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Data Modeling[Comparison of data modeling
techniques ]
By Renjini
Sindhuri
Contents
Introduction E-R modeling
Peter Chen Information Engineering Barkers Notation IDEFIX
UML modeling XML modeling
X- Entity modeling XUML
Conclusion
Introduction
Data modeling is the act of exploring data oriented structures.
Examines and compares different data modeling techniques
In the data modeling techniques we have traditional modeling and object oriented modeling of data
E-R modeling
It is a conceptual data model that views the real world as consisting of entities and relationships
It is used to transform relational tables that are easy to understand that enables easy communication with the end user
Peter –Chen developed E-R model
Peter –Chen notation
Entities are represented in the squared cornered and circles as attributes
Many –Many relationships can be represented without associative entity
Relationship itself has attributes and are considered as objects
It failed to represent unique identifier
Peter Chen’s Model
Information Engineering model
Developed by Clive Finkelstein Entities are represented in the squared cornered and
attributes are not shown at all they are shown in a separate list called entity list
Relationships like mandatory 1 and many can be represented
Unique identifiers are not represented
Information Engineering model diagram
Barkers Notation
Adopted by Oracle corporation for its CASE method Entities can be represented by round cornered
rectangle Same entity can be represented for role an interaction
or another kind of association Relationship names are prepositions and not verbs Unique identifiers can be represented by hash marks
next to the attribute
Barkers Notation diagram
IDEFIX Notation
It is a modeling technique that is used by many branches of the United States Federal government
A relationship name is a verb IDEFIX shows subtypes as separate entity boxes IDEFIX permits multiple inheritance and multiple type
hierarchies
IDEFIX diagram
UML
UML is an object modeling technique It models object classes instead of entities In the object oriented world the relationships are called
as associations Cardinality and optionality in UML is conveyed by
characters or numbers Express in the form of more complex upper and
lower limits UML introduces a small flag that includes text
describing any business rules
UML diagram
XML Notation
Describing data and interchanging structured and unstructured data on the Internet
It is a universal language of data on web XML tags are used to create data structures XML documents have been widely used for
interchanging data between heterogeneous systems.
XML notation
An example of XML notation
http://www.essentialstrategies.com/publications/modeling/xml.htm
X-Entity model
Conceptual model of XML uses X entity model in order to represent additional features
The entity can be denoted by ‘E’ ({A1,….An},{R1,…Rm},{D1,….Dk}) Each attribute A is associated with a domain Dom(Ai)
Which specifies its value set
Cardinality is denoted by Card(Ai)=(min,max)
X entity model diagram
XUML
XUML comprises the characteristics of XML and UML2.
It is used to express the containment semantics more explicitly
Supporting the concept of Business Components Specifying the data dependencies in multiple context
XUML diagram
UML and XUML model of a book store
Comparison of data modeling techniques
S.No Modeling Technique
Peter Chen Information Engineering
IDEFIX Richard Barker’s notation
UML
1. Entities squared cornered and circles as attributes
Squared cornered, attributes are not shown at all.
Round or square cornered rectangle
Round cornered rectangle
Models object classes
2. Relationship Nouns. So the relationships can be represent as objects and has attributes
Verbs Verb or verb phrase
Preposition not verb
Associations
3. Constraints between relationships
Failed to represent the constraints directly exclusive or)
Can represent
Constraints exclusive or ,inclusive
Cannot represent
Can represent
Constraints exclusive or)
Can represent
Constraints exclusive or )
Comparison of Data modeling techniques
S.No Modeling Technique
Peter Chen Information Engineering
IDEFIX Richard Barker’s notation
UML
4. Cardinality Many to Many relationships can be represented between the entities without the associative entity
Can represent Can represent in different ways
Can represent zero or more ,atleast
at least one
up to many,up to one
relationships
express more complex upper limits, zero, 3, 6-7, or 9
5. Sub types/
Super Types Cannot represent the sub types and
super type
sub-types can be represented inside their super-type
box
Sub types can be represented as separate entity boxes separate from its super type.
sub-types can be represented inside their super-type box
Can represent
6. Unique Identifier
Cannot represent
Cannot represent
Represented in the form of
primary key
Represented in the form of hash next to
the attribute
Can represent
Comparison of Data Modeling techniques
S.No Modeling Technique
Peter Chen Information Engineering
IDEFIX Richard Barker’s notation
UML
7. Aggregation Cannot represent
Cannot represent
Cannot represent
Cannot represent
Can represent only binary aggregations
8. Business Rules /
Components
Cannot Represent
Cannot Represent
Cannot Represent
Cannot Represent
Can Represent
Comparison of Data Modeling techniques
S.No Modeling Technique
Peter Chen Information Engineering
IDEFIX Richard Barker’s notation
UML
9.
Aesthetic Simplicity Score
High Medium Low High High
10. Completeness Score
Low medium medium medium medium
11. Language Notation Score
medium medium low medium High
Advantages of XUML
XUML can express the containment semantics more accurately.
Support the concept of Business Component. Can specify the data dependencies in
multiple context.
Contd..
XUML is more expressive, precise and
understandable. More rigorous and accurate.
Conclusion
By comparing the aesthetic simplicity, completeness, language notation (relationship) Mr. Barker's notation is favorable for requirement analysis model
XML is used in recent trends it follows a standard format for representing structured and semi structured data on web
X-Entity model has the advantages of both XML schemas and extends the ER model so that it can explicitly represent important features of XML schemas
The distinctive features of XUML made this technique of data modeling the latest trend for conceptual modeling of data.
References
1. Conceptual Modeling of XML schemas, Bernadette Farias Losio,Ana Carolina Salgado , Year: 2003,Publisher: ACM
2. XML conceptual modeling with XUML, HongXing Liu HuaZhong University of Science and Technology, P. R. China, YanSheng Lu HuaZhong University of Science and Technology, P. R. China,Qing Yang Wuhan Uni Pages: 973 – 976, Year of Publication: 2006, Publisher: ACM Press
3. PETER PIN-SHAN CHEN, “The Entity Relationship Model-Toward a Unified View of Data” , Massachusetts Institute of Technology, ACM Transactions on Data base System Volume1, Issue 1,Publisher-ACM
4. Data modeling in the understanding database course: adding UML and XML modeling to the traditional content. Journal of Computing Sciences in Colleges, Volume 17, Issue 5 (April 2002)
References
5. Data Modeling101.
http://www.agiledata.org/essays/dataModeling101.html
6.A comparison of Data Modeling ,David C Hay,Essential Strategies
Inc,October 1999.