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CWI and W3C
Kruislaan 413
1098 SJ Amsterdam
The Netherlands
Steven.Pemberton@cwi.nl
www.cwi.nl/~steven
HTML Forms, introduced in 1993, were the basis of the e-commerce revolution and have become the mainstay for interaction and data submission on the web. After 10 years experience however it has become clear how to improve on them, for the end user, the author, and the owners of the services that the forms are addressing. XForms is the new technology replacing HTML Forms.
The advantages of XForms include:
The approach taken is to separate data, functionality, controls and presentation. The data collected is essentially an XML document, which can be anything from a single data value, right up to a complete document, even XHTML. The data can be internal to the form, or in an external document loaded separately. Functionality includes assigning types and other properties to values, and describing declarative relationships between them. Data can be submitted in traditional 'legacy' form, or posted as XML; communication with web services is therefore simple. The form controls are intent-based, describing their purpose rather than how they look or how they should be implemented. This aids device independence since rather than saying you want radio buttons, you say that one value should be chosen from a list of values. The device can then choose a suitable representation. The controls additionally support use cases like data with repeating elements, and wizard-style approaches. Finally style sheets are used to describe representations for particular devices or modalities.
This talk will discuss the design aims of XForms and the approach taken for usability, accessibility and device independence, and demonstrate some new use cases.
Researcher at the Dutch national research centre CWI
Organised 2 workshops at the first Web conference in 1994
Co-author of CSS, HTML4, XHTML, XML Events, XForms, etc
Chair of HTML and Forms working groups
Until recently, editor-in-Chief of ACM/interactions.
W3C and its standards you know.
Recently W3C launched the Mobile Web Initiative (MWI) to make Web access from a mobile device as simple, easy, and convenient as Web access from a desktop device.
Soundbite: "Javascript accounts for 90% of our headaches in complex forms, and is extremely brittle and unmaintainable."
The essence is to separate what is being returned from how the values are filled in.
The model specifies the values
being collected (the instance), and their related logic:
The data may be pre-populated from local or external sources, and repopulated at any time in the form-filling process.
An essential difference with HTML is that XForms controls are intent-based rather than presentation oriented.
Rather than specifying that a control consists of radio buttons, or a menu, XForms specifies what the control does, for instance that it selects one item from a list of items. CSS or similar can be used to provide the necessary presentation.
This approach allows the same XForm to be used across different devices without change.
The labels may be populated from local or external sources (good for localisation and multi-lingual environments)
XForms has been designed to allow much to be checked by the browser, such as
It also allows you to calculate values, such as the sum of a group of figures.
This reduces the need for round trips to the server or for extensive script-based solutions, and improves the user experience by giving immediate feedback on what is being filled in.
Because XForms uses declarative markup to declare properties of values, and to build relationships between values, it is much easier for the author to create complicated, adaptive forms, and doesn't rely on scripting.
An HTML Form converted to XForms looks pretty much the same, but when you start to build forms that HTML wasn't designed for, XForms becomes much simpler.
XForms is properly integrated into XML: it is in XML, the data it collects in the form is XML, it can load external XML documents as initial data, and can submit the results as XML.
By including the user in the XML pipeline, it at last means you can have end-to-end XML, right up to the user's desktop.
It can talk to web services, using SOAP or XML-RPC; however, it still supports 'legacy' servers.
XForms is also a part of XHTML2.
Rather than reinventing the wheel, XForms uses a number of existing XML technologies, such as
This has a number of benefits:
Data can be pre-loaded into a form from external sources.
Existing Schemas can be used.
It integrates with SOAP and XML RPC.
Doesn't require new server infrastructure.
Thanks to the intent-based controls, the same form can be delivered
without change to a traditional browser, a PDA, a mobile phone, a
voice browser, and even some more exotic emerging clients such as an Instant
Messenger.
This greatly eases providing forms to a wide audience, since forms only need to be authored once.
The first XForms-enabled mobile phone was announced by KDDI last year.
Thanks to using XML, there are no problems with loading and submitting non-Western data.
XForms has been designed so that it will work equally well with accessible technologies (for instance for blind users) and with traditional visual browsers; this means that XForms are accessible out of the box.
Apart from regular HTML forms uses, XForms supports:
XForms is rather easy to implement
XMLDOMCSSJavascriptXHTMLXPathXForms
=Regular XHTML Browser
Time to build all of above: 3 programmers, 4 months
Total footprint (on IPAQ implementation): 400K (above Java VM)
So there can be no vendor lock-in! (If you think this is a good idea, join W3C!)
As you would expect with a new technology, first adopters are within companies and vertical industries that have control over the software environment used. As more industries adopt XForms, the expectation is that it will then spread out into horizontal use. Examples:
Adoption and implementation of XForms was unexpectedly fast and is growing.
XForms addresses problems identified with Forms in HTML. The essential benefits are:
The origin: www.w3.org/Markup/Forms, and for members www.w3.org/Markup/Forms/Group
XForms: http://www.w3.org/TR/xforms/
XForms for HTML Authors: www.w3.org/MarkUp/Forms/2003/xforms-for-html-authors.html (Just Google the title)
These slides: www.w3.org/2005/Talks/07-steven-mGov