Aurora: A Conceptual Model for Web-content Adaptation

to Support the Universal Accessibility of Web-based

Services

Anita W. Huang, Neel Sundaresan

Presented by Allan Spale – EECS 578

Introduction

• The World Wide Web is a place for information and commerce

• Electronic information distribution removes previous accessibility barriers

– Flexible presentation of information

• The use of HTML on web pages removes its meaning and functionality

Problems Using HTML

• Makes “comprehension, navigation, and input difficult or completely impossible”

– Literal content

– Services

Improving Web Accessibility

• Low-level accessibility

– Provide alternatives to different media types

• High-level accessibility

– Make Web services in a service domain accessible to a large audience

Description of Aurora

• Aurora provides high-accessibility

– Analyzes web objects according to their functions within a particular domain of Web pages

– Based on a transaction model• Provides a framework for encapsulating

general goals within a service domain

• “[P]rovides a set of schemas that describes how a user obtains the identified services”

Transaction Model and XML

• Converts web data in service domains into XML

• XML data is input to interface adaptors

• Each interface adaptor creates the new Web page

User Scenario

• Blind user visits an on-line auction site

• Semantic obstacles appear on the page to “hide” information necessary to make a bid

– Aurora can improve this situation• Access the site using Aurora

• Aurora will render the page in a format acceptable to the user

Electronic Information Accessibility

• Web Accessibility

– “…add provisions to existing Web pages.”

– Focus on low-level issues

• Provide alternate presentation forms for different electronic media

Electronic Information Accessibility

• Adaptive Hypermedia

– Offers adaptive measures for “new Web-based information systems”

– Challenges

• Incorporating each user’s goals into a user model

• Structuring of information to permit translation across presentation formats

Electronic Information Accessibility

• Wrapper generation

– Wrapper applications have two roles

• Extract information from data

• Reorganize the data into structured forms

Aurora’s Transaction Model

• Specifies the user’s abstract goals

• “Scrapes” information from the Web page relevant to the user goals

• Relevant to a specific service domain

– Common services

– Sequences of tasks to receive services

– Declaration of specific steps to accomplish tasks

Transaction Model Specifics

• Services

– Analyze a service domain to determine “a discrete, common set of abstract user goals”

• Transactions

– Tasks to be done to receive a service

Transaction Model Specifics

• Task Hierarchical Work-Flow Model

– Create a node for each step

– Connect the nodes according to sequences of steps

– Label transitions between nodes where appropriate

Web Content Classification

• Transaction model tracks each page’s function in relation to the user goal

– Model applies to sets of web pages

• Transaction model used to transform content without altering Web pages

• Can provide additional structure to data at the source

Benefits for Universal Usability

• Consistency

– Currently web sites differ in many ways from one another

– Transaction model reduces this problem

• Consistent interface

• “[M]odel specifies a common set of goal-orientated transactions for each service domain”

Benefits for Universal Usability

• Simplicity

– Web pages usually contain some irrelevant information in relation to user goals

– Solution

• “Scrape” information from the Web page according to the transaction model that encapsulates the user goal

Benefits for Universal Accessibility

• Adaptability

– Semantic information is implicit according to its appearance

– Solution

• Use a transaction model to extract functional semantics and add semantic markup

• Interface adaptors take output from transaction model to create presentations for a user group

XML Framework

• eXtensible Markup Language used for creating structured data

• The transaction model that maps web objects can be stored using a DTD (Document Type Definition)

• XML data will maintain the functional semantics which will allow interface adaptation

Using DTDs for Translation Schemas

• Describe abstract tasks for every service goal

• Contains the semantics and sequence of task steps

• Together with the “scraped” web page data, Aurora can write the transaction document in XML

Operation of AuroraUsing XML

• User requests a Web page

• Aurora downloads Web page and recreates the page

– Downloads the web page

– Extracts information and objects

– Creates XML document using a DTD

• Aurora uses the interface adaptor on the XML document to create the new HTML page

Example of User-Aurora Interaction

• User views Aurora-generated Web page of an auction site converted from XML to be displayed in HTML

– This is a node in the current transaction document

– Current node is the item for bidding

– Hyperlinks in the generated HTML page lead to other nodes in the XML document

Example of User-Aurora Interaction

• User selects a hyperlink

– Each XML hyperlink will link to a Web page and a transformation rule

– Aurora will download the web page and apply the transformation rule

– A hyperlink links to a downloaded HTML document and the extracted XML segment

Example of User-Aurora Interaction

• Present the downloaded page to the user

– XML segment serves as input to the interface adaptor

– Aurora will use the XML segment as input to the interface adaptor

– The result is a displayable web page typically in HTML

• The process repeats for future interactions

Aurora’s Method ofContent Extraction

• Uses PatML

* XML transformation tool that…match[es] and transform[s] patterns in XML documents

– Three parts to a PatML transformation rule

* XML pattern to match (source)

* Way to transform the matched pattern (target)

* Java code block to invoke on the pattern (action)

*Items quoted directly from the paper

Aurora’s Method ofContent Extraction

• A transaction step has one PatML rule

– This rule will be used for all pages on a single Web site

• Three parts of PatML rule, specifically

– Source: matches HTML tag patterns

– Target: turns matched part into an XML part

– Action: gets the XML part and returns its output

Aurora Architecture UsingWeB Intermediaries (WBI)

• “…enables applications to manipulate HTTP streams during a Web transaction.”

• Three components– Request editor

• Interface adaptor translates user actions

– Document generator• Downloads web pages, applies transformation rules to web

pages, returns XML parts

– Document editor• Interface adaptor adapts requested Web pages

Extensible Architecture

• Interface Adaptors

– “[S]ends XML data and receives user responses.”

– Transforms XML data into a low-level presentation format

– DTDs used to help generate additional semantic meaning

– Two types of adaptors• HTML text-only, Icon-enhanced HTML

Extensible Architecture

• Service Domains and Web Sites

– XML configuration document stores all service domain definitions

• Adding new domains or sites into a domain only involves editing the XML document

• Transcoding Engine

– Aurora can use other “transcoding and/or extraction technologies”

• Currently uses PatML within its transformer interface

Implementation Details

• Java plug-in for “WBI using PatML as the transcoding tool”

• Schemas include auction and search engine service domains

• PatML rules written for specific sites– Auctions: eBay, Yahoo! Auctions

– Search Engines: AltaVista, Yahoo!, Google

• Uses previously mentioned interface adaptors

Summary

• Transaction Model

– Extracts semantics of web sites within selected service domains

– Uses XML to maintain structured data from Web pages

• Semantic Transcoding System

– “Scrapes” and adapts web pages to help the user accomplish abstract goals within an XML framework

Summary

• Extensible Structure

– Supports custom adapters that convert XML data into some presentation format

• Improvements

– Needs “to support semi-automated or automated rule generation and maintenance”

Resources

• XML 1.0

– http://www.w3c.org/TR/REC-xml

• Web Content Accessibility Guidelines 1.0

– http://www.w3c.org/wai-webcontent

• PatML

– http://www.alphaworks.ibm.com/aw.nsf/techmain/00ADAB375888BDD2882566F300703F7F?OpenDocument

• WeB Intermediaries (WBI) Development Kit

– http://www.almaden.ibm.com/cs/wbi/doc