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signalk-server

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An implementation of a [Signal K](http://signalk.org) server for boats.

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<!DOCTYPE HTML> <html lang="en" class="sidebar-visible no-js light"> <head> <!-- Book generated using mdBook --> <meta charset="UTF-8"> <title>Resource Providers - Signal K Server Documentation</title> <!-- Custom HTML head --> <meta name="description" content="A Guide for users and developers."> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="theme-color" content="#ffffff" /> <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 ? 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before it is displayed --> <script> var html = document.querySelector('html'); var sidebar = null; var sidebar_toggle = document.getElementById("sidebar-toggle-anchor"); if (document.body.clientWidth >= 1080) { try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { } sidebar = sidebar || 'visible'; } else { sidebar = 'hidden'; } sidebar_toggle.checked = sidebar === 'visible'; 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"> <a href="/" style="width:155px;height:30px;background-image:url(/signal-k-logo-image-text.svg);display:inline-block;background-repeat:no-repeat;background-position:center center;background-size:150px auto;"></a> <ol class="chapter"><li class="chapter-item expanded affix "><a href="../../index.html">Introduction</a></li><li class="chapter-item expanded affix "><li class="part-title">Getting Started</li><li class="chapter-item expanded "><a href="../../installation/install.html"><strong aria-hidden="true">1.</strong> Installation</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../installation/raspberry_pi_installation.html"><strong aria-hidden="true">1.1.</strong> Installing on Raspberry Pi</a></li><li class="chapter-item expanded "><a href="../../installation/updating.html"><strong aria-hidden="true">1.2.</strong> Updating your installation</a></li><li class="chapter-item expanded "><a href="../../installation/command_line.html"><strong aria-hidden="true">1.3.</strong> Runtime environment & options</a></li></ol></li><li class="chapter-item expanded "><a href="../../security.html"><strong aria-hidden="true">2.</strong> Security</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../setup/generating_tokens.html"><strong aria-hidden="true">2.1.</strong> Generating tokens</a></li></ol></li><li class="chapter-item expanded "><li class="part-title">Setup</li><li class="chapter-item expanded "><a href="../../setup/configuration.html"><strong aria-hidden="true">3.</strong> Configuration</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../setup/seatalk/seatalk.html"><strong aria-hidden="true">3.1.</strong> Seatalk Connections</a></li></ol></li><li class="chapter-item expanded "><li class="part-title">Feature How Tos</li><li class="chapter-item expanded "><a href="../../features/anchoralarm/anchoralarm.html"><strong aria-hidden="true">4.</strong> Anchor Alarm</a></li><li class="chapter-item expanded "><a href="../../features/navdataserver/navdataserver.html"><strong aria-hidden="true">5.</strong> NMEA0183 Server</a></li><li class="chapter-item expanded "><a href="../../features/datalogging/datalogging.html"><strong aria-hidden="true">6.</strong> Data Logging</a></li><li class="chapter-item expanded affix "><li class="part-title">Support</li><li class="chapter-item expanded "><a href="../../support/help.html"><strong aria-hidden="true">7.</strong> Help & Support</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../support/faq.html"><strong aria-hidden="true">7.1.</strong> FAQs</a></li></ol></li><li class="chapter-item expanded "><a href="../../support/sponsor.html"><strong aria-hidden="true">8.</strong> Sponsor</a></li><li class="chapter-item expanded affix "><li class="part-title">Develop</li><li class="chapter-item expanded "><a href="../../develop/developer_notes.html"><strong aria-hidden="true">9.</strong> Notes for Developers</a></li><li class="chapter-item expanded "><a href="../../whats_new.html"><strong aria-hidden="true">10.</strong> What's New in V2</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../breaking_changes.html"><strong aria-hidden="true">10.1.</strong> Changes & Deprecations</a></li></ol></li><li class="chapter-item expanded "><a href="../../develop/webapps.html"><strong aria-hidden="true">11.</strong> WebApps</a></li><li class="chapter-item expanded "><a href="../../develop/plugins/server_plugin.html"><strong aria-hidden="true">12.</strong> Plugins</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../develop/plugins/deltas.html"><strong aria-hidden="true">12.1.</strong> Processing Data</a></li><li class="chapter-item expanded "><a href="../../develop/plugins/server_plugin_api.html"><strong aria-hidden="true">12.2.</strong> Server API</a></li><li class="chapter-item expanded "><a href="../../develop/plugins/resource_provider_plugins.html" class="active"><strong aria-hidden="true">12.3.</strong> Resource Providers</a></li><li class="chapter-item expanded "><a href="../../develop/rest-api/course_calculations.html"><strong aria-hidden="true">12.4.</strong> Course Providers</a></li><li class="chapter-item expanded "><a href="../../develop/plugins/autopilot_provider_plugins.html"><strong aria-hidden="true">12.5.</strong> Autopilot Providers</a></li></ol></li><li class="chapter-item expanded "><a href="../../develop/plugins/publishing.html"><strong aria-hidden="true">13.</strong> Publishing to the AppStore</a></li><li class="chapter-item expanded "><a href="../../develop/rest-api/open_api.html"><strong aria-hidden="true">14.</strong> REST APIs</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../develop/rest-api/course_api.html"><strong aria-hidden="true">14.1.</strong> Course API</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../develop/rest-api/course_calculations.html"><strong aria-hidden="true">14.1.1.</strong> Course Calculations</a></li></ol></li><li class="chapter-item expanded "><a href="../../develop/rest-api/resources_api.html"><strong aria-hidden="true">14.2.</strong> Resources API</a></li><li class="chapter-item expanded "><a href="../../develop/rest-api/notifications_api.html"><strong aria-hidden="true">14.3.</strong> Notifications API</a></li><li class="chapter-item expanded "><a href="../../develop/rest-api/autopilot_api.html"><strong aria-hidden="true">14.4.</strong> Autopilot API</a></li><li class="chapter-item expanded "><a href="../../develop/rest-api/anchor_api.html"><strong aria-hidden="true">14.5.</strong> Anchor API</a></li></ol></li><li class="chapter-item expanded "><a href="../../develop/contributing.html"><strong aria-hidden="true">15.</strong> Contribute</a></li></ol> </div> <div id="sidebar-resize-handle" class="sidebar-resize-handle"></div> </nav> <!-- Track and set sidebar scroll position --> <script> var sidebarScrollbox = document.querySelector('#sidebar .sidebar-scrollbox'); sidebarScrollbox.addEventListener('click', function(e) { if (e.target.tagName === 'A') { sessionStorage.setItem('sidebar-scroll', sidebarScrollbox.scrollTop); } }, { passive: true }); var sidebarScrollTop = sessionStorage.getItem('sidebar-scroll'); sessionStorage.removeItem('sidebar-scroll'); if 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</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">Signal K Server Documentation</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> <a href="https://github.com/SignalK/signalk-server/tree/master/docs/src" title="Suggest an edit" aria-label="Suggest an edit"> <i id="git-edit-button" class="fa fa-edit"></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="resource-provider-plugins"><a class="header" href="#resource-provider-plugins">Resource Provider plugins</a></h1> <h2 id="overview"><a class="header" href="#overview">Overview</a></h2> <p>The Signal K server <em>Resource API</em> provides a common set operations for clients to interact with routes, waypoints, charts, etc but it does NOT provide the ability to persist or retrieve resources to / from storage.</p> <p>This functionality needs to be provided by one or more server plugins that interface with the <em>Resource API</em> to facilitate the storage and retrieval of resource data.</p> <p>These plugins are called <strong>Provider Plugins</strong>.</p> <p><em>Resource API architecture:</em> <img src="../../img/resource_provider.svg" width="275"/></p> <p>This de-coupling of request handling and data storage provides the flexibility to persist resource data in a variety of different storage types as well as Internet based services.</p> <p><em>Note: Signal K server comes with the <a href="https://github.com/SignalK/signalk-server/tree/master/packages/resources-provider-plugin">resources-provider-plugin</a> pre-installed which persists resource data to the local file system.</em></p> <h3 id="resources-api"><a class="header" href="#resources-api">Resources API:</a></h3> <p>The <em>Resources API</em> handles all client requests received via the <code>/signalk/v2/api/resources</code> path, before passing on the request to registered provider plugin(s).</p> <p>The <em>Resources API</em> performs the following operations when a request is received:</p> <ol> <li>Checks for registered provider(s) for the resource type <em>(i.e. route, waypoint, etc.)</em></li> <li>Checks that the required ResourceProvider methods are defined for the requested operation <em>(i.e. POST, PUT, GET, DELETE)</em></li> <li>Performs an access control check</li> <li><code>POST</code> and <code>PUT</code> requests for <strong>Standard</strong> <em>(Signal K defined)</em> resource types are checked for validity of the submitted:</li> </ol> <ul> <li><code>resource id</code></li> <li><code>resource data</code> against the OpenAPI definition.</li> </ul> <p>Only after successful completion of all these operations is the request passed on to the registered provider plugin(s).</p> <hr /> <h2 id="provider-plugins"><a class="header" href="#provider-plugins">Provider plugins:</a></h2> <p>A resource provider plugin is a Signal K server plugin that implements the <strong>Resource Provider Interface</strong> which:</p> <ul> <li>Tells server the resource type(s) provided for by the plugin <em>(i.e. route, waypoint, etc.)</em></li> <li>Registers the methods used to action requests passed from the server and perform the writing, retrieval and deletion of resources from storage.</li> </ul> <p>Note: multiple providers can be registered for a resource type <em>(e.g. 2 x chart providers)</em></p> <p>The <code>ResourceProvider</code> interface is defined as follows in <em><code>@signalk/server-api</code></em>:</p> <pre><code class="language-typescript">interface ResourceProvider { type: ResourceType methods: ResourceProviderMethods } </code></pre> <p>where:</p> <ul> <li> <p><code>type</code>: The resource type provided for by the plugin. These can be either <strong>Standard</strong> <em>(Signal K defined)</em> or <strong>Custom</strong> <em>(user defined)</em> resource types <em>(e.g. <code>'routes'</code>, <code>'fishingZones'</code>)</em></p> </li> <li> <p><code>methods</code>: An object implementing the <code>ResourceProviderMethods</code> interface defining the functions to which resource requests are passed by the SignalK server. <em>Note: The plugin <strong>MUST</strong> implement each method, even if that operation is NOT supported by the plugin!</em></p> </li> </ul> <p>The <code>ResourceProviderMethods</code> interface is defined as follows in <em><code>@signalk/server-api</code></em>:</p> <pre><code class="language-typescript">interface ResourceProviderMethods { listResources: (query: { [key: string]: any }) =&gt; Promise&lt;{[id: string]: any}&gt; getResource: (id: string, property?: string) =&gt; Promise&lt;object&gt; setResource: ( id: string, value: { [key: string]: any } ) =&gt; Promise&lt;void&gt; deleteResource: (id: string) =&gt; Promise&lt;void&gt; } </code></pre> <p><em><strong>Note: The Resource Provider is responsible for implementing the methods and returning data in the required format!</strong></em></p> <h3 id="provider-methods"><a class="header" href="#provider-methods">Provider Methods:</a></h3> <p><strong><code>listResources(query)</code></strong>: This method is called when a request is made for resource entries that match a specific criteria.</p> <p><em>Note: It is the responsibility of the resource provider plugin to filter the resources returned as per the supplied query parameters.</em></p> <ul> <li><code>query:</code> Object contining <code>key | value</code> pairs repesenting the parameters by which to filter the returned entries. <em>e.g. {region: 'fishing_zone'}</em></li> </ul> <p>returns: <code>Promise&lt;{[id: string]: any}&gt;</code></p> <p><em>Example: Return waypoints within the bounded area with lower left corner at E5.4 N25.7 &amp; upper right corner E6.9 &amp; N31.2:</em></p> <pre><code>GET /signalk/v2/api/resources/waypoints?bbox=[5.4,25.7,6.9,31.2] </code></pre> <p><em>ResourceProvider method invocation:</em></p> <pre><code class="language-javascript">listResources( { bbox: '5.4,25.7,6.9,31.2' } ); </code></pre> <p><em>Returns:</em></p> <pre><code class="language-JSON">{ "07894aba-f151-4099-aa4f-5e5773734b69": { "name":"my Point", "description":"A Signal K waypoint", "distance":124226.65183615577, "feature":{ "type":"Feature", "geometry":{ "type":"Point", "coordinates":[5.7,26.4] }, "properties":{} }, "timestamp":"2023-01-01T05:02:54.561Z", "$source":"resources-provider" }, "0c894aba-d151-4099-aa4f-be5773734e99": { "name":"another point", "description":"Another Signal K waypoint", "distance":107226.84, "feature":{ "type":"Feature", "geometry":{ "type":"Point", "coordinates":[6.1,29.43] }, "properties":{} }, "timestamp":"2023-01-01T05:02:54.561Z", "$source":"resources-provider" } } </code></pre> <hr /> <p><strong><code>getResource(id, property?)</code></strong>: This method is called when a request is made for a specific resource entry with the supplied <code>id</code>. If <code>property</code> is supplied then the value of the resource property is returned. If there is no resource associated with the id the call should return Promise.reject.</p> <ul> <li><code>id</code>: String containing the target resource entry id. <em>(e.g. '07894aba-f151-4099-aa4f-5e5773734b99')</em></li> <li><code>property</code> (optional): Name of resource property for which to return the value (in dot notation). <em>e.g. feature.geometry.coordinates</em></li> </ul> <p>returns: <code>Promise&lt;object&gt;</code></p> <p><em>Example resource request:</em></p> <pre><code>GET /signalk/v2/api/resources/routes/07894aba-f151-4099-aa4f-5e5773734b99 </code></pre> <p><em>ResourceProvider method invocation:</em></p> <pre><code class="language-javascript">getResource( '07894aba-f151-4099-aa4f-5e5773734b99' ); </code></pre> <p><em>Returns:</em></p> <pre><code class="language-JSON">{ "name":"myRoute", "description":"A Signal K route", "distance":124226.65183615577, "feature":{ "type":"Feature", "geometry":{ "type":"LineString", "coordinates":[[-8,-8],[-8.5,-8],[-8.5,-8.4],[-8.7,-8.3]] }, "properties":{} }, "timestamp":"2023-01-01T05:02:54.561Z", "$source":"resources-provider" } </code></pre> <p><em>Example resource property value request:</em></p> <pre><code>GET /signalk/v2/api/resources/routes/07894aba-f151-4099-aa4f-5e5773734b99/feature/geometry/type </code></pre> <p><em>ResourceProvider method invocation:</em></p> <pre><code class="language-javascript">getResource( '07894aba-f151-4099-aa4f-5e5773734b99', 'feature.geometry.type' ); </code></pre> <p><em>Returns:</em></p> <pre><code class="language-JSON">{ "value": "LineString", "timestamp":"2023-01-01T05:02:54.561Z", "$source":"resources-provider" } </code></pre> <hr /> <p><strong><code>setResource(id, value)</code></strong>: This method is called when a request is made to save / update a resource entry with the supplied id. The supplied data is a complete resource record.</p> <ul> <li> <p><code>id:</code> String containing the id of the resource entry created / updated. <em>e.g. '07894aba-f151-4099-aa4f-5e5773734b99'</em></p> </li> <li> <p><code>value:</code> Resource data to be stored.</p> </li> </ul> <p>returns: <code>Promise&lt;void&gt;</code></p> <p><em>Example PUT resource request:</em></p> <pre><code>PUT /signalk/v2/api/resources/routes/07894aba-f151-4099-aa4f-5e5773734b99 {resource_data} </code></pre> <p><em>ResourceProvider method invocation:</em></p> <pre><code class="language-javascript">setResource( '07894aba-f151-4099-aa4f-5e5773734b99', { name: 'test route', distance': 8000, feature: { type: 'Feature', geometry: { type: 'LineString', coordinates: [[138.5, -38.6], [138.7, -38.2], [138.9, -38.0]] }, properties:{} } } ); </code></pre> <p><em>Example POST resource request:</em></p> <pre><code>POST /signalk/v2/api/resources/routes {resource_data} </code></pre> <p><em>ResourceProvider method invocation:</em></p> <pre><code class="language-javascript">setResource( '&lt;server_generated_id&gt;', { name: 'test route', distance': 8000, feature: { type: 'Feature', geometry: { type: 'LineString', coordinates: [[138.5, -38.6], [138.7, -38.2], [138.9, -38.0]] }, properties:{} } } ); </code></pre> <hr /> <p><strong><code>deleteResource(id)</code></strong>: This method is called when a request is made to remove the specific resource entry with the supplied resource id.</p> <ul> <li><code>id:</code> String containing the target resource entry id. <em>e.g. '07894aba-f151-4099-aa4f-5e5773734b99'</em></li> </ul> <p>returns: <code>Promise&lt;void&gt;</code></p> <p><em>Example resource request:</em></p> <pre><code>DELETE /signalk/v2/api/resources/routes/07894aba-f151-4099-aa4f-5e5773734b99 </code></pre> <p><em>ResourceProvider method invocation:</em></p> <pre><code class="language-javascript">deleteResource( '07894aba-f151-4099-aa4f-5e5773734b99' ); </code></pre> <hr /> <h3 id="registering-as-a-resource-provider"><a class="header" href="#registering-as-a-resource-provider">Registering as a Resource Provider:</a></h3> <p>To register a plugin as a provider for one or more resource types with the SignalK server, it must call the server's <code>registerResourceProvider</code> function for each resource type being serviced during plugin startup.</p> <p>The function has the following signature:</p> <pre><code class="language-typescript">app.registerResourceProvider(resourceProvider: ResourceProvider) </code></pre> <p>where:</p> <ul> <li><code>resourceProvider</code>: is a reference to a <code>ResourceProvider</code> object containing the <strong>resource type</strong> and <strong>methods</strong> to receive the requests.</li> </ul> <p><em>Note: More than one plugin can be registered as a provider for a resource type.</em></p> <p><em>Example: Plugin registering as a routes &amp; waypoints provider.</em></p> <pre><code class="language-javascript">import { ResourceProvider } from '@signalk/server-api' module.exports = function (app) { const plugin = { id: 'mypluginid', name: 'My Resource Providerplugin' } const routesProvider: ResourceProvider = { type: 'routes', methods: { listResources: (params) =&gt; { fetchRoutes(params) ... }, getResource: (id, property?) =&gt; { getRoute(id, property) ... }, setResource: (id, value )=&gt; { saveRoute(id, value) ... }, deleteResource: (id) =&gt; { deleteRoute(id, value) ... } } } const waypointsProvider: ResourceProvider = { type: 'waypoints', methods: { listResources: (params) =&gt; { fetchWaypoints(params) ... }, getResource: (id, property?) =&gt; { getWaypoint(id, property) ... }, setResource: (id, value )=&gt; { saveWaypoint(id, value) ... }, deleteResource: (id) =&gt; { deleteWaypoint(id, value) ... } } } plugin.start = function(options) { ... try { app.registerResourceProvider(routesProvider) app.registerResourceProvider(waypointsProvider) } catch (error) { // handle error } } return plugin } </code></pre> <h3 id="methods"><a class="header" href="#methods">Methods</a></h3> <p>A Resource Provider plugin must implement ALL methods to service the requests passed from the server.</p> <p>Each method should return a <strong>Promise</strong> on success and <code>throw</code> on error, if a request is not serviced or is not implemented.</p> <p><em>Example:</em></p> <pre><code class="language-javascript">// SignalK server plugin module.exports = function (app) { const plugin = { id: 'mypluginid', name: 'My Resource Providerplugin', start: options =&gt; { ... app.registerResourceProvider({ type: 'waypoints', methods: { listResources: (params) =&gt; { return new Promise( (resolve, reject) =&gt; { ... if (ok) { resolve(resource_list) } else { reject( new Error('Error fetching resources!')) } }) }, getResource: (id, property?) =&gt; { return new Promise( (resolve, reject) =&gt; { ... if (ok) { resolve(resource_list) } else { reject( new Error('Error fetching resource with supplied id!')) } }) }, setResource: (id, value )=&gt; { throw( new Error('Not implemented!')) }, deleteResource: (id) =&gt; { throw( new Error('Not implemented!')) } } }) } } } </code></pre> </main> <nav class="nav-wrapper" aria-label="Page navigation"> <!-- Mobile navigation buttons --> <a rel="prev" href="../../develop/plugins/server_plugin_api.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> <a rel="next" href="../../develop/rest-api/course_calculations.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> <div style="clear: both"></div> </nav> </div> </div> <nav class="nav-wide-wrapper" aria-label="Page navigation"> <a rel="prev" href="../../develop/plugins/server_plugin_api.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> <a rel="next" href="../../develop/rest-api/course_calculations.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> </nav> </div> <script> window.playground_copyable = true; 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