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Design and Implementation of the QBOE
Query Language for Multimedia Database
Systems
Ye-In Chang, Shih-Hao Jair, and Hong-Nian Chen
Department of Applied Mathematics
National Sun Yat-Sen University
Kaohsiung, Taiwan, R.O.C.
ABSTRACT
A multimedia database (denoted as MMDB) management system manages multimedia
data, where multimedia data is dened as any combination of data in the form of text,
images, animation, sound and video. Due to these complex combination of dierent types
of data, and many special properties of multimedia applications, traditional record-based
DBMS techniques are not eective and not powerful enough to support those multimedia
applications. In this paper, we design and implement a QBOE (Query-By-Object-Example)
query language for multimedia database systems. Our system is based on an object-oriented
model. The query language is called Query-By-Object-Example, since either DDL (Data
Denition Language) or DML (Data Manipulation language) is through an object example. In the part of DDL, the user can specify the prototype of a multimedia application,
including the specic keywords for the application and related operations. In the part of
DML, the user can access data by contents or keywords which are specied in attributes.
Key words: data modeling, database management systems, multimedia database management systems, query languages
QBOE Query Language for Multimedia Database Systems
1
I. Introduction
A multimedia database (denoted as MMDB) management system manages multimedia
data, where multimedia data is dened as any combination of data in the form of text,
images, animation, sound and video (Berra et al., 1993 Grosky, 1994 O'Docherty and
Daskalakis, 1991). Due to these complex combination of dierent types of data, and
many special properties of multimedia applications, traditional record-based DBMS techniques are not eective and not powerful enough to support those multimedia applications.
Therefore, dierent models to describe the properties of data and the relationship (and constrains) among data, dierent storage structure techniques and query languages for ecient
data access, dierent transaction management techniques (including concurrency control
and recovery) and version management mechanisms for reliable data sharing are required
(Christodoulakis et al., 1986 Huang and Lo, 1994 Little and Ghafoor, 1990, 1993 Oomoto
and Tanaka, 1993).
In the part of data modeling, multimedia databases require a data model that allows a
very natural and exible denition and evolution of the schema which can represent the
composition of compound document and capture the complex relationships among parts
of compound data. The traditional well-known record-based relational data model does
not provide the possibility of directly modeling complex data. Moreover, many complex
relationships among data, for example, instantiation, aggregation and generalization, can
not be well dened in the relational data model. Furthermore, the relational data model
does not provide mechanisms to associate data behavior with data denitions at schema
level. An object-oriented data model not only provides great expressive power to describe
data and to dene complex relationships among data, it but also provides mechanisms for
behavioral abstraction. Therefore, an object-oriented approach to modeling multimedia
data has been studied largely in past years (Ishikawa et al., 1993 Woelk, 1986, 1997). In
the part of query languages for ecient data access, multimedia databases require a userfriendly query language that can retrieve data by content, by keywords or by relationships.
The major characteristics of a query language are its high-levelness, declaractiveness, eciency and application independence.
In this paper, we design and implement a QBOE (Query-By-Object-Example) query
language for multimedia database systems. Our system is based on an object-oriented
model. In this version of QBOE MMDB, we consider only three types of media: text,
graph and image. The query language is called Query-By-Object-Example, since either
DDL (Data Denition Language) or DML (Data Manipulation language) is through an
object example. In the part of DDL, the user can specify the prototype of a multimedia
application, including the specic keywords for the application and related operations. In
the part of DML, the user can access data by contents or keywords which are specied
in attributes. Based on well-trained knowledge about X-lib (for X window systems) (Nye,
1992), database systems and image processing, we have developed a user-friendly interface
for QBOE MMDB (Jair, 1995).
The rest of the paper is organized as follows. In Section 2, we describe the objectoriented model for our QBOE (Query-By-Object-Example) multimedia database system.
QBOE Query Language for Multimedia Database Systems
2
We use a multimedia poster as an example. We also show the logical structure of this
example. In Section 3, we present the DDL (Data-Denition-Language) and DML (DataManipulation-Language) of our QBOE multimedia database system. In Section 4, we describe the implementation of our QBOE query language for multimedia database systems.
Finally, Section 5 gives the conclusion.
II. The Object-Oriented Model for Multimedia Database
Systems
In this Section, we briey describe the object-oriented model proposed by Woelk et al.
(1986) for multimedia database systems.
1. The Object-Oriented Data Model
The core object-oriented concepts include the following items (Shah and Wong, 1994):
(1) Objects and object identiers. In an object-oriented system, all real-word entities are
represented as objects and each object has a unique identier. An object may be a simple
object or it may contain other objects. (2) Attributes and methods. An object can have
one or more attributes and methods, which operate on the values of these attributes. (3)
Encapsulation and message passing. External entities cannot directly access the attributes
of the object. To access the values of these attributes, messages have to be sent to the object.
(4) Classes and instances. Classes provide means to group objects that share the same set
of attributes and methods. Objects that belong to a class are called instances of that
class. (5) Class hierarchy and inheritance. The classes in an object-oriented systems form
a hierarchy (the class hierarchy), where a subclass inherits all the attributes and methods
of its superclass(es). Inheritance provides an important means for sharing behavior among
related objects.
2. Representation of a Multimedia Application
Figure 1 shows a typical example of a multimedia poster. It contains three kinds of the
typical multimedia information: text, drawing and image.
In this poster example, Time, Place and Dept. are keywords for a typical poster. The
rst line is the topic of the poster. The poster header contains the topic and those key
words and related data. The poster body contains a paragraph, a drawing graph, an image,
a drawing graph, and a paragraph. The logical data model of this example is described in
Figure 2. Note that there are six types of information represented in Figure 2, which are
described as follows (Woelk et al., 1986): (1) The connected circles represent the logical
parts of the Poster. They are connected to form the aggregation hierarchy. Unshaded circles represent what we might consider to be parts of a template for a Poster. For example,
all Posters contain a Poster-Header and a Poster-Body. This can be through of as representing the schema for a Poster. (2) Shaded circles represent the portion of the aggregation
QBOE Query Language for Multimedia Database Systems
3
Figure 1: An example of a multimedia poster.
Font-Size = 12
Poster
PosterHeader
Poster
Body
TimeLine
Topic
PlaceLine
By
Drawing
Text
Time:
Time
Dept.:
DepartName
Image
Drawing
draw
Place:
Place
vi
Time:
1995.6.9
13:00
Dept.
Applied
Mathematics
Place:
Science
4013
room
Figure 2: Representation of Poster hierarchy.
Text
QBOE Query Language for Multimedia Database Systems
4
hierarchy which is unique to this particular Poster. For example, the Text contained in
the Poster-Body of the Poster are unique to this particular Poster. (3) The Squares represent uniformmated intrinsic data such as text, digitized image and complex vector graphics
drawings. The Unshaded Squares represent data which is present for every Poster. For
example, the word \Time:" will occur in every Poster. (4) The Shaded Squares represent
text, image which we might consider to be unique to this particular Poster. For example,
the words \1995.6.9 13:00" would only occur on this Poster. (5) The Ovals represent information about the data in the Shaded and Unshaded Squares as well as information about
the Shaded and Unshaded Circles of the aggregation hierarchy. For example, all of the text
in the Poster is to be displayed in Font-Size = 12. (6) The Rectangles represent operations
on the data in the Squares, Circles, and Ovals of the aggregation hierarchy. For example,
the Rectangle labelled Draw in Figure 2 contains procedural operations for drawing the
drawing part.
In Figure 2, a multimedia application is described in terms of diagrams. The diagram
is a directed acyclic graph containing nodes and directed arcs. The types of nodes and the
legal directed arcs from each type of nodes are shown in Figure 3: token objects representing classes, token objects representing instances, attributes, method objects, and intrinsic
data objects (Woelk et al., 1986). The following describes the legal directed arcs which are
associated with a token object as shown in Figure 3: (1) Instantiation. Each instance
is represented by a token object which has an IS-INSTANCE-OF directed arc to an
object. For example, the IS-INSTANCE-OF directed arc between the Poster instance
node and the Poster class node in Figure 3 represents instantiation. (2) Generalization.
An object class, represented by a token object, can have an IS-TYPE-OF directed arc
to another token object representing another object class. (3) Aggregation. In Figure
3, there is a HAS-PARTS directed arc between the Poster-Body instance and the Text
instances, the Drawing instances, and the Image instance. (4) Attributes. Each token
object has a HAS-ATTRIBUTES arc which points to multiple attributes. An example
of an attribute is the Font-Size=12 in Figure 3. (5) Methods. Each token object has a
HAS-METHODS arc which points to one or more programs which are stored independently from the token object. Figure 4 and Figure 5 represent the logical data structure
of the Poster class and instances, respectively. The MIN and the MAX values specify the
minimum number and maximum number of instances of the class which can be contained,
respectively.
III. DDL and DML
In this Section, we present our QBOE query language for multimedia database systems.
We rst describe our design of DDL (Data Denition Language). Next, DML (Data Manipulate Language) is introduced. For convenience, we use the example shown in Figure 1
to illustrate the process of DDL and DML.
QBOE Query Language for Multimedia Database Systems
Poster
IS-INSTANCE-OF
Poster
5
Instance
arc for each
class/Instance pair
HAS-ATTR
HAS-PART
HAS-PART
Font-Size
= 12
1
Poster
Header
instance
1
Poster-
Poster
Header
Body
PosterBody
instance
HAS-PART
HAS-PART
n
HAS-PART
Drawing
HAS-PART
n
n
Text
Image
Text
instance
Drawing
instance
Image
instance
Drawing
instance
HAS-DATA
HAS-DATA
HAS-DATA
HAS-DATA
Text
instance
HAS-DATA
1
HAS-METHOD
HAS-METHOD
Timedraw
Line
CAN-HAVE-PART
1
Time-Line
instance
vi
3003
3004
3005
3006
HAS-PART
1
Time:
Time:
instance
Time
HAS-DATA
HAS-DATA
3001
3001
TOKEN OBJECT
FOR CLASS
TOKEN OBJECT
FOR INSTANCE
ATTRIBUTE
Time
instance
HAS-DATA
3002
METHOD
OBJECT
INSTRINSIC
DATA OBJECT
Figure 3: Representation of Poster Class and Poster Instance.
3007
QBOE Query Language for Multimedia Database Systems
obj-id
100
110
111
120
121
can-have-parts
is-type-of
obj-id
class-name
has-data
obj=id
min
max
1
1
110
1
1
111
Poster-Header
1
1
120
Poster-Body
0
n
121
0
n
122
Poster
Time-Line
6
has-attributes
has-methods
obj-id
0
n
123
1
n
130
1
n
131
Font-size=12
Text
2002
122
Image
123
Drawing
130
Time:
131
Time
2001
3001
obj-id
method
2001
draw
2002
vi
Figure 4: Logical data structure (class).
obj-id
200
is-instance-of
obj-id
has-parts
obj-id
100 (Poster}
has-data
obj-id
has-attributes
210 (Poster-Header)
211 (Poster-Body)
210
110 (Poster-Header)
211
111(Poster-Body)
220 (Time-Line)
221 (Text)
223(Drawing)
222(Image)
224(Drawing)
225 (Text)
220
120 (Time-Line)
230 (Time:)
231 (Time)
221
121 (Text)
3003
222
122 (Image)
3004
223
123 (Drawing)
3005
224
123 (Drawing)
3006
225
121 (Text)
3007
230
130 (Time:)
3001
231
131 (Time)
3002
Figure 5: Logical data structure (instances).
has-method
QBOE Query Language for Multimedia Database Systems
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Figure 6: Information about an object Poster.
Figure 7: Specication of Poster-Header.
1. DDL (Data Denition Language)
For the commercial purpose, the most important communication channel between human
and machine is the user interface, especially in growth of the nonprofessional users of
database system. Therefore, the design of the user interface of database system must let
users do the least thing and get the most prot.
When a user enters the system, there are two options: query and create. To dene a
Poster class, a user rst chooses the create option. Next, the system will ask the user to
enter an object name. For each object, the system will ask for some more information:
Class Type, Part Number, Data, Attribute and Method as shown in Figure 6.
Those elds must be lled with an integer which means the number of related information. For example, in Figure 6, the user enters 2 in the Part Number eld, which means
that the Poster object contain two parts. The system will ask the user to input those two
children names one at a time. Figure 7 shows an example to input the child Poster-Header.
Moreover, for each child, the user has to specify the low bound and upper bound of the
number of occurrence of that child in Min Part and Max Part, respectively. Since each
QBOE Query Language for Multimedia Database Systems
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Figure 8: Specication of child Text of Poster-Body.
Figure 9: Specication of data in object Time:.
Poster can contain one and only one Poster-Header, those value are all 1's as shown in
Figure 7. For the Poster object, the user can also specify some attributes. In this example,
as shown in Figure 2, the Poster object has a Font-Size = 12 attribute.
In the same way, Figure 8 shows the process after four parts of Poster-Header have been
specied. In the part of Post-Body, it can contain Text, Drawing and Image. The number
of those parts can be from 0 to N (i.e., no limitation). Therefore, the user inputs 0 and N
in Min Part and Max Part, respectively.
Since in a standard Poster object, there are always some keywords like Time, Dept. and
Place. Therefore, we also support users to input those keywords as built-in data for each
Poster object. Figure 9 shows the way to specify the number of built-in data. After that,
the user can input a le name as the input data. If the le exists, the system will load the
data stored in the le and show it in the screen. If the le does not exist, the system will
ask the user to choose the type of data: Text, Drawing or Image, and will invoke related
editor as shown in Figure 10. For example, since Time is of text type, the system will
invoke \vi" as shown in Figure 11. The nal result is shown in Figure 12.
QBOE Query Language for Multimedia Database Systems
Figure 10: Specication of data in object Time: (continued).
Figure 11: Specication of data in object Time: (continued).
Figure 12: Specication of data in object Time: (continued).
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QBOE Query Language for Multimedia Database Systems
10
Figure 13: Final structure of object Poster.
Figure 14: The Poster class hierarchy.
For some object, there may be some related methods with it. For example, as shown in
Figure 2, there is a Draw method for the Drawing object. In the same way, after specifying
the number of methods in the Method eld , the system will ask the user to input a method
name for the Drawing object. Finally, Figure 13 shows the nal structure of object Poster.
2. DML (Data Manipulation Language)
We have described the Create function in the previous section and have created a new
Poster schema. Next, we will show how the other function { Query { works. After we
choose the Query function, the system will pop up a window that shows all of the functions
that the system provides: Insert, Delete, Select, and Modify. After we choose the Insert
function, a pop-up window appears, which asks the user to enter an object class name.
After Poster is entered, the system returns the Poster class hierarchy as shown in Figure
14, where the circle nodes mean the data which has been created by DDL. Every instance
of the Poster class shares those data objects.
QBOE Query Language for Multimedia Database Systems
11
Figure 15: The control table and the output window.
After the addNewOne function is chosen, two windows pop up at the same time as shown
in Figure 15. The upper one is called the control table and the lower one is called the output
window. The control table shows the objects which you can edit on the output window at
this moment.
After we choose the Poster-Header, the objects shown in the control table is replaced by
the children of the Poster-Header. At this time, a new rectangle box shows up in the output
window, which represents the position where any of these four objects: Topic, Time-Line,
By and Place-Line, can place. The rectangle can be moved to any place as we want in the
output window.
After we move the rectangle to a certain position, we can start to enter data. For
example, after we choose the Topic object, a pop-up window which inquires the user to
input data appears again. Then, another window appears to ask the user to input the le
name. After examine is entered, the system will ask for the data type of the specied le
name. In this case, Text is chosen. Assume that the examine le dose not exist therefore,
a test editor \vi" is invoked. After we edit the le and exit \vi", the le is ready and is
copied to the output window as shown in Figure 16. Next, the system will ask the user to
input a keyword for the data as shown in Figure 17. (Note that if the examine le already
exist, then the contents of the le will directly show up in the output window without
invoking the text editor \vi".)
In the same way, when other object is chosen, the system will rst ask for a le name,
and then the data type of the specied le name. If the le already exists, the le is copied
to the position where the new rectangle appears in the output window. If the le does not
exist, the related editor is invoked. Consider a drawing object is chosen. First, the system
shows a window to input the le name. Then, the data type Drawing is chosen. Assume
that the le does not exist therefore, the drawing editor is invoked as shown in Figure
QBOE Query Language for Multimedia Database Systems
Figure 16: The topic shows up in the output window.
Figure 17: Input a keyword.
Figure 18: The drawing editor.
12
QBOE Query Language for Multimedia Database Systems
13
18. This drawing editor is implemented by ourself. (Note that the reason why we do not
use an existing drawing editor, for example, xfig, is that we do not realize the internal
representation of a gure in xfig.) Figure 19 shows the output window after the drawing
le is loaded. Finally, Figure 20 shows the output window after the insertion is nished.
This is the example that we have used through the paper.
Let us consider the case of data selection. First, the system will ask for an object name.
Then the object hierarchy appears and two selection options, contain-based and keywordbased, are shown up on the left upper corner. After the user chooses the Topic object,
the word Topic will appear on the bottom line of the screen. The user then chooses the
contain-based function. At this time, an empty box will appear on the left upper corner. In
this example, the user types \Jair" in the box. After that, a sentence (Topic CONTAINS
"Jair") appears on the bottom line of the screen as shown in Figure 21. Now, the user has
entered the condition which is equivalent to a SQL statement (select * from Poster where
Topic CONTAINS "Jair"). The result is shown in Figure 1.
Next, let us see an example of a keyword-based query. After the user chooses the
Drawing object, the word Drawing will appear on the bottom line of the screen. The
user then chooses the keyword-based function. At that time, an empty box will appear on
the left upper corner. In this example, the user types "pain" in the box. After that, a
sentence (Drawing: KEYWORD = "pain") appears on the bottom line of the screen as
shown in Figure 22. Now, the user has entered the condition which is equivalent to a SQL
statement (select * from Poster where Drawing: KEYWORD = "pain"). The same result
is obtained.
To implement the SQL statement (select Text from Poster where Topic CONTAINS
"Jair"), the user can move the cursor to the Text part which the user is interested in and
clicks the button one time, which results in a new Text window showing up. In the same
way, the user can move the cursor to the Drawing part or the Image part, and clicks the
button one time to open a new Drawing window or a new Image window. Figure 23 shows
that the output window, the Text window, the Drawing window and Image window can
appear at the same time. Moreover, we can extend our system to handle a query which
contains AND, OR logical operations for more complex queries. We also can extend our
system to handle a set of results by providing Previous and Next functions to browse a set
of results.
For the Delete function, the user follows the way of using the Select Function to nd
out what he (she) wants to delete. After the data shows up, the system will ask the user
to conrm his (her) choice as shown in Figure 24.
For the Update function, there are four options: modify, move, insert and delete. Those
four options operate on a single object at a time. First, the user also follows the way of
using the Select function to nd out what he (she) wants to update. After the data shows
up, the user can move the cursor to the part which he (she) wants to modify by choosing
the modify option. After the user clicks the part, the related Text or Drawing or Image
windows will occur. Take the Drawing window as an example, the user then can enter the
drawing editor \MyDraw" environment to modify the drawing part. After the user exists
the drawing editor, the updated le will copy to the output window. Figures 25, 26 and
QBOE Query Language for Multimedia Database Systems
Figure 19: The output window after a drawing le is loaded.
Figure 20: The output window after the insertion is nished.
14
QBOE Query Language for Multimedia Database Systems
Figure 21: A contain-based query.
Figure 22: A keyword-based query.
15
QBOE Query Language for Multimedia Database Systems
Figure 23: The four windows on the display.
16
QBOE Query Language for Multimedia Database Systems
17
Figure 24: An example of deleting the whole Poster instance.
27 show such an example. That is, the updated result shows up. When the delete option
is chosen, the selected object will be deleted one at a time as shown in Figure 28. When
the move option is chosen, the selected object can be moved to any place in the output
window as shown in Figure 29. When the insert option is chosen, a new object can be
inserted as shown in Figure 30 by pressing the Yes button. Then, the system will ask the
user to choose the type of the data as following the steps of the Insert function described
before. The related editor will be invoked if it is necessary. Figure 31 shows the result of
the single object insertion. The BNF grammar of the QBOE language is shown in Figure
32, which is similar to the one proposed by Kau and Tseng (1994).
IV. The Implementation
In this section, we describe the implementation details of our QBOE query language for
multimedia database systems. Our system is implemented by C++ and X-lib (Jair, 1995).
We describe the data structure and owcharts for DDL and DML.
Figure 33 shows the logical implementation of an object-oriented data model described
in Section 2. This structure dened in C++ is shown in Figure 34. Note that there are ve
additional elements { isTypeOfCount, partCount, dataObjCount, attrCount, and methodCount. We use these ve elements of CLASS structure to record the variable parts of the
CLASS structure { isTypeList, partList, dataObjList, attrList, and methodList, respectively.
QBOE Query Language for Multimedia Database Systems
Figure 25: An example of a modication operation.
Figure 26: An example of a modication operation (continued).
18
QBOE Query Language for Multimedia Database Systems
Figure 27: An example of a modication operation (continued).
Figure 28: An example of deleting an object at a time.
19
QBOE Query Language for Multimedia Database Systems
Figure 29: An example of moving an object.
Figure 30: An example of inserting a new object.
20
QBOE Query Language for Multimedia Database Systems
21
Figure 31: An example of inserting a new object (continued).
<S> ::=
<A> ::=
<R> ::=
<C> ::=
<C1>::=
<E> ::=
<L> ::=
SELECT <A> FROM <R> WHERE <C>
<attribute_name> | *
<class_name>
(<C1> ( AND | OR ) <C> | <C1> )
("(" <C> ")" | <E> )
<L> ("=" | "<" | ">" | CONTAINS | : KEYWORD = ) <L>
<string>
Figure 32: The BNF grammar of the QBOE language (the selection part).
obj-id
class-name
is-type-of
obj-id
has-data
can-have-parts
min
max
obj-id
obj-id
has-attributes
Figure 33: Logical data structure of a class object.
has-methods
QBOE Query Language for Multimedia Database Systems
struct CLASSf
int objectID
int isTypeOfCount
int partCount
int dataObjCount
int attrCount
int methodCount
char *className
int *isTypeList
PART *partList
char *dataObjList
char **attrList
int *methodList
CLASS *next
g
struct PARTf
int min
int max
CLASS *object
char *objName
int objID
g
Figure 34: The C++ implementation of a logical class object.
15570 0 0 0 0 0 Topic
13150 0 0 1 0 0 Time: Time:
10250 0 0 0 0 0 Time
42300 0 2 0 0 0 Time-Line 1 1 13150 1 1 10250
16480 0 0 1 0 0 Dept.: Dept.:
62730 0 0 0 0 0 Depart-Name
3080 0 2 0 0 0 By 1 1 16480 1 99999 62730
18360 0 0 1 0 0 Place: Place:
14880 0 0 0 0 0 Place
51300 0 2 0 0 0 Place-Line 1 1 18360 1 1 14880
88640 0 4 0 0 0 Poster-Header 1 1 15570 1 1 42300 1 1 3080 1 1 51300
11100 0 0 0 0 0 Text
28810 0 0 0 0 1 Drawing 6
14990 0 0 0 0 0 Image
64730 0 3 0 0 0 Poster-Body 0 99999 11100 0 99999 28810 0 99999 14990
23000 0 2 0 1 0 Poster 1 1 88640 1 1 64730 Font-Size=12
Figure 35: The format of a class object stored in classFile.
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QBOE Query Language for Multimedia Database Systems
23
QueryClassID(X)
start
Yes
End of classFile
return NULL
stop
No
No
className = X
Yes
return objectID
stop
Figure 36: The owchart of constructing a class hierarchy.
constructClassHierarchy(X)
start
End of
classFile
Yes
End
No
No
objectID= X
Yes
return the data
record
Yes
PartCount = 0
No
stop
i=1
i < PartCount
No
Yes
constructClassHierarchy(Part.objID)
Link the return object
to the Part.CLASS
i++
Figure 37: The owchart of constructing a class hierarchy (continued).
QBOE Query Language for Multimedia Database Systems
struct ObjInstf
int objectID
int partCount
int dataCount
int attrCount
int methodCount
int keywordCount
int classID
int *partList
int *rstPartEntry
ObjInst **partEntry
char **dataList
char **attrList
int *methodList
char **keywordList
char *type
char *upperleftX, *upperleftY
char *lowerrightX, *lowerrightY
ObjInst *next
g
Figure 38: The data structure of an object instance.
684 0 1 5 0 1 15570 examine exam type=1 wx1=1 wy1=1 wx2=376 wy2=19
686 0 1 5 0 1 13150 Time: Time: type=1 wx1=2 wy1=2 wx2=53 wy2=20
687 0 1 5 0 1 10250 time examtime type=1 wx1=56 wy1=2 wx2=188 wy2=20
685 2 0 5 0 0 42300 686 687 type=0 wx1=1 wy1=23 wx2=501 wy2=60
689 0 1 5 0 1 26660 Dept.: Dept: type=1 wx1=1 wy1=1 wx2=61 wy2=19
690 0 1 5 0 1 62730 AM math type=1 wx1=64 wy1=1 wx2=331 wy2=19
688 2 0 5 0 0 3080 689 690 type=0 wx1=3 wy1=49 wx2=503 wy2=83
692 0 1 5 0 1 18360 Place: Place: type=1 wx1=1 wy1=1 wx2=61 wy2=19
693 0 1 5 0 1 14880 S4013 4013 type=1 wx1=65 wy1=1 wx2=225 wy2=19
691 2 0 5 0 0 51300 692 693 type=0 wx1=2 wy1=72 wx2=502 wy2=102
683 4 0 5 0 0 88640 684 685 688 691 type=0 wx1=1 wy1=1 wx2=519 wy2=106
695 0 1 5 0 1 11100 outline QBOE type=1 wx1=12 wy1=1 wx2=477 wy2=145
696 0 1 5 0 1 28810 pain pain type=2 wx1=157 wy1=126 wx2=320 wy2=274
697 0 1 5 0 1 14990 j2.pcx jair type=3 wx1=406 wy1=91 wx2=605 wy2=351
698 0 1 5 0 1 28810 smile smile type=2 wx1=5 wy1=121 wx2=172 wy2=289
699 0 1 5 0 1 11100 jair born type=1 wx1=5 wy1=365 wx2=632 wy2=404
694 5 0 5 0 0 64730 695 696 697 698 699 type=0 wx1=5 wy1=124 wx2=771 wy2=528
682 2 0 0 0 0 23000 683 694
Figure 39: The format of instances stored in PosterInstances.
24
QBOE Query Language for Multimedia Database Systems
25
All class objects that have been created are saved in the classFile, as shown in Figure 35.
The rst columns are the objectID. The following ve columns are the additional elements
which are described above. Let's examine the 4th row in Figure 35 the 3rd column of that
row has a value 2. It indicates that the object has two children. So, the numbers following
Time-Line describe the children's characteristic. The rst number indicates that at least
one child exists, and the second number indicates the maximum number of children of this
class. The third number is the ID of the rst child.
Figures 36 and 37 shows the owcharts of constructing a class hierarchy. First, the
system scans the classFile le to search the assigned class. If the named object does not
exist in the classFile le, then NULL is turned. If the named object is in the classFile
le, then the related objectID is returned. Next, the system recursive calls the function
constructClassHierarchy to construct the children of the assigned objectID. In our example,
it is 23000 for the Poster object. The children of the Poster is saved in the PART structure.
Figure 38 shows the data structure of an instance of a class object. Figure 39 shows an
example of the instance le. All instances of Poster class is stored in this PosterInstances
le. Let's examine the 3rd row in Figure 39. The third column of that row has a value 1,
which indicates that the object has a data le whose name is following the object identier
10250, i.e., time. The 6th column of that row has a value 1, which indicates that the
object has a keyword whose content is following the data le name, i.e., examtime. The
5th column of that row has a value 5, which indicates that the object has 5 more attributes
to be recorded, i.e., type, upperleftX , upperleftY , lowerrightX , lowerrightY . Following
the keyword content, there is a string type=X , which indicates that the data is of type
text, drawing, image and none of the above for X =1, 2, 3, 0, respectively. The next four
strings record the coordinates of the upper left corner and the bottom right corner of the
data shown in the output window.
For the type of contain-based selection, let us take (select * from Poster where Topic
CONTAINS "Jair") shown in Figure 21 as an example. First, we search the Poster class
hierarchy constructed by following the owcharts shown in Figures 36 and 37 to nd the
objectID of Topic, which is 15570. Second, we search all the data les recorded in dataList
which have classID = 15570 in the PosterInstances le to see whether they contain a string
"Jair". In this example, the le name is examine. Since there may exist many instances
of Poster class, to speed up such a search for those data le names, we can create a le
classID-dataList-objectID to record only classID, dataList and objectID of type text (i.e.,
type = 1) when data of type text is inserted, and then create an index on classID for this le.
Note that for this version of QBOE MMDB, we support data access by contents for data of
type text only. In this case, we nd that le examine contains "Jair". Third, after we nd
out the le which contains the required contents, we then have to nd out the objectID
which contains such a le from the classID-dataList-objectID le. In this case, it is 684.
Forth, we have to nd out the objectID of the root node of the Poster instance hierarchy
which contains a leaf node with objectID = 684. That is, in the object-oriented data model,
for such a Poster aggregation hierarchy, we want to nd an answer for a nested predicate
Poster.Poster-Header.Topic.objectID = 684 (which is expressed in a path expression). There
have been several index organization proposed to support object-oriented query languages,
QBOE Query Language for Multimedia Database Systems
26
including multiindex (Maier and Stein, 1986), join index (Valduriez, 1987), nested index
(Berstino and Kim, 1989), path index (Berstino and Kim, 1989), and full index (Lee et al.,
1996). Among them, nested index provides a direct association between an ending object
and the corresponding starting object along a path in the given aggregation hierarchy.
Therefore, we can create a nested index for the Poster instances and eciently nd out
the objectID of the root, which is 682. Finally, based on the objectID of the root, we can
construct the required Poster instance by following a similar owchart shown in Figure 37.
For the type of keyword-based selection, let us take (select * from Poster where Drawing
: KEYWORD = "pain") shown in Figure 22 as an example. First, we search the Poster
class hierarchy to nd the objectID of Drawing, which is 28810. Second, we search the
PosterInstances le to nd out whether there exists a keyword = "pain" (recorded in
keywordList) which has classID = 28810. To speed up this search, for each data type (text,
drawing and image), we create a le classID-keywordList-objectID to record only objectID,
keywordList and objectID when data is inserted, and then create an index on classID for
this le. In this case, we nd that objectID = 696 of classID 28810 (Drawing) has a key =
"pain". Third, by making use of the nested index for the nested predicate Poster-PosterBody.Drawing.objectID = 696, we nd out the objectID of the root, which is 682. Finally,
based on the objectID of the root, we can construct the required Poster instance. (Note
that if more then one instances are found, we collect the objectID of the roots together and
display one instance at a time.)
V. Conclusion
In this paper, we have designed and implemented a QBOE (Query-By-Object-Example)
query language for multimedia database systems. Our system is based on an object-oriented
model. In this version of QBOE MMDB, we have considered only three types of media:
text, graph and image. The query language is called Query-By-Object-Example, since
either DDL (Data Denition Language) or DML (Data Manipulation language) is through
an object example, In the part of DDL, the user can specify the prototype of a multimedia
application, including the specic keywords for the application and related operations. In
the part of DML, the user can access data by contents or keywords which are specied
in attributes. Based on well-trained knowledge about X-lib, database systems and image
processing, we have developed a user-friendly interface for QBOE MMDB.
In traditional DBMS, once transaction updates have been committed and permanently
installed, the previous values of data usually are discarded. However, advanced multimedia
applications, especially design applications, require facilities to maintain data versions, i.e.,
to keep dierent status of the same data (called historical versions). Moreover, versions can
be used to provide a dierent alternatives of the same data (called alternative versions).
How to provide mechanisms to manage historical and alternative versions is the further
research work.
QBOE Query Language for Multimedia Database Systems
27
Acknowledgments
This research was supported by the National Science Council of the Republic of China,
Grant No. NSC 84-2213-E-110-009.
QBOE Query Language for Multimedia Database Systems
28
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