCAD" in sys.modules:
            FreeCAD.Console.PrintMessage("CommandClient sending> " + cmd +
                                         "\n")
        else:
            print("CommandClient sending> " + cmd + "\n")
        self.tcpSocket.write(block)
        if not self.tcpSocket.waitForBytesWritten(msecs=WAIT_TIME_MS):
            if "FreeCAD" in sys.modules:
                FreeCAD.Console.PrintError(
                    "CommandClient.sendCommand error: " +
                    "Block not written\n")
            else:
                print("CommandClient.sendCommand error: Block not written\n")
            return CLIENT_ERROR_BLOCK_NOT_WRITTEN

        # Wait for a response from the host server
        if not self.tcpSocket.waitForReadyRead(msecs=WAIT_TIME_MS):
            if "FreeCAD" in sys.modules:
                FreeCAD.Console.PrintError(
                    "CommandClient.sendCommand error: " +
                    "No response received.\n")
            else:
                print("CommandClient.sendCommand error: " +
                      "No response received.\n")
            return CLIENT_ERROR_NO_RESPONSE

        # Try to read the response
        instr = QDataStream(self.tcpSocket)
        instr.setVersion(QDataStream.Qt_4_0)
        if self.blockSize == 0:
            if self.tcpSocket.bytesAvailable() < 2:
                return CLIENT_ERROR_RESPONSE_NOT_COMPLETE
            self.blockSize = instr.readUInt16()

        if self.tcpSocket.bytesAvailable() < self.blockSize:
            return CLIENT_ERROR_RESPONSE_NOT_COMPLETE
        response = instr.readString()
        if "FreeCAD" in sys.modules:
            FreeCAD.Console.PrintMessage("CommandClient received> " +
                                         response + "\n")
        else:
            print("CommandClient received> " + response + "\n")

        # Wait until the host server terminates the connection
        self.tcpSocket.waitForDisconnected()
        # Reset blockSize to prepare for sending next command
        self.blockSize = 0

        # Return value representing a command execution status
        if response == COMMAND_EXECUTED_CONFIRMATION_MESSAGE:
            return CLIENT_COMMAND_EXECUTED
        else:
            return CLIENT_COMMAND_FAILED