| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Client implementation of the HTTP/2 protocol."><meta name="keywords" content="rust, rustlang, rust-lang, client"><title>h2::client - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc mod"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle">☰</button><a class="sidebar-logo" href="../../h2/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a><h2></h2></nav><nav class="sidebar"><a class="sidebar-logo" href="../../h2/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a><h2 class="location"><a href="#">Module client</a></h2><div class="sidebar-elems"><section><ul class="block"><li><a href="#structs">Structs</a></li><li><a href="#functions">Functions</a></li></ul></section></div></nav><main><div class="width-limiter"><nav class="sub"><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1 class="fqn">Module <a href="../index.html">h2</a>::<wbr><a class="mod" href="#">client</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../../clipboard.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="srclink" href="../../src/h2/client.rs.html#1-1604">source</a> · <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Client implementation of the HTTP/2 protocol.</p> |
| <h2 id="getting-started"><a href="#getting-started">Getting started</a></h2> |
| <p>Running an HTTP/2 client requires the caller to establish the underlying |
| connection as well as get the connection to a state that is ready to begin |
| the HTTP/2 handshake. See <a href="../index.html#handshake">here</a> for more |
| details.</p> |
| <p>This could be as basic as using Tokio’s <a href="https://docs.rs/tokio-core/0.1/tokio_core/net/struct.TcpStream.html"><code>TcpStream</code></a> to connect to a remote |
| host, but usually it means using either ALPN or HTTP/1.1 protocol upgrades.</p> |
| <p>Once a connection is obtained, it is passed to <a href="fn.handshake.html"><code>handshake</code></a>, which will |
| begin the <a href="http://httpwg.org/specs/rfc7540.html#ConnectionHeader">HTTP/2 handshake</a>. This returns a future that completes once |
| the handshake process is performed and HTTP/2 streams may be initialized.</p> |
| <p><a href="fn.handshake.html"><code>handshake</code></a> uses default configuration values. There are a number of |
| settings that can be changed by using <a href="struct.Builder.html"><code>Builder</code></a> instead.</p> |
| <p>Once the handshake future completes, the caller is provided with a |
| <a href="struct.Connection.html"><code>Connection</code></a> instance and a <a href="struct.SendRequest.html"><code>SendRequest</code></a> instance. The <a href="struct.Connection.html"><code>Connection</code></a> |
| instance is used to drive the connection (see <a href="#managing-the-connection">Managing the connection</a>). |
| The <a href="struct.SendRequest.html"><code>SendRequest</code></a> instance is used to initialize new streams (see <a href="#making-requests">Making |
| requests</a>).</p> |
| <h2 id="making-requests"><a href="#making-requests">Making requests</a></h2> |
| <p>Requests are made using the <a href="struct.SendRequest.html"><code>SendRequest</code></a> handle provided by the handshake |
| future. Once a request is submitted, an HTTP/2 stream is initialized and |
| the request is sent to the server.</p> |
| <p>A request body and request trailers are sent using <a href="struct.SendRequest.html"><code>SendRequest</code></a> and the |
| server’s response is returned once the <a href="struct.ResponseFuture.html"><code>ResponseFuture</code></a> future completes. |
| Both the <a href="../struct.SendStream.html"><code>SendStream</code></a> and <a href="struct.ResponseFuture.html"><code>ResponseFuture</code></a> instances are returned by |
| <a href="struct.SendRequest.html#method.send_request"><code>SendRequest::send_request</code></a> and are tied to the HTTP/2 stream |
| initialized by the sent request.</p> |
| <p>The <a href="struct.SendRequest.html#method.poll_ready"><code>SendRequest::poll_ready</code></a> function returns <code>Ready</code> when a new HTTP/2 |
| stream can be created, i.e. as long as the current number of active streams |
| is below <a href="http://httpwg.org/specs/rfc7540.html#SettingValues"><code>MAX_CONCURRENT_STREAMS</code></a>. If a new stream cannot be created, the |
| caller will be notified once an existing stream closes, freeing capacity for |
| the caller. The caller should use <a href="struct.SendRequest.html#method.poll_ready"><code>SendRequest::poll_ready</code></a> to check for |
| capacity before sending a request to the server.</p> |
| <p><a href="struct.SendRequest.html"><code>SendRequest</code></a> enforces the <a href="http://httpwg.org/specs/rfc7540.html#SettingValues"><code>MAX_CONCURRENT_STREAMS</code></a> setting. The user |
| must not send a request if <code>poll_ready</code> does not return <code>Ready</code>. Attempting |
| to do so will result in an <a href="../struct.Error.html"><code>Error</code></a> being returned.</p> |
| <h2 id="managing-the-connection"><a href="#managing-the-connection">Managing the connection</a></h2> |
| <p>The <a href="struct.Connection.html"><code>Connection</code></a> instance is used to manage connection state. The caller |
| is required to call <a href="struct.Connection.html#method.poll"><code>Connection::poll</code></a> in order to advance state. |
| <a href="struct.SendRequest.html#method.send_request"><code>SendRequest::send_request</code></a> and other functions have no effect unless |
| <a href="struct.Connection.html#method.poll"><code>Connection::poll</code></a> is called.</p> |
| <p>The <a href="struct.Connection.html"><code>Connection</code></a> instance should only be dropped once <a href="struct.Connection.html#method.poll"><code>Connection::poll</code></a> |
| returns <code>Ready</code>. At this point, the underlying socket has been closed and no |
| further work needs to be done.</p> |
| <p>The easiest way to ensure that the <a href="struct.Connection.html"><code>Connection</code></a> instance gets polled is to |
| submit the <a href="struct.Connection.html"><code>Connection</code></a> instance to an <a href="https://docs.rs/futures/0.1/futures/future/trait.Executor.html">executor</a>. The executor will then |
| manage polling the connection until the connection is complete. |
| Alternatively, the caller can call <code>poll</code> manually.</p> |
| <h2 id="example"><a href="#example">Example</a></h2> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code> |
| <span class="kw">use </span>h2::client; |
| |
| <span class="kw">use </span>http::{Request, Method}; |
| <span class="kw">use </span>std::error::Error; |
| <span class="kw">use </span>tokio::net::TcpStream; |
| |
| <span class="attribute">#[tokio::main] |
| </span><span class="kw">pub async fn </span>main() -> <span class="prelude-ty">Result</span><(), Box<<span class="kw">dyn </span>Error>> { |
| <span class="comment">// Establish TCP connection to the server. |
| </span><span class="kw">let </span>tcp = TcpStream::connect(<span class="string">"127.0.0.1:5928"</span>).<span class="kw">await</span><span class="question-mark">?</span>; |
| <span class="kw">let </span>(h2, connection) = client::handshake(tcp).<span class="kw">await</span><span class="question-mark">?</span>; |
| tokio::spawn(<span class="kw">async move </span>{ |
| connection.<span class="kw">await</span>.unwrap(); |
| }); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>h2 = h2.ready().<span class="kw">await</span><span class="question-mark">?</span>; |
| <span class="comment">// Prepare the HTTP request to send to the server. |
| </span><span class="kw">let </span>request = Request::builder() |
| .method(Method::GET) |
| .uri(<span class="string">"https://www.example.com/"</span>) |
| .body(()) |
| .unwrap(); |
| |
| <span class="comment">// Send the request. The second tuple item allows the caller |
| // to stream a request body. |
| </span><span class="kw">let </span>(response, <span class="kw">_</span>) = h2.send_request(request, <span class="bool-val">true</span>).unwrap(); |
| |
| <span class="kw">let </span>(head, <span class="kw-2">mut </span>body) = response.<span class="kw">await</span><span class="question-mark">?</span>.into_parts(); |
| |
| <span class="macro">println!</span>(<span class="string">"Received response: {:?}"</span>, head); |
| |
| <span class="comment">// The `flow_control` handle allows the caller to manage |
| // flow control. |
| // |
| // Whenever data is received, the caller is responsible for |
| // releasing capacity back to the server once it has freed |
| // the data from memory. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>flow_control = body.flow_control().clone(); |
| |
| <span class="kw">while let </span><span class="prelude-val">Some</span>(chunk) = body.data().<span class="kw">await </span>{ |
| <span class="kw">let </span>chunk = chunk<span class="question-mark">?</span>; |
| <span class="macro">println!</span>(<span class="string">"RX: {:?}"</span>, chunk); |
| |
| <span class="comment">// Let the server send more data. |
| </span><span class="kw">let _ </span>= flow_control.release_capacity(chunk.len()); |
| } |
| |
| <span class="prelude-val">Ok</span>(()) |
| }</code></pre></div> |
| </div></details><h2 id="structs" class="small-section-header"><a href="#structs">Structs</a></h2><div class="item-table"><div class="item-row"><div class="item-left module-item"><a class="struct" href="struct.Builder.html" title="h2::client::Builder struct">Builder</a></div><div class="item-right docblock-short">Builds client connections with custom configuration values.</div></div><div class="item-row"><div class="item-left module-item"><a class="struct" href="struct.Connection.html" title="h2::client::Connection struct">Connection</a></div><div class="item-right docblock-short">Manages all state associated with an HTTP/2 client connection.</div></div><div class="item-row"><div class="item-left module-item"><a class="struct" href="struct.PushPromise.html" title="h2::client::PushPromise struct">PushPromise</a></div><div class="item-right docblock-short">A pushed response and corresponding request headers</div></div><div class="item-row"><div class="item-left module-item"><a class="struct" href="struct.PushPromises.html" title="h2::client::PushPromises struct">PushPromises</a></div><div class="item-right docblock-short">A stream of pushed responses and corresponding promised requests</div></div><div class="item-row"><div class="item-left module-item"><a class="struct" href="struct.PushedResponseFuture.html" title="h2::client::PushedResponseFuture struct">PushedResponseFuture</a></div><div class="item-right docblock-short">A future of a pushed HTTP response.</div></div><div class="item-row"><div class="item-left module-item"><a class="struct" href="struct.ReadySendRequest.html" title="h2::client::ReadySendRequest struct">ReadySendRequest</a></div><div class="item-right docblock-short">Returns a <code>SendRequest</code> instance once it is ready to send at least one |
| request.</div></div><div class="item-row"><div class="item-left module-item"><a class="struct" href="struct.ResponseFuture.html" title="h2::client::ResponseFuture struct">ResponseFuture</a></div><div class="item-right docblock-short">A future of an HTTP response.</div></div><div class="item-row"><div class="item-left module-item"><a class="struct" href="struct.SendRequest.html" title="h2::client::SendRequest struct">SendRequest</a></div><div class="item-right docblock-short">Initializes new HTTP/2 streams on a connection by sending a request.</div></div></div><h2 id="functions" class="small-section-header"><a href="#functions">Functions</a></h2><div class="item-table"><div class="item-row"><div class="item-left module-item"><a class="fn" href="fn.handshake.html" title="h2::client::handshake fn">handshake</a></div><div class="item-right docblock-short">Creates a new configured HTTP/2 client with default configuration |
| values backed by <code>io</code>.</div></div></div></section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="h2" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
