HTML and CSS Reference
Figure 2-3. A simple jQuery effect highlights HTML5 tags when their names are hovered. The <time> element is
highlighted when the user hovers over the <time> text
PHP is a server-side scripting language that provides powerful tools for processing data. It was created to give
developers a way to build dynamic content in their HTML markup, and has since grown into one of the most widely
used server-side scripting languages on the Internet.
PHP isn't the only language we could use because there are many languages that let us build web applications.
Many languages also let us use realtime web technologies, but some do it better than others. Node.js is heavily
associated with realtime web technologies, mainly due to its evented nature and socket.io, 4 which is probably the
most well known of realtime web frameworks; Ruby has a number of solutions with the most popular being FAYE; 5
.NET has a reasonably new Microsoft-backed solution called SignalR; 6 Python has a number of solutions based on the
Tornado framework; 7 and so on.
Interestingly enough, PHP applications, which most commonly run on Apache, don't tend to be all that well
suited to realtime web technologies because they have been built with HTTP and the request response paradigm in
mind. They haven't been built to handle maintaining large numbers of persistent connections or even high volume
polling. This actually gives us a great reason to use Pusher, which, as a hosted service, takes away the potential pain of
maintaining our realtime web technology infrastructure.