I have started to study SSE and I found an example with php chat application (http://www.developphp.com/video/JavaScript/Server-Sent-Events-Simple-Chat-Application-Example). The video shows that the messages are not delayed. But when I tried the example on my own server (WAMP) I have a very long delay to the point that it is no longer a real-time application as it claims. I found that if I changed the retry:15000 to a value much much smaller (for example 100 millisecond) only then getting near real-time. But this is not good. This is polling and not truly real-time application. It seems that after each message the connection to the server is lost and resets accordingly to retry. It doesn't seem like a very smart application because we have not avoided constant requests from client to server like plain Ajax polling. Thanks
It seems that we have to make an infinity loop to the server side code to keep connection opened with only one request. But this makes no sense because we turn again to old plain polling!! Or we have to write code that is synchronous waiting for something in each iteration like, for this particular example, an update of the chat.txt file.