Hypertext, Logical Organisation and Stordyboards

Hypertext (Hypermedia): term used to describe bodies of text that are linked in a nonsequential manner. the related term hypermedia is an extension of hypertext to include links to a variety of different media types including image, sound and video. (text that link to other blocks of texts)

The Logical organisation of hyptertext/Hypermedia:  based on links (hyperlinks) and nodes. a set of nodes and their various links form a web - e.g. www.

Node: a point where links are connected. in a computer network a node is a device connected to the network.  in hypertext terms node is usually some block or unit of information.

Storyboards: technique that was first used for the creation of video infromation, includign film, television and animation.

• shows the various interfaces (screens)
• to identify the purpose, contents and design elements
• should identify area's used fro input, output and nagitaional elements.

4 Types of Storyboards:

Linear navigation: one single path -> simple to navigate, but not very flexible must go through each board before reaching a specified one

Hierarchical navigation: particularly suited to information that falls into categories and sub categories. once in a particular category, users are not overwhelmed by information from other categories, to navigate into another category user must move back up the hierarchy and then select another path.

Non-Linear navigation: difficult to visualise. allows maximum flexibility of design, but is easy for a user to get lost in a maze of screens. if a non linear structure is used in most cases some form of map is also provided.
e.g games

Composite: combines aspect of each of the other structures. in reality most hypertext webs use composite structure. makes sense as most web include instructional nodes that form a sequence, together with informational nodes that have some form of inherent classification.

Normalising Databases

Normalising: getting rid of redundant data
if there is redundant data:

• takes up too much space
• if one needs to be edited than all will required to be edited
• creates maintainence problems

Normalisation process is theorectically by progressional decomposing design into a sequence of normal forms - first, second and third.

First Normal Form (1NF):

• deals with the removal of repeating attributes across horizontal rows abnd ensures each field holds single data items.
• each field stores single data
• no multiple data items within individual fields and no fields are repeated

Second Normal Form (2NF)

• removes redundant data within verticle columns ro fields
• all tables must be in first normal form
• every non-key attribute is funtionally dependant on the table's primary key - but not unique (primary key defines the attribute + identifies the non key attribute - functionallt dependant) 
• e.g date of birth, address and phone number are functionaly dependant on student ID

Third Normal Form (3NF)

• removes furyher redundant data within vertical columns or fields
• all tables must be in second normal form
• every non-key attribute is functionally dependant only on teh table's primary key and not on any other attributes of the table.
• e.g. Kmart Layby! -> Layby no. -> phone number, suburb, surname -> functionally dependant on customer details

T1 Week 3: Relational Databases

http://bettscomputers.com/moodle/course/view.php?id=26&topic=all

Primary Key: Composite key - they are unique fields
Foreign Key: e.g The foreign keys generally define parent-to-child relationships between tables.

Database for School Library Loans

Set B - (pg 126)

1. C
2. C
3. A
4. B
5. C
6. D
7. D
8. B
9. A
10. B

Adv/Disadv : Flat file database system

duplicate of data -redundancy
copy or data -> have to write it out
takes up too much soon
can not be updated easily

adv: no need for power

T1 Week2: Methods of organsising databases: Flatfile DB (pg 119)

1. Read pg 119 - identify three computer based methods of organiising data

• Flatfile
• Realtional
• Hypertext/hypermedia/hyperlinks

2. Read page 121 - 122 on choosing appropriate field data types. summarise what must be considered when selecting data types.
Arithmetic operations: numeric data type,
Digits: no mathematical operations:-> text data type
Dates and Times: - dates and times
Data Text: limited number of characters, cannot be indexed
Unlimited characters : Memo
Numeric data: determine if its an interger or not. -> calculates the number of possible variations, roughly each character on the key board is a bite.
Numbers: Currency or money values -> use currency data type

• Fixed point: specifies how many decimal points - rarely used, doesnt represent accurately e.g has more that 2 decimal points, reserved for specialised docs, limited representation
• Floating: use of any number of decimal, commonly used, more range, more versatile, 7 significant figures.

Sorting a text field:  ascending sort of text -> 0,1,2,3 ... A,B,C
Alpha numeric characters: e.g.
1
10
103
12
2
21

value of currency: modified forms of fixed point representation

3.  Create a data dictionary (http://bettscomputers.com/moodle/course/view.php?id=26&topic=all#datadictionaries ) for the information system you documented last week (RTA, Video Store or School). Use sample HSC question on pg 123 as a guide. 

T1 Week 1: "Group Tasks" - pg 112 & pg 113

Software description to match DFD of School Timetable:

SQL server DBMS: Create Initial Timetable
LAN: Genertate student, teacher, adn locate teacher and student timetables and execute timetable query.
Timechart: Create initial timetable, generate teacher and student timetable.
SAS timetable module: Locate teacher or student, execute timetable query.

Classify external entities on C.D (fig 2.4) as either source and/or a sink.

Vocal Inspectors: Source,
Customers: Source, sink
Police departments: Source, sink
Other governemnt departments: Source, sink
Vehicle Dealers: Source
Insurance Companies:  Source

Context System - School Timetable

csv: comma seperated values: - used for the digital storage of data structured in a table of lists form, importing and exchanging data.

Servers: provide resources and information to a network,
e.g email, file storage, internet, databse, library, print servers,

Client:

Node (network PC): has client applications not server application

Information Systems and Databases

The aim of all information systems is to produce information from data for use by the system's end users. End users analyse the information to gain knowledge and only then the system's purpose is achieved.
All information processes are required to produce information for the database, two in particular are:

• data needs to be appropriately organised
• must be able to be stored and retrieved efficiently.

Databases contain the raw data used by majority of information systems.

Examples of Databases Information Systems:

• Flat-File Databases - including non- computer examples 
• Relational Databases
• Hypermedia or hypertext

consists of:

• Environment/boundaries
• Purpose
• Data/information
• Participants
• Information technology
• Information process