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An XML Object Database:
Design Implementation and Applications
Ching-Long Yeh 葉 慶 隆
Department of Computer Science and Engineering
Tatung University
Taipei 104, Taiwan
ROC
Introduction
• XML improves upon HTML in
– capturing the meaning of a document and
– extending the tag set.
• At the same time, it also reduces the complexity of
SGML.
• It is believed that XML will soon be the standard of
data exchanges on the Web.
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Introduction
• Due to lack of indices in files, we are not able to
make full use of the meaning (or metadata) in an
XML document, if it is stored in a file.
• Since an XML document can be easily viewed
according to the object-oriented model, a promising
solution is to employ object database technology to
manage the access of XML documents.
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Introduction
• In this talk, I will present our research work in
– the design and implementation of an XML object
DB,
– an extensible template-based query interface to
accessing to XML object database, and
– the applications implemented on the XML object
database
• content-based video query system, and
• electronic commerce
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The Remainder of the Talk
• An Introduction to XML
• Design and Implementation of an XML Object
Database
• An Extensible Template-based Interface
• A Content-Based Query Interface to Video Database
• XML Object Database and Electronic Commerce
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An Introduction to XML
HyperText Markup Language
• HTML is a language used to create hyperlink text in
the WWW.
• The text is presented according to a set of predefined
tags.
• The definition of tags is based on the Document Type
Definition (DTD) of SGML.
• In other words, HTML is an application of SGML in
the WWW.
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Standard Generalized Markup Language
• Central to SGML is the concept that documents have
structure, content, and format.
• These three ingredients combine to form a document.
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Content
• What is Content?
– Content is the actual data within a document.
– The words and illustrations that make up a bicycle assembly
manual are its contents.
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Format
• What is Format?
– Format consists of how the words, sentences, and
paragraphs are visually presented and distinguished from
one another within a document.
– Boldface for title, italics for special terms, and blank lines
between sections are examples of document formats.
– People often confuse format with structure.
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Structure
• What is Structure?
Coconut Pudding
12 ounces coconut milk
4 to 6 tablespoons sugar
4 to 6 tablespoons cornstarch
Recipe
Title
Ingredient
List
Ingredient
3/4 cup water
Pour coconut milk into saucepan.
Combine sugar and cornstarch; stir in water
and blend well.
Stir sugar mixture into coconut milk; cook
and stir over low heat until thickened.
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Instruction
List
Step
11
Document Type Definition
• Defining structures in SGML
– The structure of a document  its type  is defined by a
document type definition, or DTD.
– The DTD lays out the rules for a document through the use
of elements, attributes, and entities.
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Document Type Definition
• A DTD looks like
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
recipe -- ( title,
ingredientList,
instructionList)>
title -- (#PCDATA)>
ingredientList -- (ingredient*)>
instructionList -- (step*)>
ingredient -- (#PCDATA) >
step -- (#PCDATA)>
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Document Instance
<!DOCTYPE RECIPE PUBLIC ”recipe" ”recipe">
<RECIPE><TITLE>Coconut Pudding</TITLE>
<INGREDIENTLIST>
<INGREDIENT> 12 ounces coconut milk</INGREDIENT>
<INGREDIENT> 4 to 6 tablespoons sugar </INGREDIENT>
<INGREDIENT> 4 to 6 tablespoons cornstarch </INGREDIENT>
<INGREDIENT> 3/4 cup water </INGREDIENT>
<INGREDIENTLIST>
<INSTRUCTIONLIST>`
<STEP> Pour coconut milk into saucepan. </STEP>
<STEP>Combine sugar and cornstarch; stir in water and blend well.
</STEP>
<STEP>Stir sugar mixture into coconut milk; cook
and stir over low heat until thickened.
</STEP>
…
</INSTRUCTIONLIST>
</RECIPE>
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HTML, SGML, XML
• HTML helped establish the Internet by providing a
universal way to present information.
• However, HTML only addresses the presentation of
data.
• Using SGML, user can add structure along with the
content of a document.
• However, SGML has proven too heavy-weight for the
Internet.
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Extensible Markup Language
• The XML is a simple dialect of SGML.
• HTML is sufficient for sending web pages that are
viewed by human beings.
• XML, however, adds the tags that enable computers
to understand, act on or process the information.
• XML has been designed for ease of implementation
and for interoperability with both SGML and HTML.
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XML Application Profile
•
•
•
•
•
•
Electronic commerce
Electronic data interchange (EDI)
Fine-grain content publishing
Internet search engines
Distributed application design
etc.
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Data Type Requirements of Documents
• HTML
– One file per page
– Simple uni-directional linking
• XML
–
–
–
–
–
Tens, hundreds or even thousands of objects per page
Multiple DTDs
Hierarchical structure and rich linking
Query and navigation capabilities required
Agents and business rules interact with the data
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Data Types of Storage
File System
• File system
– Store monolithic stuff.
– Folder system on top of them
– Good at storing multimedia data
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Data Types of Storage
Relational DB
• Relational database
– Tabular in nature
– Good at storing rows and columns of data like
spreadsheets and data from forms like invoices.
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Data Types of Storage
Object-Oriented DB
• Object-oriented database
– Good at managing structured, hierarchical rich
linked information.
– That’s exactly what XML is.
– XML is the object representation of data.
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Design and Implementation of an
XML Object Database
System Architecture
Schema
generation
rules
XML
rules
DTD
DTD
parser
s
t
r
u
c
t
u
r
e
Schema
generator
Schema definitions
DI parser
generator
Object definitions
DB
language
processor
User
interface
produces
Parser
generation
rules
DI parser
and object
generator
XML repository
DI
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DTD Parser
elementdecl::=
’<!ELEMENT S Name S
contentspec S? ‘>’
elementdecl(contentModel(N,C))-->
elementPrefix,
name(N),
contentSpec(C),
rightAngle.
contentspec::=
‘EMPTY’| ‘ANY’|
Mixed | children
contentSpec(C)-->
empty,{C=’EMPTY’};
any,{C={ANY’};
mixed(C);
children(C).
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Parsing Result
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
top (p,spec,div1)>
p (#PCDATA|a|ul|b|i|em)*>
spec (front,body, back?)*>
div1 (head,(p|list1
|note)*, div2*)>
name (#PCDATA)>
a (#PCDATA)>
ul (#PCDATA)>
b (#PCDATA)>
i (#PCDATA)>
em (#PCDATA)>
front (#PCDATA)>
body (#PCDATA)>
back (#PCDATA)>
head (#PCDATA)>
list1 (#PCDATA)>
note (#PCDATA)>
div2 (#PCDATA)>
[contentModel(top,seq([p/null,spec
/null,div1/null])/null),
contentModel(p,mixed([pcdata,a,ul,b,i,em]
)),
contentModel(spec,seq([front/null,body/nu
ll,back/question])/star),
contentModel(div1,seq([head/null,alt([p/n
ull,list1/null,note/null])
/star,div2/star])/null),
contentModel(name,pcdata),
contentModel(a,pcdata),
contentModel(ul,pcdata),
contentModel(b,pcdata),
contentModel(i,pcdata),
contentModel(em,pcdata),
contentModel(front,pcdata),
contentModel(body,pcdata),
contentModel(back,pcdata),
contentModel(head,pcdata),
contentModel(list1,pcdata),
contentModel(note,pcdata),
contentModel(div2,pcdata)]
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Schema Generation
defineClass 'Top' super: SingleSeq
{
instance:
'P' 'p';
'Spec' 'spec';
'Div1' 'div1';};
defineClass 'P' super: Mixed
{
instance:
List<Mixedp> mixedp;};
defineClass Mixedp super: SingleAlt
{
instance:
String pcdata;
'A' 'a';
'Ul' 'ul';
'B' 'b';
'I' 'i';
'Em' 'em';};
defineClass 'Spec' super: MultiSeq
{
instance:
List<Seqspec> seqspec;};
defineClass 'Seqspec' super: SingleSeq
{
instance:
'Front' 'front';
'Body' 'body';
'Back' 'back';};
defineClass 'Div1' super: SingleSeq
{
instance:
'Head' 'head';
List<Alt1> 'alt1';
List<Div2> 'div2';};
defineClass 'Alt1' super: SingleAlt
{
instance:
'P' 'p';
'List1' 'list1';
'Note' 'note';};
defineClass 'Name' super: Unstructured
{
instance:
String pcdata;};
...
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DI Parser
top(V) -->
stg(top),
p(P),spec(Spec),div1(Div1),
etg(top).
p(V) -->
stg(p), mixedp(Mixedp),etg(p).
mixedp(V) -->
(pcdata(Pcdata);
a(A);ul(Ul);b(B); I(I);
em(Em);{false}),
mixedp(_);
[].
spec(V) -->
stg(spec),
spec1(Spec),
etg(spec).
spec1(V) -->
front(Front),
body(Body),
(back(Back);[ ]),
spec1(_);
[].
div1(V) -->
stg(div1),
head(Head),
alt1(Alt1),
div21(Div21),
etg(div1).
alt1(V) -->
(p(P);
list1(List1);
note(Note);
{false}),
alt1(_);
[].
div21(V) -->
div2(Div2),
div21(_)
;
[].
name(V) -->
stg(name),
pcdata(Pcdata),
etg(name).
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DI Parser Generation
Rule_Head -->
Start_Tag,
Rule_Body,
End_Tag, {Semantic Actions}.
for each contentModel(ElementName,ContentStructure) do
generate the rule head for ElementName;
generate the start tag for ElementName;
generate the rule body for ContentStructure;
generate the end tag for ElementName;
generate the semantic action;
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Implementation
• We have built a prototype of the system using LPA
Win-Prolog V3.5 on personal computer.
• It consists of a DTD parser, Schema generator and
DI parser generator.
• After creating the physical store and class family for
XML documents, we can proceed to build the
database schema for DTD by executing the ODQL
codes generated by the DTD schema generator.
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An Extensible Query-By-Template Interface
to Accessing XML Document Database
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Motivation
• Vastness of search results on current WWW search
engines
• Textual-based query language with a simple Englishlike syntax is inconvenient for the user.
• Current user interfaces primarily use form-based
queries.
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Goal
• The goal is to design a convenient interface for user
to access XML document without knowing the
knowledge of the document types.
• The interface will relieve user from typing complex
query language.
• The interface should be web-based and platformindependent.
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System Architecture
Visual Query Interface
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Related Knowledge
• XML( eXtensible Markup Language )
•
•
•
•
Jasmine Database
Structured Document Database
Visual Query Facility
Java Language
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XML
• XML has the potential to be the standard of WWW
document and electronic data interchange of the
future.
• In XML, the structure of the document is defined
using a Document Type Definition (DTD).
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Recipe DTD
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Recipe Document
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Jasmine Database
• Jasmine is a multimedia object-oriented database
management system(DBMS) with built-in Webconnectivity.
• It provides a powerful Object Data Query
language(ODQL) which is very similar to the ODMG
2.0(ODL,OML,OQL) standard.
• It provides an extensive array of application
development tools, which includes JADE, ActiveX, CAPI, J-API, Weblink.
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Strucutured Document Database
• Combine structured document with OODB
technology:
– VERSO project at INRIA
– News-On-Demand Application
– Document Database from GMD-IPSI
• Other Related Document Database:
–
–
–
–
Open Text
DocBase
The Poet XML Repository
ODI’s eXcelon
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Visual Query Facility
• Query By Example (QBE)
– The interface is composed of tabular skeletons representing
tables in the database.
• Query By Forms (QBF)
– The interface is presented with a list of searchable fields,
each with an entry area that can be used to indicate the
search string.
• Query By Template (QBT)
– The interface is displayed a template for a representative
entry of the database. User express their queries by
indicating the search keywords in the appropriate regions of
the template.
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Document Database Schema
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Building an XML Document Database
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Example of Image-based QBT
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Limits of Image-based QBT
• The image template is divided into regions, each of
which corresponds to an element in the document
structure.
• Associated with each regions is the query action.
• Its significant drawback is the lack of flexibility in the
template creation.
• It is difficult to automate the task of reconfiguration of
query action associate with the new template.
• A single interface template for all types of document
is probably not a good idea.
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Concept of eXtensible QBT (XQBT)
• The environment provides a template creator which
consists of a DTD schema browser and a scene for
presentation design.
• The environment aims at providing automatic
configuration of query actions associated with
presentation of template.
• The design of the template presentation must be tightly
coupled with the arrangement of document data stored
in the repository.
• The component in the design of presentation must be
properly associated with corresponding nodes in the
object database schema.
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Environment for XQBT
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Template Creator
• The template creator consists of a DTD schema
browser a scene for template draft, and functional
area.
• The template creator in mainly relied on a DTD
schema browser, which corresponds to the database
schema.
• The scene is a visual display area where the
designer can organize a template draft for certain
purpose.
• The content of template draft is exported to a file,
which contains the template presentation and
additional information.
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Template Creator
Functional area
Functional Area
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Exported File
• The file contains the information about the template
presentation property associate with each element.
• Each element is appended with the path information in
the database schema, in order that the template
executor, which can make use of the information to
carry out query actions.
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Template Executor
• The template executor loads the exported file and
presents the template as was originally designed in
the template creator.
• The path of each node in the DTD schema browser is
used to carry out the query action required by the
user.
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Comparison between Image-based QBT and XQBT
• The template is an
image by taking a
photograph or by
scanning from existing
pages.
• The query action
associate with each
region is hand-coded.
• Either planar or nested
template is limited to
region level that is not
very deep.
• The template is
generated for a
representative
document.
• The associated query
action can be generated
automatically for the
interface program.
• The designer can
change the template to
meet the requirement of
various region level.
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Implementation
• Java Proxies (Jp) for Jasmine
– Jp allows developer to build their application in J-API, and
take advantage of Jasmine class libraries.
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The interface for our XML document database
ingredient
Ingredient
name
Ingredient
step
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Query Formulation
– Such searches are performed by simply entering the search
string in the corresponding region of the template.
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Query Formulation (cont.)
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Query Formulation (cont.)
• The multiple condition are specified in different
regions which are combined using logical
conjunctions(such as AND, OR, NOT).
• The approach used to derive the logical expression
from its graphical representation is using the default
precedence.
• User can insert parentheses as necessary in the
condition box, which used in QBE interface.
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The results of the query formulation
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Template Creator
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Template Executor
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Future Works
• A first step towards enhancement is improved the
template ability in order to support more complex
query facility.
• An enhancement of the template creator would
be to provide more sophisticated facility for manage
the template, such as layout, size, color, position, etc.
• We will try to include other document types to test
the applicability of the XQBT.
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A Video Content Query System
Based on an OODB
Introduction
• We store the content description of video in an
OODB (Jasmine[CA]) to provide the user to query
video segments according to the video content.
• A VDBMS needs to address the following important
issues :
–
–
–
–
Video data modeling
Video data insertion
Video data indexing
Video data query and retrieval
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Introduction(cont.)
• Overview of System Architecture
Raw Video
Data
Segmentation
&
Annotation
Repository
(databases)
Annotator
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Query
Interface
User
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Related Research
• R. Jain and A. Hampapur, “Metadata in Video
Databases.”
–
–
Application of Video
Query Dimensionality
• M. Carrer, L. Ligresti, G. Ahanger, and T.D.C.
Little, “An Annotation Engine for Supporting Video
Database Population.”
–
–
Video Segmentation
A Newscast Video Data Model
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Related Research
• E. Hwang and V. S. Subrahuanian, “Querying Video
Libraries.”
–
A Formal Model of Video Data Structures
• R. Hjelsvold and R. Midtstraum, “Modelling and
Querying Video Data.”
–
Structure of the Generic Video Data Model
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Related Research
• Dublin Core-based Video Description Scheme
–
Hunter proposes to extend part of Dublin Core elements, i.e.,
Type, Description, Format, Relation, and Coverage, to cope with
video content metadata requirements.
• Hunter breaks film and video documents into the following
hierarchical segments:
Sequence
Scene
Shot
Frame
Object/Actor/Person
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Research Issues
• Video Data Modeling
–
–
–
Characteristics of Video Data
Video Logical Structure
Content of Video Data
Shot
Shot
Shot
Scene
Scene
Sequence
Video
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Research Issues
• Video data insertion
–
–
–
–
Extract key information
Break the given video stream into a set of basic
units.
Manually or semi-automatically annotate the video
unit.
Index and store video data into the video database
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Research Issues
• Video Data Indexing
–
–
–
Annotation-Based Indexing
Feature-Based Indexing
Domain-Specific Indexing
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Research Issues
• Video Data Query
–
–
–
–
–
Query content
Query matching type
Query granularity
Query behavior
Query specification
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Research Issues
• Content Description Language
–
–
–
Every video subset of a video has a set of associated
objects and associated activities, which can be what we
may describe.
Content description language is used to describe the
video content and video structure.
An example is to describe video content by applying
qualified Dublin Core to a hierarchical segmented video
structure .
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System Architecture
System Architecture
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Video Data
Video Player
Video Entity
Segment
Program
Video Entity
Segment
Video Content Annotator
Video Content
Annotating Program
XML Document
Internet
Video Logical Structure and
Content (ODQL programs)
Video Content
Query Interface
OODB
Users
System Architecture
• Video Content Annotating Program
–
–
Output in two formats: one is in XML and the other
is in an object database language, the Object Data
Query Language (ODQL) of Jasmine.
The video content annotating program of the
system employs a bottom-up approach to guide the
human annotator to describe the content of video
segments.
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System Architecture
Video
Sequence
Scene
Shot
Bottom-Up
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System Architecture
• Query Interface
–
–
The matching type used in the query interface is
keyword match, which is a kind of exact match.
The user specifies the keyword he or she wishes
to find in the value field of each attribute, the
interface then looks for the content description of
each SHOT in the object database in order to find
the satisfied ones.
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Implementation
• The Jasmine Object-Oriented Database
–
–
–
We use Jasmine OODB [CA] to store the video content description.
Jasmine provides the ODQL to define, manipulate, and query the
data in OODB
An ODQL program
SHOT shot0;
shot0=SHOT.new(shotnumber:=0,name:="Shot_0
",filename:="F:\\G.ARMANI\\Shot1.MPG",star
ttime:="00:00",stoptime:="00:13",comment:=
comment0);
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Implementation
• The Content Description of Fashion Show Video
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
<!ELEMENT
VIDEO
(ABSTRACT?,SEQUENCE+)>
SEQUENCE (DESIGNER,SCENE+)>
SCENE
(TOPIC,BACKGROUND,SHOT+)>
SHOT
(CLOTHES+,ACCESSORY*)>
ABSTRACT
(#PCDATA)>
BACKGROUND
EMPTY>
CLOTHES
EMPTY>
ACCESSORY
EMPTY>
DESIGNER
EMPTY>
TOPIC
EMPTY>
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Implementation
<!ATTLIST SCENE
scenenumber NUMBER #REQUIRED
name CDATA #IMPLIED
starttime CDATA #REQUIRED
endtime CDATA #REQUIRED>
<! ATTLIST CLOTHES
name
CDATA #REQUIRED
department CDATA #REQUIRED
type (Men|Women|Children) “Men”
color CDATA #REQUIRED
season (Arbitrary|SpringSummer|FallWinter)
“Arbitrary”
fabric CDATA #IMPLIED
narrative CDATA #IMPLIED >
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Implementation
• Video Content Annotation Program
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Implementation
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Video Content Query Interface
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Conclusion
• A video content-based query system
• A hierarchical scheme for the content
descriptions of fashion show video
• The content description of video is made by
using XML DTD.
• The annotation of video content description
based on the scheme is stored in an object
database
• We then build the form-based query interface on
the object database.
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Future Work
• The problem of video transmission.
• How detailed should we describe the video
content?
• In the future we will develop a Query-By-Template
interface with key frame image, and an iterative
query interface to allow user to incrementally
refine their queries until the satisfying result is
obtained.
• The study of how to produce the query interface
automatically with different kinds of video.
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An Agent-Based EC System
Based on an OODB
Background
• Software Agent
• XML
• KQML
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Software Agent
• Properties:
– Autonomous, Reactive, Goal-driven, Persistent, Social,
Intelligent, Mobile
• Agency:
– A collection of software agents that communicate and
cooperate with each other is called an agency.
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XML
• XML(eXtensible Markup Language) is a description
language for structural documents; it is a markup
language, but unlike HTML it does not keep a fixed
set of tags.
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KQML
• KQML (Knowledge Query and Manipulation Language) is a
language and protocol for exchanging information and
knowledge. KQML is both a message format and a messagehandling protocol to support run-time knowledge sharing among
agents.
• A KQML message is called a performative, in that the message
is intended to perform some action by virtue of being sent.
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System Architecture
Agency
OODB
Manager 1
Rule Base
Agent states
& properties
Reasoning
KQML
Interpreter
agent 1
Document
Handler
Message
Handler
History
Messages
agent 2
Authentication
Documents
User
Interface
Resource
Manager
(products,
services)
Manager 2
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Agency
• Agent
• Facilator
–
–
–
–
–
–
Authentication
Message Handler
Reasoning
Document Handler
Resource Manager
KQML Interpreter
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Analysis of System Components
• Facilitator
– authentication, create agents, delete agents, sleep agents,
resume agents, and communicate with others.
• Agent
– action handling, display result, and communicate with others.
• Message Handler
– send message, receive message, and parse message.
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Future Work
• How the schema hierarchy of XML object database
affects the performance of accessing the document.
• Extensible template-based query interface
• Applications of XML object database in electronic
commerce
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