| XFORMS |
 XForms
is an XML format for the specification of a data processing model
for XML data and user interface(s) for the XML data, such as web forms.
XForms was designed to be the next generation of HTML / XHTML forms,
but is generic enough that it can also be used in a standalone manner
or with presentation languages other than XHTML to describe a user
interface and a set of common data manipulation tasks.
XForms, much like XHTML 2.0 which is currently under development as of November 2006 and within which XForms will be embedded, differs from previous versions of XHTML. Because of this there is a learning curve for developers, but because XForms in general provides a large time savings for the development of enterprise quality web forms, it can be an attractive alternative for many uses. XForms 1.0 (Second Edition) was made an official W3C Recommendation on 14th March 2006. An indispensable list of errata to the 1.0 specification is available, fully incorporated into the main specification as of the Second Edition. XForms 1.1, which introduces a number of improvements, is in progress as a W3C Working Draft as of November 2006. Differences from HTML forms
An XForms document can be as simple as an HTML form (by only specifying the submission element in the model section, and placing the controls in the body), but XForms includes many advanced features. For example, new data can be requested and used to update the form while it is running, much like using XmlHttpRequest/AJAX except without scripting. The form author can validate user data against XML schema data types, require certain data, disable input controls or change sections of the form depending on circumstances, enforce particular relationships between data, input variable length arrays of data, output calculated values derived from form data, prefill entries using an XML document, respond to actions in real time (versus at submission time), and modify the style of each control depending on the device they are displayed on (browser versus mobile versus text only, etc.). There is often no need for any scripting with languages such as JavaScript. Like
legacy forms, XForms can use various non-XML submission protocols
(multipart/form-data, multipart/x-www-url-form-encoded), but a new
feature is that XForms can send data to a server in XML format.
XML documents can also be used to prefill data in the form. Because
XML is a standard, many tools exist that can chop and modify data
upon submission, unlike the case with legacy forms where in general
the data needs to be parsed and manipulated on a case by case basis.
XForms is itself an XML dialect, and therefore can create and be
created from other XML documents using XSLT. Using transformations,
XForms can be automatically created from XML Schemas, and XForms
can be converted to legacy XHTML forms: this is basically how server
side XForms work today. |
Unlike
the original HTML forms, the creators of XForms have used a Model-View-Controller
approach. The "model" consists of one or more XForms models
describing form data, constraints upon that data, and submissions.
The "view" describes what controls appear in the form,
how they are grouped together, and what data they are bound to.
CSS can be used to describe a form's appearance.