International Journal of Computational Engineering Research(IJCER)

I nternational Journal Of Computational Engineering Research (ijceronline.com) Vol. 3 Issue. 1

Reengineering of relational Databases to Object Oriented Database
Mr.R.S.Mawale 1, Prof.A.V.Deorankar2, Prof. P.U. Malve 3
1
M.Tech. Scholor, (CSE), Govt. Co llege of Engineering, A mravati, Maharashtra, India
2
Associate Professor, Dept. of CSE, Govt. Co llege of Engineering, A mravati, Maharashtra, India
3
Lecturer, Govern ment Polytechnic, Murt izapur , Dept. of Co mputer Engineering, Maharashtra, India

Abstract:
Many information systems use relational database systems for efficient sharing, storage, and retrieval of large
quantities of data. On the other hand, object-oriented programming has been gaining wide acceptance in the
programming co mmunity as a parad ig m for developing co mp lex applications that are easy to extend and maintain.
This paper discusses development of an integrated environment which maps a relational schema to an object -oriented
schema without the need to modify the existing relational schema and providing a platform for migrating data fro m
relational database to object oriented database.

Keywords: Schema Mapping, RDBMS, OODBMS, Reengineering

1. Introduction
Relational database management systems (RDBMS) provide a variety of tools and services for data
management. There are many tools that interface with RDBMSs to enable end-users to carry out reporting,
querying, and other data analysis activities easily. On the other hand, object -oriented programming has been gaining
wide acceptance in the programming community as a paradigm for developing comp lex applic ations that are easy to
extend and maintain. Developers typically implement object-oriented applications using object-oriented programming
languages such as C# and Java. These applications use a schema made up of object classes and relationships between
those object classes. Each object has a set of attributes. The value of an attribute could be another object itself, thus
giving rise to complex objects. The main problem arises when the data corresponding to such objects are persistent in a
relational database. The problem is due to incompatibility between relations and objects. At first, a solution for this
problem may seem to be to use an ODBMS instead of RDBM S. If an ODBMS is managing the persistent data, the
objects do not lose their structure after the application stores them in the object database. Moving to an ODBMS might
mean throwing away all of the old (“legacy") data and applications. Most users of databases will not accept such a
solution. They wish to be able to run their existing applications on existing databases and have access to the same data
fro m object-o riented programs, too. Therefore, we need special techniques to convert the data that is residing in a
relational database to a format that is suitable for access and manipulat ion by object-oriented applications.

2. Literature review
The problem of migrating data is present in almost every application development process, such as data
warehousing and application integration. The algorithm imp lements process of migrat ing data involves firstly the
mapping between the structures of the source and target databases and secondly the mig ration of the data fro m the source
to the target [3].
The problem is how to effectively migrate existing RDBs, as a source, into OODB/ORD B/XM L, as targets, and
what is the best way to enrich and maintain RDBs’ semantics and constraints in order to meet the characteristics of the
three targets? Existing work does not appear to provide a complete solution for more than one target database. We tackle
this question by proposing a solution for migrat ing an RDB into the three targets based on available standards [4].
One general approach to migrate to object technology is to divide the process into two phases, where the first one
transforms the relational into an object-oriented schema and the second one migrates the data into the object -oriented
database system discussed in [5].
The goal of re-engineering is to mechanically reuse past development efforts particular relat ional databases
(RDBs).in order to reduce maintenance expense and improve software flexibility [4]. The object behavior of eight Java
programs including four real-world Java object oriented database management systems and a counterpart of four real-
world Java programs are analy zed in [6]. A technique for transferring query optimizat ion techniques, developed for
relational databases, into object Databases. This technique for ODM G database schemas defined in ODL and object
queries exp ressed in OQL. The object schema is represented using a logical representation (Datalog) [7].

3. Analysis of problem
Moving to an ODBMS might mean throwing away all of the old (“legacy") data and applications. Most users of
databases will not accept such a solution. They wish to be able to run their existing databases and have access to the

Issn 2250-3005(online) January|| 2013 Page 74


same data fro m object-oriented program.
Thus we need to implement a system that builds an understanding of a given conventional database by taking
these characteristics as input and produces the corresponding object-oriented database as output. Finally, we handle the
migrat ion of data fro m the conventional database to the constructed object -oriented database.
The Primary object ives of proposed work are as follows.
1. Study the automatability of the relational-to-OO schema mapping process.
2. Define an interactive process for mapping an existing relat ional schema to an object -oriented schema.
3. Develop an interactive system to validate proposed work

4. System architecture
The architecture contains two major components needed for fulfilling our aim. The first component deals with
mapping the relational schema to an object-oriented schema. The second component deals with the mapping between the
relational data and objects.

Figure 1. S ystem Archi tecture
Schema Mapping
The static schema mapp ing process is a two-phase process. In the first phase, the relational schema is adjusted and
transformed into another virtual relational schema that has some specific properties . In the second phase, object-oriented
structures are ext racted fro m the virtual relational schema.

Figure 2.Two Phases of Static Schema Mapping

Phase I: Adjusting the Rel ati onal Schema
There are four specific aspects that are addressed during phase one. They are as follo ws:
Step 1. Eliminate 2NF relat ions and replace them with new 3NF virtual relations.
Step 2. Create virtual subclass relations for widow super class relations
Step 3. Create virtual superclass relations for orphan subclass relations.
Step 4. Eliminate mu lti-valued attributes and replace them with new 3NF virtual relations.

Phase II: Generation of the Object Schema
At the end of phase one of the schema mapping process, the relational schema has been adjusted to a form in wh ich
schema mapping rules can be applied unifo rmly.
Step1. Identifying Object Classes:
Those relations that correspond to object- classes must be identified.
Step2. Identifying Relationshi p:
There are three types of relationships that can be represented in an object model. They are associations, generalizat ions
specializations, and aggregations.
Identifying each of these constructs constitutes a step in the mapping process.
Identi fying Associations. Since the object model allo ws associations to be modeled as classes, we must either establish
a simple association between two object classes or identify relat ionships where the associations are modeled as
classes.
Identi fying Inheritance. Inheritance structures capture the generalizat ion and specializat ion relations hips between
object classes that have been identified so far.



Identi fying Aggregation. The aggregation relat ionship models the co mposition of one object with other objects. such
complex object must be identified. The difference between aggregation and association is that the former involves
existence dependence of the sub-object on the whole object. For example, a door object, wh ich is a part-of" of a car
object, cannot exist if the car object does not exist. On the other hand, the enrollment of a student in a course is
an association rather than an aggregation because the student and course objects can exist independent of each other.
Step 3. Es tablishing Cardinalities : Establishing the card inalities of associations is important in o rder to facilitate
the imp lementation of the object schema in a g iven programming language (e.g., C#). The d ifferent possible
cardinalities are one-one, one-many, and many-many.

5. Conclusion
We will imp lement the architecture having two phases in the data mapping process; one mapping procedure
specifies the data mapping between the original relat ional schema and the adjusted relational schema. The second
mapping procedure specifies the data mapping between the adjusted relational schema and the object schema. The data
mapping procedures have been specified using relat ional algebra for each new virtual relation that is created
during phase one of the static schema mapping.

References.
[1] Ramanathan, C. Providing object-oriented access to a relational database. In Proceedings of the 32nd ACM annual southeast
conference held in Tuscaloosa, Alabama, M arch, 1994.
[2] Andersson M . Extracting an entity-relationship schema from a relational database through reverse engineering. In Proceedings
of the 13th international conference on entity relationship approach held in M anchester, UK, December, 1991
[3] Elton M anoku, Guido Bakema, A fact approach on Data M igration published in Academy of Communication and Informat ion
Technology HAN University of Applied Sciences, The Netherlands In June 2006
[4] Abdelsalam M aatuk, Akhtar Ali, and Nick Rossiter , A Framework for Relational Database M igration published in School of
Computing, Engineering & Information Sciences Northumbria University, Newcastle upon Tyne, UK in 2001
[5] Andreas Behm, Andreas Geppert, Klaus R. Dittrich2 ,On the migration of relational schemas and data to object -oriented
database published in Proceedings of the 5th International Conference on Re-Technologies in Information Systems,
Klagenfurt, Austria, December 1997
[6] William J Premerlani, M ichael R Blaha, An Approach for Reverse Engineering of Relational Databases published in M ay
1994 Communications of the ACM
[7] Chia-Tien Dan Lo, M orris Chang, Ophir Frieder and David Grossman, The Object Behavior of Java Object-Oriented Database
M anagement Systems published in the Proceedings of the International Conference on Information Technology: Coding and
Computing (ITCC.02) IEEE 2002
[8] John Grant, Jarek Gryz, Jack M inker, and Louiqa Raschid, Logic-Based Query Optimization for Object Databases published in
IEEE Transactions on knowledge and data engineering, vol. 12, no. 4, July/August 2000.

Authors Profile:

M r.R.S.M awale has received his B.E. degree from Govt. College of Engineering, Amravati,
India. He is currently pursing his M .Tech in Computer Science & Engineering from Govt.
College of Engineering, Amravati, India. He has published one paper in International Journal.

Prof A.V.Deorankar has received his M .E. degree in Electronics Engineering from Govt.
College of Engineering, Amravati, India and pursing his PHD from Computer Science. He
has 19 years experience in Teaching in various Government engineering Colleges in
M aharashtra. He has published nine papers in national and seven papers in international
journals. He has also patent of one paper. His area of research includes Computer network,
Web M ining. Currently he is working as an Associate Professor at Govt. college of
Engineering, Amravati, M aharashtra, India .

Prof.P.U.M alve has received His M .E.Degree in Information Technology from Sant
Gadegebaba Amravati University in 2011. He has published Two papers in National and Three papers in
International Journals. He has Five years experience in teaching various
Government engineering Colleges & Polytechnics in M aharashtra. His area of research includes Computer
Networks, Software Engineering, Network Security He is currently woking as a Lecturer in Department of
Computer Engineering, at Government Polytechnic, M urtizapur, M aharashtra India


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