Annotation-based Web content Transcoding

Masahiro Hori, Goh Kondoh, Kouichi Ono, Shin-ichi Hirose, and Sandeep Singhal

IBM Tokyo Research Laboratory

Outline

• Introduction• Annotation Framework• Annotation-Based Transcoding System• Page Fragmentation • Discussion

Introduction

• Content adaptation is crucial for transparent Web access under different conditions. Such content adaptation also called transcoding.

• Results in better presentation and faster delivery to the client device.

• The role of annotations is to provide hints that enable a transcoding engine to make better decisions on transcoding.

• Existing Web documents are associated with content adaptation hints as separate annotation files.

Introduction(Cont.)

• Transcoding system with particular focus on the authoring-time integration between a WYSIWYG annotation tool and a transcoding module.

• Finally, after giving an example of content adaptation using a page fragmentation module for small-screen devices,

Annotation Framework

• The role of annotation is to characterize ways of content adaptation rather than to describe individual contents.

• The framework needs to specify a vocabulary for constraining the possibilities for decomposition, combination,and partial replacement of contents.

• The Resource Description Framework(RDF) is used as the syntax of annotation files.

• The RDF data model defines a simple model for describing relations among resources in terms of named properties and values.

Figure 1: Adaptation of HTML documents for personal computing devices

Figure 2: Framework of external annotation

Annotation Framework(Cont.)

• An annotation file refers to portions of an annotated document.

• Example:/HTML/BODY/P[3] points to the third P element of the BODY element of the annotated document.

• Annotation Vocabulary for Transcoding ：The vocabulary includes three types of annotation ：alternatives, splitting hints and selection criteria.

Annotation Framework(Cont.)

• Alternatives <pcd ： Alternatives> For example, a color image may have a grayscale image as an alternative for clients with monochrome displays.A transcoding proxy selects the one alternative that best suits the capabilities of the requested client device.

• Splitting hintsAn HTML file may be divided into multiple pages on clients with smaller display screens.The <pcd:Group> tag specifies a set of elements to be considered as a logical unit. Another usage is to provide appropriate page break points.

Annotation Framework(Cont.)

• <rdf:Description about="http://foo.com/catalog.html#xpointer(//H2[2] to //P[3])" > <pcd:Group /> </rdf:Description>

• Selection criteria– Client device capability– Resource requirements– Role of an annotated element– Importance of an annotated element

• The role tag is provided with a value attribute,which may be either proper content,advertisement,decoration or icon.

Annotation Framework(Cont.)

• <pcd:importance> tag specifies the priority of an annotated element. The importance value ranging from -1 (low) to 1(high).

• An element may not be sent to a lightweight client, when the element is provided with a decoration role and a low importance value such as –0.2.<rdf:Description about="http://foo.com/catalog.html#//IMG[1]" > <pcd:role value="decoration" /> <pcd:importance value="-0.2" /> </rdf:Description>

Annotation-Based Transcoding System

• Transcoding Architecture

• Computational entities stay along the Web transaction path are called intermediaries. The intermediary-based approach allow us to provide a transcoding module as an intermediary without modifying browser or server.

Annotation-Based Transcoding System

• WBI ： a programmable proxy server for HTTP requests and responses.

• The processing is controlled by plugins available at an intermediary processor.WBI’s plugin is constructed from three fundamantal blocks ： Monitors,Editors and Generators.

• It realized a page-splitting module as a WBI plugin that adapts a requested document to the capabilities of a particular client.

Figure 4: Annotation-based transcoding by a page-splitting plugin

Annotation-Based Transcoding System

• Authoring-Time Transcoding– Annotation description may be too complicated for a si

mple source tag editor to maintain.

– It developed an annotation tool for the external annotation by extending an existing HTML authoring tool.

– It consists of a WYSIWYG editor, a source editor and a previewer.

Figure 5: Annotation tool configuration for authoring-time transcoding

Annotation-Based Transcoding System

– When a previewer is invoked, a transcoding proxy is called over HTTP and the corresponding annotation is applied to the subject document.

– The annotation tool is fully integrated with the transcoding proxy, users can see the results of content adaptation and revise annotation on the fly.

Page Fragmentation

Table[1]

Table[2]

Table[3]

Search form

Side bar Menu

omitted

Page Fragmentation

• Figure 9 illustrate how the news page will be fragmented in a small display.

• According to the header role of the top table, the same header appears in the previewer as in the original page.

• The “Side bar ” anchor in the center is created in accordance with the auxiliary role.

Figure 9: Annotation for fragmentation of an actual

news page

Discussion

• The purpose is to distinguish content with meta information.

• The external annotation approach allows such application-specific meta-information to be specified separately from the HTML spec.