I've done a LOT of research on my following problem, but it all ends up pointing to Websockets which I can't use because my host doesn't allow command line or ssh. I've also tried the postMessage(data, targetDomain) technique, but that's not entirely where I want to go either.
Here's what I want to do:
Execute javascript from one person to the other users that are on that page without reloading it or anything.
Example: A user clicks a button on the page and it sends a javascript code that automatically executes a function on every other listeners page. Kind of like a chat feature you could say, but less dense maybe?
This is my first time exploring this field so I'm a bit confused over the concepts. I've read multiple documentations of programs that offer socket like usage, but not really any luck here. (Like I said, I can't really use sockets because of my host).
Any help is appreciated, thanks!
If you are on a hosting platform that doesn't allow WebSockets then you can outsource the realtime communications layer to a hosted realtime service (I work for Pusher which is one such service).
Hosted services tend to have a free tier so depending on what you are trying to achieve that may be enough. If not, then contact them, explain your app and your situation and they may be able to help.
If you want to use a self hosted solution then you may need to go with something HTTP-based. But, again, if you are on a small shared hosting platform this may be quite resource intensive and your hosting provide may tell you off.
If updates aren't all that frequent they you could use standard AJAX polling at reasonably long intervals. It sounds like you'd like to avoid this though.
Personally, I'd recommend using a hosted service as what you are trying to achieve is inherently difficult with PHP as it was built with request/response in mind.
Related: Realtime websocket-like behavior possible on Heroku?
Related
I have added a chat capability to a site using jquery and PHP and it seems to generally work well, but I am worried about scalability. I wonder if anyone has some advice. The key area for me I think is efficiently managing awareness of who is onine.
detail:
I haven't implemented long-polling (yet) and I'm worried about the raw number of long-running processes in PHP (Apache) getting out of control.
My code runs a periodic jquery ajax poll (4secs), that first updates the db to say I am active and sets a timestamp.
Then there is a routine that checks the timestamp for all active users and sets those outside (10mins) to inactive.
This is fairly normal from my research so far. However, I am concenred that if I allow every active user to check every other active user and then everyone update the db to kick off inactive users, then I will get duplicated effort, record locks and unnecessary server load.
So I have implemented an idea of the role of a 'sweeper'. This is just one of the online users, who inherits the role of the person doing the cleanup. Everyone else just checks whether there is a 'sweeper' in existence (DB read) and carries on. If there is no sweeper when they check, they make themselves sweeper (DB write for their own record). If there are more than one, make yourself 'non-sweeper', sleep for a random period and check again.
My theory is that this way there is only one user regularly writing updates to several records on the relevant table and everyone else is either reading or just writing to their own record.
So it works OK, but the problem possibly is that the process requires a few DB reads and may actually be less efficient than just letting everyone do the cleanup as with other research as I mentioned.
I have had over 100 concurrent users running OK so far, but the client wants to scale up to several 100's, even over 1,000 and I have no idea of knowing at this stage whether this idea is good or not.
Does anyone know whether this is a good approach or not, whether it is scalable to hundreds of active users, or whether you can recommend a different approach?
AS an aside, long polling / comet for the actual chat messages seems simple and I have found a good resource for the code, but there are several blog comments that suggest it's dangerous with PHP and apache specifically. active threads etc. Impact minimsed with usleep and session_write_close.
Again does anyone have any practical experience of a PHP long polling set up for hundreds of active users, maybe you can put my mind at ease ! Do I really ahve to look to migrate this to node.js (no experience) ?
Thank you in advance
Tony
My advice would be to do this with meteor framework, which should be pretty trivial to do, even if you are not an expert, and then simply load such chat into your PHP website via iframe.
It will be scalable, won't consume much resources, and it will get only better in the future, I presume.
And it sure beats both PHP comet solutions and jquery & ajax timeout based calls to server.
I even believe you could find on github more or less a completed solution that just requires tweaking.
But of course, do read the docs before you implement it.
If you worry about security issues, read security with meteor
Long polling is indeed pretty disastrous for PHP. PHP is always runs with limited concurrent processes, and it will scale great as long as you optimize for handling each request as quickly as possible.
Long polling and similar solutions will quickly fill up your pipe.
It could be argued that PHP is simply not the right technology for this type of stuff, with the current tools out there. If you insist on using PHP you could try ReactPHP, which is a framework for PHP quite similar to how NodeJS is built. The implication with React is also that it's expected to run as a separate deamon, and not within a webserver such as apache. I have no experience on the stability of this, and how well it scales, so you will have to do the testing yourself.
NodeJS is not hard to get into, if you know javascript well. NodeJS + socket.io make it really easy to write the chat-server and client with websockets. This would be my recommendations. When I started with this is, I had something nice up and running within several hours.
If you want to keep your application stack using PHP, you want the chat application running in your actual web app (not an iframe) and your concerned about scaling your realtime infrastructure then I'd recommend you look at a hosted service for the realtime updates, such as Pusher who I work for. This way the hosted service handles the scaling of the realtime infrastructure for you and lets you concentrate on building your application functionality.
This way you only need to handle the chat message requests - sanitize/verify the content - and then push the information through Pusher to the 1000's of connected clients.
The quick start guide is available here:
http://pusher.com/docs/quickstart
I've a full list of hosted services on my realtime web tech guide.
Apologize if this particular problem has been answered already (a search didn't turn anything directly relevant up).
We are developers of a web app that is used to provide community commenting and "social" to our partners websites. Our app uses Javascript and HTML on the front end, PHP and mySQL on the back.
Currently we are running everything through our own servers, which is getting very expensive.
We would like to ask our partners if we can host the app through their servers, with them getting a discount to our monthly charge due to the bandwidth/cpu load they would help us share.
My question is, is there a way to host our app through our partner's web servers in such a way that we can offload most of the CPU time and bandwidth without exposing our source code?
I would greatly appreciate any ideas/help!!
Thank you very much all!
If you also serve static or rarely changing content your clients could run a caching reverse proxy to remove some load from your servers without giving them any source code at all. But you need to implement caching headers for this to work properly.
You may want to look into nginx.
On second thought: Did you try to compile your scripts using facebooks Hip-Hop for PHP? First of all the script should perform way better, second of all, if you still had to outsource the hosting, you deploy a compiled program, no source code involved.
If you put the code on their server they can find out. So that won't be 100% working. Though you can make it difficult but it's still not great.
Most doable solution might be to separate parts of the application and share them. So: You give away a process (so source and other needed data) but it's only part of the total. That way no partner has your total solution but you do outsource the parts.
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
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 interested in a really good way of doing instant messaging like meebo and facebook and myspace all have, also for notifications on a page. Example on my site now, when a user receives a new mail message, photo comment, profile comment, friend request, some other things, they will receive a notification message and link on the page they are on using jQuery and AJAX.
I believe on a large scale that this is not the best way to do it though as my jquery code will have to basically run a PHP script to query the mysql table every 30 seconds or so for every user who has the page open with this script running. I would like to eventually add in some sort of instant messaging like facebook has in a chat bar at the bottom of the screen if I can find out an efficient way of doing it.
I have heard the terms Comet and HTML5 WebSockets but I am not sure if these are the solutions I should be looking at for such a feature? I would like to keep bandwidth at a minimum and running a query every few seconds does not seem very efficient on a high traffic site.
If you know some good solutions, please explain how they work a little bit please
You're looking for a "comet" server. Since you're talking PHP, your best solution would be a SaaS solution, such as WebSync On-Demand, since PHP has issues with scaling when it comes to large numbers of concurrent connections being held open. See also this question.
I think Facebook uses XMPP for their chat, so have a look at it.
XMPP is
an open technology for real-time communication, which powers a wide range of applications including instant messaging, presence, multi-party chat, voice and video calls, collaboration, lightweight middleware, content syndication, and generalized routing of XML data.
You'd install a separate server to handle messaging and in your app you'd implement a client with one of the available libraries.
Could you have a shared message queue that ajax can query? Maybe its a php script that stores a majority of the message in memcached (and possibly write to db in case of failure).
Not sure, but curious to hear other solutions ...
The basic problem is that you need to implement a Comet server (ie implement Server Push). The standard web hosts and apache don't readily allow you to do this easily. Another hosted solution (apart from Web Sync) is Goldfish Server. Currently free.