I have a server-sent event (SSE) implementation that is working with almost no issues. The only issue that I am having is "one user can have many connections to the server". Basically, If a user opens more than one web browser's tab, each tab will create a brand new server-sent event request to the server which cause many requests to run from a single user.
To solve this problem, I would like to run the SSE inside a Javascript's SharedWorker.
This means that I have only one SSE communicating with a SharedWorker. Then, every page/web browser will communication with the SharedWorker. This gives me the advantage of only allowing one SSE per user.
This is how my SSE working currently without any type of worker.
$(function(){
//connect to the server to read messages
$(window).load(function(){
startPolling( new EventSource("poll.php") );
});
//function to listen for new messages from the server
function startPolling(evtSource){
evtSource.addEventListener("getMessagingQueue", function(e) {
var data = JSON.parse(e.data);
//handle recieved messages
processServerData(data);
}, false);
evtSource.onerror = function(e) {
evtSource.close();
};
}
});
I would like to have the same setup running. However, I would like to run it inside a javascript's SharedWorker to eliminate having more than one SSE per user.
I am struggling to implement the SharedWorker. Here is what I tried so far
I created a file called worker.js and added this code to it
var ports = [] ;
onconnect = function(event) {
var port = event.ports[0];
ports.push(port);
port.start();
var serv = new EventSource(icwsPollingUrl)
serv.addEventListener("getMessagingQueue", function(e) {
var data = JSON.parse(e.data);
processServerData(data);
}, false);
}
Then on the page where I want to listed to messages I have this code
$(function(){
$(window).load(function(){
var worker = new SharedWorker("worker.js");
worker.port.start();
worker.port.onmessage = function(e) {
console.log(e.data);
console.log('Message received from worker');
}
});
});
What am I missing here?
What am I doing wrong?
How can I correct the implementation?
EDITED
Based on the comments below from @Bergi, here is an updated version of my implementation which is still not posting messages to the connectors. I added comments to my code explaining understanding of what is going on with the code.
On a landing page i.e. index.php I connect to my SharedWorker like this
$(function($){
//establish connection to the shared worker
var worker = new SharedWorker("/add-ons/icws/js/worker1.js");
//listen for a message send from the worker
worker.port.addEventListener("message",
function(event) {
console.log(event.data);
}
, false
);
//start the connection to the shared worker
worker.port.start();
});
This is the code as my worker1.js file contains
var ports = [] ;
//runs only when a new connection starts
onconnect = function(event) {
var port = event.ports[0];
ports.push(port);
port.start();
//implement a channel for a communication between the connecter and the SharedWorker
port.addEventListener("message",
function(event) {
listenForMessage(event, port);
}
);
}
//reply to any message sent to the SharedWorker with the same message but add the phrase "SharedWorker Said: " to it
listenForMessage = function (event, port) {
port.postMessage("SharedWorker Said: " + event.data);
}
//runs every time and post the message to all the connected ports
function readNewMessages(){
var serv = new EventSource(icwsPollingUrl)
serv.addEventListener("getMessagingQueue", function(e) {
var queue = JSON.parse(e.data);
notifyAllPorts(queue);
}, false);
}
//check all open ports and post a message to each
function notifyAllPorts(msg){
for(i = 0; i < ports.length; i++) {
ports[i].postMessage(msg);
}
}
Here is one more version of my worker1.js
var ports = [] ;
//runs only when a new connection starts
onconnect = function(event) {
var port = event.ports[0];
ports.push(port);
port.start();
//implement a channel for a communication between the connecter and the SharedWorker
port.addEventListener("message",
function(event) {
listenForMessage(event, port);
}
);
}
//reply to any message sent to the SharedWorker with the same message but add the phrase "SharedWorker Said: " to it
listenForMessage = function (event, port) {
port.postMessage("SharedWorker Said: " + event.data);
}
readNewMessages();
//runs every time and post the message to all the connected ports
function readNewMessages(){
console.log('Start Reading...');
var serv = new EventSource(icwsPollingUrl);
serv.addEventListener("getMessagingQueue", function(e) {
var queue = JSON.parse(e.data);
console.log('Message Received');
console.log(queue);
notifyAllPorts(queue);
}, false);
}
//check all open ports and post a message to each
function notifyAllPorts(msg){
for(i = 0; i < ports.length; i++) {
ports[i].postMessage(msg);
}
}
