Chapter 13. Writing for HTML and WML
IN THIS CHAPTER
Providing one URL for the users of your application is one thing, but actually being able to deliver appropriate content for a variety of devices from that same URL is another issue all together. The holy grail of Web development is indeed the ability to "write once, display anywhere," and while to some extent this may be a fantasy, some guidelines can help you get closer to that goal.
Just as there are several browsers out there that render HTML in different ways, not all WAP browsers render the same WML content in the same way. This chapter will not tell you how to deliver content to every client out there, but it will lay the framework that will allow you to deliver content in a meaningful way to just about any device.
There are many books available that will provide you with all the guidelines, sample code, and suggestions that you could ever imagine for developing HTML applications. If that's what you're interested in, you should go get another book. The focus of this chapter will not be how to write good or compelling HTML, but instead how you can build your site and/or data structures so that you can readily deliver both HTML and WML from the same data store.
Note
It is worth noting that the concepts and ideas discussed here are useful beyond the world of WAP. As new standards for data communication and presentation evolve, so will the number of delivery types and transports you'll need to work with. By paying special attention to creating reusable and portable data upfront you'll be ready for future technologies as they start to appear.
The principle that must be involved is the same as that of CSS, DHTML, DOM, or XML, depending on what you are most familiar with. It boils down to the process of abstracting the presentation layer from the data. There are many HTML browsers out there with varying levels of support for CSS in different formats. It will be some time before you can rely on all Web browsers to understand XML/XSL, so until that happens, you will have to live with the fact that everyone is going to have a different level of capability when they reach your site. How do you serve them all? What do you serve them? Is it all relevant? You must ask yourself these questions to build a successful site.