W3C Workshop on Delivery Context

Position Paper

Luu Tran
Sun Microsystems, Inc.


In this paper we outline the apparent overlap in the scopes of the Device Independence Activity, the Voice Browser Activity, and the proposed Multimodal Interaction Activity.  We go on to identify current limitations of single web authoring approaches for multiple delivery contexts that impose a tradeoff between interface optimization for limited devices and ease of use for customization.  We also discuss the need for current device independent delivery systems to limit the level of content adaptation to multiple delivery contexts for the sake of performance and maintainability.  We then raise the question of whether delivery context considerations need to be incorporated into service and application specific preferences.  We conclude with a number of recommendations that we hope will provide input into the rechartering of Working Groups within the Device Independence Activity.

Multimodal Interaction

The Device Independence Principles [1] document states:
"The focus of the W3C Device Independence Activity is on making the Web accessible anytime and anyhow, in particular by supporting many access mechanisms (including mobile and personal devices, that can provide access anytime) and many modes of use (including visual and auditory ones, that can provide access anyhow)."
This focus seems to be closely related to the efforts of the Voice Browser Activity [2] and the proposed Multimodal Interaction Activity [3].  While we acknowledge that the voice browser and multimodal interaction efforts warrant the attention of Working Groups, we are not clear on the need for three separate activities.  According to the W3C Process Document [4], Groups are created within Activities and the creation of single-group Activities should be the exception, not the norm.

We also would like to know how device independence is or is not distinguished from multimodal interaction.  Where does independence from a particular mode leave off and the ability to use multiple modes begin?

Single Web Authoring Limitations

While single web authoring for multiple delivery contexts is clearly a goal, current authoring approaches present a difficult tradeoff.  On the one hand, the multitude of devices that are now accessing the web and the expected introduction of many more types of devices in the future represent vastly disparate capabilities.  Limited devices, where screen real estate, bandwidth, etc., are at a premium require careful design of interfaces to maximize their usefulness.  On the other hand, the huge amount of content on the web will continue to grow and change and authors need to easily customize the presentation of this content.

Current authoring solutions either provide the flexibility to optimize interfaces to specific devices while forcing authors to manage the complexity of multiple delivery contexts, or impose a proprietary abstract intermediate representation that cannot be adequately adapted to fully utilize the capabilities of all devices.

Device Independent Delivery Systems

The promise of a device independent delivery system is that it can identify the delivery context and adapt content appropriately and sufficiently from the perspective of the user and the author of the content.  This often involves dynamic determination of the delivery context capabilities and associated user preferences and then some processing to convert the content into a suitable form.

To achieve the efficiencies necessary in current high performance and maintainable systems, the identification and adaptation processes must be constrained.  Delivery contexts must currently be grouped together and preconfigured instead of dynamically constructed for every request.  Also, content adaptation must currently be done primarily through a selection process instead of a transformation process, again because of performance requirements.  Therefore, only a subset of all possible permutations of delivery context capabilities and preferences can be handled in current systems if high performance and maintainability are required.

Service and Application Preferences

While the CC/PP Working Group [5] has defined how user preferences related to device capabilities are structured and handled, it is not clear how to structure and handle user preferences for service and application parameters that are device specific.  For example, a user may only be interested in new messages when accessing his or her email from a phone as opposed to a personal computer.  Ultimately, device capabilities and preferences should be independent of service and application preferences.  But current systems often require a tight coupling and manual user configuration of the relationship between these preferences.  How deep should awareness of the delivery context go?  Should services and applications change their behavior based on different delivery contexts?


We recommend that the Voice Browser Activity and the Multimodal Interaction Activity be merged under the Device Independence Activity and their respective Working Groups be brought over under the latter; this may need a slight modification of the Device Independence Activity, and perhaps a new name for it.

We would also like to see further work in the Device Independence Activity to address:

  1. current limitations of single web authoring approaches,
  2. the needs of high performance and maintainable device independent delivery systems, and
  3. the role of services and applications in delivery context awareness.


[1] "Device Independence Principles",  http://www.w3.org/TR/2001/WD-di-princ-20010918/
[2] "Voice Browser Activity", http://www.w3.org/Voice/
[3] "Multimodal Interaction Activity Proposal", http://www.w3.org/2001/11/multimodal-activity.html
[4] "W3C Process Document", http://www.w3.org/Consortium/Process-20010719/activities.html
[5] "Composite Capabilities/Preferences Profile Working Group", http://www.w3.org/Mobile/CCPP/