I'm developing a web application with Symfony2. I need to create a push notifications sysmte (like Facebook). When an user publish something, I need some of another users receive a notification.
I saw that Node.js it's the easiest manner to do this. But, I did some simple examples and all works fine, but I don't know how can I integrate this node.js application with my Symfony2 application, or really with a PHP application.
Anybody can help me?
Thanks in advance!
Please note that you've not given enough details, so I will respond as a front-end developer and not as a mobile developer
Integrating NodeJS and PHP (in general) is not a good way since you need to launch both servers separatly, create the websocket server in JS while your application is in PHP and finally create a request (GET or POST) from your PHP to you JS server. Well, a big mess, so I'll expose my solution here under.
Quick insight for mobile apps. Well, technically, there's no easy way. You can use the Push "protocol" (http://www.wikiwand.com/en/Push_technology) with NotificationPusher (https://github.com/Ph3nol/NotificationPusher). I didn't used it before so I can't help you with it.
In general.
Most of the time when people thinks of Push, long polling will do the trick. For starters it means that the request is made client-side and the server don't send data & close connection until there's new data.
How do you implement this ?!?
Basically, you change the max_execution_time using ini_set or set_time_limit to a very long time for the current script and launch a loop (like a do..while) with a sleep and the check to your data inside. From your Javascript just make an Ajax call, for example with jquery: $.get. Just remember to remove the timeout and stay in asynchronous mode.
The only drawback of this solution is that you will always have a connection opened to your server which will consume a bit more of battery on a mobile device. If you have multiple types of data to receive do not hesitate to merge the calls and publish a type in your response data, since most of the browsers allows only 2 or 3 simultaneous connections to the same server.
I sounds like your describing WebSockets.
Take a look at Socket.io, its a module for node.js.
Also there is a example at GitHub https://github.com/Automattic/socket.io/tree/master/examples/chat
Interesting files for you should be the index.js and the public/main.js.
You can see the example live at http://socket.io/demos/chat/
Related
So I have a table with content from a database and I want it to automatically refresh if new content arrive to the database. How can I do it?
I have seen this code but I don't want it to be asking everytime the server if information has arrived. I think that way it will overload the server. What do you think?
Please give me some tip to how can I do this.
Thanks in advance
HTML5 supports websockets.
Nearly all major PC browsers supports web sockets. You can check the compatibility in http://caniuse.com/websockets
You can learn more about the html5 websockets in http://www.html5rocks.com/en/tutorials/websockets/basics/
for push Notification I don't think php is best language for. I think you should use Nodejs for this.
write your entire page in php and use node.js for live notifications. Simply run node.js on differant port and then run on apache. remind that php and node.js are two differant processes. so nither you can call stuff between them nor you can call node.js function to client side.
I recently asked one question :- Handle Web Server with multiple clients
I have gone through the basic techniques to implement comet server like streamhub,Maven/Jetty etc.
I have following questions for that :
After that I found the issues like in case of Maven/Jetty internet
connection is required for downloading certain files from net.So it
it possible to implement it if no internet connection is there on
machine where the web server is hosted ?
Also I want the open source tools/technologies to achieve the thing
mentioned in the above question. and I think stream hub is not a
open source free version. Please help if you know any tool which is
free/open source to use.
Currently the web application is running on apache web server. so if
I use comet server what changes I need to do in that ??
Please help...
Thanks in advance...
For comet, pick a server which can handle many open connections. For a chat app I implemented which currently handles 10k open connections, I used Mochiweb. You might want to give that a look.
Going along the Mochiweb path, I will also recommend Erlang for implementing you server. It will be a small piece of code. Basically, you will listen on a path and hold the connection open till you have some data to respond with or timeout.
On the client side, you would write a simple JS function which will make an AJAX call and handle response timeout and data responses as and when they come. Nothing too different here. However, you may need JSONP instead (crossdomain/subdomain because of different servers for web and long poll), so ensure that your LongPoll server replies accordingly.
I put together an AJAX chat a while back ASP.NET MVC and jQuery. The javascript would hit the server about every 7 seconds to check for new messages. Obviously this was horrible on performance as the chat grew and included more and more users. The site traffic grew exponentially with so many requests going on. A user could leave the computer on all day and not even be there and they would still be making hits every 7 seconds.
Is there a better way to do this? I have heard of something called "push" but I haven't really been able to wrap my head around it. I think I just need pointed in the right direction.
1.) What is the best way to develop an AJAX chat and have it be scalable?
2.) What is push and how would I just that with jQuery?
1.) What is the best way to develop an AJAX chat and have it be scalable?
I agree with #freakish about the complexity and potential lack of scaling of IIS.
However, there is a relatively new Microsoft option in the works called SignalR which could become a core part of ASP.NET. More details in this related SO Question:
AJAX Comet - Is there any solution Microsoft is working on or supports to allow it to be scalable?
2.) What is push and how would I just that with jQuery?
Partially answered elsewhere, but it's a long-held persistent connection between the server and the client which means the server can instantly 'push' data to the client when it has new data available.
jQuery does support making AJAX requests but the core library doesn't support expose ways of doing HTTP Long-Polling or HTTP Streaming. More information in this SO answer to 'Long Polling/HTTP Streaming General Questions'.
Server push is a technology that allows the server to push data back to the client without forcing client to make many requests (like every 7 seconds). It is not really a matter of javascript but rather good server scripting. The upcoming HTML5 will make it simple due to server-sent events and/or WebSockets. This will be a true TCP connection between different machines.
But if you intend to make a webpage compatible with older browsers, then the most common technique is the long polling. The client sends request to the server and the server does not respond to it until it has new data. If it does then the response is made and the client immediatly after receiving data calls the server with new request. In practice however this requires the server to be well-written (for example it has to maintain thousands of idle requests at the same time) and can become a rather big challenge for developers.
I hope this helps. :) Good luck!
The technique you should use is the real-time persistent long running connections over a web page using WebSockets. You can use this library.
Node.js is becoming quite popular to build something like this and supports socket connections so you could push the data out only when there is a new message. But that would be learning something completely new.
Another nice potential would be to use MVC's OutputCacheAttribute and use the SQL dependency option so your AJAX page could be cached and would only be a new request when a new chat message appears. Also you would want your controller to be an Asynchronous controller to help reduce the load on IIS.
Enjoy, optimization is always fun and very time consuming!
Google's GMail service does it because it integrates Google Talk -- and Etherpad (now typewith.me) made famous the system which is used by, for example, Google Wave. All such systems update the page the user is working on effectively instantly when other users make changes to the page. It's easy to tell the server that a change has happened when it has happened, but it's more difficult to get clients to update themselves.
How does this kind of realtime editing work? Does it simply have the client ping the server tens of times per second for updates?
You can use Comet.
Asynchronous JavaScript and XML or AJAX
With Ajax, web applications can retrieve data from the server asynchronously in the background without interfering with the display and behavior of the existing page. The use of Ajax techniques has led to an increase in interactive or dynamic interfaces on web pages. Data is usually retrieved using the XMLHttpRequest object. Despite the name, the use of XML is not actually required, nor do the requests need to be asynchronous.
Just in case someone falls on that question.
Comet was an old way of doing real-time updates, now it has been made obsolete by technologies like websockets
I suggest using AJAX & jQuery for Asynchronous JS
http://api.jquery.com/category/ajax/
There are many options but basically i'd recommend you look into XMPP. i don't think i'm good enough to boil it down correctly, so i'll let a wiki talk for me
In fact, google voice and video uses it for these systems.
About AJAX, i think it's a communication channel, not a platform or a protocol for multiple person exchange. You could also answer "Use xml over http!" and still be at the same point :)
AFAIK, they use some form of AJAX. However, I would recommend you use the AJAX libraries via jQuery. AJAX is simplified a lot if you use jQuery to do it.
Javascript / Ajax allows you to send code to be executed on the client-side (that means, by the browser).
Now if you e.g. define a loop which checks for new messages on server every 5 seconds, you can update the web-page "in-real-time" (plus the time for the server to process the req and send response), or similar. A practical example would be the RoR Prototype periodically_call_remote Ajax helper.
Hope this helps!
As everyone says.. AJAX.
The client keeps on asking the server, after say 30 secs if there is anything new for it to do. Also, you can set the timeout value on an ajax request. keep the time out a bit high.. and the server replies whenever there is something new.
There is no way that the server can other wise ask the client to load some data.
If you are thinking of implementing something on the same lines, look up strophe.js which is an XMPP js-library
It can be done via POlling and Push design.
Polling is a client side information pulling technique after a given timeperiod.
Push technique involves the server to push the new updates to the client using websockets or new websocket like technology for example pusher.
Article
I am currently having an idea where I want to save an image from a c++/openGL application on demand from a browser. So basically I would like to run the application itself on the server and have a simple communication layer like this:
JS -> tell application to do calculations (and maybe pass a string or some simple data)
application -> tell JS when finished and maybe send a link, text or something as simple as that.
I don't really have alot of experience with webservers and as such don't know if that is possible at all (it's just my naive thinking). And note: I am not talking about a webGL application, I just want to have simple communication between a c++ serverside application, and the user.
Any ideas how to do that?
Thanks alot!
Basically no matter what your language/framework you choose for your web server, you just need a interface that is callable from your browser JS, and you can do whatever you want in the server once it recieves the call.
Most likely any web service interface exposed from the server.
Just need to safeguard your server not to get DoS since it sounds like it's a huge process.
As far as I know, JavaScript (at least when embedded in HTML) is executed on your local machine and not on the server so that there is IMHO no way to directly start your server-application using JS.
PHP for example is executed on the server-side and so you could use e.g. the php system function to call your C++/OpenGL application on the server - initiated on demand through a web-browser.
When the call is finished you could then directly present the image.
Well you could always use the cgi interface to invoke your application
and have it save that image somewhere accessible to the webserver.
Then have your js load that via ajax.
Or make a cgi App that talks to the app and then serves a small
page with the pic in it.
[EDIT]
Answering the comments:
CGI is not complex to learn, it is mostly a simple convention
you can follow. I think it would give you the maximum of
flexibility. I don't know which php mods allow you to leave the cozy protection of the server-application and interact with other stuff on your server.