AN OBJECT ORIENTED APPROACH FOR DOCUMENT

MANAGEMENT

S. Khaddaj

School of Computing and Information Systems, Kingston University, Kingston upon Thames KT1 2EE, UK.

Keywords: Object Oriented Modelling, Object Versioning, Document Management Systems

Abstract: It is already widely accepted that the use of data

abstraction in object oriented modelling enables real world

objects to be well represented in information systems. In this work we are particularly interested with the

use of object oriented techniques for document management. Object orientation is well suited for such

systems, which require the ability to handle multiple types content. However, the matter of how to deal with

the reuse and management of existing documents over time remains a major issue. This paper aims to

investigate a conceptual model, based on object versioning techniques, that will represent the semantics in

order to allow the continuity and pattern of changes of documents to be determined over time.

1 INTRODUCTION

Object oriented techniques have been used

successfully in many different applications that

range from numerical modelling to web applications.

The main benefits, apart from the abstraction power

to represent real objects, are the provision for the

extensibility needed to create new models and the

semantic needed to construct complex objects of

similar states [

Yourdon 1994, Martin and Odell 1995,

Bertrand 1997].

The use of object oriented techniques in

nformation management has been given

considerable attention in the past decade [

Cattell

1991

, Won 1998, Loomis 1995]. Recent research works

have used temporal information and object oriented

techniques to explicitly define the relationship

between object behaviour over time [

Khaddaj et al.].

The ability to examine the continuity of object

changes over time is very important for many

different applications.

The object oriented appro

ach provides the

flexibility to make the changes to attributes and/or

behaviour of objects independent of one another, in

order to allow the examination of detailed

information of object application models. Therefore,

it can be used to identify the pattern of changes

within the objects. The simplest way to store

changes to objects is that every time a change occurs

the whole object is stored again, but this can be

prohibitively costly in terms of storage space, and

might compromise system performance particularly

if objects are updated regularly (fast changes). An

altern

ative is to use object versioning techniques in

order to track the evolution of objects. This paper

aims to investigate a document management object

model that will represent the semantics to allow the

continuity and pattern of changes of objects to be

determined over time.

2 OBJECT ORIENTATION AND

INFORMATION MANAGEMENT

The object-oriented approach has the abstraction

power to represent real objects and it has been used

successfully for the unification of temporal and other

information related to objects. It is supported by

efficient design tools such as UML (Universal

Modelling Language), programming tools such as

C++ and Java and, more recently, by object oriented

databases such as Objectivity and Versant. The

choice of a particular database, however, clearly

depends on the actual application. A relational

database is a better choice for a project where

relationships among objects are fairly fixed and well

known. Object-oriented databases can outperform

relational databases at handling complex

relationships among objects [

Loomis 1995]. The

problem becomes acute, however, when the changes

are too fast for a database to be redesigned so it can

rapidly deliver necessary information.

558

Khaddaj S. (2004).

AN OBJECT ORIENTED APPROACH FOR DOCUMENT MANAGEMENT.

In Proceedings of the Sixth International Conference on Enterprise Information Systems, pages 558-561

DOI: 10.5220/0002620705580561

 SciTePress

3 OBJECT VERSIONING

Associating additional temporal information with

individual objects provides a means of recording

object histories, and thereby allowing the histories of

objects and the types of objects to be easily traced

and compared. This means that the temporal aspects

can also be described by their temporal topological

relationships. The object-oriented approach has been

used in different ways to effectively track versions

of the original object and these include the use of

version management [

Wachowicz and Healey 1994]

and the identity-based method [

Hornsby 2000].

Moreover, other strategies such as schema

versioning can also be considered [

Grandi 2002].

There are a number of methods for dealing with

object versioning. The first technique stores the

versions as complete objects, which is easy to

implement in existing database systems but it is

costly in storage space. The second approach stores

one version as a complete object and the rest of the

versions are presented as differences between the

current version and the previous version. The

technique is difficult to implement but it solves the

storage space problems. These two approaches have

been examined for relational databases [

Dadam et al.,

1984

3.1 Complete Versions

The first approach can be stated using the following

equation (1):

Versions(x)=(CV

(n), CV

(n-1) ,….., CV

)) (1)

In equation (1), CV

(n) represents the complete

version, n indicates the number of the version, x is

the object and n

is the oldest version number. Each

version can be accessed directly by reference to the

number of the version, n.

3.2 Linear Versioning

Using this technique one version is stored as a

complete object, and the rest of the versions are

presented as differences between the versions. The

relationship using this approach is based on one-to-

one versioning of objects, which means any parent

or base object will have only one child or derived

object. The technique can be classified into two

versioning strategies. The first strategy allows the

current version to be calculated from the previous

version and is referred to as forward oriented

versioning. The second strategy enables the previous

version to be evaluated from the current version and

is referred to as backward oriented versioning

[

Dadam et al., 1984]. Using forward linear versioning

the temporal relationships between the generic

object and versions is given by:

Versions(x)=(

∆

(n,n-1),

∆

(n-1,n-2),.. .,

∆

+1, n

), CV

)) (2)

Where n

indicates the generic version, which holds

the complete attributes and behaviour.

∆

(k, k’)

represents the difference between the current version

(k) and the previous version (k’) of object x. As

shown in equation (2) access to the current version n

requires n-1 iterations, which means that this

strategy provides faster access time for the oldest

version.

In backward linear versioning the current object

holds the complete attributes and behaviour. The

temporal relationships between the current object

and versions is given by:

Versions(x) = (CV

(n),

∆

(n,n-1),

∆

(n-1,n-2), . .,

∆

+1, n

)) ( 3)

As shown in the equation (3), the rest of the

versions are expressed as delta to the successor-in-

time version, which means that this strategy

provides faster access time for the newest versions.

As a result, this strategy is bound to be more useful

than the previous one for most applications.

3.3 Branching

This technique is also classified into two versioning

strategies. The branch forward oriented strategy is

based on one-to-many object versioning (object

splitting), which

means any parent or base object

will have many children or derived objects. The

branch backward oriented strategy is based on

many-to-one object versioning (object merging)

which means any child or derived object will have

many parents or base objects. The relationship using

the first strategy provides the same access time for

all versions:

Versions(x) = (∆

(n,n

), ∆

(n-1,n

), . . . .,

∆

+1, n

), CV

) ) (4)

The relationship using the second strategy provides a

faster access time for the current version:

Versions(x) = (CV

(n),

∆

(n,n-1),

∆

(n,n-2), . .,

∆

(n, n

)) ( 5)

AN OBJECT ORIENTED APPROACH FOR DOCUMENT MANAGEMENT

559

Document Type Class

Location Class

Temporal Class

Document Ob

ect Class

Version, Event and

Manager Classes

ation

Inheritance

Figure 1: Composite classes of a document object

4 DOCUMENT MANAGEMENT

Documents can now be generated and distributed

easily, but what is still needed is support in

managing the information contained in those

documents [

Barth 2000, Bielawski 1998]. This is vital

because by putting pieces of information from

different documents together, the user can generate

new knowledge [

Davenport et al., 1998]. The ability to

collect, store, manage, analyse, retrieve and utilise

information about documents, and present

information in text, graphics and, increasingly,

multimedia form has received considerable attention

in the past few years [

Bielawski and Boyle 1998,

Outsell 2001

, Outsell 2001]. However, the matter of

how to deal with the reuse and management of

existing information over time remains a major

issue.

4.1 Object Oriented Model for

Document Management

In this section we are concerned with a generic

document management, context independent, object

model reflecting the structure and semantic linking

for different types of documents. The model should

take into account document structuring and content

referencing; and includes issues like document

versions, ownership, notification and propagation of

changes, particularly in a collaborative environment.

Of particular interest in this approach, are

scenarios when documents are regularly updated,

and new versions are created whether there is a need

for time stamping or not. Clearly, it is more useful

when time stamping is required, i.e. where there is a

need to keep a history of activities and changes in

managed documents, such as user manuals, online

help, tourist guides, web applications, etc. The idea

is to simplify the management of all types of

documents such as scanned paper documents, faxes,

emails, word processing generated reports,

spreadsheets, html forms, and so on.

Using this approach, changes to documents are

handled by version management. A version of the

object consists of composite classes as in figure 1.

The aggregated composite classes include a

document type class (documents can be classified

according to their types which can take the form of

texts, graphics, multimedia etc, and can be regarded

as derived classes from the type base class), location

class and temporal class. The associated composite

classes include manager class and event class. The

location class deals with queries about the location

of the object document within the federated database

(including the ability to search documents by either

context or index term, text extraction and full text

search engine). The type class deals with queries

about the features of an object (e.g. length, content

types etc). The temporal class deals with the queries

about the time attributes of the object (e.g. when was

the document created). Furthermore, an event class

deals with the changes (and their causes) of the

document object (e.g. adding new manuals after an

operating system upgrade). And, a manager class

with persistent object store, including the ability to

store documents, to control the access to documents,

to deal with the effect of the changes of the object,

to assure changes are not confused, and to co-

ordinate documents transformation, extension, etc.

4.2 The Version Class

As figure 2 illustrates, a document object is

represented as a generic object and any subsequent

changes are represented as versions. Each version of

the object consists of changes (involving an attribute

or behaviour) of the aggregated classes (type,

location and temporal) and the associated class

(event and manager). Subsequent changes of

attributes of the versions will generate related

dynamic attributes and temporal links to be updated

to the respective versions. The relationships between

the generic object and the versions of the object are

represented by temporal version management

[

Dadam 1984]. To save storage space, only the

generic version hold the complete attributes and

behaviour of the object.

ICEIS 2004 - DATABASES AND INFORMATION SYSTEMS INTEGRATION

560

4.3 System Implementation

A successful implementation of the model will

require an Object Oriented Database System

(OODBS). The OODBS considered in this work is

based on Objectivity/DB [

Objectivity/DB 2000]. The

classes (version, temporal, location, type, event and

manager) are defined in the application schema file,

called Data Definition Language (DDL). The DDL

processor generates the schema header file and the

schema source code which are linked with the

application source code.

Objectivity/DB has the capabilities to represent

the various versioning approaches: linear, splitting

and merging. As discussed earlier, simple changes

are represented by a linear versioning method while

complex changes, involving splitting and merging,

are represented by branching. document objects

persist by storing the object within the container of

the database. Persistent objects are identified using

the object identifier (OID) which remains unique

within a federated database. Objectivity/DB uses an

object handling class to access persistent objects

automatically by the DDL process for every

persistence class found in the schema header. All the

objects and versions in the database can be

determined by scanning through the database using

iterative scanning functions.

5 CONCLUSIONS

The applications of object oriented techniques to

document management have been discussed in this

paper. Particular attention was paid to the concept of

object versioning and its applications. The presented

object oriented approach provides an integrated

framework for effective tracking of the evolution of

objects. It also promotes good temporal modelling,

because the temporal attributes and behaviour of the

versions are independent but have relationships that

enable the tracking of patterns of change. Also, less

data storage is required since only the generic object

and its versions are stored.

REFERENCES

Yourdon, E. “Object-Oriented System Design: An

Integrated Approach”, Yourdon Press, 1994.

Martin J., Odell J.J., “Object-Oriented Methods: A

Foundation”, Prentice Hall, Englewood Cliffs, 1995.

Bertrand M., “Object-Oriented Software Construction”,

Prentice Hall Publishing International Series in

Computer Science. 1997.

Cattell R.G.G., “Object Data Management, Object-

Oriented and Extended Relational Database Systems”,

Addison-Wesley Publishing, 1991.

Won K, Lochovsky, F., “Object-Oriented Concepts,

Databases, Applications”, ACM press Frontier Series.

Addison-Wesley Publishing, 1989.

Loomis M.E.S., “Object Databases; The Essentials”,

Addison-Wesley Publishing,1995.

Khaddaj S., Adamu A., M. Morad, "Object versioning

and Information Management”, Journal of Information

and Software Technology,to appear.

Wachowicz, M. and Healey, R. “Towards temporality in

GIS” Innovation in GIS I, by Worboys M. F. Vol 1

pp.105- 115, Taylor & Francis, 1994.

Dadam, P., Lum, V., Werner, H. D., “Integrating of time

versions into relational database systems”, Very Large

Database Conference, pp. 509-522, 1984.

Hornsby K., Egenhofer M., “Identity-Based Change: A

Foundation For Spatio- Temporal Knowledge

Representation”, International Journal of Geo

Information Systems 14(3), pp 207-224, 2000.

Grandi F., Mandreoli F., “A Formal Model for Temporal

Schema Versioning in Object-Oriented Databases”. A

Timecenter Technical Report, 2002.

Barth S, “KM Horror stories”, Knowledge Management 3,

No 10, pp 36-40, 2000.

Bielawski L., Boyle J, “Electronic Document Management

Systems: a User Centered Approach for Creating,

Distributing and Managing Online Publications”,

Upper Saddle River, P Hall 1998.

Davenport T. H, De Long D. W. and Beers M. C.,

“Successful Knowledge Management Projects”, Sloan

Management Review, 39, pp 43-57, 1998.

Outsell Inc. “ Taxonomies: Structuring Today’s

Knowledge Systems”, Infor Briefing 4, pp 1-18,2001.

Outsell Inc., “ Knowledge Management: It’s All About

Behavior”, InforBriefing 4, pp 1-16, 2001.

Objectivity/DB, “Complete handbook for objectivity/C++

Instruction Manual”, 2000.

= Generic Objec

, V

(n+1)

= Version changes

= Temporal topology link

2 V

(n+1)

Figure 2: Relationship between the versions and generic object

AN OBJECT ORIENTED APPROACH FOR DOCUMENT MANAGEMENT

561