System Analysis and Design
System Design
- Mr. Ahmad Al-Ghoul
learning Objectives
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Understand the components of a
database management system (DBMS)
Describe Web-based data design,
including characteristics of Web-Based
Design, Internet terminology,
connecting a Database to the Web, and
data Security
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System Analysis and Design
System Design
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DBMS Components
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A DBMS provides an interface between a database and users who
need to access the data
In addition to interfaces for users, database administrators, and
related systems, a DBMS also has a data manipulation language, a
schema and subschemas, and a physical data repository
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DBMS Components
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Interfaces for Users, Database Administrators,
and Related Systems
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When users, database administrators, and related
information systems request data and services, the
DBMS processes the request, manipulates the data,
and provides a response
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Users: typically work with predefined quires and switchboard
commands, but also use a query language to access stored
data
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Query language: A query language allows a user to specify a
task without specifying how the task will be accomplished.
Some query languages use natural language commands that
resemble ordinary English sentences.
SQL (structured query language): is a query language that
allows PC users to communicate with servers and mainframe
computers.
System Analysis and Design
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DBMS Components
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Interfaces for Users, Database Administrators, and
Related Systems
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Database Administrators
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Related information systems
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A DBA is responsible for DBMS management and support
DBA is concerned with data security and integrity, preventing
unauthorized access, providing backup and recovery, audit
trails, maintaining the database, and supporting users needs
A DBMS can support several related information systems that
provide input to, and require specific data from, the DBMS
A data manipulation language (DML) controls database
operations, including storing, retrieving, updating, and
deleting data
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Commands in this category allow you to manipulate data in
existing database objects. The most popular commands in this
category are INSERT, UPDATE, and DELETE.
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DBMS Components
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Schema
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The complete definition of a database,
including descriptions of all fields, tables, and
relationships, is called a schema
You also can define one or more subschemas.
A subschema is a view of the database used
by one or more systems or users. A
subschema defines only those portions of the
database that a particular system or user
needs or is allowed to access.
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DBMS Components
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Physical Data Repository
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The data dictionary which describes all data elements
included in the logical design, is transformed into a
physical data repository, which also contains the
schema and subschemas
The physical repository might be centralized, or
distributed at several locations
To resolve potential database connectivity and access
problems, companies use
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ODBC – open database connectivity: is an industry-standard
protocol that makes it possible for software from different
vendors to interact and exchange data uses SQL statements
JDBC – Java database connectivity: JDBC enables Java
applications to exchange data with any database that uses
SQL statements and is JDBC-compliant
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System Design
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Web-Based Database Design
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Characteristics of Web-Based Design
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In a Web-based design, the Internet serves as
the front end, or interface for the database
management system. Internet technology
provides enormous power and flexibility
In internet the system is not tied to any specific
combination of hardware and software
Access to the database require only a Web
browser and an Internet connection
Web-based systems are popular because they
offer ease of access, cost-effectiveness, and
worldwide connectivity
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Web-Based Database Design
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Web-based design characteristics [1]
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Web-Based Database Design
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Internet Terminology
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Web browser: An application that enables the user to
navigate, or browse the Internet and display Web
pages on his or her local computer.
Web page: Text and multimedia documents that are
found on the World Wide Web.
HTML – Hypertext Markup Language: Is the language
used to write Web pages for the Internet.
Web server: A computer that is used to store and
house Web sites.
Web site: A collection of related Web pages.
Intranet: A private, company-owned network that
provides Web-based access to internal users
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Web-Based Database Design
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Internet Terminology
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Extranet: An extension of a company intranet that allows access
by external users, such as customers and suppliers.
Protocols: A set of standards that govern network data
transmission. Also, preset conditions used by firewalls to
determine whether or not to allow traffic to pass.
Web-centric: A strategy or approach that emphasizes a high
degree of integration with other Web-based components. A
Web-centric architecture follows Internet design protocols and
enables a company to integrate the new application into its ecommerce strategy.
Clients: Workstations that users interact with in a client/server
design. These workstations, or computers, are supplied data,
processing services, or other support from other computers,
called servers.
Servers: Computers in a client/server design that supply data,
processing, and services to the client workstations.
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Web-Based Database Design
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Connecting a Database to the Web
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Database must be connected to the Internet or
intranet
The database and Internet speak two different
languages
Database are created and managed using various
programming languages and commands that have
nothing to do with HTML
To bridge the gab, it is necessary to use middleware
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Middleware: is software that connects dissimilar applications
and enables them to communicate and exchange data. For
example, middleware can link a departmental database to a
Web server that can be accessed by client computers via the
Internet or a company intranet.
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Web-Based Database Design
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When a client workstation requests a Web page (1), the Web server uses
middleware to generate a data query to the database server (2). The
database server responds (3) and middleware translates the retrieved data
into an HTML page that can be sent by the Web server and displayed by
the user's browser (4).
[1]
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Web-Based Database Design
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Data Security
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Web-based data must be totally secure, yet
easily accessible to authorized users
To achieve this goal, well-designed systems
provide security at three levels:
the database itself, the Web server, and the
telecommunication links that connect the
components of the system
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Sequence Summary
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DBMS components include interfaces for users, database
administrators, and related systems; data manipulation
language; a schema; and physical data repository
The physical repository might be centralized, or distributed at
several locations
In a Web-based design, the Internet serves as the front end,
or interface for the database management system.
Internet terminology include, web browser, web page, web
server, web site, HTML, intranet, extranet, protocols, webcentric, clients, and servers
When connecting database to the Internet they speak two
different languages you need To bridge the gab, it is
necessary to use middleware
Middleware: is software that connects dissimilar applications
and enables them to communicate and exchange data
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System Analysis and Design
System Design
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Sequence Summary
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In this Sequence we have
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Avicenna
Described the components of a database
management system (DBMS)
Described Web-based data design, including
characteristics of Web-Based Design, Internet
terminology, connecting a Database to the
Web, and data Security
System Analysis and Design
System Design
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Reference
[1] System Analysis and Design, Sixth
Edition
Authors: Gary B. Shelly, Thomas J.
Cashman and Harry J. Rosenblatt
Publisher: SHELLY CASHMAN SEWIES.
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System Analysis and Design
System Design
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