I have two channels for my subscribers: Broadcast and Unique channel. On the Broadcast channel I have all the Subscribers listening to. The Unique channel is for One-To-One communication between the Publisher and the Subscriber.
I need to achieve the following solution: If the Subscriber goes offline/loses connection, after he comes back online he needs to poll the two channels for the single latest message on each of them and determine if the message is still valid based on the property in the message object:
//HERE IS THE MESSAGE OBJECT THAT THE PUBLISHER SENDS ON THE BROADCAST AND THE UNIQUE
//CHANNELS TO THE SUBSCRIBERS.
message = {
alarm: null, //BOOLEAN: DESIGNATES IF THE ALARM IS ON/OFF
body: null, //STRING: SOME MESSAGE/ALARM TEXT
image: null, //STRING: SOME IMAGE IF YOU WANT TO APPEAR WITH THE ALARM TEXT
createdAt: null, //UNIX TIMESTAMP OF WHEN THE MESSAGE WAS CREATED/SENT
validUntil: null //UNIX TIMESTAMP - AFTER THIS PERIOD THE MESSAGE IS CONSIDERED INACTIVE AND THE SUBSCRIBER SHOULD IGNORE THIS MESSAGE ON RECONNECT
};
Here is my sample code for the Subscriber(The problem is marked in the comments in the code):
$(document).ready(function(){
var uuid = PUBNUB.uuid(),
id = 'vlatkorun-' + uuid,
controlChannel = 'vlatkorun-control',
broadcastChannel = 'vlatkorun-broadcast',
uniqueChannel = 'vlatkorun-unique-';
var state = {
id: id,
uniqueChannel: uniqueChannel
};
//INIT PUBNUB
var pubnub = PUBNUB.init({
subscribe_key : 'YYY',
keepalive: 30
});
//SUBSCRIBE TO THE CONTROL CHANNEL FIRST
//THE CONTROL CHANNEL IS FOR MAINTENANCE BETWEEN PUBLISHER
//AND THE SUBSCRIBERS
pubnub.subscribe ({
channel: controlChannel,
message: function(m){console.log(m)},
state: state,
heartbeat: 30,
connect: function(m){/*console.log(JSON.stringify(m))*/},
reconnect: function(m){console.log(JSON.stringify(m))}
});
//NOW SUBSCRIBE TO THE BROADCAST AND THE UNIQUE CHANNELS
pubnub.subscribe ({
channel: [broadcastChannel, uniqueChannel],
state: state,
message: function(data){
//SHOW THE ALARM IN THE BROWSER WHEN MESSAGE ARRIVES
//OUTPUT OMMITED
},
connect: function(m){
//THIS ARRAY IS GOING TO HOLD THE LATEST MESSAGES FROT THE BOTH CHANNELS
var channelLatestMessages = [];
//GET THE MOST RECENT MESSAGE ON THE BROACAST CHANNEL
pubnub.history({
channel: broadcastChannel,
count: 1,
callback: function (m) {
if(m[0].length > 0)
{
//GO OVER THE RETURNED MESSAGES AND PUT THEM IN THE ARRAY FOR COMPARING LATER
$.each(m[0], function(index, value){
channelLatestMessages.push(value);
});
}
//I HAVE THE VARIABLE POPULATED WITH THE MESSAGES FROM THE CHANNEL IN THE CALLBACK
console.info(channelLatestMessages);
},
});
//GET THE MOST RECENT MESSAGE ON THE UNIQUE CHANNEL
pubnub.history({
channel: uniqueChannel,
count: 1,
callback: function (m) {
if(m[0].length > 0)
{
//GO OVER THE RETURNED MESSAGES AND PUT THEM IN THE ARRAY FOR COMPARING LATER
$.each(m[0], function(index, value){
channelLatestMessages.push(value);
});
}
//I HAVE THE VARIABLE POPULATED WITH THE MESSAGES FROM THE CHANNEL IN THE CALLBACK
console.info(channelLatestMessages);
},
});
//I HAVE THE VARIABLE POPULATED WITH THE MESSAGES FROM THE CHANNEL IN THE CALLBACK, BUT HERE THE ARRAY IS EMPTY BECAUSE THE CALLBACKS ARENT
//FISHED.
//HERE IS MY QUESTION: HOW CAN I WAIT FOR THE CALLBACKS TO FINISH SO I CAN CONTINUE WITH MY CODE BELLOW???
console.info(channelLatestMessages);
//IF THERE ARE NO MESSAGES DO NOTHING
if(channelLatestMessages.length == 0) return;
//ASSUME THAT THE FIRST MESSAGE IN THE ARRAY IS THE MOST RECENT
latestMessage = channelLatestMessages[0];
//NOW FIGURE OUT THE MOST RECENT MESSAGE
$.each(channelLatestMessages, function(index, message){
if(latestMessage.createdAt < message.createdAt)
{
latestMessage = message;
}
});
//GET THE CURRENT DATE IN UNIX TIMESTAMP
var currentDate = parseInt(moment().format('X'));
//CHECK IF THE MESSAGE VALIDITY IS EXPIRED
if(currentDate > latestMessage.validUntil) return;
//HERE WE CAN SHOW THE LATEST MESSAGE IN THE BROWSER
//OUTPUT OMMITED
},
reconnect: function(m){//THE SAME LOGIN LIKE IN THE CONNECT METHOD APPLIES HERE}
});
});
How to wait for the callbacks to finish so I can have the channelLatestMessages filled with the latest messages from the Broadcast and Unique channels so I can further determine which message is more recent and if the more recent message is still active?
