如何在您的网站中使用长轮询或Ajax推送

I want to know how to use ajax push . i have learnt from various Web articles that Ajax push can be obtained by using few programmes like COMET, APE (AJAX PUSH ENGINE) etc.... But i want to know whether there is a simpler way of using it and what language is used to implement ajax push. because in the articles which i have seen. they are using java. which i did not learn :( so i would like to know whether there is something like : a javascript in your server which sets an interval to a particular item and then if any changes found then echo it out using php. ? please help me out for this . its been a week now i tried to achieve this. i tried to use normal ajax and php by using intervals but not able to get the result. Thank you. P.S : Please show me an easy way of using it with an example or something.I want to know how to use ajax push . i have le