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/
Related
I've been working on sockets, generally in PHP for a while. Currently I have a PHP client for connecting to a chat server, and output every each data sent from server it's connected to.
To explain that in a wider matter, I accomplished this using flush() function in PHP to write out every each buffer waiting in the loop. Buffer reader is withing a while where the condition is the status of the connection socket. But this matters less.
Now to what I want to accomplish. I want to keep socket handling to server side and data from server outputted to client, via AJAX/jQuery. So far, my researches always returned me HTML5 WebSocket and node.js, however, I "have to" be real picky about this, as for users of this, my minimal dependency might be:
WinXP IE6 users(Already disables jQuery, even)
Users without JAVA/Flash installed
So I have to think of possibilities in this, which is why I can't use a Flash/Java backend or a new technology like WebSockets, and neither I want to handle server stuff in the client. I really hate to be stuck in old technology but for this it's a must.
As I was searching around, I found this one being as similiar to my needs.
Is PHP socket a viable option for making PHP jQuery based chat?
And to quick review the answers, they all point to one direction, PHP multi-process and memory eating. I know this is a minus, but it's the best I can take for now. But yet still, there'll be timeout disconnects for inactive connections within a certain delay, and extension of the delay if wanted. So I'm not much onto this one.
Secondly, the last answer pointing to "Ajax Chat Application Tutorial", I made an overall review but whoa, writing each line into an html file and re-including it each time, that is which I could do without using an extra file but, is it really necessary? Plus re-reading the file from server side, and re-importing the whole read file into document every each time, isn't that just worse for "both sides"?
Either ways that's about it, I wasn't able to come to a conclusion for a while, and it happened, here I am again. (:P) Waiting for your answers/suggestions/ideas, thanks by now.
Regards.
There is server software available that specializes in such matters. Is called a push server/service. There's for example APE (http://www.ape-project.org/); according to their website, it's compatible with all web browsers and they even got a demo chat there. I'd suggest you to go for that solution.
I have been in search of making live websites by using PHP. (COMET) I have been searching for a very long time already. (around a month) I have even checked some PHP chat scripts and used on my webserver, but I had some problems on most of them. (will be explained)
So far, most of the people tells the same thing: PHP isn't the best language could be used with COMET. The chat/comet examples are hacky at best.
I am asking this because, I want to have some features on my websites, like allow logged in people to chat with each other. That is where I need an alive connection to PHP pages. I am also planning on making a browser based game, and an alive connection will still be a must!
AJAX was a rare thing 2 years ago, shined with Facebook. Now pretty much everyone uses it, and it became a standard on web development. Now, the COMET based websites are growing. Youtube, Google+, Facebook, EA's Battlelog and such. I believe I should learn how to use it.
Okay, here are my questions. (Some of the information at below are the ones I gathered while searching on Google. Not sure if they're correct or not.)
Some languages like Python have special web servers designed for this job. I believe one of them is called Tornado Web Server. Developed and configured to simulate thousands of alive connections. I believe there is no such option in Appserv, but some people told NGINX can handle it with a decent configuration. Is it true? What configurations should be made? Is there any PHP web servers for this job?
Some of the most suggested things are:
a. Using APE.
b. Using Socket.IO
c. Node.js
Is there any way we can use them with PHP? Which one is the most promising? Could you give some guidance on them? Is there anything else than these?
I have used a comet chat script. Basically, you kept querying database and output the result with flush() to browser by sleeping it with usleep() in a loop. (This one became hard to understand so I will provide a quick code)
while(true)
{
// query database
// output the result
// flush the browser
// sleep for few seconds to lower cpu load
}
usleep() function basically destroyed my web server on Windows based operating systems. Is it normal to rely on usleep() on comet applications which runs on windows based OS? I mean, is there even a way to "sleep" PHP scripts? No matter what I do, CPU load goes to %100 on both WIN and UNIX servers.
Is PHP "really" that weak on this area? Should I give up with PHP and focus on other languages? If so, which language would you suggest? (That language should be promising. For example, there is no much use of AS3 after HTML5 addition, and AS3 is more likely to die soon while JS shines.)
What is WebSync? Can it be used with PHP?
Please bear in mind that I need to use COMET to make following applications:
A chat script, where logged in players will be able to chat eachother.
A browser based game. I already use JSON/AJAX and things like that when coding, but to receive opponents steps, I should pull the data, so an alive connection is needed. (Don't imagine advanced games, I am speaking about games like chess at best.)
I would appreciate if you can give me a short guidance. After all, I have been getting confused day by day since there are SO MANY random articles on internet. People even call setInterval() as COMET, so it is a complete mess.
There needs to be some clarification here. What you're looking for is not language specific per se. If you wanted to achieve the comet functionality with PHP you'd be relying on the Web Server (e.g Apache) to do the HTTP streaming. Also you need to understand that this is not supported in HTTP versions prior to HTTP/1.1. With that said, if you want to have a non-blocking event based web server, you're better off looking at Tornado and Node as suggested.
Comet is a programming technique that enables web servers to send data to the client without having any need for the client to request it This technique will produce more responsive applications than classic AJAX The user must create a request (for example by clicking on a link) or a periodic AJAX request must happen in order to get new data fro the server.
but it's create lots of traffic on your web server. If you want to build chat application in PHP use pusher which is a third party service and easy to use.
here is a link for pusher https://pusher.com/tutorials/realtime_chat_widget
the second suggestion is use ratchet for creating a chat application.
here is link for ratchet http://socketo.me/docs/hello-world
i hope it will help you
Short task description: I want one signed in user to be able to send an instant short plain text message to another signed in user. The solution needs to be easily scalable and not too resource demandinng in terms of bandwidth and server load (and $$).
The first idea was do client polling but this idea was quickly abandoned since it didn't meet scalability requirement. So, after that I went into research and came accross a number of concepts including sockets, node.js, xmpp. The amount of information is a bit overwhelming, so I was hoping for some advice to point me in the right directions. Hopefully something with readily available hosting solutions.
#epascarello:
thanks for quick response. I did, but not in detail. Before going in-depth into any technology, I want to be know that this is actually what I need.
Most of the examples concetnrate on instant chat but my requirements are somewhat different. I don't need every signed in user to see a message, but only one particular user, for whom it was meant, while there can be, say, 100 000 users logged in...
#Saeed Neamati:
thanks! Yes, I pretty much understand the two client-server communication options and have come to the conclutions that the pulling is a no-go. What I am trying to find now is the most scalable (that's the main prerequisite) and (hopefully) easy to implement push option. For instance, the socket option is relatively easy but it seems like it's not going to scale well due to server overload (or am I wrong). The node.js (at least by concept description) should be better at that, but I wanted to get some confirmation to this assumption. With xmpp - I'm not even sure how relevant it is to my task and how to approach it.
#andyuk:
Andy thanks, yes socket.io is also something that I came accross while doing research. As far as I understand it requires a server module that needs to run on a host. Do you know if possible to run on any server or do I need to look for a specialized hosting company? THe socket.io site for some reason doesn't work on my PC (neither IE or FF).
Did you look at the source code of nodejs chat.?
Look, you only have two options for client-server communication. Either client starts a request (an HTTP request on the web), which is called pull model (like client pulls the request out of the server), and server responds to that, or server starts a response directly without receiving any request (an HTTP response on the web), which is called push model (like the server pushes the data out to the client).
What you described as polling is actually the pull model, and indeed it takes lots of resources from the server.
But on the other hand, when you want to use push model, your server should know the client. In other words, we know that HTTP (based on TCP/IP) is a stateless protocol, which means that after each request, your connection is closed, and server loses you and forgets about you.
If you want the server to know the client, you should keep the connection open. This is usually done via some HTTP headers like Keep-Alive and Connection.
But to do that you should read Comet Programming. However, this reduces your scalability, because more connections are kept open for a one-to-one map between connection and client (To understand this better, you can think of connections as doors of the server. The more you occupy the door as a client, the less other clients can use it).
Checkout socket.io. If web sockets isn't supported by the browser it will fallback to the next best transport technology.
There is even a chat example included in the source code.
As for your concerns about scalability, node.js is perfect for this due to it's event driven, non-blocking nature. Handling many open connections is one of Node's real strengths.
Plurk uses Node.js for their real time chat features and they support 100k+ users.
We need to create a web-based frontend for displaying some data. The problem is that the data needs to be updated about once a second.
For me as a web-developer the obvious solution is AJAX.
Unfortunately, one of the purposes of this web frontend is to be displayed inside of embedded browser window which is expected to run constantly for months or even years. That's it, months of work with no restart / refresh.
During testing we ran a proof of concept interface (which requested a simple set of data each 1,5s) in Safari for over a month. During this period of time, the memory usage of Safari raised from ~30 MB to over 100MB.
Thus we're afraid of stability of such a solution.
I'm wondering if you could recommend us any other technique for this task, possibly with less overhead (when requesting simple sets of data - as in our case - I'm afraid the HTTP headers are very significant part of data)
I would suggest looking into node.js and the now.js plugging, which allows for realtime updates via websockets. It even has support for older browsers, so if the browser does not support websockets, it will do a fall over to either a comet server implementation, AJAX or an iframe.
It's extremely easy to setup on a linux environment, and there's ample documentation to get you started.
It works with javascript and runs on the Google V8 javascript engine, so if you've ever worked with OOP Javascript, you should be able to pick it up relatively easy.
LINKS:
http://nodejs.org/
http://nowjs.com/
How about Adobe AIR as front-end? You can use Flash/FLEX inside which have decent garbage collectors so long running shoudn't be a problem. AIR also allows to write in XHTML and JavaScript so it could be a good option if you're only familiar with those technologies
PHP is not a good choice for this kind of requests. Comet seems to be a good way to receive data from server. You can use for example excellent Tornado (Python) as backend.
ActionScript allows to use TCP sockets so you can write your own protocol for even better performance and use BOOST Asio (C++) or Netty (Java) as scalable backend
Maybe websocket ? Instead of making an AJAX request each X seconds, the server push new data as they comes.
My personal faverite is php4+, mysql, apache or lightpd webserver.
Tough I also suggest Python.
I specialize in what you are mentioning, with that said, will you be actually looking at the screen? If not you should request the page using an http socket or via a wget cronjob on a linux box.
Yes the http header is very important, if you try to strip them out the webserver will issue a "Server - Bad Request" Error.
Let me know what you decide, I have a lot to share :)
I suspect that the problem is not AJAX per se, but using a browser an sich: I don't think any where made with constant running in mind, and I'm assuming that all (re)loading processes will become some form of extra memory in the end.
I think you would be best off to consume your data trough something simple you design yourself. You can obviously produce it on the same spot (server, requestable via HTTP or whatever you like most), but you do not need a complete webbrowser if your goal is first "a couple of years uptime".
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.