Learning WML, and WMLScript: Programming the Wireless Web [Illustrated] (Paperback)

This book is by far the most concise and 'to the point' of all of the WML books I have seen. It is also useful for a reference because it is easy to find details at a later date.

Ok, this is a lot shorter than many of the other books but it cuts all the junk without loosing the real information.

This is a great book and I would recommend it to anyone.

The reason for this is that when you begin developing on a new platform you need a fastpath through the standard problems and gotchas - anyone who can read syntax can write the code but it is the quirky implementations that cause you trouble and frustration. Although this book does give examples they are not of much practical use to a commercial developer (the two main examples are for a Calculator and Battleships - those standard student exercises).

Although, as the title implies, the book only covers WML and WMLScript, it is impossible to write about them without considering the context in which they are deployed. For example, it would have been useful to include some information about the state of the micro-browsers at the time of publication or at least a discussion of some of the issues involved in writing to different WAP devices. Another useful example would have been how to limit your deck sizes to the lowest common denominator of circa 1500 bytes and how to manage paging in that situation. I am not asking for a full specification for each WAP device but a discussion of the principles.

It is also not made clear how WMLScript is embedded (or not) in WML. For example, on page 69 after discussing the expense of round trips to the server, it says:

"To use WMLScript to solve this problem, the <go> task that sends the data to the server needs to be changed to call WMLScript instead of loading a WML card. (Don't worry about the details of this process. They are explained in later chapters."

Despite having my worries allayed by the kindly author I had to wait 38 pages (page 107) for my curiousity to be partially satisfied but even then I was still left wanting. The author explains the mechanics of how to call WMLScript from the <go> task but then confuses the reader even further by explaining that the go tag has an href attribute whose value is a relative or absolute URL in the classic sense. Numerous examples are given, eg, '<go href="http://...;. I was unable to find an explanation of how and when the browser resolves the URL and processes the script: does it do it when the WML deck is processed or when the go task is executed? If it's the former, does it affect the size of the data you can send in a deck? If it's the latter, doesn't it also involve a round trip to the server?

I am sure that the author understands all this to his own satisfaction but because he is an expert he has not anticipated what a novice needs to know. He has provided us with a digest of the various specifications but I don't feel there is much added value to reading the specifications yourself. For example, most programmers would like to know what data structures a language offers, for example arrays, hash tables, etc. The WMLScript Version 1.2 specification has an Arrays section (6.3.6), pointing out that they are not supported but you can simulate them using a string list and then referencing elements using the String.elementAt method. However, if you look for arrays in the index of "Learning WML & WMLScript" you will not find an entry, nor for 'Data Structures'.

In the fast changing world of web/wireless development, it is important to know which specification is being referred to. Is this book referring to WMLScript 1.1 or 1.2 (the latter was published June 2000)? It is not stated anywhere. I will probably keep this book at hand, only because the WML specifications are published in Acrobat PDF format and are too clumsy to navigate.

Rob Kent

4 December, 2000