A data flow diagram (DFD) visually shows the requirements of an information system through inputs, outputs, processes, data storage, and external entities. It uses standard symbols like processes, data flow, data stores, and external agents. The direction of data flow is top to bottom and left to right. Lower level DFDs expand processes into more detail. An event table lists events that trigger system responses. It includes the event, trigger, source, activity, response, and destination. Event tables define functional requirements and integrate with DFDs by showing how data flows when events are triggered. Each event table row represents a DFD fragment used to create a single process.

1. 08. Ankita
14. Ashutosh
18. Samiksha
19. Laksh

2.  A data flow diagram (i.e. DFD) is a graphical system
model that shows all of the main requirements for an
information system in one diagram: inputs and
outputs , processes and data storage.
 Process
 Data Flow
 Data store
 External Agent
 Real Time Link

3.  Processes should be named and numbered for easy
references.
 The direction of flow is from top to bottom and left to right.
 When a process is exploded into lower level details they are
numbered PHYSICAL and LOGICAL DFDs.
 Readable
 Internally Consistent
 Accurately represents system requirements.
 Minimizing complexity
1. 7+-2 (Miller’s number)
2. Interface minimization
 Data flow consistency

4. A data dictionary is a structured repository of data about data.
The three classes of items to be defined in data
dictionary are as follows:
 Data Element:
The smallest unit of data that provides for no further
decomposition.
 Data Structure:
A group of data elements handled as a unit.
 Data Flow & Data Store:
Data flows are data structures in motion, whereas data stores
are data structures at rest.

11.  An event is some change or activity that takes place in the user’s
environment that stimulates a response from the software
system
 An event-response table (also called an event table or an event
list) lists all such events and the behavior the system is expected
to exhibit in reaction to each event.

12. # Event Table #
Event: An event which causes the system to do something.
Trigger: A signal that tells the system that an event has occurred,
either the arrival of data needing processing or a point in time.
Source: the source of an event (an actor for an EE and the system for
a TIE and CIE).
Activity: Behaviour that the system performs when an event occurs.
Response:An output, produced by the system, that goes to a
destination
Destination: An actor that receive the result of an
event execution
Event Trigger Source Activity Response Destination

13. In the event table, there are three types of events, that is:
1. External Event (EE): an event that occurs outside of the system,
usually initiated by external actor or user;
For example:
Student wants to search for a book item.
2. Temporal Internal Event (TIE): an event that happens when the system
reaches a specific point of time;
For example:
time to print book items report.
3. Conditional Internal Event (CIE): an event occurs when something
happens inside the system and the system must initiate some process
to response for this event;
For example:
student reordered new books when the reordered point is reached.

14. Example (student wants to search for a book item) and for an EE, we can
split this event into three main parts:
Student- Source
EE Search- Action
Book item-affected object
The TIE example (time to print book items report) can be divided into
three main parts as the following:
Time or "System"- Source
TIE Print- Action
Book item- Affected object
Finally, we can split the CIE (student reordered new books when the
reordered point is reached) into the following three main parts:
Student - Source
CIE Reordered- Action "if the reordered point is reached"
Book item- Affected object

15. Event Trigger Source Activity Response Destination
Customer
contacts
Owner
Contact
request Customer
Personal/Tele
-Contact
Meet/Receive
Call
Owner
Customer
booked
Vehicle
Rent a
Vehicle
request
Customer Personal/Tele
-Contact
Vehicle
approved
Owner
Owner
contact’s
Driver
Work
request
Owner Personal/Tele
-Contact
Drive/will not
Drive.
Driver
Owner
contacts
Agent
Contact
request
Owner Tele-Contact Request fulfilled Agent
Owner ask
for
Payment
Payment
request
Owner Payment by
Cash/Cheque
Full/Partial
Payment Done
Customer
Driver ask
contact
Details
Details
request
Driver Personal/Tele
-Contact
Give Contact
Details
Customer
Driver ask
payment
Payment
request
Driver Payment by
Cash/Cheque
Full payment
Done
Owner
-: Event Table of a Travels Business :-

16.  Event table defining functional requirements to
Traditional Approach model, Data Flow Diagrams
 The DFD integrates the Event table and the ERD
 When event gets triggered(input) the data flow
into system has to respond(output)
 External gents, data flow, & the process come from
DFD about the event is place in event table

17.  An event table is used to create a data flow
diagram by analyzing each event and the
data used and produced by the event
 Every row in an event table represents a data
flow diagram fragment and is used to create
a single process on a data flow diagram