I have a fairly big web application build with SproutCore and PHP as backend. What I want now is to use websockets to update my client application in real time.
From what I know, PHP is really bad to handle persistent connections. So I've been thinking that I could use Go to handle the websockets connections and call my PHP scripts each time a request is received (this package seem to make it possible).
So my first question is, do you guys think it's a good idea (and a viable idea, I haven't been able to find people doing so) or should I stick with PHP ?
If I use Go to handle the websockets connections I've also been thinking that I could progressively move away from PHP to only use Go (since it is a lot faster than PHP). If I do that, I will have to be able to call some Go package from PHP. Can this be done with the PHP exec function ? Is there a better way ? And again, is that a good idea ?
Go is a natural fit for websocket servers. I've built websocket servers in Go and have been extremely happy with how it all worked out. I have one service handling 300k users a month on a Go websocket server and it barely uses 1% CPU of an Amazon AWS micro instance. Couldn't be happier.
Websockets really need event driven frameworks like Go and Node.js in order to maximize server resources. Forked web processes like PHP consume far more resources than an event driven framework.
If you need to call Go from PHP at some point, I suggest using API calls. Although exec would work too.
It is an old question, but my two cents on this subject...
There is a very good php library that does exactly what you are asking for - websockets. It is called Ratchet. I would not use node.js (over hyped) or go when php can do exactly the same thing and it is the language that I am most comfortable with. In majority of cases, little gain in performance over websockets is not worth switching stack.
Other useful links if you plan on using Ratchet:
Backend - Ratchet Examples
Frontend - Autobahn WS
Related
I am writing Web chat where you have several one-on-one conversations with people on the screen at the same time. (Basically, like a personal messenger, without group chats).
My technology options seem to be Long Polling and WebSockets, and I'm trying to choose.
The upside with Long Polling is that's it's very easy to implement, and I can return whatever data i want (a customized JSON-object with the data required to update the page).
What I'm afraid of with WebSockets is that there's no native library for it in PHP, so you have to shop between different 3rd party ones, and the concepts seem more complicated, what with channels and subscriptions and what have you.
Browser compatibility is not an issue for me.
Is the performance of Long Polling much poorer than with Websockets? If no, then my decision is easy!
Is there a really simple Websocket server for PHP? Or is the concept so simple I could write my own? (Mozilla has a really simple tutorial on writing a client, but not on a server).
Assuming that your long-polling scheme involves an endpoint hosted by the same web server as your frontend, this will mean two active connections for every user of the application, so you will basically cut the number of users you can support in half. Your websocket server would run on a different port and can bypass your web server, so the connections are a lot of saved overhead with websockets.
Another place websockets save on overhead is that once your connection is established, there is no need for constant requests and responses. Zombie websocket connections are essentially free in terms of both bandwidth and CPU.
Finally, I would not think that long polling would be simpler to implement. Since websockets are designed to do exactly what you want, I think that leveraging an existing websocket package will actually save you some lines of code. I would look at Ratchet (feature-rich) or phpwebsocket (lite), if you want to use PHP.
Long Polling is definitely way much poorer than Werbsockets.
It is not recommended to use whatever websockets library with PHP, specially for chat applications.
I suggest using Python, Ruby or Node.js instead.
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
I have been reading about websockets and also about socket.io.
I understand websockets are not support but enough browsers yet to be realistically used.
socket.io has browser support but appears to need node.js. With my hosting solution I have some space on a shared server, very limited control over the server and have access to php but there is no node.js.
I have read that people can get socket.io to work with PHP.
Question: seeing I have very limited server access, not control over ports, command line etc is it realistic that I could get socket.io working with PHP or should I just stick with the AJAX calls (I'm currently using)?
Note: I've developed a chat solution and it appears it would be much more light weight if it was running with a socket solution.
Also - is there good security with Sockets.io?
thx
Trying to make PHP talk to socket.io I suspect will be a big task.
Certainly it's not a great idea to run websockets via a pre-fork or threaded apache. Any event based server should be OK if you can handle the number of PHP processes. A better approach would be to write an event based server in php. Like this one
i researched a few websocket server implementations. i read, that there is a way to use node.js in production. using apache many years, i also searched for a module to handle websockets within apache, but found only half-hearted stuff. nothing which seemed solid.
i stumbled upon yaws, which is a websocket capable server written in erlang, which has the advantages of beeing the right language for a highly parallel application such as the chat thing, and also because websockets should be well integrated within the main server.
now, i'm developing a php chat server, which uses a framework called ratchet. -> google for 'ratchet php'. they got a good tutorial.
i start it via the commandline, and although for you it should be possible to also start the ratchet server via a browser call, i would not recommend that.
so in your constrained hosting environment, i would stick to ajax.
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.
Is there a real solution for COMET AND PHP combination? Basically, I've come to a point that I need to update a user home page periodically whenever there is new data in the database. As far as I understand, I need to open a persistent connection between my server and my clients browsers to update the contents of their home page as soon as new info. available without dedicating a lot of resources but I had no luck finding anything clear about this issue. I read many articles suggests that PHP is not a good language to implement COMET. My web application is completely programmed in PHP and I don't want to learn another language but if I'm forced to, Would you suggest a good language to start with? Do you think that I can program an interface just to handle this issue?
Thanks in advance.
The times I've heard people say that PHP was not well suited for COMET (like you said yourself) was because of the way webservers and PHP work -- mostly, because there is one process per page, which means if you want 200 users connected to your server, you'll need 200 processes (which can quickly become a problem for a couple of hundred more users).
Maybe a solution to that problem would be to use nginx_http_push_module ?
I've not tried it (yet ?), but it might be just what we need...
I was working on a school project and ran into the exact same problem. Because each PHP process has so much memory overhead, it's impossible to support to many connections per box. It was at this point I decided to switch to using BOSH and XMPP. This is a rather new "wave" of technology but there is already quite a few libraries to help you on your way. I would suggest using Strophe and XMPPHP. Then your clients can connect to a BOSH server (I'm using Openfire) and that can scale to thousands of active connections per server.
You don't have to learn a new language to implement such a feature.
For example, you could use Quercus (Java implementation of PHP) and implement a server Comet application using the JVMs memory management model.
There are solutions you need:
almost COMET solution (uses php and one file written with perl):
http://translate.google.com/translate?js=y&prev=_t&hl=ru&ie=UTF-8&layout=1&eotf=1&u=http://dklab.ru/lib/dklab_multiplexor/&sl=ru&tl=en
exact COMET solution in php (this is what you want, I think):
http://translate.google.com/translate?hl=ru&sl=ru&tl=en&u=http://dklab.ru/lib/dklab_realplexor/
You would first need to understand what is a comet application like. The concept involved in building a comet application are explained at wiki at Comet (programming)
What you need to understand is that you can use any programming language to build a comet application as long as it follows the concepts explained at wiki
1.Ajax with long polling
2.Streaming
You can check some sample code at Simple “Long Polling” example code
Now coming to the problems -
1.You use ajax long polling then the browser(ajax request) would keep polling the server for data. This may eat up memory on the server or slow down the browser after some time.
Few Suggestions
JQuery PeriodicalUpdater (AJAX long polling/server polling)
Handling Long Polling
RobertFischer / JQuery-PeriodicalUpdater
What you need to check to implement this -
a) How often do you expect data to be updated on the server.
b) How much time the server side script would run to check, fetch and process data before sending it to the client side.
2.You can implement streaming by using the following -
How to implement COMET with PHP
Lightstreamer Dojo
Dojo Charting + Lightstreamer Comet Demo
Demo
Ajax Push Engine or The APE Project
What you need to check for this -
a) Will your hosting provider allow you to install these on hosting servers
b) Your RAM and Bandwidth utilization (You will need a dedicated server with package that gives you lots of RAM and Bandwidth)
It depends on what and how your requirements are. You will have to analyze and approach.
If what you are implementing is a small application you can go for Ajax Long polling given the fact that you analyzed and handled the negatives of this approach.
If you have a large application you can go for steaming.
Ajax with long polling is a easy solution, there are plugins in jquery and any other major js framework to help you do this.
Node.js seems like a pretty sweet solution for stuff like this. (Still a little gamey for production but cool all the same). PHP is a horrible environment for stuff like this, you have to change the way the server interacts with requests because you are no longer immediately responding. Python has a handful of servers like Twisted that are great for this because they let you be the server. No matter what language you write it in you've got to alter the typical request/response model. (Glassfish's Grizzly Comet server does this for Java as an example)
You should try Dmitry Koterov's Realplexor, which is a comet server, that provides Javascript and PHP APIs.
Readme.txt in english is provided in the package.