The future of Web presentation isn't high tech, it's high concept. And it's here today. It's not an information superhighway - it's an adaptive avenue.

Flexible, Web-based presentation engines are creating new options for Web presentation. As an integrated presentation and viewing environment that enables active presentation of Web content, a presentation engine uses XML-based presentation specifications to define the user experience. As a managed service that enables active presentation without reprogramming of content and without installation of software in the client or server environment, a presentation engine uses the Web services model to integrate with an array of host environments.

Web presenters and Web viewers alike are growing impatient with the limited navigation and presentation options of the existing Web environment. Static navigation methods like point-and-click don't hold viewers' attention sufficiently to draw them deep into Web content. And these primitive methods squander advances in digital bandwidth by diverting the "cognitive bandwidth" of viewers from content to navigation, producing "knowledge fatigue." A greater page-per-click ratio is essential to improving the satisfaction and productivity of the Web experience.

Dynamic presentation methods like animation and streaming media are available. But they're not feasible on all sites and whole sites... and they require installation of specialized components in the server and client environments. Web presenters want economical ways to deliver more content in a more dynamic mode. Despite the sophisticated experiences that high-end methods can produce, site producers are frustrated with the expense and inertia of high-end media development. They want the ability to reassemble content quickly and leverage their existing content investments for new and different audiences and situations. The Web awaits more efficient and dynamic presentation methods - implemented on a broad scale - to achieve its next stage of real growth in value and activity.

The landscape of Web presentation capabilities is changing. It offers more options - and more power - in the middle ground between these extremes. Web presenters can provide an interactive experience without imposing the burden of manual navigation. Presenters know site terrain better than viewers, and they can improve satisfaction and productivity by actively guiding the viewer experience. Adaptive presentation methods will be characterized by presentation engines and virtual sites. XML-based presentation models will enable adaptive presentation and expedite its adoption.

Adaptive Presentation: The Middle Ground
Some Web presenters are demonstrating their impatience with the extremes of high-end dynamic presentation and low-end static navigation by migrating slideshow content to the Web. They have the right motivation and they're moving in the right direction. But migrating conventional slideshow content is a transitional (and suboptimal) solution. This approach seems quick and easy, but it has serious limitations. Slideshow content is inherently static and monolithic, and it lacks the flexibility/agility of pages constructed from Web objects. Conventional slideshow applications aren't optimized for Web presentation, and they don't support essential features like auto-advance across multiple objects. The Web environment needs presentation solutions optimized for presentation of Web content in slideshow fashion - not suboptimized versions of desktop applications.

Viewers need more active content and presenters need more flexible content. Those requirements aren't supported by the current model of Web presentation or the current array of presentation environments. They demand a new presentation paradigm and a new set of presentation solutions. The middle ground between high end and low end is a vast wasteland, devoid of practical alternatives. It's where most of the progress will occur in the next development cycle (see Figure 1). Emerging alternatives are beginning to populate the territory. This segment will be characterized by relatively radical, discontinuous innovation and the emergence of disruptive technologies. The slideshow-migration trend described above signals the need for more dynamic and flexible content. The real answer to this need isn't migration of slideshow content to the Web. It's continued design and implementation of content optimized for the Web - acceleration of that trend, including production of more graphically oriented content - and presentation of that content as objects in slideshow format.

The static, hierarchical Web site as we know it will gradually disappear. Web sites will gradually become "vessels of objects" that can be presented dynamically and flexibly under various circumstances. Instead of being confined to a hierarchical, static identity, Web sites will become virtual "receptacles of potential." Presentation engines will unleash that potential, producing adaptive sites. A presentation engine includes server-side components for static and dynamic assembly of presentation objects and a client-side presentation component for accelerated delivery of objects to the user interface as directed by the assembly components (see Figure 2). Assembly and presentation components interact on the basis of presentation specifications, and XML will be the format of choice for most interactions.

Just as current Web publishing technology produces coherent Web pages from individual objects, presentation engines produce coherent presentations (site "views") from individual pages (pages that are, in turn, constructed dynamically from individual objects). In the adaptive scenario, individual Web pages aren't fixed in location and limited in purpose - they become flexible resources for general use within the object portfolio. The rapid rise of site-based search illustrates this trend. Site-based search has proven to offer a more flexible method of content delivery than hierarchical navigation, and represents the majority of the search opportunity in general.

The combination of Web sites as vessels of objects (and Web pages as objects) plus emerging platforms for composing dynamic presentations from object portfolios defines the next generation of Web presentation. Presentation engines as "object handlers" will emerge in nearly every Web context, transforming inherently static content into dynamic experiences. Choreography will become a dominant motif as Web designers assemble the elements of their object universe to create the desired effect across time. Web content will dance - or walk, or run, or crawl - depending on the context and preferences of the presenter and viewer. Object handlers will serve as a "content bus" that operates on a layer separate from the content itself, nonintrusively organizing and accelerating it.

Content (and content development tools) will improve incrementally to leverage the new opportunities that presentation engines provide. But the presentation engines themselves will provide the most interesting developments. They'll leverage the Web services model to create presentations without reprogramming content, and without installing components in the server or client environments. They'll focus on assembling coherent, television-like viewing experiences from discrete objects. Just as component-based system development is object assembly across a landscape of functionality, next-generation Web presentation is object assembly across a landscape of time. Just as dynamic content frameworks like JSP and ASP produce modular presentations of content from individual objects at a point in time, presentation engines produce modular presentations of content from individual objects across a period of time. Just as HTML governs the presentation of individual Web pages, XML-based presentation specifications govern the presentation of entire page sequences (see Figures 3 and 4). The document-type definition (DTD) for adaptive presentation represents a universally available "presentation protocol" that any presentation service can access. XML-based presentation specifications enable seamless interaction of diverse server-side assembly components with client-side presentation components (see Listing 1).

Broader Implications for XML and Web Services
Besides enabling interaction among the assembly and presentation components of a particular presentation engine, XML-based presentation specifications enable decoupling of content sets from presentation services. Any (XML-based) presentation environment can access any content set that conforms to the adaptive presentation DTD (see Listing 2).

The Web Service Choreography Interface (WSCI), an interface description language for complex, multicycle transaction sequences recently proposed by Sun Microsystems and BEA Systems, recognizes the need for definition of Web services that operate across a period of time instead of at a point in time. The WSCI experience might suggest an analogous Web Service Rendition Interface (WSRI) that governs single-cycle presentation sequences (see Table 1).

Application Development and Market Acceptance
Existing Web browser and database technology enables a standards-based environment that accommodates either static, manually defined content or dynamic, automatically defined content. Dynamic formats include both query results and extract results. Presentation specifications include an array of presentation objects and an array of presentation attributes that govern presentation behavior. An emerging XML-based presentation model will enable a universe of presentation objects to interact seamlessly with a universe of presentation environments.

This new presentation paradigm will establish entirely new presentation possibilities. Because presentation engines are economical and easy to implement, they extend the potential for dynamic presentation to all sites and whole sites. Presentation engines will become the PC of Web presentation by making dynamic presentation widely available. As dynamic presentation becomes widely available, it will become pervasive. Viewers will gradually experience the Web in a whole new way.

Because presentation engines interface easily with existing capabilities like search functions, e-mail applications, and content management systems, they'll also become the spreadsheet of Web presentation. Presentation engines will find a diverse, almost unimaginable array of applications. Besides presenting site and catalog tours, they'll present query results at both the site and portal levels and they'll bring life to e-mail presentation. Scrolling through long, tedious e-mail messages will give way to lively presentations of individual, Web-based objects. Presentation engines are equally capable in the Internet and the intranet/extranet environments, and they'll serve objects adeptly within commerce hubs, corporate libraries, and document management systems.

A cluster of new providers will emerge with various offerings differentiated by their inherent functionality, features, and architectural configurations. It would be no more logical for individual applications to develop dedicated presentation environments than it would be for those applications to spawn their own Web browsers. They'll leverage third-party presentation services that deliver their content to the Web browser in standard formats, providing a critical mass of functionality for presenters and a consistent interface for viewers. Nearly every application that currently presents Web content in static mode will integrate with an object handler as a "content driver" to produce a more dynamic viewing experience.

Competition will emerge around various approaches to the new paradigm, but the landscape will be dominated by new entrants with fresh, original thinking that will bring flexible and low-cost alternatives to light. An XML standard for a common presentation specification will enable various "presentation brokers" to process their unique formats interchangeably. Presentation engines also support audio content, and they'll be adept at integrating aural and visual objects into seamless multimedia presentations. They'll also allow for sharing of control between presenter and viewer, and they'll provide rich, accessible annotation features that preserve viewer orientation.

Site viewers (Web viewers, content viewers) will become as common to the Web environment as document viewers (Adobe's Acrobat Reader) and media players (Macromedia's Flash, Real Networks' RealPlayer, Microsoft's Media Player). They'll make the typical experience of Web viewing more continuous - more like viewing television. The most interesting developments for viewers will be viewer-initiated composition and automatic generation of presentations without presenter intervention. Viewers will use simplified versions of presenter-oriented tools to compose dynamic presentations of their favorite Web content. And they'll invoke "automatic composition" functions to explore the depths of their favorite sites, effortlessly. The emergence of automatic composition will instantly unleash storehouses of existing Web content for dynamic viewing. With that development, the Web browser will graduate from its current status as a mere pointer to its ultimate role as a true browser.

These new presentation capabilities will be especially valuable to business users in the disciplines of knowledge management, corporate memory, business intelligence, decision support, project management, and operations management. Anywhere clusters of knowledge accumulate, object handlers will serve as convenient instruments for aggregating the clusters into coherent and reusable "knowledge objects" and "learning objects." The ability to create shared experiences by building and preserving clusters of Web objects - as quickly and easily as using e-mail and word-processing applications - will mitigate information overload and transform the potential for groups to engage in collaborative design and organizational development. An adaptive, distributed approach to interactive learning environments will surpass the current, monolithic approaches that co-locate the integrative principle (library systems) and the productive principle (book publishing). Although adaptive presentation of Web objects will find a beachhead in interactive learning and knowledge management applications, it will enter the mainstream and impact the consumer segment in the realms of interactive journalism and interactive commerce. Adaptive presentation will shift the emphasis in commerce from "selling" to "learning," recognizing the goal-driven nature of consumer behavior and introducing a new era of "commerce as learning."

Despite the ultimate value of manual composition, the compelling experience of automatic composition will be the fire-starter for adaptive presentation. It will bring rapid acceptance of the new medium among Web viewers. Viewer acceptance will promote adoption of the new paradigm by Web presenters, and Web viewers will find ever-increasing amounts of precomposed content at their disposal. As the Semantic Web gains momentum and unified classification of Web content becomes more pervasive, it will feed the "object appetites" of presentation engines and further stimulate their adoption.