Question

I would like to dip into Google’s protocol buffers in Qt development, but I am having trouble figuring out how to incorporate them best.

Ultimately, I want to send with QUdpSocket and QTcpSocket using protocol buffers.

What is the best method for going between a protocol buffer message to sending the data over a socket (QByteArray) and then back again at the other side?

Answer 1

Instead of:

std::ostringstream out;
person.SerializeToOstream(&out);
QByteArray byteArray(out.str().c_str());

you can also write:

QByteArray byteArray(person.SerializeAsString().c_str());

EDIT: Above two gives the same result, but I’m not sure wether it’s correct. This one seems to work better:

QByteArray byteArray(QString::fromStdString(person.SerializeAsString()));

EDIT2: OK, now I know how it works: first two ways are wrong if there are \0 char in serialization – everything after it it’s then lost. To correct it one can write:

QByteArray byteArray(person.SerializeAsString().c_str(), person.ByteSize());