Create a tcp client/server without using QDataStream

tham

Question :

Is is possible to create a TCP client/server without using QDataStream?

Why I cannot use QDataStream :

Because clients prefer the clients be written by node.js

Without QDataStream, how could I handle different endianness, string sizes under different platforms between clients(node js) and servers(Qt)?

jsulm

@tham You can still write the server using QDataStream.
"how could I handle different endianness, string sizes under different platforms between clients(node js) and servers(Qt)?" - you can define all this as a part of your protocol.

tham

@jsulm Please correct me if I am wrong

If all of the messages are composed by ASCII characters, all of the characters will always occupy 1 byte only and do not need to deal with endianness problem. All I need to do is make sure I have read the complete messages. The client can send their messages as following

//8 bytes of characters to indicate how many bytes the messages is, after that come with json contents
12345678{json content}

jsulm

@tham Yes, ASCII is one byte encoding.

VRonin

use QTextStream...

read the first 8 bytes either raw (reinterpret_cast but you lose control over endinaness) or with QDataStream. Then attach a QTextStream and read the json string

to detect endianness you could send a fixed 32bit integer 16777216 read it

char endianBuffer[4]; 
socket.read(endianBuffer,4); 
if(endianBuffer[0]) 
// bigendian
else
// littleendian

tham

@VRonin said in Create a tcp client/server without using QDataStream:

to detect endianness you could send a fixed 32bit integer 16777216 read it

This is a great idea, thanks. However, in this project I tend to make the all of the data as ASCII characters, no need to deal with endianness or string per byte, right now every info we need should be able to cover by json.

Please point out the main drawback of this solution if any, thanks

VRonin

json is used so widely because it's effective. I see no problem in sending, even utf-8 json via socket

tham

@VRonin If it is utf-8, do I need to deal with endianness and bytes per character issues?

VRonin

No, QTextCodec (inside QTextStream) takes care of everything for you

tham

@VRonin said in Create a tcp client/server without using QDataStream:

QTextCodec (inside QTextStream) takes care of everything for you

Thanks, this is awesome