Custom packet to send over a socket

Question

Any recommendations on how to encode data to send over a socket?

Example

struct {
    int id,
    std::string name,
    std::string address
}

I have this currently:

std::string s;
client_type client = { INVALID_SOCKET, -1, "" };
send(client.socket, s.c_str(), strlen(s.c_str()), 0);

I can send a string. What would be the best way to send the above information to the server?

Answer 1

Use a serialization library and convert your data into one of the known data formats via that library. I, for instance, use cereal (check the link for an example) library to serialize my data into json format. This is a good list of C++ serialization libraries. Choose the format which suits best for you and then choose a library to serialize and de-serialize the data.

Here is an example of xml serialization with cereal for your case (edit: compiles now):

#include <cereal/archives/xml.hpp>
#include <sstream>
#include <iostream>


struct SomeData{
    int id;
    std::string name;
    std::string address;

    template <class Archive>
    void serialize( Archive & ar )
    {
        ar( id, name, address );
    }
};

int main()
{
    std::stringstream ss;

    // this block is used to make sure the destrcutor of archive is called
    // which flushes the output into string stream.
    {
        cereal::XMLOutputArchive archive( ss );

        SomeData myData{4, "name", "address"};
        archive( myData );
    }
    std::string s = ss.str();

    // test output 
    std::cout << s << std::endl;

    // send data
    send(client.socket, s.c_str(), s.length(), 0);
    return 0;
}

This is the output:

<?xml version="1.0" encoding="utf-8"?>
<cereal>
    <value0>
        <value0>4</value0>
        <value1>name</value1>
        <value2>address</value2>
    </value0>
</cereal>