419 mdns - first time

Author: phoddie

examples/io/dnssd/main.js

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+/*
+ * Copyright (c) 2025 Moddable Tech, Inc.
+ *
+ *   This file is part of the Moddable SDK.
+ *
+ *   This work is licensed under the
+ *       Creative Commons Attribution 4.0 International License.
+ *   To view a copy of this license, visit
+ *       <http://creativecommons.org/licenses/by/4.0>.
+ *   or send a letter to Creative Commons, PO Box 1866,
+ *   Mountain View, CA 94042, USA.
+ *
+ */
+
+import Timer from "timer";
+
+const mdns = new (device.network.mdns.io)(device.network.mdns);
+
+const claim = mdns.claim({
+	host: "a-server",
+	onReady() {
+		trace(`a-server claimed\n`);
+	},
+	onError() {
+		trace("couldn't claim a-server\n");
+	}
+});
+
+const ad = mdns.advertise({
+	serviceType: "_http._tcp",
+	instanceName: "419 Web Server",
+	host: "a-server",
+	port: 8080,
+	txt: new Map([
+		["home", "/index.html"]
+	]),
+	onError(error) {
+		trace("advertise failed\n");
+	}
+});
+ad.counter = 0;
+
+Timer.repeat(() => {
+	ad.updateTXT(new Map([
+		["home", "/index.html"],
+		["counter", (++ad.counter).toString()],
+	]));
+}, 1000)
+
+mdns.discover({
+	serviceType: "_airplay._tcp",
+	onFound(service) {
+		trace(`Found: "${service.name}" on ${service.host} @ ${service.address}:${service.port}\n`);
+		this.history ??= new Map;
+		const txt = service.txt ?? new Map;
+		this.history.set(service.host, txt); 
+		for (const [key, value] of txt)
+			trace(`  ${key}:${value}\n`);
+	},
+	onUpdate(service) {
+		trace(`Update: ${service.name}\n`);
+
+		const previous = this.history.get(service.host);
+		const txt = service.txt ?? new Map;
+		this.history.set(service.host, txt);
+
+		for (const [key, value] of previous) {
+			if (!txt.has(key))
+				trace(`  removed ${key}:${value}\n`);
+		}
+		for (const [key, value] of txt) {
+			if (!previous.has(key))
+				trace(`  added ${key}:${value}\n`);
+		}
+		for (const [key, value] of txt) {
+			if (previous.has(key) && (previous.get(key) !== txt.get(key)))
+				trace(`  changed ${key} from ${previous.get(key)} to ${txt.get(key)}\n`);
+		}
+	},
+	onLost(service) {
+		trace(`Lost: ${service.name}\n`);
+		this.history.delete(service.host);
+	},
+	onError(error) {
+		trace(`failed\n`);
+	}
+});

examples/io/dnssd/manifest.json

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+{
+	"include": [
+		"$(MODDABLE)/examples/manifest_base.json",
+		"$(MODDABLE)/modules/io/manifest.json",
+		"$(MODULES)/io/dnssd/manifest.json"
+	],
+	"modules": {
+		"*": "./main"
+	}
+}

modules/io/dnssd/config.js

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+import "system"		// system initializes globalThis.device. this ensures it runs before this module.
+
+import UDP from "embedded:io/socket/udp";
+import MDNS from "embedded:network/mdns" 
+
+globalThis.device = Object.freeze({
+	...globalThis.device,
+	network: {
+		...globalThis.device?.network,
+		mdns: {
+			io: MDNS,
+			socket: {
+				io: UDP
+			}		
+		}
+	},
+}, true);