I'd like to create an API for a project I'm working on, allowing developers to create desktop and mobile applications built around its functionality. One thing I've always wanted to learn how to do is create a stateless, push notification system, similar to Twitter's Streaming API.
Basically, I want to be able to notify users of any changes to the data in real time, or as close to it as possible. I know that this might be difficult on mobile devices, which is why mobile applications will probably be built to check for updates periodically, to save battery. However, desktop applications won't have that limitation. I'd like to avoid making the application ask the server if there is new information, and instead let the server tell the application that there is new data.
My programming language is PHP and my server is Apache. If I absolutely had to I could switch to Lighttpd or nginx, but that's an absolute last resort since it would require a lot of changes to all of my existing code.
I've read this article:
http://www.zeitoun.net/articles/comet_and_php/start
And tested it out, but unfortunately all that happens is my browser keeps attempting to load the page and never actually displays the time. I suspect this is because, for whatever reason, I've never been able to get output buffering to work on my server, unless I send 64kb (or more) of data. I heard that I had to disable gzip, which I did, and it still didn't work, so I don't know.
Have a look at some existing technologies to help you do this:
Tornado
Tornado is an open source version of the scalable, non-blocking web server and tools that power FriendFeed. The FriendFeed application is written using a web framework that looks a bit like web.py or Google's webapp, but with additional tools and optimizations to take advantage of the underlying non-blocking infrastructure.
Pusher
Pusher is a hosted API for quickly, easily and securely adding scalable realtime functionality via WebSockets to web and mobile apps.
Both are extremely fast and scalable, and I have setup both relatively easily.
Well you could do this in several ways, you could build in a poller at the client side, or you could use something like NodeJS. (http://nodejs.org/) or web sockets.
Yeah another good piece is
http://socket.io/
and
http://elephant.io/
some tuorials like this might also be useful.
http://www.phpbuilder.com/articles/application-architecture/optimization/creating-real-time-applications-with-php-and-websockets.html
Related
Lately, I have been doing a lot of research (of course googling :P) on building real-time application (like chat application). So far I have come across Elephant.io, Socket.io and Ratchet. And some of the terms I stumbled upon were web-sockets, bi-directional communication etc..
I am building an auction site where it involves countdown timer. I am trying to achieve something like when one user bids, the timer gets updated in all the client's browser without page refresh (something like server broadcasting the change of event to all other connected users).
The problem is, I am building the application with PHP (Pyro-cms). The server, where it will be uploaded is Apache-based server and does not support node.js. One of the most common stuff I notice was most of the real-time applications were utilizing node.js.
Is it possible to build real-time application using PHP , Socket.io and javascript only? or may be with angular.js?
I really cannot use the server that support node.js so have to completely rely on apache server. I even dont know if it is possible. If there is any resources, reference or tutorial, it will be very helpful.
I've been "recruited" so to speak to help work on a web project that is currently written in PHP with an Apache server. We would like to integrate a real-time (or at least something very close to it) chat feature. Scalability is a definite concern, and this type of work is definitely not my typical.
Everything I've read about creating such a chat feature requires the use of "long-polling" so the servers don't get rapidly overloaded and, well, crash. PHP and Apache are not conducive to implementing such a feature, so I've explored some alternatives, like Twisted Python for example.
The website has roughly ~7,000 lines of PHP (i.e., it'd pretty difficult to just straight switch languages for the entire thing), so my question is how can I manage this situation as far as trying to integrate python and setting up a separate server? Or, is this a very bad way to do this? Are there other alternatives that would be better suited? (Sadly many of the PHP Comet, or even AJAX, solutions I've found don't scale in the slightest. Note, the Apache server is not necessarily required; however, any server used must work with PHP and Python etc, short of having separate servers.)
Thanks for the help!
I would use Tornado on the server to write the chat application. Client server communication can then be over websockets. If you use SockJS on the client side you can also support older browsers via long polling. There are plenty of example chat clients written using Tornado. It's very simple to get started and it is wonderfully scalable. A chat server like this can be serving thousands of clients without showing any appreciable CPU activity.
This is an example, possibly a bit over engineered https://github.com/diggidanne/websocket-chat/blob/master/server.py
With all the buzz around WebSockets, it's pretty hard to find a good walkthrough on how to use them with an Apache server on Google.
We're developing a plugin, in PHP (symfony2), which will run from time to time kind of a chat instance. And we find WebSockets more interesting, standard and quick than AJAX for this matter. The thing is, we don't have much sysadmin ressources in our group and we find hard to gather good informations on the following matters:
Can we run a WebSocket instance on a traditional Apache, dedicated server, and if yes, do you have useful links for us?
If we need to mod the server, what kind of tools would you recommend knowing that we are not too skilled in sysadmin so we can't afford to have a high maintenance b*** on this.
Thank you very much,
ps: we'll link back to your blog/site as we'll make a technical/informational post on our devblog about this part of our app.
Thank you again!
As #zaf states you are more likely to find a standalone PHP solution - not something that runs within Apache. That said there is a apache WebSocket module.
However, the fundamental problem is that Apache wasn't built with maintaining many persistent connections in mind. It, along with PHP, is built on the idea that requests are made and responses are quickly sent back. This means that resources can very quickly be used up if you are holding requests open and you're going to need to look into horizontal scaling pretty quickly.
Personally I think you have two options:
Use an alternative realtime web technology solution and communicate between your web application and realtime web infrastructure using queues or short-lived requests (web services).
Off load the handling of persistent connections and scaling of the realtime web infrastructure to a realtime web hosted service. I work for Pusher and we fall into this category.
For both self-hosted and hosted options you can check out my realtime web tech guide.
One path is to use an independent installed web sockets server.
For PHP you can try:
http://code.google.com/p/phpwebsocket/ or http://github.com/Devristo/phpws/
There are some other projects which you can try as well.
Basically, you need to upload, unpack and start running the process.
On the frontend, you'll have javascript connecting to the server on the specific port.
Most websocket servers have a demo which echoes back whatever it hears, so this is a good place to write some test code. You may even find a rudimentary chat implementation.
The tricky part is to monitor the web socket server and to make sure it runs smoothly and continuously.
Try to test on as many browsers/devices as possible as this will decide on which websocket server implementation you choose. There are old and new protocols you have to watch out for.
I introduced another websocket server: PHP Ratchet (Github).
This is better and complete list of client & server side codes and browser support.
Please check this link.
Another Path is to use a dedicated websocket server.
Try Achex Websocket Server at www.achex.ca and checkout the tutorials.
OR
If you really want Apache, check out Apache Camel. (but you have to set it up and its a bit more complicated than achex server)
http://camel.apache.org/websocket.html
Only yesterday, I was asking a friend of mine how he would go about emulating direct communication channels between two clients through a web server, for the purpose of creating a chat application, but by using solely PHP/MySQL/JavaScript.
He told me that the best way to do this was by the use of SOCKETS, a term I had only heard of until then. This morning I started looking into it for the purpose of creating my chat application, but I'm quickly starting to believe that it's not as easy as I'd hoped.
So my question is this: if I don't have access to my own server (I have a domain hosted on a shared server that I also use for testing purposes), can I still use sockets to achieve my goal? If so, how exactly? (Please understand that I am completely new to the idea)
If not, what other way is there to accomplish the communication channels?
My only idea so far is to simply send periodic requests (AJAX) to the web server the application would be stored on and request any new messages, if any. But this does not seem very feasible.
Thanks in advance for your help!
I think what your friend is trying to get to is implementing Comet for your chat site.
Assuming he's getting you to use PHP sockets to act as a daemon, I highly doubt a shared hosting provider will let you do it.
You could try hanging the PHP script until there's data available. However, this will quickly consume resources on a CGI-based server since the PHP server can't tell if the client is still connected. I know this from experience.
For these kind of things, I highly recommend you get a dedicated server or VPS and write your backend in something like socket.io which automagically handles all your communication problems on both the client and server side. PHP, MYSQL and servers that fork to serve requests are usually the worst case scenarios for implementing Comet since they incur quite a bit of overhead and aren't scalable.
If you can't afford to run your own Comet server, then polling may be your only option. This will be the most resource intensive and least responsive.
I am developing a non-real time browser RPG game (think Kingdom of Loathing) which would be played from within a Flash app. At first I just wanted to make the communication with server using simply URLLoader to tell PHP what I am doing, and using $_SESSION to store data needed in-between request.
I wonder if it wouldn't be better to base it on a socket connection, an app residing on a server written in Java or Python. The problem is I have never ever written such an app so I have no idea how much I'd have to "shift" my thoughts from simple responding do request (like PHP) to continuously working application. I won't hide I am also concerned about the memory and CPU usage of such Server app, when for example there would be hundreds of users connected. I've done some research.
I have tried to do some research, but thanks to my nil knowledge on the sockets subject I haven't found anything helpful. So, considering the fact I don't need real time data exchange, will it be wise to develop the server side part as socket server, not in plain ol' PHP?
Since your game isn't something that's working in realtime you probably don't need to go down the socket route, though it's certainly a viable option. The nice thing about sockets is that updates would be instant without requiring page refresh (or server poll), so you're right to at least consider it.
If you do want to do a more real-time server setup, you might consider using something like Electroserver - this abstracts out much of the setup for you so you don't have to write your own server from scratch, plus it's free up to a certain number of concurrent users if I recall correctly.
Finally, a third option you have is a modified POST approach using AMF. Look into AMFPHP, it lets you call methods on a PHP back-end directly from your flash application. A little bit faster and easier than simply using POST stuff, but not quite as seamless as a socket connection or a specifically built gaming server.
Lots of options out there, it sounds like you are aware of this and kudos for trying to come up with the best approach rather than just rolling with what you know! I hope this helps, let me know if you have any questions.
Here's a link to Electroserver - http://www.electro-server.com/