nghttp2/doc/sources/libnghttp2_asio.rst

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libnghttp2_asio: High level HTTP/2 C++ library
==============================================
libnghttp2_asio is C++ library built on top of libnghttp2 and provides
high level abstraction API to build HTTP/2 applications. It depends
on Boost::ASIO library and OpenSSL. Currently libnghttp2_asio
provides server side API.
libnghttp2_asio is not built by default. Use ``--enable-asio-lib``
configure flag to build libnghttp2_asio. The required Boost libraries
are:
* Boost::Asio
* Boost::System
* Boost::Thread
To use libnghttp2_asio, first include following header file:
.. code-block:: cpp
#include <nghttp2/asio_http2.h>
Also take a look at that header file :doc:`asio_http2.h`.
Server API
----------
Server API is designed to build HTTP/2 server very easily to utilize
C++11 anonymous function and closure. The bare minimum example of
HTTP/2 server looks like this:
.. code-block:: cpp
#include <nghttp2/asio_http2.h>
using namespace nghttp2::asio_http2;
using namespace nghttp2::asio_http2::server;
int main(int argc, char* argv[])
{
http2 server;
server.listen
("*", 3000,
[](std::shared_ptr<request> req, std::shared_ptr<response> res)
{
res->write_head(200);
res->end("hello, world");
});
}
First we instantiate ``nghttp2::asio_http2::server::http2`` object.
Then call ``nghttp2::asio_http2::server::http2::listen`` function with
address and port to listen to and callback function invoked when
request arrives.
The ``req`` and ``res`` represent HTTP request and response
respectively. ``nghttp2::asio_http2_::server::response::write_head``
constructs HTTP response header fields. The first argument is HTTP
status code, in the above example, which is 200. The second argument,
which is omitted in the above example, is additional header fields to
send.
``nghttp2::asio_http2::server::response::end`` sends responde body.
In the above example, we send string "hello, world".
Serving static files and enabling SSL/TLS
+++++++++++++++++++++++++++++++++++++++++
In this example, we serve a couple of static files and also enable
SSL/TLS.
.. code-block:: cpp
#include <nghttp2/asio_http2.h>
using namespace nghttp2::asio_http2;
using namespace nghttp2::asio_http2::server;
int main(int argc, char* argv[])
{
http2 server;
server.tls("server.key", "server.crt");
server.listen
("*", 3000,
[](std::shared_ptr<request> req, std::shared_ptr<response> res)
{
if(req->path() == "/" || req->path() == "/index.html") {
res->write_head(200);
res->end(file_reader("index.html"));
} else {
res->write_head(404);
res->end("<html><head><title>404</title></head>"
"<body>404 Not Found</body></html>");
}
});
}
Specifying path to private key file and certificate file in
``nghttp2::asio_http2::server::http2::tls`` will enable SSL/TLS. Both
files must be in PEM format.
In the above example, if request path is either "/" or "/index.html",
we serve index.html file in the current working directory.
``nghttp2::asio_http2::server::response::end`` has overload to take
function of type ``nghttp2::asio_http2::server::read_cb`` and
application pass its implementation to generate response body. For
the convenience, libnghttp2_asio library provides
``nghttp2::asio_http2::server::file_reader`` function to generate
function to server static file.
Server push
+++++++++++
Server push is also supported.
.. code-block:: cpp
#include <nghttp2/asio_http2.h>
using namespace nghttp2::asio_http2;
using namespace nghttp2::asio_http2::server;
int main(int argc, char* argv[])
{
http2 server;
server.tls("server.key", "server.crt");
server.listen
("*", 3000,
[](std::shared_ptr<request> req, std::shared_ptr<response> res)
{
if(req->path() == "/") {
req->push("GET", "/my.css");
res->write_head(200);
res->end(file_reader("index.html"));
return;
}
if(req->path() == "/my.css") {
res->write_head(200);
res->end(file_reader("my.css"));
return;
}
res->write_head(404);
res->end("<html><head><title>404</title></head>"
"<body>404 Not Found</body></html>");
});
}
When client requested "/", we push "/my.css". To push resource, call
``nghttp2::asio_http2::server::request::push`` function with desired
method and path. Later, the callback will be called with the pushed
resource "/my.css".
Enable multi-threading
++++++++++++++++++++++
Enabling multi-threading is very easy. Just call
``nghttp2::asio_http2::server::http2::num_threads`` function with the
desired number of threads:
.. code-block:: cpp
http2 server;
// Use 4 native threads
server.num_threads(4);