Ubiquitous

"Ubiquitous"

Something that is common place
Something that is taken for granted and fades into the background
Something that so familiar it takes little conscious effort to use

Ubiquitous computing

The pervasiveness of networked computing devices in everyday life
"Everything from the family fridge to the office coffee pot—as well as heating, cooling, and security systems—will be managed through the Internet, possibly using souped-up mobile phones doubling as universal remote controls", Vint Cerf, co-designer of TCP/IP

Today’s devices will disappear. Electronics will instead be embedded in our environment, woven into our clothing, and written directly to our retinas from eyeglasses and contact lenses, predicts inventor, entrepreneur, author, and futurist Ray Kurzweil. “Devices will no longer be spokes on the Internet—they will be the nodes themselves,” he says.

From Red Herring, April 10, 2006
The success of the Web as a pervasive technology
The opportunities for the Web to include a much wider range of devices and applications

Introduction to the Ubiquitous Web

Making it easier to develop distributed applications
Applications involving multiple devices with widely varying capabilities
Reaching out into the physical world of sensors and effectors
- Increasing range of networked devices in everyday environments
Context awareness - dynamically adapting to the users, devices and environment
Based upon familiar Web technologies such as markup and scripting
Providing clean abstractions on top of other technologies
- Events instead of raw access to HTTP
- Using hierarchy of DOM nodes to represent the device context (DCI)
Declarative models encompassing clients and servers
- Blurring the distinction between the two
Importance of the Semantic Web for describing resources
- Discovery and binding into application sessions
- Trust/identity relationships

The aim is to make it easier to create distributed applications that are context aware and which dynamically adapt to users, devices and the environment. These applications may involve multiple devices of widely varying capabilities. The Ubiquitous Web will reach out into the physical world of sensors and effectors. Web technologies such as markup and scripting have the potential to simplify the development of applications, providing clean abstractions on top of other technologies. This involves declarative models that encompass clients and servers, and which blurs the distinction between the two. The Ubiquitous Web is coupled to the Semantic Web through the need to describe resources for the purposes of discovery and for trust/identity relationships. This is expected to lead to work on signed RDF.

The Ubiquitous Web hides the details of how events are conveyed between devices, which should be welcome to developers struggling with today's AJAX-based applications. The higher level treatment is also essential for preserving the sandbox security model whilst allowing for eventing between multiple devices. By contrast, AJAX provides low-level access to HTTP, but is limited to the server that the Web page was downloaded from. Workshops

Device Coordination

The means for discovering and binding resources into application sessions
Based upon a means to describe user preferences, device capabilities and services as a basis for discovery
For a printer this may involve questions such as
- Does it support color?
- What about double sided (duplex) printing?
- Does it have enough paper and toner for the job?
- May necessitate the use of a separate service for converting the data into a format the printer accepts
- Will the printer send a message when the job is done or when a problem occurs?
- Where is the printer situated? Is it nearby?

Discovery and Binding

How can a Web application discover a resource?

The resource might be
- already exposed via the DCI
  - representation of the device context as a hierarchy of DOM nodes
  - covers user preferences, device capabilities and environmental conditions
  - changes are signaled via DOM events
  - binding adds new nodes to the DCI
- available on the same device
- available on a local network
- available on a remote server
Discovery starts by naming the resource or describing it in some way
- in a markup language this could be as an element that will stand for the resource once it is bound
- discovery mechanism could be implicit or named in some way, e.g. by a URI
Resource binding is for the duration of an application session
- temporary and persistent sessions applications join and leave
- sessions as first class objects (resources) named with URIs

Declarative Application Modelling

Traditional view of Web in terms of pages
Breaks down when devices have widely varying capabilities
Page designed for one device may be impractical on another
Transformational techniques for static pages break down for AJAX based applications
Solution is to describe application at a level that encompasses clients and servers
Layered models allow lower levels to adapt to context without impacting higher levels
Range of modeling techniques, e.g.
- Event drivent state transition models
- Task/sub-task models
- Policies for resolving multiple/conflicting goals
- Mechanisms for supporting remote user interfaces via events

Event Driven State Transition Models

Network of named states together with an application data model
Application is deemed to be in one named state at a time
States are associated with event handlers that determine what actions to take upon an event
Actions may be conditional on application data model and on event history
Actions may update the data model, switch to a new named state, and even raise events
Recursive models include support for call/return semantics
Hierarchical models decompose named states into substates
- inheritance of event handlers from parent state
- initialization and clean-up actions
- possibility of concurrent active states
SCXML is a W3C proposal for an XML language for Harel State Charts

Task Models

Each task describes how to complete the task by doing a number of other tasks
- alternative sub-tasks when there are several ways to do something
- a strict/partially ordered sequence of sub-tasks
- opportunistic or even concurrent execution of tasks
- tasks are associated with pre and post conditions
- conditions and actions in terms of events and data models
- opaque tasks that aren't further decomposable
- defining tasks as variants of other tasks
- agenda mechanisms, e.g. goal stacks
- history mechanism recording which tasks have been carried out and in what order
Declarative task models can be used top-down or bottom-up, or some combination of the two
- top-down when the application has the initiative
- bottom-up when the user has the initiative, and where the application works out what the user is doing and offers advice

Policies

Policy based layout describes goals for each page
- e.g. establishing the corporate brand, situating the user within the website, navigation and search facilities, advertising links, the main topic, and related sidebars
Policies determine what compromises are appropriate
- assembling and styling Web pages in terms of component templates for markup and associated style sheets, scripts and images, etc.
- expressed as a combination of declarative rules and object oriented layout mechanisms
- conditional on user preferences and device capabilities, etc.
- on a small device, low priority goals may be dropped and others addressed using smaller graphics and less text, and possibly through using a sequence of pages
Policies may describe conditions for access to services and for sharing information with others

Remote User Interfaces

Run the application logic on a server and drive the remote user interface via an exchange of events
User interface is described in XML and downloaded to the client
- e.g. combination of XHTML, SVG, XForms, ...
UI events are forwarded to the server
Server responds by sending the client events to update the UI via changes to the XML DOM tree
REX is a W3C proposal for a means to serialize DOM events as XML
Current draft only deals with mutation events
Application to streaming updates to SVG graphics
W3C Multimodal Interaction working group is looking at life cycle events
IETF Widex working group is addressing binding to protocols, e.g. SIP, HTTP, RTSP, BEEP

Trust, Identity, Privacy and Security

An effective treatment is essential for distributed applications

Which component can be trusted to safely add a particular capability to a given web browser?
Is the particular capability itself safe to use and I am permitted to use it?
How will information on my preferences be handled by a server?
How can I control who has access to what information about me?
This is critical to realizing the opportunities for servers to combine information and services involving multiple people/organizations (mashups)
Identity systems
- must only reveal information with the user's consent
- should only reveal the minimum information necessary
- must support requirements for audit trails
Will digitally signed RDF be useful as part of the solution?

More details were presented at WWW2006 in the panel session on Challenges in Web Security.

Next Steps

Following on from the Ubiquitous Web Workshop, 9-10 March 2006, Keio University Tokyo

Collaborative study:

Public Ubiquitous Web Wiki + Mailing list
- To clarify vision, relate to existing work and identify scope for standardization work
Application Modeling Workshop
- Declarative techniques for modelling Web applications at a level that includes both clients and servers
Draft charter for further standards work
- Web application modelling
- Device coordination
- Resource descriptions
- Modeling trust relationships
Series of small specifications that can be progressed quickly
Your assistance is welcomed!