fileserver/lib/restbed-4.8/documentation/example/HTTP_PIPELINING.md

Overview
--------

"HTTP pipelining is a technique in which multiple HTTP requests are sent on a single TCP connection without waiting for the corresponding responses.
As of 2017, HTTP pipelining is not enabled by default in modern browsers, due to several issues including buggy proxy servers and HOL blocking." -- [Wikipedia](https://en.wikipedia.org/wiki/HTTP_pipelining)

Example
-------

```C++
#include <memory>
#include <cstdlib>
#include <restbed>
#include <stdexcept>

using namespace std;
using namespace restbed;

void get_method_handler_one( const shared_ptr< Session > session )
{
    const auto request = session->get_request( );
    
    if ( request->get_header( "Connection", String::lowercase ) == "keep-alive" )
    {
        session->yield( OK, "Hello, from first resource.\n", { { "Content-Length", "28" }, { "Connection", "keep-alive" } } );
    }
    else
    {
        session->close( BAD_REQUEST );
    }
}

void get_method_handler_two( const shared_ptr< Session > session )
{
    const auto request = session->get_request( );
    
    if ( request->get_header( "Connection", String::lowercase ) == "keep-alive" )
    {
        session->yield( OK, "Hello, from second resource.\n", { { "Content-Length", "29" }, { "Connection", "keep-alive" } } );
    }
    else
    {
        session->close( BAD_REQUEST );
    }
}

void get_method_handler_three( const shared_ptr< Session > session )
{
    const auto request = session->get_request( );
    
    if ( request->get_header( "Connection", String::lowercase ) == "keep-alive" )
    {
        session->yield( OK, "Hello, from third resource.\n", { { "Content-Length", "28" }, { "Connection", "keep-alive" } } );
    }
    else
    {
        session->close( BAD_REQUEST );
    }
}

void error_handler( const int status_code, const exception error, const shared_ptr< Session > session )
{
    if ( session not_eq nullptr and session->is_open( ) )
    {
        string message = error.what( );
        message.push_back( '\n' );
        
        //we must leave the socket intact on error,
        //otherwise follow up messages will be lost.
        session->yield( status_code, message, { { "Content-Length", ::to_string( message.length( ) ) }, { "Connection", "keep-alive" } } );
    }
}

int main( const int, const char** )
{
    auto resource_one = make_shared< Resource >( );
    resource_one->set_path( "/resource/1" );
    resource_one->set_method_handler( "GET", get_method_handler_one );
    
    auto resource_two = make_shared< Resource >( );
    resource_two->set_path( "/resource/2" );
    resource_two->set_method_handler( "GET", get_method_handler_two );
    
    auto resource_three = make_shared< Resource >( );
    resource_three->set_path( "/resource/3" );
    resource_three->set_method_handler( "GET", get_method_handler_three );
    
    auto settings = make_shared< Settings >( );
    settings->set_port( 1984 );
    settings->set_default_header( "Connection", "close" );
    
    Service service;
    service.publish( resource_one );
    service.publish( resource_two );
    service.publish( resource_three );
    service.set_error_handler( error_handler );
    service.start( settings );
    
    return EXIT_SUCCESS;
}
```

Build
-----

> $ clang++ -o example example.cpp -l restbed

Execution
---------

> $ ./example
>
> $ (echo -e "GET /resource/1 HTTP/1.1\r\nHost: localhost\r\nConnection: keep-alive\r\n\r\nGET /resource/2 HTTP/1.1\r\nConnection: keep-alive\r\nHost: localhost\r\n\r\nGET /resource/3 HTTP/1.1\r\nHost: localhost\r\nConnection: keep-alive\r\n\r\n"; sleep 5) | netcat localhost 1984
>
> $ (echo -e "GET &&%$£% /resource/1 HTTP/1.1\r\nHost: localhost\r\nConnection: keep-alive\r\n\r\nGET /resource/2 HTTP/1.1\r\nConnection: keep-alive\r\nHost: localhost\r\n\r\nGET /resource/3 HTTP/1.1\r\nHost: localhost\r\nConnection: keep-alive\r\n\r\n"; sleep 5) | netcat localhost 1984