Expression of Query in XML object-oriented database

International Journal of Computer Applications Technology and Research
Volume 4– Issue 9, 664 - 667, 2015, ISSN: 2319–8656
www.ijcat.com 664
Expression of Query in XML object-oriented database
Roghayeh Madani
Department of Computer Engineering, Ardabil
Science and Research Branch, Islamic Azad
University,
Ardabil, Iran
Department of Computer Engineering, Ardabil
Branch, Islamic Azad University,
Ardabil, Iran
Ali Harounabadi
Department of Computer Engineering, Central
Branch, Islamic Azad University,
Tehran, Iran
Abstract: Upon invent of object-oriented database, the concept of behavior in database was propounded. Before, relational database
only provided a logical modeling of data and paid no attention to the operations applied on data in the system. In this paper, a method
is presented for query of object-oriented database. This method has appropriate results when the user explains restrictions in a
combinational matter (disjunctive and conjunctive) and assumes a weight for each one of restrictions based on their importance. Later,
the obtained results are sorted based on their belonging rate to the response set. In continue, queries are explained using XML labels.
The purpose is simplifying queries and objects resulted from queries to be very close to the user need and meet his expectation.
Keywords: Object Oriented, disjunctive queries, conjunctive queries, object-oriented database, XML.
1. INTRODUCTION
Upon paying attention to the data existing around ourselves,
we understand that plenty of these data may not be stored to
the same existing form. For storage of this type of data as well
as combined and complex data existing around ourselves, we
have no option but to use the new type of database that can
record complex and combined data, therefore we approach to
object-oriented database.
Contrary to the relational database (classic) that availability
samples in certain perceptual level are exhibited by table
records, in object-oriented database, objects are observed; in
other word, queries in this type of database are similar to
classic database, but responses are different.
Database queries are analyzed in this paper as simple and
combined modes. In combined mode, disjunctive and
conjunctive queries were used. In continue, queries are
explained by XML labels. In second part of paper,
background and in third part, Related Works and in fourth
part, Proposed Method was presented. The queries are
explained by disjunctive and conjunctive predicate, in
addition can be stored by XML labels. Fifth part was allocated
to Case Study and sixth part to Conclusion.
2. BACKGROUND
The background of this study includes object-orientation
concept, object-oriented database and XML.
2.1 Concept of object-orientation
Object-orientation emphasizes on the objects, in the object-
oriented programming, the objects are propounded abstractly.
Object-oriented programming is a modern style therein
components may be created and used in different programs.
Readability of programs written in this method is high and
their testing, fault detection and amendment is easy. Object-
orientation is formed based on several principles, as follows:
 Inheritance: In object-oriented programming, the
concept of inheritance is used frequently. There are
classes that inherited their attributes from main
classes referred to as super class. Reusability of
code is one of main advantages of inheritance.
 Encapsulation: it is referred to as placing
implementation in a capsule so that external user is
not aware of implementation procedure and only
knows that this capsule performs a specified work.
 Polymorphism: Assume that you inherit the
characteristics of father and his works, but do it in
another manner. It is just the same thing that is
called polymorphism.
 Abstraction: abstracting! It is referred to an abstract
class that methods are implemented therein.
 Interface: it shows the relationship between objects.
2.2 Object-oriented database
The weaknesses of relational model caused the experts to
think of make new models that one of their best types is
object-oriented model. Maximum object-oriented power
is arising out of its ability in real world modeling
phenomena. Object-oriented databanks model combines
the power of object-oriented languages and data storage
and retrieval systems and converted to very powerful
systems. Definition of concepts such as class, inheritance
and polymorphism etc. has empowered it extraordinarily.
In the object-oriented databank model, the data is stored
only as shape and includes the relationship between data,
attributes, restrictions and time and place problems. In
the object-oriented model, each phenomenon is related to
a class and output of queries may be a part of an object
or combination of a few objects.

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Object Class Name
Attribute1=Value1
Attribute2=Value2
.
.
AttributeN=ValueN
2.3 XML (extensible markup language)
Extensible Markup Language (XML) is a language for
showing data that was standardized by consortium web W3C
[1]. Within recent years, XML has been taken into
consideration as a standard language and structure for
exchange and exhibition of data on various applied program
particularly in web-based applications. Following web
integration and continuous production of a great volume of
electronic data, XML has been converted to a standard for
electronic exchange of information documents. The XML can
be used in the following:
 Exchange the data between disparate applications,
businesses and databases.
 Enable a model to display the same data on various
devices with different purposes and readers.
 A suitable format for storing data.
3. RELATED WORKS
Upon upraising the demand and need to new methods for
working with the data and relationships between these data
and applied programs focusing on enormous volume of data,
it was proved that object-oriented databases are better than
relational database and other databases.
Fong [2] proposed a reengineering engineering methodology
for transfer of an EER model to object modeling technique
(OMT) for production of object-oriented database plan. In this
paper, a series of mapping rules from EER model to general
object-oriented model were provided.
In [3], a language was presented that one of its characteristics
is defining classes that differ from other classes in a few
aspects. It is possible through separating the concept of “type”
and “class” and allows queries compilers to detect the type
errors even at the presence of objects contrary to the definition
of classes.
In [4], an independent query language with high class range
was introduced for visual and alphabetic database
management that is called PICQuery.
In [5], XML in the most specific state is assumed as database
and XML documentations are self-defined, means that
structure and name of types are specified at the use time. In
addition, data may be presented in two tree and graph forms.
In [6], a software was offered for direct use of Query
languages on XML. Whereas for exchanging the data between
XML and database, it is required to establish a
correspondence between documented XML schema and
database schema, relevant software for data exchange is
founded in high level of this correspondence.
In [7], use of XSLT was presented that allows the user before
data exchange to convert the data to respective format.
Two XQuery and XPath languages are accepted more
extensively for whom working with XML. In XPath language,
to select each data, a XML document of Path Expression
corresponding thereto is used [8] and XQuery language is
mostly similar to SQL and more familiar for programmers [9].
4. THE PROPOSED METHOD
Our proposed method is mapping queries by XML, designing
an object-oriented database and applying on the queries. In
this paper, the queries can be stored with XML labels. So,
labels in XML may be presented for support of object-
oriented database.
4.1 Definition of class structure in XML
document
To define class structure in XML, respective class must be
shown in XML schema. For this purpose, class exhibition
must be mapped to DTD schema.
Figure 1. Class mapping by DTD
4.2 Exhibition of samples of class in XML
document
Whereas class was formed based on XML schema, at this
stage, the defined samples of class may be easily shown in
XML document as below:
<Object Class Name>
<Attribute1>Value </Attribute1>
<Attribute2>Value </Attribute2>
.
<AttributeN>Value </AttributeN>
</Object Class Name>
4.3 Query procedure
Query processing in the object-oriented database refers to a
process therein objects of classes are selected that meet the

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designated condition. In the method proposed by Zung Ma, it
was not possible for the user to prioritize his assumed
attributes and only membership rate of each object in the
relative class (µ) was analyzed. In the proposed method of this
paper, upon allocating weight to queried attributes, setting the
priority of each attribute in the query is assigned to the user.
Therefore, syntax rule of a SQL query based on object-
oriented database will be as follows:
SELECT <attribute list> FROM <class1,…, classm> WHERE
<query condition >
In above relation, attribute list includes the attributes that are
going to be appeared in the output and related to the objects
that meet the user condition. The classes that are written in
front of FROM include classes that query operation in
performed therein. Query condition is a condition that user
expected to be met. Queries related to object-oriented
database may be written in XML format that a sample thereof
is shown in figure 2:
Figure 2. Schema of Select query using XML
5. Case study
In this part, the book information registration system is used
for evaluation of proposed method. In this system, the books
information is registered so that different books can be
searched based on different fields. In addition, considering
proposed method, insert , delete, select and edit operation of
XML object-oriented database is carried out.
The classes related to book information registration system
include two classes in the name of book and Author with the
below-mentioned particulars:
Class Book {
Int ID;
String Title;
String ISBN;
String Publisher;
Date Date;
double Price;
Float Weight;
String Subject;
Author Author; //Object as Data in Object Oriented Database
}
Class Author{
String FirstName;
String LastName;
}
According to the defined classes and proposed method, a
mapping to DTD model must be applied to obtain XML
document related to respective system, easily.
<!ELEMENT Book(ID, Title, ISBN, Publisher, date, Price,
Weight, Subject, author)>
<!ATTLIST Book ID CDATA #REQUIRED>
<!ELEMENT Title (#PCDATA)>
<!ELEMENT ISBN (#PCDATA)>
<!ELEMENT Publisher (#PCDATA)>
<!ELEMENT Date (#PCDATA)>
<!ELEMENT Price (#PCDATA)>
<!ELEMENT Weight (#PCDATA)>
<!ELEMENT Subject (#PCDATA)>
<!ELEMENT Author(FirstName, LastName)>
<!ELEMENT FirstName (#PCDATA)>
<!ELEMENT LastName (#PCDATA)>
6. Conclusion
In this paper, a method was presented for showing samples of
class in the XML database and so the concept of XML object-
oriented database was defined. Furthermore, different queries
related to XML object-oriented database was defined and
showed. Consequently, the concepts of object-oriented
database and its relevant queries can be shown by XML
labels.
7. REFERENCES
[1] B. Tim, P. Jean, C. M. Sperberg, M. Eve,”
ExtensibleMarkup Language (XML)1.0”, World Wide Web
Consortium (W3C) , (2006), http://www.w3c.org/TR/REC-
xml. Fourth Edition, 29 September. (Visited on 2008-02-09).

www.ijcat.com 667
[2] J. Fong, " Mapping Extended Entity Relationship Model to
Object Modelling Technique", SIGMOD, (1995), Record
24.PP.18-22.
[3] A. Borgida, " Modelling Class hierarchies With
Contradictions", Proc of ACM SIGMOD International
Conference on data management
Chicago,US,Vol.17,no.3,(1998), pp.434-443.
[4] A. F. Cardenas, I. T. Leong, R. K. Taira, R. Barker, C. M.
Breant, " The Knowleadge Based Object Oriented PICQuery+
Language", IEEE Transaction on Knowledge and Data
Engineering, Vol.5, no.4, (1993), PP.644-657.
[5] R. Bourret, " XML Database Products",
WWW.rpbourret.com/xml/XML And Databases.htm, (2003).
[6] J. E. Funderburk, " XTABLES:Bridging Relational
Technology and XML", IBM Systems Journal, Vol.41,
(2002).
[7] J. shanmugasundaram, " A General Technique for
Querying XML Documents Using a Relational Database
System", Special ISSUE: Special Section on advanced
XML data Processing, (2001).
[8] A. Berglund, S. Boag, D. Chamberlin, M. F. Fernández,
M. Kay, J. Robie, J. Siméon, " XML Path language (XPath)
2.0", World Wide Web Consortium (W3C), (2007),
http://www.w3.org/TR/xpath20 ,. (Visited on 2008-03-17).
[9] S. Boag, D. Chamberlin, M. F. Fernández, D. Florescu,
J. Robie, J. Siméon, " XQuery 1.0: An XML Query
Language", World Wide Web Consortium (W3C), (2007),
http://www.w3.org/TR/xquery, January 2007. (Visited on
2008-03-17).

Expression of Query in XML object-oriented database

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Expression of Query in XML object-oriented database