Add Server Sent Events

core/modules/server/server-sent-events.js

@@ -0,0 +1,75 @@
+/*\
+title: $:/core/modules/server/server-sent-events.js
+type: application/javascript
+module-type: library
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+/**
+ * @param {string} prefix
+ * Usually the plugin path, such as `plugins/tiddlywiki/tiddlyweb`.
+ * The route will match `/events/${prefix}` exactly.
+ * @param {(
+ *   request: import("http").IncomingMessage,
+ *   state,
+ *   emit: (event: string, data: string) => void,
+ *   end: () => void
+ * ) => void} handler
+ * A function that will be called each time a request
+ * comes in with the request and state from the
+ * route and an emit function to call.
+ */
+var ServerSentEvents = /** @class */ (function () {
+
+  function ServerSentEvents(prefix, handler) {
+    this.handler = handler;
+    this.prefix = prefix;
+  }
+  ServerSentEvents.prototype.getExports = function () {
+    return {
+      bodyFormat: "stream",
+      method: "GET",
+      path: new RegExp("^/events/" + this.prefix + "$"),
+      handler: this.handleEventRequest.bind(this)
+    };
+  };
+  /**
+   *
+   * @param {import("http").IncomingMessage} request
+   * @param {import("http").ServerResponse} response
+   * @param {*} state
+   */
+  ServerSentEvents.prototype.handleEventRequest = function (request, response, state) {
+    if (request.headers.accept && request.headers.accept.startsWith('text/event-stream')) {
+      response.writeHead(200, {
+        'Content-Type': 'text/event-stream',
+        'Cache-Control': 'no-cache',
+        'Connection': 'keep-alive'
+      });
+      this.handler(request, state, this.emit.bind(this, response), this.end.bind(this, response));
+    }
+    else {
+      response.writeHead(406, "Not Acceptable", {});
+      response.end();
+    }
+  };
+  ServerSentEvents.prototype.emit = function (response, event, data) {
+    if (typeof event !== "string" || event.indexOf("\n") !== -1)
+      throw new Error("type must be a single-line string");
+    if (typeof data !== "string" || data.indexOf("\n") !== -1)
+      throw new Error("data must be a single-line string");
+    response.write("event: " + event + "\ndata: " + data + "\n\n", "utf8");
+  };
+  ServerSentEvents.prototype.end = function (response) {
+    response.end();
+  };
+  return ServerSentEvents;
+}());
+
+exports.ServerSentEvents = ServerSentEvents;
+
+})();

plugins/tiddlywiki/tiddlyweb/sse-client.js

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+/*\
+title: $:/plugins/tiddlywiki/tiddlyweb/sse-client.js
+type: application/javascript
+module-type: startup
+
+GET /recipes/default/tiddlers/:title
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+exports.name = "/events/plugins/tiddlywiki/tiddlyweb";
+exports.after = ["startup"];
+exports.synchronous = true;
+exports.platforms = ["browser"];
+exports.startup = function () {
+  //make sure we're actually being used
+  if($tw.syncadaptor.name !== "tiddlyweb") return;
+  //get the mount point in case a path prefix is used
+  var host = $tw.syncadaptor.getHost();
+  //make sure it ends with a slash (it usually does)
+  if(!host.endsWith("/")) host += "/";
+  //setup the event listener 
+  var events = new EventSource(host + "events/plugins/tiddlywiki/tiddlyweb");
+  events.addEventListener("change", function () {
+    $tw.syncer.syncFromServer();
+  });
+}
+
+})();

plugins/tiddlywiki/tiddlyweb/sse-server.js

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+/*\
+title: $:/plugins/tiddlywiki/tiddlyweb/sse-server.js
+type: application/javascript
+module-type: route
+
+GET /events/plugins/tiddlywiki/tiddlyweb
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+/** @type {Record<any, {
+ *   request: import("http").IncomingMessage,
+ *   state: {wiki,pathPrefix},
+ *   emit: (event: string, data: string) => void,
+ *   end: () => void
+ * }[]>} */
+var wikis = {};
+/**
+ * Setups up the array for this wiki and adds the change listener
+ * 
+ * @param {$tw.Wiki} wiki The wiki object to listen to changes on
+ */
+function setupWiki(wiki) {
+  // add a new array for this wiki (object references work as keys)
+  wikis[wiki] = [];
+  // add the change listener for this wiki
+  wiki.addEventListener("change", function (changes) {
+    wikis[wiki].forEach(function (item) {
+      item.emit("change", JSON.stringify(changes));
+    });
+  });
+}
+/**
+ * 
+ * @param {import("http").IncomingMessage} request 
+ * @param {{wiki,pathPrefix}} state 
+ * @param {(event: string, data: string) => void} emit 
+ * @param {() => void} end 
+ */
+function handleConnection(request, state, emit, end) {
+  // setup this particular wiki if we haven't seen it before
+  if (!wikis[state.wiki]) setupWiki(state.wiki);
+  // add the connection to the list of connections for this wiki
+  var item = { request: request, state: state, emit: emit, end: end };
+  wikis[state.wiki].push(item);
+  // remove the connection when it closes
+  request.on("close",function(){
+    wikis[state.wiki].splice(wikis[state.wiki].indexOf(item),1);
+  });
+}
+// import the ServerSentEvents class
+var ServerSentEvents = require("$:/core/modules/server/server-sent-events.js").ServerSentEvents;
+// instantiate the class
+var events = new ServerSentEvents("plugins/tiddlywiki/tiddlyweb", handleConnection);
+// export the route definition for this server sent events instance
+module.exports = events.getExports();
+
+})();