HANd:A New Transcoding Technique

for PDA Browsers

Enrique Costa Montenegro

Departamento de Ingeniería Telemática

ETSI Telecomunicación

Universidad de Vigo, Spain

kike@det.uvigo.es

• HANd: Hierarchical Atomic Navigation

• New transcoding technique for WWW navigation on PDA

• Keeps all original information

• One navigator page and several atomic pages

• Replaces unreadable elements by icons

Introduction

• Fragmentation of original page into zones• Zones are sets of elements (pictures, links,

text, tables...)• Only one zone is displayed at original scale• Navigator page: a reduced overview of the

original page, with links to atomic pages• Atomic pages: readable elements or zones,

pieces of the original page

HANd philosophy

• Representations of elements– Reduced version: if readable– Representative icon: if reduced element or zone is

unreadable

• Dependence between elements: an element is unreadable if all its descendants are unreadable

• Navigation page: representatives in the same relative locations of original elements

HANd philosophy (II)

HANd example

HANd example (II)

HANd example (III)

HANd example (IV)

HANd example (V)

HANd page generator

• Two stages– Preprocessing stage– Conversion stage

HANd Page Generator (II)

• Preprocessing stage– Input: HTML documents– Conversion of HTML to XHTML using Jtidy– Obtain DOM tree from XHTML using a DOM

parser– DOM tree: representation of XHTML

document as a tree of nodes, each node is an element of the XHTML document

HANd Page Generator (III)

• Conversion stage– Input: DOM Tree– Apply visibility and transformation rules to

DOM Tree– Obtain new DOM trees– Convert new DOM trees to navigation page and

associated atomic pages

Transformation rules: readability

• A PDA-to-PC screen area ratio is calculated, R<1, used to reduce elements

• Text: new font area is calculated, move to atomic page if not readable

• Images: new size is calculated, if original picture is small enough, it wont be resized

• Readability threshold, label unreadable elements with 1, 0 otherwise

Transformation rules: pruning

• Labels are propagated across the DOM tree

• Branches without 0 labels are pruned

Transformation rules: results

• Nodes with label 0 (readable) are substituted with reduced representatives

• Nodes with label 1 (unreadable) are replaced by an icon, with a link to the atomic page with the original information

• Adjacency rule: all adjacent icons associated to elements of the same type are represented by a single icon

Transformation rules: example

Conclusions

• HANd: New Transcoding Technique for PDA

• Advantages– No information loss: all elements in atomic

pages– Navigator page: readable overview of the

original page– Valid for all WWW documents and navigators

Questions!!

Example:

What is the ´d´ in HANd?

The End