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 Aurora Using 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 of Content 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 of Content 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 Using WeB 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 – Web Content Accessibility Guidelines 1.0 – PatML – 5888BDD F300703F7F?OpenDocumenthttp:// 5888BDD F300703F7F?OpenDocument WeB Intermediaries (WBI) Development Kit –