Flash MX 2004 Games : Art to ActionScript

12
Using external files
When you are using Flash, the target platform for your game is usually the web. Your game
will be seen in a browser. In order for your game to be available on the web it will need to
reside on a server that can be accessed from the web. In most cases this will mean that the
game is on a computer belonging to an ISP (Internet Service Provider). If you work for a big
company then you may well have one or more servers that are accessible from the web, but
for home and small business users this accessibility is usual provided by a third party. Once your
game is accessible to the world via the Internet you may want your game to have several levels
or you may want the ability to easily change the game monthly, weekly or even daily. You
may want the game to perform slightly differently for different users. To achieve these goals
you may have the different versions of the game on the server or the behaviour of the game
could be influenced using an external file. In this chapter we will look at using a simple text file
containing variable data so that the game you have created behaves differently by using different
configuration text files. Another popular method for setting the configuration data is to use ASP
(Active Server Pages). ASP is often used to link to databases on the server. Using a link to
the database the game can be easily updated or made to have a unique configuration for the
current user.
A brief overview of the web
You probably already know about the web and how to use it but if not here’s the briefest of brief
introductions. The web was the brainchild of Tim Berners-Lee, who came up with a common
standard for hyperlinked documents across a network. He invented the acronym that we have all
come to love, HTML (Hyper Text Mark-up Language). We link to an HTML document using
HTTP (Hyper Text Transfer Protocol). Everything on the web has a URL (Uniform Resource
Locator). The URL for the home page for this book is
http://www.niklever.net/flash/index.html
‘http’ indicates the protocol, ‘www.niklever.net’ directs the browser to the appropriate folder on
the appropriate server. Basically, the name is just a link into a big look-up table that finds the
IP address of the computer. An IP address will have the form XXX.XXX.XXX.XXX, where
XXX is a number up to 255. Although interesting, so far none of this is directly relevant to you
as a developer. Where it gets more interesting is the document itself, the HTML page. In this
example we have ‘index.html’, although because the server defaults to this file and because HTTP
168