Page 168/168 Periodic update

Hello Mark,

on page 168 you introduce the periodic update to get new chat messages from the server.
And you say that: In a cloud environment, we can’t really do something
where we say, “Update whenever someone else posts a message”.
Does that mean that Server Push won’t work either.
I found a nice GWT implementation of this. It’s called gwt-comet.

Thanks!
bekonsi

It’s not that server push doesn’t work – but that when you come down to it, “server push” is really a library abstraction which is implemented using something like Ajax.

Real server push just doesn’t work, for a variety of reasons. It doesn’t scale well to many users; it’s very error-prone; there are all sorts of painful problems with network topology.

Conceptually, you implement a program which provides a listener for receiving a push. In the actual low-level implementation code, it’s not really push – it’s just Ajax. So yes, it will work.

In the book, I was trying to explain the actual mechanisms that are used for implementing things.