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Introduction to Information Systems

Introduction to Information Systems

Table of Contents
1

Introduction to Information Systems.............................................2
1.1 Introduction.....................................................................................................2
1.2 Architecture of Information systems................................................................2
1.3 Classification of Data Models..........................................................................4
1.4 Relational Data Model (Overview)..................................................................8

Introduction to Information Systems

1 Introduction to Information Systems
1.1

Introduction

In this course, we define an Information System as any software application dealing with
persistent information (i.e. persistent data) in computer's memory.

Persistent Data exist independently of a user's session.
In other words, persistent data objects are created by a particular user and available for all
others at any time.

1.2

Architecture of Information systems

Primitively speaking, we can see an Information System as a combination of three main
components:

Introduction to Information Systems

Application Layer implements purpose-oriented data processing algorithms and a
particular user interface.
There is no common solutions which are used for designing different information
systems. For example, a project management system, electronic library, financial
transaction system, computer-based training system, etc. require essentially different data
processing algorithms and user interfaces.

Data Management Layer provides data structures and operations to be utilised by the
application layer.
Formally, a combination of data structures and data processing operations supported by
the Data Management Layer is called a Data Model.
We can speak about information systems based of a file management system, on a
relational data model, on World-Wide Web, etc.
In other words, information systems may be based on different data models.

Introduction to Information Systems

It should be especially noted that essentially different information systems may be based
on one and the same data model. For example, a collaborative document authoring
system and an university information system might well utilize one and the same
relational data model.

1.3

Classification of Data Models

Data management principles are essentially different depending on nature of information
to be processed.
Thus, we can speak at least about well-structured data and ill-structured data.

Introduction to Information Systems

We speal about well-structured data if structure of data objects may be separated from its
actual content.
In other words, there are a number of data objects having identical structure (metastructure). In this case, any data object is just an instance of a previously defined data
type.
Well-structured data management is based on so-called database technology:


data base schema contains a description of all data types which are of interest to users.



data base contains instances of the data types previously defined in the data base schema.

To build a Database:


1. Database Administrator has to accurately define a particular Database Schema;



2. Application layer programmers apply a collection of operators which are supported by
the DBMS, to retrieve, store, or modify data.

Note that data objects are created as instances of previously defined data types, i.e. by filling
predefined forms with actual data.

Introduction to Information Systems

Thus, a DBMS maintains two different but closely connected languages:


1. Data Description Language (DDL) is applied to define database schemata;



2. Data Manipulation Language (DML) is a collection of operators to create, access and
modify Databases.

We speak about ill-structured data if structure of a data object cannot be separated from
its actual content.
In other words, each data object may have an unique data structure which is coded as a
part of its actual content.

Introduction to Information Systems

In order to work with Ill-structured Data,


1. Data Objects are coded (authored) using special data encoding (mark-up) language



2. References to other objects are inserted directly into the object code (embedded links)



3. Special software interprets such object code

For example, World Wide Web (WWW) utilizes HTML as the data encoding language and
standard software packages (Internet Browsers) to interpret the code.
Such systems are normally referred to as first generation hypermedia systems.

Second generation Hypermedia supports meta-languages, i.e. general mechanisms
which can be used to define application oriented data encoding paradigms
For example, eXtensible Markup Language (XML) and Cascading Style Sheets (CSS).
Meta-language allows to manage any information in a platform- and vendor-neutral way,
and then easily share this information with any other application.

Introduction to Information Systems

Second generation Hypermedia operates with higher-level data structures called
Hypermedia Composites
Hypermedia Composites may be seen as structured collections of data objects and other
composites.
Composites facilitate collaborative authoring, usability and integrity of hypermedia
systems.

Thus, we can see a comparison of these two data management techniques as follows:

1.4

Relational Data Model (Overview)

Relational Data Model allows to operate with a database as with collection of twodimensional tables called relations.

Introduction to Information Systems

Tuples (i.e. Data Objects) are related by means of so-called foreign key/primary key
relationships.

A relational database schema may be seen as a definition of a number of relations
(tables).
Each relation is defined as a unique name with a list of domains which corresponds to
columns of the relation.
For example:


Customer(C#,Cname,Ccity,Phone)



Product(P#,Pname,Price)



Transaction(C#,P#,Date,Qnt)

Introduction to Information Systems

To insert (put) new tuples into a particular relation declared in a current data base
schema;


Step1: A user (an application programm) chooses a relation (say, Customer);



Step2: The user (programm) prepares a new tuple of the relation on the screen or in the
computer's memory.



Step3: The DBMS put a new tuple into the relation (data base).

Relational Data Model automatically supports so-called Referential Integrity:
"A foreign key can have only two possible values, either the relevant primary key value
or Null-Value. No other values are permitted"

Introduction to Information Systems

The most popular relational query language is called SQL (Structured Query Language).
The basic operation in SQL is called mapping, which transforms values from a database
to user requirements.
This operation is syntactically represented by the SQL block.

SQL blocks may be nested in order to implement more complex queries.
Consider for example the following query:
"Get names of such customers who bought the product CPU ".

Introduction to Information Systems

SQL blocks may operate with multiple relations to select data from such different
relations.
Consider for example the following query:
"Get customer names, dates and numbers of product units for transactions dealing with
the product number 1".

Introduction to Information Systems
Topics



Databases and Relation DM



HTTP, HTML and Architectur of IS



Server-Side Scripting (PHP)



Client Side Scripting (Javascript, DHTML, AJAX)



XML, XML Name Spaces, DTD



XML Schema



XML Processing (XSL)



XML Linking



Web Services



Emerging XML Standards

Introduction to Information Systems
Problems



Materials are not suitable for lecturing



Best way is Learning by Doing



Lecturing Schedule is not very good



Teaching Blocks



Learning via Internet

Introduction to Information Systems
Repository & Communication

Note, scripts, courseware and communication are essential components

Course WEB Site:
http://coronet.iicm.edu/is

Main way of communication:
News Group "tu-graz.lv.is"

Introduction to Information Systems
Examination

The Examination is carried out as evaluation of two components done by a student:
1. Constracting a simple internet-based information system.
Can be done in a group (Max. 5 students) Tutoring session: 09/11 2011 .
Deadline for uploading is January 12th 23:59
2. A special diary where students report their progress with course blocks.
Must be done individually.
Both components are evaluated as a number of points (Max. 20 points for
each component).
You will get your examination mark automatically as a result of evaluation of
your diary and constructional example
Your total mark will be calculated using the following schema:
o

37 and more points - total mark "1(A)".

o

32 - 36 points - total mark "2(B)".

o

25 - 31 points - total mark "3(C)".

o

18 - 24 points - total mark "4(D)".

Thus, please
1.

make 4-5 entries to your diary
2. develop a Constructional Example

That's it !

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