WML Doc Model – contd.. Rendering vs. display Depends on the browser

1. WML Doc Model – contd.. • Rendering vs. display • Depends on the browser • Develop general-purpose WML mark up • WML browsing is not Web browsing • Mobile users need targeted info and not surfing • So interaction between the user the device has to be concise and to the point • WML provides tools to write hotspots, i/p fields, selection list, etc and gives minimal document publishing features

2. WML Basics • What happens when the deck is rendered by the browser? • Eg. 4 different browser, display the same content in different ways

3. A WML Skeleton

4. The Content is in the Cards • The <card> element – basic element of user interaction, smallest addressable WML unit • Depending on browser, card displayed as a single or series of pages – but the order of elements within the card should be unaltered

5. The title attribute • For title bar text or as a default bookmark name for the card • Depends on browser • The ordered attribute • Boolean • Intended organization of the cards fields • True • Card to be a linear sequence of fields • Suited for short forms with no fields optional • False • Card doesn’t have a linear sequence or some elements are optional • Appropriate when the fields are being edited, ‘coz individual fields can be edited in any order • Only a hint to the browser – browser may or may not oblige – if true, then sequence of screens, else a tree • Do not put too many elements in a single card • Browser – to regard a field element and a text preceding as a logical entity and display them together Enter Name: • Generic or tailor content for specific browser

6. The onenterforward, onenterbackward and ontimer attributes • Shorthand forms for an <onevent> element of same type that specifies a <go> task • The newcontext attribute • Allows to establish a new browser context when a card loads • Context : a record of the browser’s current state including all defined variables and navigation history stack • If true, • Browser creates a context with a known, well-defined state • All WML variables become undefined, history stack cleared except the one for the current card • Some browsers may also clear the browser’s cache • Security – if sensitive info in the WML variables

7. The id attribute • Gives a name to the card • Must be unique within a deck • Used also within a deck as a fragment anchor • Identifying decks and cards • In WML, fragment anchors refer to cards only (#c1) • If the URL doesn’t specify a card name, then by default the first card of the deck will be displayed • Also if the URL references a nonexistent card, then also the first card is displayed

8. Comments • <! - - A comment - - > • Body of the comment • Can’t have a double hyphen • Can’t come between an element start or end tag • Multiple lines – yes, nesting – no • Content Generation • Static • Created using WML authoring tool or converted from other data format to WML • Eg. A company’s annual report, company stock’s daily closing price (automated program updates each day) • Dynamic • Generated in response to a particular request • Also Generated from templates, where basic deck resides in the file system, and has areas to be filled in response to a particular request • Eg. Student mark display, a page showing the company’s stock price • Factor that makes WML content generation differs from HTML • To recognize and account for differences among the various devices, browsers and networks that receive WML cotent

9. A WML language is generally insufficient for producing a complete wireless application • A complete WML application encompasses: • WML decks generated statically or dynamically • Server-side processes such as servlets or CGI programs • WMLScript and image content • Application data residing at the server or downloaded to the client as WBXML

10. Binary WML • WML specification includes a WBXML encoding for WML docs • Set of element tags and attributes are small – so no need for multiple code pages • Eg. <a> tag has the token value 0x1C • Lack of token doesn’t prevent encoding of WML1.2 docs . Eg. Xml:space attribute was introduced in WML1.2 – was not assigned a WBXML token value