A library for embedding an HTTP or HTTPS server in C++ applications.
C++ QMake CMake


via-httplib: A C++ HTTP Library

A library for embedding HTTP or HTTPS, IPV6 and IPV4 servers in C++ applications.

via-httplib is an asynchronous C++ HTTP server built upon asio (both boost and standalone) that aims to provide a simple, secure and efficient server that complies with the requirements of rfc7230 wherever possible.

SSL / TLS Configuration

The server is via::http_server, a class template requiring a SocketAdaptor to instantiate it:

  • a tcp_adaptor for a plain HTTP server
  • an ssl_tcp_adaptor for an HTTPS server

IPV6 / IPV4 Configuration

Whether the server accepts IPV6 and IPV4 connections or just IPV4 connections depends upon how the port is configured:

  • IPV6, (the default) the server accepts both IPV6 and IPV4 connections
  • IPV4 only, the server only accepts IPV4 connections

Data / Text Configuration

The server can be configured to pass HTTP message bodies in different types of containers, e.g.:

  • std::vector<char> (the default) for handing binary data, e.g. images, files, etc.
  • std::string for handing textural data, e.g. HTML, JSON, etc.
Socket Adaptor Container Description
tcp_adaptor std::vector<char> An HTTP data server.
tcp_adaptor std::string An HTTP text server.
ssl_tcp_adaptor std::vector<char> An HTTPS data server.
ssl_tcp_adaptor std::string An HTTPS text server.

The HTTP message bodies can be sent using buffered or unbuffered methods.
The unbuffered methods use "scatter-gather" write functions to avoid copying data.

Boost / Standalone asio Configuration

The library uses boost asio by default.
To use standalone asio:

  • set the environment variable $ASIO_ROOT to the path of the asio root directory;
  • add $ASIO_ROOT/include to your include path;
  • define the macro ASIO_STANDALONE.

Note: if you use qmake file and include the file via-httplib.pri then you just need to set the $ASIO_ROOT environment variable.

Portability between bost asio and standalone asio is provided by the macros:

  • ASIO,

They are defined in socket_adaptor.hpp:

  #include <asio.hpp>
  #define ASIO asio
  #define ASIO_ERROR_CODE asio::error_code
  #define ASIO_TIMER asio::steady_timer
  #include <boost/asio.hpp>
  #define ASIO boost::asio
  #define ASIO_ERROR_CODE boost::system::error_code
  #define ASIO_TIMER boost::asio::deadline_timer

It is hoped that they can continue to provide portability when asio becomes a standard C++ library: see: Networking Library Proposal.


  • A C++11 compiler.
    This version requires a complier that supports: lambdas, enum classes, member function delete and std::functional. It's been tested with MSVC 2015, GCC 6.2 and MinGw 5.3.0.

  • The asio C++ library, either standalone asio or boost asio.
    Note: if boost and standalone asio libraries are installed together, this library will use standalone asio for comms.

  • For HTTPS, the OpenSSL library, see openssl.

  • For C++ code documentation, Doxygen, see Doxygen

  • Note: there is an issue building boost::asio with Visual Studio 2015 Update 2, see Issue 4

Getting Started

Download the latest tagged version of via-httplib from Github and follow the instructions here: Make.
Or simply build the .cpp files into your application (there are 8 of them).

via-http lib depends on the standalone asio or boost libraries. If boost is not installed on your machine then download the latest package from boost and follow the instructions here: boost getting started.

Otherwise standalone asio can be downloaded from: standalone asio.

The asio library (and hence via-httplib) depends upon the OpenSSL library to implement SSL/TLS sockets. If you require an HTTPS server or client then you'll need to install the OpenSSL library as well. Please note that a plain HTTP server should not require OpenSLL.

If OpenSLL is not installed on your machine then you may download the latest stable package from openssl source and build it. Note: a binary distribution may be available for your machine, see: OpenSSL binaries.

Document Description
Build Guide How to build the library.
Server User Guide How to use the library to create HTTP servers.
Client User Guide How to use the library to create HTTP clients.
Security Guide How to configure the library securely.
Design The library design.
examples/server Example HTTP & HTTPS servers.
examples/client Example HTTP & HTTPS clients.

Namespace Structure

Via Namespaces

Directory Structure

Directory Contents
via The via-httplib API classes: http_server, http_connection and http_client.
examples/server Example HTTP & HTTPS servers.
examples/client Example HTTP & HTTPS clients.
tests A unit tests for the HTTP parsers and encoders.
docs The User Guides and design documents.
docs/html Doxygen output directory. Created by running doxygen Doxyfile in the docs directory.


Thanks to:

  • Neil Tisdale for encouraging and inspiring me to create the library
  • Louis Nayegon for helping to develop it and recommending GitHub
  • Adam Leggett for helping to identify and fix security, efficiency and CMake issues
  • Christopher Kohlhoff for the asio library, without which, this library wouldn't exist.