Re-framing content with XFrames (1/2) - exploring XML | WebReference

Re-framing content with XFrames (1/2) - exploring XML

Re-framing content with XFrames

While whole countries go on vacation in August, the W3C churns out one candidate specification after the next. Determined to fix the problems that HTML accumulated over its ten years of development, the frameset feature is under review.

Introduced in HTML4, frames were invented as a mechanism to combine multiple HTML documents into one view. The goal was to simplify the layout of Web application interfaces by allowing various components such as headers, footers, and menus to be assembled into one set of frames. Alas, the use of frames created some usability problems:

XFrames elements and attributes

XFrames defines a separate XML application, not a part of XHTML per se, that allows similar functionality to HTML Frames, with fewer usability problems, principally by making the content of the frameset visible in its URI. The XFrames Module supports the following element and attributes:

Element Attributes Content Model
frames class (NMTOKENS), id (ID), title (CDATA), xml:base (URI) head?, (row | column | frame+)
head class (NMTOKENS), id (ID), title (CDATA) title, style*
title class (NMTOKENS), id (ID), title (CDATA) PCDATA
style class (NMTOKENS), id (ID), title (CDATA), type* (ContentType) PCDATA
row class (NMTOKENS), id (ID), title (CDATA) (column | frame)+
column class (NMTOKENS), id (ID), title (CDATA) (row | frame)+
frame

class (NMTOKENS), id (ID), title (CDATA), source (URI)

EMPTY

Most elements are familiar from the HTML standard:

ElementDescription
frames a specification for composing several documents, potentially of different types, together in a view, just like an HTML frameset. An optional attribute xml:base exists for specifying a base URL used for resolving relative URIs when populating frames within the document.
head contains meta-data about the document, specifying a title, and a style sheet. Use of the META element and RDF is under consideration.
title contains an identifying text for the document, that may be used by a user agent to label the document.
style allows the specification of styling instructions that affect the presentation of the frames in the document. The required type attribute specifies the style sheet language of the element's contents, e.g. "text/css."
row specifies a series of columns and single frames. The columns and single frames are placed next to each other horizontally, from left to right.
column specifies a series of rows and single frames. The rows and single frames are placed one above the other, from top to bottom.
frame a place holder for the content of a document. It has one additional attribute, source, specifying a URI-reference for a default document to populate the frame, if that is not done via a parameter to the frameset document's URI.

Common Attributes

All elements can have the following attributes:

id

This attribute assigns a name to an element. This name must be unique in an XFrames document. It may be used as a style sheet selector, a target anchor for hypertext links or as a means to reference a particular element for general purpose processing by user agents.

class

This attribute assigns a class name or set of class names to an element. Any number of elements may be assigned the same class name or names. Multiple class names must be separated by white space characters. It may be used as a style sheet selector (when an author wishes to assign style information to a set of elements) or for general purpose processing by user agents.

title This attribute offers advisory information about the element for which it is set. It may be used to document the purpose of a frame, and may be useful for non-visual user agents to help the user understand the structure of a set of frames.

Examples

The examples assume at least a surrounding <frames xmlns="http://www.w3.org/2002/06/xframes"> element. The id attributes have been omitted from the frame elements for clarity.

LayoutSpecification
 -------
|   |   |
|   |   |
|   |   |
 -------
<row><frame/><frame/></row>
 -------
|   |   |
|---|   |
|   |   |
 -------
<row>
    <column>
        <frame/>
        <frame/>
    </column>
    <frame/>
</row>

Now we look at the process of populating a frameset.


Produced by Michael Claßen

URL: http://www.webreference.com/xml/column63/index.html
Created: Sep 02, 2002
Revised: Sep 02, 2002