Solution of Assignment No. 2
Object Oriented DBMS – CS713
Muhammad Mustafa - MS120400114
Question No.1
(15 Marks)
Elaborate Extended Relational Data
Model DBMSs. Discuss POSTGRES iterative quires, alerters and triggers with the
help of their examples from real world scenarios.
Answer:
Extended Relational
Data Model DBMSs:
Extended
RDM DBMSs are the DBMSs that support and basically work on relational data
models and they are extended to provide the functionality of object oriented
concepts as well. INGRES and POSTGRES are the examples of extended relational
data model DBMSs. They are designed to provide the extensions of complex
objects, UDTs and their access methods, time varying data etc.
Iterative Queries in
POSTGRES:
Iterative
queries are special type of queries in POSTGRES. These queries contain
sub-queries in them. Theses queries are also repeated several times. These
queries are made to support transitive closure. It means we don’t know how many
times an iterative query will execute. The iterative query will remain
executing unless a certain condition becomes false.
For example:
Ahmad
is the supervisor of Ali, and Ali is the supervisor of Tahira. Now if we want
to find out all the sub-ordinates of Ahmad we will run the iterative query. The
query will also out put all the sub-ordinates of Tahira because they are indirectly
also the sub-ordinates of Ahmad.
Alerters and Triggers:
Alerters
and triggers perform some automatic task in the database when the database
enters into a particular state. Alerters and triggers work in conjunction. They
are built into the schema of DBMS.
For example:
We
have a course. Some students are enrolled in that course. Now we want that if a
course has zero students the the course should be automatically deleted from
the database. We can set alerters and trigger to perform this task. Now the user
will only delete students. And when the number of students in the relevant courses
goes to zero, the alerters and triggers will run update queries and the course
will be automatically deleted.
Question No.2
(15 Marks)
Which well-known problems of existing
research in OODBMS are addressed by STARTBURST project and how it is solved at
what level of extent? Give examples of real world scenarios with queries.
Answer:
STARTBURST
project address the following problems of existing research in OODBMS:
·
Present typical
database applications were growing complex. Moreover, advanced database
applications in the field of engineering were difficult to handle. STARTBURST
addresses these problems
·
To implement the
object oriented concepts, one of the techniques used was to extend the
relational data model. But these extensions were going towards saturation. So STARTBURST
was introduced.
·
Users were
greatly influenced by object oriented concepts. They wanted to incorporate these
concepts in DBMSs. STARTBURST does this for users.
·
Users were
demanding expert features in the database application. For example, features
like knowledge base systems, forward chaining, backward chaining etc.
·
The distributed
computing was becoming cost effective. STARTBURST wanted to utilize this.
·
Fixed data types
and functions were the major limitations in the traditional database management
systems. STARTBURST tries to achieve these by using scalar functions, aggregate
functions, set predicate functions and table functions
Question No.3
(10 Marks)
Draw architecture of Open ODB. Discuss
the key functionalities offered by the main components in Open ODB architecture
in client and server side.
Answer:
Clint
Server Architecture of Open ODB
Interactive
OSQL Interface (IOSQLI)
|
Object
Browser
|
Applications
and Tools
|
ALLBASE/SQL
util & IOSQL utilities
|
Object
Manager
|
User
defined extension functions
|
Object
Application Call Interface (OACI)
|
HP
external function library
|
ALLBASE/SQL
storage manager
|
Data
|
Clint
|
Server
|
Discussion on key
functions:
Client Side:
Interactive OSQL
Interface (IOSQLI): This is an interface that allows the
user to make interactive use of OSQL. User can query the DBMS through interface
and get the relevant results.
Object Browser (OB): This
is an interactive graphical browser. It allows the user to connect to the
database and perform updates to the data in the database dynamically.
Object Application Call
Interface (OACI): This interface allows the user to write
applications in any programming language. This interface links the applications
to the DBMS. OSQL statements are passed through arguments in the programming
language.
Applications and Tools:
These
are the applications written by the application programmers and they become the
part of the system being developed.
Server Side:
Object Manager (OM): This
is the main processor in the architecture. It receives the OSQL calls from the
client and passes them to storage manager for further processing. It also
passes calls to external functions.
Storage Manager (SM): In
the architecture it is known as ALLBASE/SQL. It performs all the database
activities.
External Function
Libraries (EFLs): Applications are written using the
EFLs. These functions are of two types;
user defined and systems defined. These can be called in OSQL statements.
Data: This
is the data on which everything is performed.
Question No.3
(10 Marks)
Discuss the main components of ILLUSTRA
architecture. How it can relate with Open ODB? Elaborate its commands with
examples.
Answer:
ILLUSTRA
architecture has three main components:
·
Main Server DB
Engine
·
Visualization
Tools
·
Datablades
Main Server DB Engine: It
adds object oriented features to the table. Wherever the OO queries are
launched it converts those queries to be suited for relations. It produces
database stories etc.
Visualization Tools: it
visually presents the objects and schema to the users so that they may work
easily.
Datablades: some
specific applications use the datablades for manipulations in the databases. In
conjunction with Razor (a type of DBMS), it performs specific functions.
Datablades are a type of add-ons. Image datablades perform functions on images.
Spatial datablades works for shapes. Text datablades perfrom search type
functions on text strings.
ILLUSTRA
can be related to Open ODB because both fall in the category of Object
Relational Data Model DBMSs.
ILLUSTRA DBMS Commands:
Table Creation:
CREATE
table Staff (name text, department text)
Creates
the table named Staff with the attributes name and department
Inheritance:
CREATE
table staff of type staff-t under people
‘People’
is a table already created and it is a super type. The new table staff is
create whose type is staff-t and super table is people
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