332 lines
22 KiB
HTML
332 lines
22 KiB
HTML
<!DOCTYPE HTML>
|
|
<html lang="en" class="sidebar-visible no-js light">
|
|
<head>
|
|
<!-- Book generated using mdBook -->
|
|
<meta charset="UTF-8">
|
|
<title>Subscriptions - Juniper Book (GraphQL server for Rust)</title>
|
|
|
|
|
|
<!-- Custom HTML head -->
|
|
|
|
<meta name="description" content="User guide for Juniper (GraphQL server library for Rust).">
|
|
<meta name="viewport" content="width=device-width, initial-scale=1">
|
|
<meta name="theme-color" content="#ffffff" />
|
|
|
|
<link rel="icon" href="../favicon.svg">
|
|
<link rel="shortcut icon" href="../favicon.png">
|
|
<link rel="stylesheet" href="../css/variables.css">
|
|
<link rel="stylesheet" href="../css/general.css">
|
|
<link rel="stylesheet" href="../css/chrome.css">
|
|
<link rel="stylesheet" href="../css/print.css" media="print">
|
|
|
|
<!-- Fonts -->
|
|
<link rel="stylesheet" href="../FontAwesome/css/font-awesome.css">
|
|
<link rel="stylesheet" href="../fonts/fonts.css">
|
|
|
|
<!-- Highlight.js Stylesheets -->
|
|
<link rel="stylesheet" href="../highlight.css">
|
|
<link rel="stylesheet" href="../tomorrow-night.css">
|
|
<link rel="stylesheet" href="../ayu-highlight.css">
|
|
|
|
<!-- Custom theme stylesheets -->
|
|
|
|
</head>
|
|
<body>
|
|
<div id="body-container">
|
|
<!-- Provide site root to javascript -->
|
|
<script>
|
|
var path_to_root = "../";
|
|
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light";
|
|
</script>
|
|
|
|
<!-- Work around some values being stored in localStorage wrapped in quotes -->
|
|
<script>
|
|
try {
|
|
var theme = localStorage.getItem('mdbook-theme');
|
|
var sidebar = localStorage.getItem('mdbook-sidebar');
|
|
|
|
if (theme.startsWith('"') && theme.endsWith('"')) {
|
|
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
|
|
}
|
|
|
|
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
|
|
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
|
|
}
|
|
} catch (e) { }
|
|
</script>
|
|
|
|
<!-- Set the theme before any content is loaded, prevents flash -->
|
|
<script>
|
|
var theme;
|
|
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
|
|
if (theme === null || theme === undefined) { theme = default_theme; }
|
|
var html = document.querySelector('html');
|
|
html.classList.remove('no-js')
|
|
html.classList.remove('light')
|
|
html.classList.add(theme);
|
|
html.classList.add('js');
|
|
</script>
|
|
|
|
<!-- Hide / unhide sidebar before it is displayed -->
|
|
<script>
|
|
var html = document.querySelector('html');
|
|
var sidebar = null;
|
|
if (document.body.clientWidth >= 1080) {
|
|
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
|
|
sidebar = sidebar || 'visible';
|
|
} else {
|
|
sidebar = 'hidden';
|
|
}
|
|
html.classList.remove('sidebar-visible');
|
|
html.classList.add("sidebar-" + sidebar);
|
|
</script>
|
|
|
|
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
|
|
<div class="sidebar-scrollbox">
|
|
<ol class="chapter"><li class="chapter-item expanded "><a href="../index.html"><strong aria-hidden="true">1.</strong> Introduction</a></li><li class="chapter-item expanded "><a href="../quickstart.html"><strong aria-hidden="true">2.</strong> Quickstart</a></li><li class="chapter-item expanded "><a href="../types/index.html"><strong aria-hidden="true">3.</strong> Type System</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../types/objects/defining_objects.html"><strong aria-hidden="true">3.1.</strong> Defining objects</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../types/objects/complex_fields.html"><strong aria-hidden="true">3.1.1.</strong> Complex fields</a></li><li class="chapter-item expanded "><a href="../types/objects/using_contexts.html"><strong aria-hidden="true">3.1.2.</strong> Using contexts</a></li><li class="chapter-item expanded "><a href="../types/objects/error_handling.html"><strong aria-hidden="true">3.1.3.</strong> Error handling</a></li></ol></li><li class="chapter-item expanded "><a href="../types/other-index.html"><strong aria-hidden="true">3.2.</strong> Other types</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../types/enums.html"><strong aria-hidden="true">3.2.1.</strong> Enums</a></li><li class="chapter-item expanded "><a href="../types/interfaces.html"><strong aria-hidden="true">3.2.2.</strong> Interfaces</a></li><li class="chapter-item expanded "><a href="../types/input_objects.html"><strong aria-hidden="true">3.2.3.</strong> Input objects</a></li><li class="chapter-item expanded "><a href="../types/scalars.html"><strong aria-hidden="true">3.2.4.</strong> Scalars</a></li><li class="chapter-item expanded "><a href="../types/unions.html"><strong aria-hidden="true">3.2.5.</strong> Unions</a></li></ol></li></ol></li><li class="chapter-item expanded "><a href="../schema/schemas_and_mutations.html"><strong aria-hidden="true">4.</strong> Schemas and mutations</a></li><li class="chapter-item expanded "><a href="../servers/index.html"><strong aria-hidden="true">5.</strong> Adding A Server</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../servers/official.html"><strong aria-hidden="true">5.1.</strong> Official Server Integrations</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../servers/warp.html"><strong aria-hidden="true">5.1.1.</strong> Warp</a></li><li class="chapter-item expanded "><a href="../servers/rocket.html"><strong aria-hidden="true">5.1.2.</strong> Rocket</a></li><li class="chapter-item expanded "><a href="../servers/iron.html"><strong aria-hidden="true">5.1.3.</strong> Iron</a></li><li class="chapter-item expanded "><a href="../servers/hyper.html"><strong aria-hidden="true">5.1.4.</strong> Hyper</a></li></ol></li><li class="chapter-item expanded "><a href="../servers/third-party.html"><strong aria-hidden="true">5.2.</strong> Third Party Integrations</a></li></ol></li><li class="chapter-item expanded "><a href="../advanced/index.html"><strong aria-hidden="true">6.</strong> Advanced Topics</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../advanced/introspection.html"><strong aria-hidden="true">6.1.</strong> Introspection</a></li><li class="chapter-item expanded "><a href="../advanced/non_struct_objects.html"><strong aria-hidden="true">6.2.</strong> Non-struct objects</a></li><li class="chapter-item expanded "><a href="../advanced/implicit_and_explicit_null.html"><strong aria-hidden="true">6.3.</strong> Implicit and explicit null</a></li><li class="chapter-item expanded "><a href="../advanced/objects_and_generics.html"><strong aria-hidden="true">6.4.</strong> Objects and generics</a></li><li class="chapter-item expanded "><a href="../advanced/multiple_ops_per_request.html"><strong aria-hidden="true">6.5.</strong> Multiple operations per request</a></li><li class="chapter-item expanded "><a href="../advanced/dataloaders.html"><strong aria-hidden="true">6.6.</strong> Dataloaders</a></li><li class="chapter-item expanded "><a href="../advanced/subscriptions.html" class="active"><strong aria-hidden="true">6.7.</strong> Subscriptions</a></li></ol></li></ol>
|
|
</div>
|
|
<div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
|
|
</nav>
|
|
|
|
<div id="page-wrapper" class="page-wrapper">
|
|
|
|
<div class="page">
|
|
<div id="menu-bar-hover-placeholder"></div>
|
|
<div id="menu-bar" class="menu-bar sticky bordered">
|
|
<div class="left-buttons">
|
|
<button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
|
|
<i class="fa fa-bars"></i>
|
|
</button>
|
|
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
|
|
<i class="fa fa-paint-brush"></i>
|
|
</button>
|
|
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
|
|
<li role="none"><button role="menuitem" class="theme" id="light">Light</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
|
|
</ul>
|
|
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
|
|
<i class="fa fa-search"></i>
|
|
</button>
|
|
</div>
|
|
|
|
<h1 class="menu-title">Juniper Book (GraphQL server for Rust)</h1>
|
|
|
|
<div class="right-buttons">
|
|
<a href="../print.html" title="Print this book" aria-label="Print this book">
|
|
<i id="print-button" class="fa fa-print"></i>
|
|
</a>
|
|
|
|
</div>
|
|
</div>
|
|
|
|
<div id="search-wrapper" class="hidden">
|
|
<form id="searchbar-outer" class="searchbar-outer">
|
|
<input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
|
|
</form>
|
|
<div id="searchresults-outer" class="searchresults-outer hidden">
|
|
<div id="searchresults-header" class="searchresults-header"></div>
|
|
<ul id="searchresults">
|
|
</ul>
|
|
</div>
|
|
</div>
|
|
|
|
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
|
|
<script>
|
|
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
|
|
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
|
|
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
|
|
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
|
|
});
|
|
</script>
|
|
|
|
<div id="content" class="content">
|
|
<main>
|
|
<h1 id="subscriptions"><a class="header" href="#subscriptions">Subscriptions</a></h1>
|
|
<h3 id="how-to-achieve-realtime-data-with-graphql-subscriptions"><a class="header" href="#how-to-achieve-realtime-data-with-graphql-subscriptions">How to achieve realtime data with GraphQL subscriptions</a></h3>
|
|
<p>GraphQL subscriptions are a way to push data from the server to clients requesting real-time messages
|
|
from the server. Subscriptions are similar to queries in that they specify a set of fields to be delivered to the client,
|
|
but instead of immediately returning a single answer a result is sent every time a particular event happens on the
|
|
server. </p>
|
|
<p>In order to execute subscriptions you need a coordinator (that spawns connections)
|
|
and a GraphQL object that can be resolved into a stream--elements of which will then
|
|
be returned to the end user. The <a href="https://github.com/graphql-rust/juniper/tree/master/juniper_subscriptions"><code>juniper_subscriptions</code></a> crate
|
|
provides a default connection implementation. Currently subscriptions are only supported on the <code>master</code> branch. Add the following to your <code>Cargo.toml</code>:</p>
|
|
<pre><code class="language-toml">[dependencies]
|
|
juniper = "0.16.0"
|
|
juniper_subscriptions = "0.17.0"
|
|
</code></pre>
|
|
<h3 id="schema-definition"><a class="header" href="#schema-definition">Schema Definition</a></h3>
|
|
<p>The <code>Subscription</code> is just a GraphQL object, similar to the query root and mutations object that you defined for the
|
|
operations in your <a href="../schema/schemas_and_mutations.html">Schema</a>. For subscriptions all fields/operations should be async and should return a <a href="https://docs.rs/futures/0.3.4/futures/stream/trait.Stream.html">Stream</a>.</p>
|
|
<p>This example shows a subscription operation that returns two events, the strings <code>Hello</code> and <code>World!</code>
|
|
sequentially: </p>
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">extern crate futures;
|
|
</span><span class="boring">extern crate juniper;
|
|
</span><span class="boring">use std::pin::Pin;
|
|
</span><span class="boring">use futures::Stream;
|
|
</span><span class="boring">use juniper::{graphql_object, graphql_subscription, FieldError};
|
|
</span><span class="boring">
|
|
</span><span class="boring">#[derive(Clone)]
|
|
</span><span class="boring">pub struct Database;
|
|
</span><span class="boring">impl juniper::Context for Database {}
|
|
</span>
|
|
<span class="boring">pub struct Query;
|
|
</span><span class="boring">#[graphql_object(context = Database)]
|
|
</span><span class="boring">impl Query {
|
|
</span><span class="boring"> fn hello_world() -> &'static str {
|
|
</span><span class="boring"> "Hello World!"
|
|
</span><span class="boring"> }
|
|
</span><span class="boring">}
|
|
</span>pub struct Subscription;
|
|
|
|
type StringStream = Pin<Box<dyn Stream<Item = Result<String, FieldError>> + Send>>;
|
|
|
|
#[graphql_subscription(context = Database)]
|
|
impl Subscription {
|
|
async fn hello_world() -> StringStream {
|
|
let stream = futures::stream::iter(vec![
|
|
Ok(String::from("Hello")),
|
|
Ok(String::from("World!"))
|
|
]);
|
|
Box::pin(stream)
|
|
}
|
|
}
|
|
<span class="boring">
|
|
</span><span class="boring">fn main () {}</span></code></pre></pre>
|
|
<h3 id="coordinator"><a class="header" href="#coordinator">Coordinator</a></h3>
|
|
<p>Subscriptions require a bit more resources than regular queries and provide a great vector for DOS attacks. This can can bring down a server easily if not handled correctly. The <a href="https://docs.rs/juniper_subscriptions/0.15.0/trait.SubscriptionCoordinator.html"><code>SubscriptionCoordinator</code></a> trait provides coordination logic to enable functionality like DOS attack mitigation and resource limits.</p>
|
|
<p>The <a href="https://docs.rs/juniper_subscriptions/0.15.0/trait.SubscriptionCoordinator.html"><code>SubscriptionCoordinator</code></a> contains the schema and can keep track of opened connections, handle subscription
|
|
start and end, and maintain a global subscription id for each subscription. Each time a connection is established,<br />
|
|
the <a href="https://docs.rs/juniper_subscriptions/0.15.0/trait.SubscriptionCoordinator.html"><code>SubscriptionCoordinator</code></a> spawns a <a href="https://docs.rs/juniper_subscriptions/0.15.0/trait.SubscriptionConnection.html"><code>SubscriptionConnection</code></a>. The <a href="https://docs.rs/juniper_subscriptions/0.15.0/trait.SubscriptionConnection.html"><code>SubscriptionConnection</code></a> handles a single connection, providing resolver logic for a client stream as well as reconnection
|
|
and shutdown logic.</p>
|
|
<p>While you can implement <a href="https://docs.rs/juniper_subscriptions/0.15.0/trait.SubscriptionCoordinator.html"><code>SubscriptionCoordinator</code></a> yourself, Juniper contains a simple and generic implementation called <a href="https://docs.rs/juniper_subscriptions/0.15.0/struct.Coordinator.html"><code>Coordinator</code></a>. The <code>subscribe</code>
|
|
operation returns a <a href="https://docs.rs/futures/0.3.4/futures/future/trait.Future.html"><code>Future</code></a> with an <code>Item</code> value of a <code>Result<Connection, GraphQLError></code>,
|
|
where <a href="https://docs.rs/juniper_subscriptions/0.15.0/struct.Connection.html"><code>Connection</code></a> is a <code>Stream</code> of values returned by the operation and <a href="https://docs.rs/juniper/0.14.2/juniper/enum.GraphQLError.html"><code>GraphQLError</code></a> is the error when the subscription fails.</p>
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(dead_code)]
|
|
</span><span class="boring">extern crate futures;
|
|
</span><span class="boring">extern crate juniper;
|
|
</span><span class="boring">extern crate juniper_subscriptions;
|
|
</span><span class="boring">extern crate serde_json;
|
|
</span><span class="boring">use juniper::{
|
|
</span><span class="boring"> http::GraphQLRequest,
|
|
</span><span class="boring"> graphql_object, graphql_subscription,
|
|
</span><span class="boring"> DefaultScalarValue, EmptyMutation, FieldError,
|
|
</span><span class="boring"> RootNode, SubscriptionCoordinator,
|
|
</span><span class="boring">};
|
|
</span><span class="boring">use juniper_subscriptions::Coordinator;
|
|
</span><span class="boring">use futures::{Stream, StreamExt};
|
|
</span><span class="boring">use std::pin::Pin;
|
|
</span><span class="boring">
|
|
</span><span class="boring">#[derive(Clone)]
|
|
</span><span class="boring">pub struct Database;
|
|
</span><span class="boring">
|
|
</span><span class="boring">impl juniper::Context for Database {}
|
|
</span><span class="boring">
|
|
</span><span class="boring">impl Database {
|
|
</span><span class="boring"> fn new() -> Self {
|
|
</span><span class="boring"> Self
|
|
</span><span class="boring"> }
|
|
</span><span class="boring">}
|
|
</span><span class="boring">
|
|
</span><span class="boring">pub struct Query;
|
|
</span><span class="boring">
|
|
</span><span class="boring">#[graphql_object(context = Database)]
|
|
</span><span class="boring">impl Query {
|
|
</span><span class="boring"> fn hello_world() -> &'static str {
|
|
</span><span class="boring"> "Hello World!"
|
|
</span><span class="boring"> }
|
|
</span><span class="boring">}
|
|
</span><span class="boring">
|
|
</span><span class="boring">pub struct Subscription;
|
|
</span><span class="boring">
|
|
</span><span class="boring">type StringStream = Pin<Box<dyn Stream<Item = Result<String, FieldError>> + Send>>;
|
|
</span><span class="boring">
|
|
</span><span class="boring">#[graphql_subscription(context = Database)]
|
|
</span><span class="boring">impl Subscription {
|
|
</span><span class="boring"> async fn hello_world() -> StringStream {
|
|
</span><span class="boring"> let stream =
|
|
</span><span class="boring"> futures::stream::iter(vec![Ok(String::from("Hello")), Ok(String::from("World!"))]);
|
|
</span><span class="boring"> Box::pin(stream)
|
|
</span><span class="boring"> }
|
|
</span><span class="boring">}
|
|
</span>type Schema = RootNode<'static, Query, EmptyMutation<Database>, Subscription>;
|
|
|
|
fn schema() -> Schema {
|
|
Schema::new(Query, EmptyMutation::new(), Subscription)
|
|
}
|
|
|
|
async fn run_subscription() {
|
|
let schema = schema();
|
|
let coordinator = Coordinator::new(schema);
|
|
let req: GraphQLRequest<DefaultScalarValue> = serde_json::from_str(
|
|
r#"{
|
|
"query": "subscription { helloWorld }"
|
|
}"#,
|
|
)
|
|
.unwrap();
|
|
let ctx = Database::new();
|
|
let mut conn = coordinator.subscribe(&req, &ctx).await.unwrap();
|
|
while let Some(result) = conn.next().await {
|
|
println!("{}", serde_json::to_string(&result).unwrap());
|
|
}
|
|
}
|
|
<span class="boring">
|
|
</span><span class="boring">fn main() { }</span></code></pre></pre>
|
|
<h3 id="web-integration-and-examples"><a class="header" href="#web-integration-and-examples">Web Integration and Examples</a></h3>
|
|
<p>Currently there is an example of subscriptions with <a href="https://github.com/graphql-rust/juniper/tree/master/juniper_warp">warp</a>, but it still in an alpha state.
|
|
GraphQL over <a href="https://github.com/apollographql/subscriptions-transport-ws/blob/master/PROTOCOL.md">WS</a> is not fully supported yet and is non-standard.</p>
|
|
<ul>
|
|
<li><a href="https://github.com/graphql-rust/juniper/tree/master/examples/warp_subscriptions">Warp Subscription Example</a></li>
|
|
<li><a href="https://github.com/graphql-rust/juniper/tree/master/examples/basic_subscriptions">Small Example</a></li>
|
|
</ul>
|
|
<!-- TODO: Fix these links when the documentation for the `juniper_subscriptions` are defined in the docs. --->
|
|
<!--- --->
|
|
|
|
</main>
|
|
|
|
<nav class="nav-wrapper" aria-label="Page navigation">
|
|
<!-- Mobile navigation buttons -->
|
|
<a rel="prev" href="../advanced/dataloaders.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
<i class="fa fa-angle-left"></i>
|
|
</a>
|
|
|
|
|
|
<div style="clear: both"></div>
|
|
</nav>
|
|
</div>
|
|
</div>
|
|
|
|
<nav class="nav-wide-wrapper" aria-label="Page navigation">
|
|
<a rel="prev" href="../advanced/dataloaders.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
<i class="fa fa-angle-left"></i>
|
|
</a>
|
|
|
|
</nav>
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<script>
|
|
window.playground_copyable = true;
|
|
</script>
|
|
|
|
|
|
<script src="../elasticlunr.min.js"></script>
|
|
<script src="../mark.min.js"></script>
|
|
<script src="../searcher.js"></script>
|
|
|
|
<script src="../clipboard.min.js"></script>
|
|
<script src="../highlight.js"></script>
|
|
<script src="../book.js"></script>
|
|
|
|
<!-- Custom JS scripts -->
|
|
|
|
|
|
</div>
|
|
</body>
|
|
</html>
|