Fundamentals of WML

I am here to gain some information about fundamentals of WML. Let me tell you that I am not having any good knowledge about the topic. I just know that Wireless Markup Language, that is based on XML, is a markup language intended for devices that execute the Wireless Application Protocol (WAP) specification, such as mobile phones, and herald the use of additional markup languages now used with WAP, such as HTML/XHTML (which are ahead in reputation as processing power in mobile devices increases). I can having quite good knowledge about XML, hence thought to focus on WML. I am sure that some members over there must be having an idea about it. Please provide some appropriate notes in details.

WAP is different not only in its architecture of the web technology, but also the way in which content is constructed. The outstanding difference is that while HTML has been working oriented, content in so-called broken cards and decks WAP. When the cards are the basic units of WML. In them, the interaction between user agent and the user is defined. Several cards are combined into one deck. Decks are thus the parent of a WAP application. Reached a cover of the WAP client, it will usually open the first card - unless the client is explicitly addressed to another card. In cards, for example, selection or input fields can be defined. The main features of WML are:

• Text presentation and layout: WML supports not only text and graphics, but also allows easy formatting and layout commands.
• Card deck metaphor: information of a WAP application are organized in the form of decks and cards.
• Navigation and linking: WML supports navigation between cards and decks, similar to the navigation, as known from HTML.

As an XML-based markup language, WML is considerably more restrictive than HTML. The syntactic constructs originate mainly from XML. Sun WML is case-sensitive. The most important language elements are entities, tags, elements, attributes and comments. The structuring of documents in XML-based languages used storage units called entities. An XML document may consist of an entity or multiple entities. About this storage units a document into several independent sub-components is split, which can be edited individually. In WML Entities are used in particular for the specification of special characters. For example, the "ä" by the Entity ä represented. Entities start with the ampersand and end with a semicolon. The ampersand itself is & shown.

You are familiar to everyone who has ever closer to Web documents has dealt with it. A tag describes the item and contains the element name and a unique identifier. A tag can also contain attributes that specify additional properties of an element. Even when there is WML start, end and empty tags. Elements specify markings and structural information of a WML deck. They have a two structures on to: <tag> Inhalt </tag> or <tag/> framed. For non-empty elements is the actual information from the start and end tag. Empty elements such as <br/> for the new line have no content. Elements are divided into categories depending on functionality. Thus, for example, distinguishes between text formatting and event-based elements.Many WML elements can be provided with attributes, additional information for an element to determine the. Attributes always appear in the start tag of an element.

Even WML documents can be invisible "comments will be provided with that allows the developer at a later processing easier, in particular, to read the source code. This information is not, as in HTML & Co. represented the client. The syntax is:

<- Comment ->

WAP is different not only in its architecture, the markup and scripting language from HTML & Co., but also in the used graphics format.

Traditional GIF, JPEG or PNG graphics are simply due to their file size for WAP-enabled devices to use little if at all. So it has created a format that is tailored to the display of graphics on mini display: the wireless bitmap format, WBMP shortly. WBMP graphics have a uniform structure. Meta-information in the header, the actual data held in the body firmly. The header contains information concerning the size of the graphics and WBMP version designation. The actual data is described by the so-called type field. It contains the following information:

• Arrangement of pixels, including coding
• used color palettes and their coding
• Compression characteristics
• Animation coding

In principle, color images, compression, and animations are possible but not yet specified. The graphics data is described by a sequence of bytes. A bit here represents a pixel. WAP provides far only the WBML-Type 0 This version is not compressed and has a bit color (monochrome).

The integration of a WBMP graphic follows the same pattern, as known from HTML. About the img element graphics are integrated. Of attributes are align, for example, height, width, hspace, vspace, id and class available. WBMP graphics can be created manually or by using a WBMP-enabled editor. How from BMP files with a graphics editor creates WAP, editing files in hex mode. WML discusses the technical features of mobile devices. Unlike HTML, WML is to save a lot of overhead by grouping the pages into individual decks. However, there is still much to do here: in particular the WBMP format with a single-bit color depth is not long endure. Mobile phones with color display today are finally available from Siemens. Even WYSIWYG editors for WML pages are still rare: only Macromedia currently offers a WML-Extension Kit for Dreamweaver.