So you've heard of HDML and you've heard of WML, but you don't know the differences, and you don't know which to use. Perhaps you're already using one and thinking of switching to the other. Perhaps you've heard that they are the same (as I first did). Let's clear up some of this confusion. First, some back ...
So you've heard of HDML and you've heard of WML, but you don't know the differences, and you don't know which to use. Perhaps you're already using one and thinking of switching to the other. Perhaps you've heard that they are the same (as I first did). Let's clear up some of this confusion.
First, some background information. In May of 1997 Unwired Planet, a member of the World Wide Web Consortium (W3C), submitted a request to the W3C for the HDML (Handheld Device Markup Language) Specification. The full specification can be found at www.w3.org. Although the submission was acknowledged by the W3C, it is still considered a "working draft" and no further enhancements have been made since its inception. In June of 1999 the WAP Forum, currently enrolling over 200 members, released WML (Wireless Markup Language) v1.1 and shortly after, it released v1.2 in November of 1999. The most recent WML Specification can be found at www.wapforum.org.
Both languages share the same basic programming model and functionality; however, there are some notable differences to discuss. The main difference is that WML is XML-based, while HDML is not. The main benefit of being XML-based is that a company can use commercially available XML tools to generate, parse and manipulate WML, and they can also user XSL/XSLT to construct WML decks from XML meta-languages.
Another major difference between HDML and WML is that HDML does not allow scripting, (sorry JavaScripters), while WML allows it's own version of JavaScript, called none other than WMLScript. WMLScript allows the programmer to check the validity of user input, access other facilities on the device (make a call on a phone, add a number to the phone book, etc.), generate messages and dialogs, and other device-specific tasks. HDML has the functionality to do most of the same tasks; however, using WMLScript reduces overall network traffic by performing the task locally.
HDML does not have a DTD (Document Type Definition) while WML does. As expected, there are also other smaller functionality and syntax differences such as WML's intrinsic events and the ways in which variables are set and passed.
Feature | HDML | WML | XML-based | No | Yes | DTD available | No | Yes | Scripting | None | WMLScript | Display Cards | Yes | Yes | Choice/Select Cards | Yes | Yes | Entry/Input Cards | Yes | Yes | Nodisplay Cards | Yes | Yes | Images in Text and Anchors | Yes | Yes | Variables | Yes | Yes | Deck Access Control | Yes | Yes | Deck Cache Control | Yes | Yes | Timers | No | Yes | Multiple Choice Lists | No | Yes | Bookmarks | Yes | No* | Nested Activities | Yes | No** | Images in Labels and Choices | Yes | No** | Mobile Originated Pre-fetch | Yes | No** | Key Accelerators for Links | Yes | No** |
* UP.Browser supports this feature via WML meta tag
** Supported by Up.Browser 4.0 via Phone.com WML extended tag
So which language is the most promising pick for the future? Based on the aforementioned facts, I'd have to say that WML is going to live much longer and go farther than HDML. Unfortunately, I think Unwired Planet came out with HDML just a tad before its time. When the HDML Spec was released, XML was so new, Unwired Planet did not know enough about it to make HDML based upon it. Although the Phone.com's UP.Link platform will continue to support applications written in HDML, they are recommending to its users to move to WML. Remembering this and all the other limitations of HDML, I think WML, or some form thereof, will stick around to see the future of WAP.
In Europe and Japan, some WAP devices already do not accept the HDML format. In the US and Canada many of the commercially available CDMA and CDPD phones only support HDML. It is most likely that the future US and Canadian phones will all support WML also. Fortunately, it is not difficult to convert HDML to WML and the learning curve should be minimal.
References:
W3Schools.com
WAP Forum
W3C Submissions
Phone.com
| | DISCLAIMER: The content provided in this article is not warranted or guaranteed by Developer Shed, Inc. The content provided is intended for entertainment and/or educational purposes in order to introduce to the reader key ideas, concepts, and/or product reviews. As such it is incumbent upon the reader to employ real-world tactics for security and implementation of best practices. We are not liable for any negative consequences that may result from implementing any information covered in our articles or tutorials. If this is a hardware review, it is not recommended to open and/or modify your hardware. |
More ASP Articles
More By aspfree  developerWorks - FREE Tools!
|
Learn field-tested SOA principles, methodology, technology and implementation from the global SOA market leader - in a new e-book by an IBM SOA expert. Written by IBM Certified SOA Solution Designer Bobby Woolf, "Exploring IBM SOA Technology & Practice" is the ultimate insider's guide to SOA - a PDF e-book packed cover to cover with IBM's specific advice on how to make your SOA implementation a success.
FREE! Go There Now!
| | | |
Achieving true agility is a never-ending effort. We will showcase how you can become agile incrementally, a few practices at the time.Which practices should any agile team strive to adopt? What additional practices should you consider based on your needs to scale? Adopting practices are however made much easier with the right tool support. What about if your tools adapt to your practices? We will take a look at how the Jazz technology can be leveraged to make your process change the behavior of your tools.
FREE! Go There Now!
| | | |
Download a free trial version of IBM DB2 9.5 for Linux, UNIX, and Windows. DB2 9 is the result of a five-year development project that transformed traditional (static) database technology into an interactive data server that merges the high performance and ease of use of DB2 with the self-describing benefits of XML.
FREE! Go There Now!
| | | |
Download a free trial version of IBM Rational Software Analyzer Developer Edition V7.0 to identify bug defects earlier in the software development cycle. Rational Software Analyzer is an extensible software development solution that reduces the expense of bug-fixes by enabling static analysis code reviews and bug identification very early in the development cycle.
FREE! Go There Now!
| | | |
IBM Enterprise Modernization solutions help organizations evolve core IT systems towards modern architectures and technologies—reducing the burden of maintenance and freeing up resources to develop new business requirements and capabilities. With the IBM Enterprise Modernization Sandbox for System z you can evaluate IBM Enterprise Modernization solutions focused on five key areas: Assets, Architectures, Skills, Processes and Infrastructures, and Investment. Each solution is based upon real customer experiences and offers a proven path to get you started with your modernization projects.
FREE! Go There Now!
| | | |
Learn how Rational Build Forge can extend a simple compile and package build process by adding customization and deployment capability. Go from a manual method to automating: checking for code changes; getting the latest source; compiling and packaging; customizing; copying to and restarting a deployment server; and sending e-mail notification that a new version is available.
FREE! Go There Now!
| | | |
Listen to this webcast to get an overview of Info 2.0 and a technical demo of how to quickly build an enterprise mashup. IBM's Info 2.0 technology leverages emerging Web 2.0 technologies such as mashups, feeds, AJAX, and JSON in order to simplify assembly of information using feeds and services. Come learn about the technical elements of Info 2.0 including the Feed Generation framework, Mashup Engine, and mashup assembly components. Learn how to pull information from databases, departmental information, and the Web to create mashups critical to your company’s success. We will also discuss best practices to help you get started.
FREE! Go There Now!
| | | |
Join this Rational Talks to You teleconference on November 29 at 1:00 pm ET to participate in an interactive discusssion with Grady Booch around architecture and reuse. Get your questions answered!
FREE! Go There Now!
| | | |
Because access to government information continues to be an area of concern for many U.S. citizens with disabilities, the U.S. government enacted Section 508 of the Rehabilitation Act in 2001 to ensure that government agencies create accessible Web content, enabling all citizens to access the information they need. A fully accessible Web site makes Web content accessible to all individuals, including those with disabilities, who may be accessing Web content via a variety of user agents. Common user agents include standard Web browsers, text-only browsers, assistive devices and mobile devices such as cell phones or personal digital assistants (PDAs).
FREE! Go There Now!
| | | |
This whitepaper provides areas to consider when evaluating any software configuration management solution. It addresses how the IBM solutions (Rational ClearCase and Rational ClearQuest) meet the needs and requirements of both project leaders and developers to provide successful Software Change and Configuration Management.
FREE! Go There Now!
| | | |
All FREE IBM® developerWorks Tools!
| |
/ 4 
