An XML Object Database: Design Implementation and Applications

1
An XML Object Database Design Implementation
and Applications

• Ching-Long Yeh ? ? ?
• Department of Computer Science and Engineering
• Tatung University
• Taipei 104, Taiwan
• ROC

2
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
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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?

Recipe
Title
Coconut Pudding
Ingredient List
Ingredient
Instruction List
Step
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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

lt!ELEMENT recipe -- ( title,
ingredientList,
instructionList)gt lt!ELEMENT title --
(PCDATA)gt lt!ELEMENT ingredientList --
(ingredient)gt lt!ELEMENT instructionList --
(step)gt lt!ELEMENT ingredient --
(PCDATA) gt lt!ELEMENT step -- (PCDATA)gt
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Document Instance
lt!DOCTYPE RECIPE PUBLIC recipe"
recipe"gt ltRECIPEgtltTITLEgtCoconut
Puddinglt/TITLEgt ltINGREDIENTLISTgt ltINGREDIENTgt
12 ounces coconut milklt/INGREDIENTgt
ltINGREDIENTgt 4 to 6 tablespoons sugar
lt/INGREDIENTgt ltINGREDIENTgt 4 to 6 tablespoons
cornstarch lt/INGREDIENTgt ltINGREDIENTgt 3/4 cup
water lt/INGREDIENTgt ltINGREDIENTLISTgt ltINSTRUCTIONL
ISTgt ltSTEPgt Pour coconut milk into saucepan.
lt/STEPgt ltSTEPgtCombine sugar and cornstarch
stir in water and blend well. lt/STEPgt
ltSTEPgtStir sugar mixture into coconut milk cook
and stir over low heat until
thickened. lt/STEPgt lt/INSTRUCTIONLISTgt lt/RE
CIPEgt
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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.
• Thats exactly what XML is.
• XML is the object representation of data.

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Design and Implementation of an XML Object
Database
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System Architecture
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DTD Parser
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Parsing Result
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Schema Generation
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DI Parser
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DI Parser Generation
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
  English-like 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
  platform-independent.

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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
  Web-connectivity.
• 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,
  C-API, 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
• ODIs 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
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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
XQBT
QBT

• 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 SystemBased on an OODB
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Introduction

• We store the content description of video in an
  OODB (JasmineCA) 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

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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

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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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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
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 shot0SHOT.new(shotnumber0,name"Sh
ot_0",filename"F\\G.ARMANI\\Shot1.MPG",starttim
e"0000",stoptime"0013",commentcomment0)
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Implementation

• The Content Description of Fashion Show Video

lt!ELEMENT VIDEO (ABSTRACT?,SEQUENCE)gt
lt!ELEMENT SEQUENCE (DESIGNER,SCENE)gt
lt!ELEMENT SCENE (TOPIC,BACKGROUND,SHOT)gt
lt!ELEMENT SHOT (CLOTHES,ACCESSORY)gt
lt!ELEMENT ABSTRACT (PCDATA)gt lt!ELEMENT
BACKGROUND EMPTYgt lt!ELEMENT CLOTHES
EMPTYgt lt!ELEMENT ACCESSORY EMPTYgt lt!ELEMENT
DESIGNER EMPTYgt lt!ELEMENT TOPIC
EMPTYgt
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Implementation
lt!ATTLIST SCENE scenenumber NUMBER
REQUIRED name CDATA IMPLIED
starttime CDATA REQUIRED endtime
CDATA REQUIREDgt
lt! ATTLIST CLOTHES name CDATA
REQUIRED department CDATA REQUIRED
type (MenWomenChildren) Men color
CDATA REQUIRED season (ArbitrarySpringSu
mmerFallWinter) Arbitrary
fabric CDATA IMPLIED narrative CDATA
IMPLIED gt
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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
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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 message-handling 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
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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