Application to demonstrate the PubNub distributed counters, part of the KV Store module, accessible through PubNub Functions.
A hosted version of this demo can be found at https://distributed-counter.netlify.app/
- PubNub Account (Free)
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You’ll first need to sign up for a PubNub account. Once you sign up, you can get your unique PubNub keys from the PubNub Developer Portal.
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Sign in to your PubNub Dashboard.
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Click Apps, then Create New App.
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Give your app a name, and click Create.
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Click your new app to open its settings, then click its keyset.
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Enable the Stream Controller feature for your keyset (it should already be enabled).
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Copy the Publish and Subscribe keys and copy them into the
keys.jsfile. -
Create the PubNub Function, as detailed below
A PubNub Function is required as follows:
- Name: [You choose]
- Event:
After Signal - Channel:
functionsdemo-counter-vote
const pubnub = require('pubnub');
const db = require("kvstore");
export default (request) => {
var keysbatch1 = ["49", "50", "51", "52", "53", "54", "55", "56", "57", "48"]
var keysbatch2 = ["189", "187", "81", "87", "69", "82", "84", "89", "85", "73"]
var keysbatch3 = ["79", "80", "219", "221", "65", "83", "68", "70", "71", "72"]
var keysbatch4 = ["74", "75", "76", "186", "13", "16", "90", "88", "67", "86"]
var keysbatch5 = ["66", "78", "77", "188", "190", "191", "17", "32", "18"]
if (request.message.keypress)
{
// Somebody has pressed a key (voted). Notify everybody else
db.getCounter(request.message.keypress).then((counter) => {
pubnub.signal({
"channel": "functionsdemo-counter-result",
"message": {"k":request.message.keypress, "c":++counter}
}).then((signalResponse) => {
// Signal Sent
});
});
// And increment the counter
db.incrCounter(request.message.keypress, 1);
}
else
{
// A new client has requested the initial state of all counters
// We can only do 10 KV counter lookups per invocation of
// functions, so return in batches
var batch = keysbatch1
if (request.message.batch == 2) {batch = keysbatch2}
if (request.message.batch == 3) {batch = keysbatch3}
if (request.message.batch == 4) {batch = keysbatch4}
if (request.message.batch == 5) {batch = keysbatch5}
batch.forEach((keyElement) => {
db.getCounter(keyElement).then(function(counter) {
if (counter > 0)
{
pubnub.publish({
"channel": "functionsdemo-counter-result",
"message": {"k":keyElement, "c":counter}
}).then((messageResponse) => {
// Message Sent
});
}
});
});
}
return request.ok();
};- After adding your Pub/Sub keys to
keys.js, you can just launch index.html in any browser
Please fork the repository if you'd like to contribute. Pull requests are always welcome.