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class="tsd-panel tsd-typography"><h1 id="wasm-plugin-development-guide" class="tsd-anchor-link">WASM Plugin Development Guide<a href="#wasm-plugin-development-guide" aria-label="Permalink" class="tsd-anchor-icon"><svg viewBox="0 0 24 24" aria-hidden="true"><use href="../../assets/icons.svg#icon-anchor"></use></svg></a></h1> <h2 id="overview" class="tsd-anchor-link">Overview<a href="#overview" aria-label="Permalink" class="tsd-anchor-icon"><svg viewBox="0 0 24 24" aria-hidden="true"><use href="../../assets/icons.svg#icon-anchor"></use></svg></a></h2> <p>This guide covers how to develop WASM/WASIX plugins for Signal K Server 3.0. WASM plugins run in a secure sandbox with isolated storage and capability-based permissions.</p> <h2 id="what-makes-a-wasm-plugin" class="tsd-anchor-link">What Makes a WASM Plugin?<a href="#what-makes-a-wasm-plugin" aria-label="Permalink" class="tsd-anchor-icon"><svg viewBox="0 0 24 24" aria-hidden="true"><use href="../../assets/icons.svg#icon-anchor"></use></svg></a></h2> <p>A WASM plugin is an npm package that contains the WASM code for the plugin instead of the traditional JavaScript code. A WASM plugin is identified by the <code>signalk-wasm-plugin</code> keyword in package.json and the <strong><code>wasmManifest</code></strong> field in <code>package.json</code>:</p> <pre><code class="json"><span class="hl-0">{</span><br/><span class="hl-0"> </span><span class="hl-3">"name"</span><span class="hl-0">: </span><span class="hl-4">"my-plugin-name"</span><span class="hl-0">,</span><br/><span class="hl-0"> </span><span class="hl-3">"wasmManifest"</span><span class="hl-0">: </span><span class="hl-4">"plugin.wasm"</span><span class="hl-0">,</span><br/><span class="hl-0"> </span><span class="hl-3">"wasmCapabilities"</span><span class="hl-0">: { </span><span class="hl-8">...</span><span class="hl-0"> }</span><br/><span class="hl-0">}</span> </code><button type="button">Copy</button></pre> <p><strong>Key points:</strong></p> <ul> <li><strong><code>wasmManifest</code></strong> (required): Path to the compiled <code>.wasm</code> file. This field tells Signal K to load this as a WASM plugin instead of a Node.js plugin.</li> <li><strong><code>wasmCapabilities</code></strong> (required): Declares what permissions the plugin needs (network, storage, etc.)</li> <li><strong>Package name</strong> (flexible): Can be anything - <code>my-plugin</code>, <code>@myorg/my-plugin</code>, etc. There is <strong>no requirement</strong> to use <code>@signalk/</code> scope.</li> <li><strong>Keywords</strong>: Include <code>signalk-wasm-plugin</code> for discovery (do <strong>not</strong> use <code>signalk-node-server-plugin</code> - that's for Node.js plugins only)</li> </ul> <h2 id="language-options" class="tsd-anchor-link">Language Options<a href="#language-options" aria-label="Permalink" class="tsd-anchor-icon"><svg viewBox="0 0 24 24" aria-hidden="true"><use href="../../assets/icons.svg#icon-anchor"></use></svg></a></h2> <p>Signal K Server supports multiple languages for WASM plugin development:</p> <ul> <li><strong>AssemblyScript</strong> - TypeScript-like syntax, easiest for JS/TS developers, smallest binaries (3-10 KB)</li> <li><strong>Rust</strong> - Best performance and tooling, medium binaries (50-200 KB)</li> <li><strong>Go/TinyGo</strong> - Go via TinyGo compiler, medium binaries (50-150 KB)</li> </ul> <h2 id="why-wasm-plugins" class="tsd-anchor-link">Why WASM Plugins?<a href="#why-wasm-plugins" aria-label="Permalink" class="tsd-anchor-icon"><svg viewBox="0 0 24 24" aria-hidden="true"><use href="../../assets/icons.svg#icon-anchor"></use></svg></a></h2> <h3 id="benefits" class="tsd-anchor-link">Benefits<a href="#benefits" aria-label="Permalink" class="tsd-anchor-icon"><svg viewBox="0 0 24 24" aria-hidden="true"><use href="../../assets/icons.svg#icon-anchor"></use></svg></a></h3> <ul> <li><strong>Security</strong>: Sandboxed execution with no access to host system</li> <li><strong>Hot-reload</strong>: Update plugins without server restart</li> <li><strong>Multi-language</strong>: Write plugins in Rust, AssemblyScript, and more</li> <li><strong>Crash isolation</strong>: Plugin crashes don't affect server</li> <li><strong>Performance</strong>: Near-native performance with WASM</li> <li><strong>Self contained</strong>: WASM plugins do not install any additional dependencies</li> <li><strong>Small binaries (compared to native options)</strong>: 3-200 KB depending on language</li> </ul> <h3 id="current-capabilities" class="tsd-anchor-link">Current Capabilities<a href="#current-capabilities" aria-label="Permalink" class="tsd-anchor-icon"><svg viewBox="0 0 24 24" aria-hidden="true"><use href="../../assets/icons.svg#icon-anchor"></use></svg></a></h3> <ul> <li><strong>Delta Emission</strong>: Send SignalK deltas to update vessel data</li> <li><strong>Status & Error Reporting</strong>: Set plugin status and error messages</li> <li><strong>Configuration</strong>: The same JSON schema-based configuration as JS plugins</li> <li><strong>Data Storage</strong>: VFS-isolated file storage</li> <li><strong>HTTP Endpoints</strong>: Register custom REST API endpoints</li> <li><strong>Static Files</strong>: Serve web UI from <code>public/</code> directory</li> <li><strong>Network Access</strong>: HTTP requests via as-fetch (AssemblyScript)</li> <li><strong>Resource Providers</strong>: Serve SignalK resources</li> <li><strong>Weather Providers</strong>: Integrate with Signal K Weather API</li> <li><strong>Radar Providers</strong>: Integrate with Signal K Radar API</li> </ul> <h2 id="choose-your-language" class="tsd-anchor-link">Choose Your Language<a href="#choose-your-language" aria-label="Permalink" class="tsd-anchor-icon"><svg viewBox="0 0 24 24" aria-hidden="true"><use href="../../assets/icons.svg#icon-anchor"></use></svg></a></h2> <h3 id="assemblyscript-recommended-for-jsts-developers" class="tsd-anchor-link">AssemblyScript - Recommended for JS/TS Developers<a href="#assemblyscript-recommended-for-jsts-developers" aria-label="Permalink" class="tsd-anchor-icon"><svg viewBox="0 0 24 24" aria-hidden="true"><use href="../../assets/icons.svg#icon-anchor"></use></svg></a></h3> <p><strong>Best for:</strong></p> <ul> <li>Quick prototypes</li> <li>Simple data processing</li> <li>Migrating existing Node.js plugins</li> <li>Developers familiar with TypeScript</li> </ul> <p><strong>Pros:</strong></p> <ul> <li>TypeScript-like syntax</li> <li>Fast development</li> <li>Smallest binaries (3-10 KB)</li> <li>Familiar tooling (npm)</li> </ul> <p><strong>Cons:</strong></p> <ul> <li>Smaller ecosystem than Rust</li> <li>Some TypeScript features unavailable</li> <li>Manual memory management</li> </ul> <p><strong><a href="WASM_Plugins/AssemblyScript_Plugins.html">Jump to AssemblyScript Guide</a></strong></p> <h3 id="rust-recommended-for-performance-critical-plugins" class="tsd-anchor-link">Rust - Recommended for Performance-Critical Plugins<a href="#rust-recommended-for-performance-critical-plugins" aria-label="Permalink" class="tsd-anchor-icon"><svg viewBox="0 0 24 24" aria-hidden="true"><use href="../../assets/icons.svg#icon-anchor"></use></svg></a></h3> <p><strong>Best for:</strong></p> <ul> <li>Performance-critical plugins</li> <li>Complex algorithms</li> <li>Low-level operations</li> <li>Production plugins</li> </ul> <p><strong>Pros:</strong></p> <ul> <li>Best performance</li> <li>Memory safety</li> <li>Rich ecosystem</li> <li>Strong typing</li> </ul> <p><strong>Cons:</strong></p> <ul> <li>Steeper learning curve</li> <li>Longer compile times</li> <li>Larger binaries (50-200 KB)</li> </ul> <p><strong><a href="WASM_Plugins/Rust_Plugins.html">Jump to Rust Guide</a></strong></p> <h3 id="gotinygo-for-go-developers" class="tsd-anchor-link">Go/TinyGo - For Go Developers<a href="#gotinygo-for-go-developers" aria-label="Permalink" class="tsd-anchor-icon"><svg viewBox="0 0 24 24" aria-hidden="true"><use href="../../assets/icons.svg#icon-anchor"></use></svg></a></h3> <p><strong>Best for:</strong></p> <ul> <li>Go developers wanting to write plugins</li> <li>Medium complexity plugins</li> <li>Resource providers with hybrid patterns</li> </ul> <p><strong>Pros:</strong></p> <ul> <li>Familiar Go syntax</li> <li>Good standard library support</li> <li>Medium binaries (50-150 KB)</li> <li>Strong typing</li> </ul> <p><strong>Cons:</strong></p> <ul> <li>Requires TinyGo (not standard Go)</li> <li>Some Go features unavailable</li> <li>Slower than Rust</li> </ul> <p><strong><a href="WASM_Plugins/Go/TinyGo_Plugins.html">Jump to Go/TinyGo Guide</a></strong></p> </div></div><div class="col-sidebar"><div class="page-menu"><details open class="tsd-accordion tsd-page-navigation"><summary class="tsd-accordion-summary"><svg width="20" height="20" viewBox="0 0 24 24" fill="none" aria-hidden="true"><use href="../../assets/icons.svg#icon-chevronDown"></use></svg><h3>On This Page</h3></summary><div class="tsd-accordion-details"><a href="#overview"><span>Overview</span></a><a href="#what-makes-a-wasm-plugin"><span>What <wbr/>Makes a <wbr/>WASM <wbr/>Plugin?</span></a><a href="#language-options"><span>Language <wbr/>Options</span></a><a href="#why-wasm-plugins"><span>Why <wbr/>WASM <wbr/>Plugins?</span></a><ul><li><a href="#benefits"><span>Benefits</span></a></li><li><a href="#current-capabilities"><span>Current <wbr/>Capabilities</span></a></li></ul><a href="#choose-your-language"><span>Choose <wbr/>Your <wbr/>Language</span></a><ul><li><a href="#assemblyscript-recommended-for-jsts-developers"><span>Assembly<wbr/>Script -<wbr/> <wbr/>Recommended for <wbr/>JS/<wbr/>TS <wbr/>Developers</span></a></li><li><a href="#rust-recommended-for-performance-critical-plugins"><span>Rust -<wbr/> <wbr/>Recommended for <wbr/>Performance-<wbr/>Critical <wbr/>Plugins</span></a></li><li><a href="#gotinygo-for-go-developers"><span>Go/<wbr/>Tiny<wbr/>Go -<wbr/> <wbr/>For <wbr/>Go <wbr/>Developers</span></a></li></ul></div></details></div><div class="site-menu"><nav class="tsd-navigation"><a href="../../modules.html">Signal K</a><ul class="tsd-small-nested-navigation" id="tsd-nav-container"><li>Loading...</li></ul></nav></div></div></div><footer><p class="tsd-generator">Generated using <a href="https://typedoc.org/" target="_blank">TypeDoc</a></p></footer><div class="overlay"></div></body></html>