Why is a Push Engine Required

Our Architecture is using a Push Engine to send data to the browser , Could anybody please tell me what is the use of Push Engine ?? ( Why i开发者_运维技巧s it required , as the same thing can be achivied using a normal AJAX programming )\

Please guide me .

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let's say your visiting a website, and the website is updated continuously. Your browser needs to keep updating the data that you're viewing, meaning that the browser needs to keep communicating with the server, and get the updates.

you can use ajax to make requests every few seconds, each time fetch more data from the server. Problem is - you need to make a lot of ajax calls, and you open a connection (a socket) for each, and eventually, it is a very slow process. if the interval between the requests is large, you will have a delay between the updates on the servers, and the updates in your browser.

to solve that, we can manipulate the HTTP calls - keep the request (the connection) open, and continuously send data. that way, when the server wants to send something to the client (browser), there's an open connection, and it doesn't need to way for the next ajax call by the browser. HTTP servers have a timeout on the requests, so just before request times out, browser will close it and make a new one.

another (better) method is using XMPP protocal, which is used in chats like facebook's and msn.

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AJAX is a pull method - it requires the client to connect to the server. If you have some information that you want to display live - for example a live score in a football game - the AJAX call has to be made at regular intervals - even when there is no data waiting on the server. A Push Engine is the reverse - the client and server maintain a connection and the server pushes data when there is data to be sent.