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title: Amp - Asynchronous concurrency made simple
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            <h1>
                Leading PHP into an asynchronous future
            </h1>
            <p>
                Amp is an event-driven concurrency framework for PHP providing primitives to manage cooperative multitasking building upon an
                event loop, and promises.
            </p>
            <p>
                Event driven programming requires a different mindset, so Amp provides synchronous feeling APIs to ease the transition.
            </p>
            <p>
                A wide range of packages allows creating entire applications using non-blocking I/O and taking advantage of long running processes.
                It's also possible to integrate Amp into existing applications for concurrent data access.
            </p>
            <p>
                <a href="/getting-started" class="highlight-area-cta">Get Started <i class="fa fa-angle-right"></i></a>
            </p>
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                <pre style="border: 0; padding: 0"><code class="php">try {
    $request = new Request("https://amphp.org/");
    $response = yield <span class="help-bubble" title="Promise consumption without callbacks"></span> $http->request($request);

    if ($response->getStatus() !== 200) {
        <span class="help-bubble" title="Throw normal exceptions to indicate errors"></span> throw new HttpException;
    }
} catch (HttpException $e) <span class="help-bubble" title="Ordinary catch clauses to handle errors"></span> {
    // handle error
}</code></pre>
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            <p>
                Consumption of asynchronous results was traditionally solved via callbacks.
                Promises shift the callback from a parameter to the return value, while coroutines automate the boilerplate of callbacks entirely.
            </p>
            <p>
                Amp implements coroutines using PHP's generators to avoid callback or <code>then()</code> hells.
                Promise consumption works without callbacks and allows ordinary <code>catch</code> clauses just
                as synchronous code for handling errors.
            </p>
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    <h2>Building Blocks</h2>

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            <h3 class="headline-link"><a href="//amphp.org/amp/event-loop">Event Loop<i class="fa fa-angle-right"></i></a></h3>
            <p>
                The event loop is the main task scheduler of every asynchronous application. It dispatches
                associ&shy;ated handlers once the registered events happen.
            </p>
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            <h3 class="headline-link"><a href="//amphp.org/amp/promises">Promises<i class="fa fa-angle-right"></i></a></h3>
            <p>
                A promise is a placeholder for the result of an asynchronous operation. While synchronous
                programs block until a result is available, asynchronous programs return a placeholder which gets
                filled in with the result at a later time.
            </p>
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            <h3 class="headline-link"><a href="//amphp.org/amp/coroutines">Coroutines<i class="fa fa-angle-right"></i></a></h3>
            <p>
                Coroutines are interruptible functions that can be paused and resumed. Amp uses
                <code>Generator</code>s
                to allow promise consumption without callbacks.
            </p>
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            <h3 class="headline-link"><a href="//amphp.org/amp/iterators">Iterators<i class="fa fa-angle-right"></i></a></h3>
            <p>
                Asynchronous iterators allow the consumption of collections of values, one at a time. Instead of
                resolving a promise once all results are available, iterators make it possible to consume items of a
                collection as soon as they become available.
            </p>
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            <h3 class="headline-link"><a href="//amphp.org/byte-stream">Streams<i class="fa fa-angle-right"></i></a></h3>
            <p>
                Amp provides a stream abstraction that makes working with non-blocking I/O way easier. Don't worry
                about read- and write-watchers, buffering, and backpressure.
            </p>
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    <h2>Use Cases</h2>

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        Amp can be used wherever you have to wait for multiple I/O activities to happen without them having to happen in a specific order (sequentially). It can be used in all SAPIs reaching from Apache and PHP-FPM to PHP-CLI. If you don't have a long running application, you might find <a href="/amp/promises/miscellaneous#wait"><code>Amp\Promise\wait()</code></a> helpful.
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            <h3>Multiplexing I/O</h3>
            <p>
                The key benefit of non-blocking I/O is that it can be multiplexed. Multiple I/O requests can happen concurrently. The event loop simply waits for any I/O event to occurr instead of waiting for a single I/O operations.
                This enables <a href="/artax/">parallel HTTP requests</a>, <a href="https://github.com/amphp/mysql">SQL queries</a> or any other I/O related activity.
            </p>
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            <h3>Reacting to I/O</h3>
            <p>
                Maybe you're not interested in speeding up your application by using concurrent I/O (we bet you are), but want to write a daemon that only wakes up the CPU if some I/O event occurred so you can react to that event?
                Amp's <a href="/amp/event-loop/">event loop</a> provides exactly that. It lets you register callbacks to react to I/O events.
            </p>
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    <h2>Compatible Packages</h2>

    <p>
        Amphp offers a number of high-quality packages ranging from basic network components to more advanced
        components like our HTTP application server. All compatible packages should use the <a
            href="https://github.com/search?p=1&q=topic%3Aamphp&type=Repositories&utf8=%E2%9C%93"><code>amphp</code></a>
        tag on GitHub. Many packages are listed on our dedicated <a href="/packages">Packages</a> page.
    </p>

    <p>
        <a href="//amphp.org/react-adapter">Every ReactPHP library is compatible with Amp</a>, so you don't need to choose between those two.
    </p>
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