Since their inception in 1993, HTML forms have come to be the underpinnings of user interaction on the World Wide Web. The convenience afforded by the ability to provide consistent end-user access to information and application services via a universal Web browser created a platform-independent environment for electronic commerce across the Internet. However, building on the essential simplicity of HTML forms has resulted in an extremely complex Web programming model.

Today, Web application developers are forced to work at different levels of abstraction to deliver a satisfactory end-user experience. Given the need to perform electronic transactions with a variety of different devices and user-interface modalities, the problems become even more complex. As we deploy Web access to software at all levels of complexity, ranging from business back ends to simple electronic transactions, we can better address these issues by revisiting the design of HTML forms that are the essential underpinnings of the transactional Web.

XForms 1.0 is a revision to the existing HTML forms technology developed by the W3C and builds on the advantages of XML to create a versatile forms module that can stand the Web in good stead for the next decade. XForms provides an interoperable forms solution based on XML that can significantly ease the way structured information is collected and shared across the Internet. In conjunction with XML-based Web services, XForms goes the final step in connecting end users to their business data.

Leveraging XML for Collecting Information
Business workflows are about collecting and categorizing information that starts off in semistructured documents, for example, a travel expense report, and eventually moving the fully structured information into the relevant back-end information processing system. Until now, structured data has been the purview of database applications, while semistructured documents have been managed with a variety of tools, including word processors and spread-sheet programs. With the advent of the Web, such data gathering has also come to include Web interfaces that are typically deployed to a universal Web client.

Though this move to online interaction has brought significant productivity gains, businesses and end users still fail to reap the full benefits of electronic documents because of the need to move data across disparate systems. XML promises to bridge this gap by enabling the interchange of structured and semistructured information. In this context, XForms enables the creation of browser-based interfaces for editing and submitting XML documents. By enabling the collection and validation of structured data within a Web browser, XForms makes the original promise of the document as the interface a reality; users can now interact with Web documents that present a semistructured document-based view of the underlying structured data.

A key consequence of this evolution is that data collected via such interfaces will no longer need to be reentered into the relevant back-end information system; instead, the collected XML data can be submitted directly to a Web service that connects the user with the underlying information technology. Thus, XForms looks and feels to the end user like today's Web forms enhanced with all of the data-capture functionality you'd expect from a traditional forms package. In addition, it has been designed to be suitable for delivery to the emerging variety of pervasive devices ranging from PDAs to smart phones. Built from the ground up to work with XML, XForms can gather information that has been structured to conform to the customer's document schema, where the structure and type of content that each data element can contain has been designed to suit the needs of a specific business application. The XML instance that results from a user interacting with such a form can then be integrated with existing databases and servers, making it easier to reuse data across the enterprise via XML Web services.

XForms Innovations
One of the key innovations introduced by XForms is the separation of the data being collected from the interaction that is presented to the user. This separation of the model from the view is a key enabler with respect to creating document-based user interfaces that collect and validate structured data. In this context, XForms is designed to be embedded within other XML document formats, such as XHTML. When embedded in XHTML, the XForms model defines regions of structured data within the overall XHTML document, which continues as a traditional semistructured document. XForms user interface controls embedded within the XHTML markup connect to the underlying XForms model, thereby enabling the display and update of the values stored in the XForms instance. Finally, the data collected by the XForms application can be cleanly extracted and serialized as a structured XML document for submission to a Web service. XForms can thus address the continuum ranging from fully structured documents such as database queries to semistructured documents like expense reports, project reviews, and travel itineraries. XForms documents, when deployed inside a Web browser, provide the best of both worlds; they provide the ease of use and platform independence provided by Web forms, and the rigorous data-capture capabilities of traditional forms packages. The end result is that users end up creating structured information where they would have earlier created completely unstructured content within a myriad of desktop applications, all having their own proprietary data formats that would have required reentering the data in order to get the content ready for processing by the underlying information technology.

A key consequence of this evolution is that information technologists can continue to model business data using abstract structures that are amenable to machine processing. XForms binds a user-friendly Web browser interface to such abstract XML models, thereby empowering the average user to edit and update these abstract structures. In this sense, XForms enables a standard Web browser to associate editable views to the underlying abstract XML models. This ability to view and edit XML documents from within a standard Web browser is likely to prove a key empowering technology. In addition, industry-standard XML Schema validation and business logic validation through the XForms model enables error checking at each stage, thereby avoiding costly data errors. Finally, the XForms architecture is designed to enable the use of off-line forms, i.e. users can save forms to their computers and work on them when not connected.

Dynamic Multimodal Interaction
In addition to the static type checking provided by XML Schema, XForms includes the ability to express dynamic runtime constraints that can be used in creating smart user interfaces that react to the information collected at any given point of the user interaction. Thus, a complex insurance form might include a section for each of the applicant's children. Static constraints that are expressible via XML Schema are used to specify the type and structure of each of these sections. At runtime, the form needs to be updated dynamically based on the number of children the applicant has; thus, if the applicant has no children, all of the sections of the form pertaining to the applicant's children need to be made inactive. The XForms processing model enables the creation of such dynamic user interfaces by allowing authors to express dynamic constraints within the XForms model that further refine the constraints expressed using XML Schema. Support for such dynamic interaction is enhanced via XForms user interface constructs that allow the author to create template-based user interfaces. As an example, authors can use the XForms construct to create user interfaces that iterate over the items of a collection. This functionality can be used to advantage in producing user interfaces that allow the user to interact with structures that grow or shrink dynamically. Thus, a purchase order form might start with the user interface needed for ordering a small number of items, but can grow to accommodate additional orders. XForms includes support for a rich set of declarative action handlers that in conjunction with XML Events can create rich user interface widgets such as dynamic wizards.

The views bound to the underlying XForms model may be different visual views, e.g. a complex form that binds a details view and a summary view to the underlying data. Binding to a single XForms model automatically synchronizes these views, thereby enabling the user to view an updated summary as user interaction progresses. With the coming of age of speech interaction, and the ability to integrate speech interaction into XHTML, these views can be more than just visual views, one can bind visual and auditory view to the same underlying XForms model to produce rich multimodal interaction.

Conclusion
Online transactions form the core of most Web applications, and electronic forms are intrinsic to such transactions. Electronic transactions collect data from the end user, transmit the collected data to the appropriate back-end information technology, and communicate the result of the transaction to the user. With the advent of Web services, the data that is collected is submitted to the information back end as a structured XML document.

In this context, connecting the end user to the actual information requires the creation of intuitive user interfaces for editing and updating such structured XML documents. Deploying such user interfaces within a universal Web browser has enormous advantages for reducing the cost of deploying online transactions. With the advent of an increasing variety of electronic devices, it becomes critical to be able to perform such transactions using a variety of access devices and modalities. XForms provides an interoperable means for deploying universal access to XML content by enabling the creation and editing of structured XML content from within a universal Web client.

Acknowledgments
This work would not have been possible without the help and support of my IBM colleagues, and the stimulating intellectual environment provided by IBM Research. I would also like to thank my fellow members of the W3C XForms Working Group who have worked hard over the past three years to turn a collection of useful ideas into a practicable end-to-end solution.

References

Rich Multimodal Interaction: www.w3.org/2002/mmi

Published Jan. 31, 2003— Reads 9,659
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About T.V. Raman
T. V. Raman is an accomplished Computer Scientist with over 8 years of industry experience in research and advanced technology development. During this time, he has authored 2 books and several scientific publications; his work on auditory interfaces was profiled in the September 1996 issue of Scientific American. He has leading edge expertise in auditory interfaces, scripting languages, Internet technologies including Web server applications and Web standards. Raman participates in numerous W3C working groups and authored Aural CSS (ACSS); in 1996 he wrote the first ACSS implementation. Raman has been actively participating in defining XML specifications for the next generation multimodal WWW including XForms, XML Events, and XHTML+Voice.