Compression

Burl can advertise the content codings it accepts and transparently decode a compressed response body, so gzip, deflate, and br responses arrive already decompressed. Decoding depends on the relevant service being installed in the system context.

Installing the Decode Services

Decoding is provided by Boost.Http and must be registered in the system context once, at startup, before any request. The zlib service handles gzip and deflate; the brotli service handles br:

#include <boost/http/zlib.hpp>
#include <boost/http/brotli.hpp>

int main()
{
    http::zlib::install_inflate_service(capy::get_system_context());
    http::brotli::install_decode_service(capy::get_system_context());

    // ... run the client ...
}

These are available only when Boost.Http is built with zlib and brotli support. Guarding the calls with the feature macros keeps the program portable across builds that lack them:

#ifdef BOOST_HTTP_HAS_ZLIB
    http::zlib::install_inflate_service(capy::get_system_context());
#endif
#ifdef BOOST_HTTP_HAS_BROTLI
    http::brotli::install_decode_service(capy::get_system_context());
#endif

How It Works

With a service installed and the corresponding setting enabled, the client adds that coding to the Accept-Encoding request header and decodes a response encoded with it.

burl::client::config cfg;
cfg.gzip    = true;
cfg.deflate = true;
cfg.brotli  = false;   // do not advertise or decode br

burl::client client(co_await capy::this_coro::executor, tls_ctx, cfg);

A coding whose decode service is not installed is disabled regardless of the setting, since the client cannot honor what it advertises.

The decoding is transparent: the body you read through any of the body functions is the decoded content, and content_length() and the Content-Length header reflect the encoded size as sent on the wire.

Opting Out for a Request

A request that sets its own Accept-Encoding header is left alone: the client neither adds codings to it nor decodes the response. This is the way to control encoding for a single request:

auto [ec, r] = co_await client.get("https://example.com/data")
    .header(http::field::accept_encoding, "identity")
    .send();

Next Steps

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