Question

I created a binary file using a c++ program using protocol buffers. I had issues reading the binary file in my C# program, so I decided to write a small c++ program to test the reading.

My proto file is as follows

message TradeMessage {
required double timestamp = 1;
required string ric_code = 2;
required double price = 3;
required int64 size = 4;
required int64 AccumulatedVolume = 5;
} 

When writing to protocol buffer, I first write the object type, then object length and the object itself.

coded_output->WriteLittleEndian32((int) ObjectType_Trade); 
coded_output->WriteLittleEndian32(trade.ByteSize()); 
trade.SerializeToCodedStream(coded_output);

Now, when I am trying to read the same file in my c++ program i see strange behavior.

My reading code is as follows:

coded_input->ReadLittleEndian32(&objtype);
coded_input->ReadLittleEndian32(&objlen);
tMsg.ParseFromCodedStream(coded_input);
cout << "Expected Size = " << objlen << endl;
cout<<" Trade message received for: "<< tMsg.ric_code() << endl;
cout << "TradeMessage Size = " << tMsg.ByteSize() << endl;

In this case, i get following output

Expected Size = 33
Trade message received for: .CSAP0104
TradeMessage Size = 42

When I write to file, I write trade.ByteSize() as 33 bytes, but when I read the same object, the object ByteSize() is 42 bytes, which affects the rest of the data. I am not sure what is wrong in this. Please advice.

Regards,
Alok

Answer 1

So apparently, i was doing a very silly mistake while creating the binary files. I did not open the file in binary mode when i wrote protobuf data to it causing it to add weird ascii characters in the middle. This caused an issue while reading the data using protobuf-net library. The issue is resolved here. Shouldn’t have taken so long to resolve this.