Upload
nishu-rastogi
View
821
Download
6
Embed Size (px)
Citation preview
Presentation ByNISHU RASTOGI
Assistant Professor
Invertis University, Bareilly
1
Known as Data Flow diagram
A graphical representation of flow of data within anyinformation system
Preliminary step to create an overview of the system,which can later be elaborated
Used for the visualization of data processing
Illustrates how data is processed by a system interms of inputs and outputs.
Focus is on the flow of information, where datacomes from, where it goes and how it gets stored.
DFD
2
Function
File/Database
Input/Output
Flow Lines
3
Notations for DFD
Each process should have at least one input and an
output
Each data store should have at least one data flow inand one data flow out
Data stored in a system must go through a process
All processes in a DFD go to another process or adata store
4
DFD rules and tips
Also known as Context Diagram
It only contains one process node that generalizes thefunction of the entire system in relationship toexternal entities
Basic overview of the whole system or process beinganalyzed or modeled
It should be easily understood by a wide audience,including stakeholders, business analysts, dataanalysts and developers.
5
Level- 0 DFD
6
Example of Level 0
Highlight the main functions carried out by thesystem, as you break down the high-level process ofthe Context Diagram into its sub-processes.
7
Level-1 DFD
8
Example of Level 1
It may require more text to reach the necessary level
of detail about the system’s functioning.
9
Level-2 DFD
10
Example of Level 2
Known as Entity Relationship Diagram
An entity relationship diagram (ERD) shows therelationships of entity sets stored in a database.
ER diagrams illustrate the logical structure of databases
ER-modeling is a data modeling technique usedin software engineering to produce a conceptualdata model of a information system.
Diagrams created using this ER-modeling technique arecalled Entity-Relationship Diagrams, or ER diagrams orERDs.
11
ERD
To design database there are several important
components which are focused i.e.
Entity
Relationship
Attributes
12
ERD Notations
13
ERD Example
A decision tree gives a graphic view of the
processing logic involved in decision making and thecorresponding actions taken
The edges of a decision tree represent conditions
The leaf nodes represent the actions to be performeddepending on the outcome of testing the condition
14
Decision Tree
Consider Library Membership Automation Software(LMS) where it should support the following threeoptions-
New member
Renewal
Cancel membership
15
Example
New member option
Decision: When the 'new member' option is selected,the software asks details about the member like themember's name, address, phone number etc.
Action: If proper information is entered then amembership record for the member is created and abill is printed for the annual membership charge plusthe security deposit payable.
16
Example contd..
Renewal option
Decision: If the 'renewal' option is chosen, the LMSasks for the member's name and his membershipnumber to check whether he is a valid member ornot.
Action: If the membership is valid then membershipexpiry date is updated and the annual membershipbill is printed, otherwise an error message isdisplayed.
17
Example contd..
Cancel membership option
Decision: If the 'cancel membership' option isselected, then the software asks for member's nameand his membership number.
Action: The membership is cancelled, a cheque forthe balance amount due to the member is printedand finally the membership record is deleted fromthe database.
18
Example contd..
19
A decision table is used to represent the complex
processing logic in a tabular or a matrix form
The upper rows of the table specify the variables orconditions to be evaluated.
The lower rows of the table specify the actions to betaken when the corresponding conditions aresatisfied.
A column in a table is called a rule.
A rule implies that if a condition is true, then thecorresponding action is to be executed.
20
Decision Table
21
Decision Table of LMS
Make DFD, ERD and DT for
Hotel Management System
Inventory Management System
Hospital Management System
Railway Reservation System
Automatic Teller Machine System
College ERP System
Flipkart etc.
22
Exercise