unable to form command using protobuf - c++

Question

I have the following proto file
package DS3DExcite.Cpp.ExternalVariantSwitcher.ProtocolBuffers;
message DGCommand
{
extensions 100 to max;
enum Type
{
AttachModel = 1;
AttachModelReply = 2;
....
...
SwitchVariants = 4;
}
required Type type = 1;
required uint32 id = 2;
optional uint32 replyTo = 3 [default = 0];
optional string message = 4;
}
message SwitchVariants
{
extend DGCommand
{
required SwitchVariants command = 103;
}
message VariantState
{
required string variant = 1;
required string state = 2;
}
repeated VariantState variants = 1;
repeated string variantNames = 2;
optional string state = 3;
}
I compiled the proto file with protobuf 2.4.1 version to generate .pb.h and .pb.cc files
Now I form the commands
DS3DExcite::Net::PVCConnector::ProtocolBuffers::DGCommand commandObj;
commandObj.set_type(DS3DExcite::Net::PVCConnector::ProtocolBuffers::DGCommand_Type_SwitchVariants);
commandObj.set_id(3);
DS3DExcite::Net::PVCConnector::ProtocolBuffers::SwitchVariants *objVarState;
objVarState = commandObj.MutableExtension(DS3DExcite::Net::PVCConnector::ProtocolBuffers::SwitchVariants::command);
DS3DExcite::Net::PVCConnector::ProtocolBuffers::SwitchVariants_VariantState *state = objVarState->add_variants();
state->set_state("OFF");
state->set_variant("M_Carpaint_3");
I serialise the message
int size = commandObj.ByteSize();
int sizeSize = sizeof(int);
std::vector<char> data(size ,0);
memcpy(data.data(), &size, sizeSize);
data.resize(size + sizeSize );
commandObj.SerializeToArray(static_cast<void*>(&(data[0])+sizeSize) ,size);
QByteArray byteArray = QByteArray::fromRawData(static_cast<const char*>(data.data()), data.size());
And I send this message on a Qtcp socket to server which deserializes the message and extract the information from the message .
At the server end this is the code to read
uint32 pendingData = 0;
rcvSocket->HasPendingData(pendingData); //rcvSocket is the serversside socket
if (pendingData == 0)
{
UE_LOG(PVCConnector, Warning, TEXT("Lost connection to client."));
break;
}
TArray<char> newData; //customized Array template
newData.InsertZeroed(0, pendingData);
int32 bytesRead = 0;
rcvSocket->Recv(reinterpret_cast<uint8*>(newData.GetData()), pendingData, bytesRead);
data += newData;
However at the server end the the desired information lands up in the unknown fields of ::google::protobuf::Message . What could be the reason ?

Answer 1

I had a similar problem whe I have been sending big enough messages. We decide, that this happens when message divided into several net packages. We use blobs to prevent that, and it works. About blobs, its technique to send message length, before message

Answer 2

I was able to solve the problem . There were 2 issues
1) The way I was converting to ByteArray
I replaced
QByteArray byteArray = QByteArray::fromRawData(static_cast<const char*>(data.data()), data.size());
with
QByteArray *byteArray = new QByteArray(reinterpret_cast<const char*>(data.data()), data.size());
2) The way I was sending the message on the socket . I just used
const int nbBytes = itM->second->write(qByteArray);
instead of using QTextStream