httpxx --- HTTP Parser for C++

Authors:	André Caron
Contact:	andre.l.caron@gmail.com
Version:	0.1
Date:	2011-07-18

Description

This library is a simple C++ wrapper for the C library http-parser [1] (This code was derived from the HTTP parser code in NGINX). http-parser is a simple HTTP streaming parser (for those of you familiar with XML, it works much like a SAX parser). It knows nothing of sockets or streams. You feed it data and it invokes registered callbacks to notify of available data. Because http-parser operates at the very lowest level, it does not buffer data or allocate memory dynamically. This library attempts to make that library easily usable by C++ programs by interpreting those callbacks and buffering data where needed.

[1]	https://github.com/ry/http-parser.

Documentation

The API for defined classes is documented using Doxygen [2]. You will need to run Doxygen from the project source folder to generate the output HTML.

[2]	http://www.stack.nl/~dimitri/doxygen/

Compiled HTML documentation for official releases is available online. Check the project page.

Fetching the code

This project does not distribute the code to http-parser directly. To fetch the entire source code, make sure you fetch submodules [3] too:

$ git clone ...
$ cd httpxx
$ git submodule init
$ git submodule update

[3]	http://book.git-scm.com/5_submodules.html

Portability

http-parser itself has no dependencies and compiles with C++ compilers. httpcxx uses only standard library facilities (namely std::string and std::map) and introduces no additional dependencies.

The code should compile as is under a standard-compliant C++03 implementation.

Memory allocation policy

A good memory allocation policy is important in server programs, which typically run for a long time and suffer from memory fragmentation. httpcxx does its best to avoid repeated allocation, but it needs a little help on your part.

http::Request and http::Response parser object allocate memory as required because they buffer different parts of the incoming HTTP request/response in std::string instances. However, they are implemented carefully as to use the growing property of std::string [4] to their advantage. In particular, you may re-use http::Request and http::Response parser objects for parsing multiple request/response objects using their .clear() method. This method marks all header lengths as 0 but keeps the instances as well as the map. All this ensures that parsers avoid repeated memory allocation.

[4]	std::string instances keep the allocated memory buffer even when you resize them such that their length decreases. In particular, std::string::clear() marks the string length as 0 but keeps the allocated buffer.

Samples / demos

Check out the sample programs in the demo/ subfolder.