Meteor server and

Quick recap of Comet Why it’s good Demo of Meteor Integrating with PHP Q&A Characters reproduced (badly) from some very nifty BUPA adverts. (www.bupaworld.com)

Quick recap of Comet

Why it’s good

Demo of Meteor

Integrating with PHP

Q&A

Typically information on the web is requested by the client Sometimes, this model is very inefficient...

Are we nearly there yet? No.

Problem: the client doesn’t know when to ask So it keeps asking again and again...

Are we nearly there yet? Still no.

This kind of interaction is Short polling Same query repeated until desired response is received. Server gets pissed off rapidly.

Other problems with short polling Repetitive database queries Unnecessary load Bandwidth use Negative responses Cookies! Delay before client sees data Unpredictable data delivery times

Repetitive database queries

Unnecessary load

Bandwidth use

Negative responses

Cookies!

Delay before client sees data

Unpredictable data delivery times

These problems arise whenever something happens (an event) that affects the client , but which is not triggered by them.

Sources of relevant events Other clients/users External events Status changes Progress feedback

Other clients/users

External events

Status changes

Progress feedback

Users interacting with other users often see a site as a representation of all those other people. So, they need to know when their context changes.

Meteor is a comet server, that keeps each user’s context fresh with new information delivered as it becomes relevant to that user.

Demo Here’s one I prepared earlier* *Apologies for Blue Peter reference

It’s the Meteor-powered Real Time Teenage Angst Monitor ?

Data is sent when it’s ready on a persistent, pre-established connection, enabling: Streaming

How to use this in PHP

Event controllers Channels Subscribers Components of a Meteor app:

Event controllers

Channels

Subscribers

Create messages Inject messages into Meteor on a channel Can read stats back from Meteor Event controllers

Create messages

Inject messages into Meteor on a channel

Can read stats back from Meteor

Sample event controller in PHP // Create an array of words $sayings = array("the", "quick", "brown", "fox", "jumps", "over", "lazy", "dogs"); // Open a controller channel to Meteor server $op = fsockopen("127.0.0.1", 4671, $errno, $errstr, 5); // Write a random word $out = "ADDMESSAGE demo ".$sayings[array_rand($sayings)]."
"; fwrite($op, $out); // Read response $buf = fread($op, 4096);

Listen on one or more channels Meteor Javascript library handles comms Hook in your own callback functions Subscriber clients

Listen on one or more channels

Meteor Javascript library handles comms

Hook in your own callback functions

Sample subscriber client JS <script type=&quot;text/javascript&quot; src=&quot;http://data.example.com/meteor.js&quot;></script> <script type=&quot;text/javascript&quot;> Meteor.hostid = 1; Meteor.host = &quot;data.&quot;+location.hostname; Meteor.registerEventCallback(&quot;process&quot;, test); Meteor.joinChannel(&quot;demo&quot;, 5); Meteor.mode = 'stream'; Meteor.connect(); function test(data) { window.status = data }; </script>

Apache: example.com Meteor: data.example.com Different hostnames Can be same machine via port redirection or IP-binding Separating servers

Apache: example.com

Meteor: data.example.com

Different hostnames

Can be same machine via port redirection or IP-binding

An effective Publish-Subscribe system A great way of broadcasting updates to groups of subscribers So in summary, Meteor is: A way of pushing data to individually addressable clients Meteor is not:

An effective Publish-Subscribe system

A great way of broadcasting updates to groups of subscribers

A way of pushing data to individually addressable clients

Real world users of Meteor

Questions?