The document discusses process modeling and data flow diagrams (DFDs). It defines process modeling as a technique used to organize and document a system's processes and flow of data through those processes. DFDs are introduced as a type of process model that depict the flow of data through a system using various symbols like processes, data stores, external entities, and data flows. The document outlines the benefits of process modeling and DFDs, provides examples, and describes the basic components, guidelines, and steps for creating DFDs, including drawing a context diagram and decomposing it into level-0 and level-1 DFDs.

1. PROCESS MODELING
Presentation By: Debendra Adhikari

2. Objectives:
 Define process modeling and explain its benefits.
 Understand basic concepts and constructs of a process model.
 Deliverables and Outcomes
 Read and interpret a data flow diagram
Data Flow Diagrams(DFD)
Elements of DFD
Guidelines and Rules to draw DFD
Steps to draw DFD

3. Introduction to Process Modeling
-Model : Representation of reality that can be built for existing
systems or newly proposed System.
-Different types of Model : Process Model , System Model, Data Model
-Process modeling focuses on the Process part of a system.
Eg: Flowcharts are one type of process model.
- Processes and data structures are modeled

4. Model and it’s types
o Model is a pictorial representation of reality.
Logical model
o IT shows what a system is
or does.They are
independent of any
technical implementation.
Physical model
o It shows not only what a
system is or does, but
also how the system is to
be physically and
technically
implemented. It reflects
technology choices.

5. Why Process Modelling………..?
Process modeling – a technique used to organize and
document a system’s processes.
 Flow of data through processes
 Logic
 Policies
 Procedures

6. Deliverables and Outcomes
Deliverable : Product produced as a part of a process / project.
Eg: Hardware , Software , Planning Documents e.t.c.

7. Deliverable and Outcomes
„
 Context data flow diagram (DFD)…
Scope of system„
 DFDs of current physical system…
Adequate detail only
„
 DFDs of current logical system…
Enables analysts to understand current system
„
 DFDs of new logical system…
Show data flows, structure, and functional requirements of new system
„
 DFDs of new physical system„
Description of each DFD component

8. System Concept
o A system exits by taking input from the environment,
processing this input, and release an output.
o A system may be decomposed into subsystems.
o A subsystem has its own input and output

9. INPUT OUTPUT
Fig:A system with it’s
subsystems

10. Systems and Processes
o A system is a process. It addresses a business function.
o A process is action performed on, or in response to,
incoming data flows or conditions.
o A process can be decomposed into sub-processes.

11. The
System
is a
Process
input output
input
input output
output
Feedack and
Control Loop
The System's Environment
(constantly changing)
Fig: A System with Process

12. Process Modeling with DFD
Data Flow Diagram (DFD) : A process model used to
depict the flow of data through a system.
Also called bubble charts, transformation graph, and
process model.

13. Advantages of Diagrammatic representation
of data :
 It helps the analysts to analyze the system and to
model system components.
 An analyst can communicate better with the user.
 It is easier for the user to understand and how the
analyst has interpreted his/her problem after
looking at DFD’s.

14. Data Flow Diagrams
o DFD describes how data is manipulated within and at the
boundaries of the system.
o Logical DFD describes the flow of information of a
system
o Physical DFD describes how an information system is
physically implemented.

15. Components of DFD
 Process
 Data flow
 Data stores
 External Entities.

16. Symbolic Representation
External Entity
Data Flow
Process
Data Store
Pay Bill
AP Clerk
3

17. Processes
o A Process is a work or action performed on input data flow to
produce an output data flow.
o A Process must have at least one input data flow and at least
one output data flow.

18. Types of Processes
o Function: A set of related and ongoing activities of a
business: e.g. sales.
o Event: A logical unit of work that must be completed as a
whole : e.g. collect payment.
o Elementary Process: A discrete, detailed activity or task
required to respond to an event.

19. Data Flows
o A Data Flow represents a movement of data (info) among
processes or data stores
Data Stores
o A Data Store is a storage of data, it contains information
o There may be Physical or Computerized Data Stores.
External Entities
o An external entity defines a person, organization unit, or
other organization that lies outside of the scope of the
project

20. Fig: Example of a DFD

22. Guidelines for drawing DFD
 Should have no crossing lines.
 Should not split into a number of data flows.
 Should have no any flowchart structure like decision, iteration etc.
 Do not include control or flow of control information.
 Do not try to put too much information in one data flow diagram.
 Data flows can only be from:
 External entity to process
 Process to external entity
 Process to process
 Process to stores
 Stores to process

23. Some Rules for Data Flows
o A data flow should
never go
unnamed.
o In logical
modeling, data
flow names should
describe the data
flow without
describing the
implementation
o All data flows
must begin and/or
end at a process.

24. Advantages of Using
DFD’s
 Represent data flows.
 May be used at. high or low level of analysis.
 Provide good system documentation.

25. Steps to draw DFD
Context Diagram
o Identify the system and its boundaries (the context)
o Identify external entities (providers, receivers of system
info)
o Identify external data flows (input, output)

26. Level-0 DFD
o Identify what is being done between each input and its
corresponding output
o Identify the processes (functions of the system)
o Identify external data flows between external entities and
processes
o Identify internal data flows between processes and data
stores
Level-1 DFD’s
o Sub-processes (activities of tasks) of Level-0 processes
(system functions)

27. IS 431 : Lecture 4
M
N
P
M
N
P
Context Diagram
Level-0 Diagram
Level-1 Diagram
1 3
2
0
D1
Fig: Decomposition of Context
Diagram

28. Any
Queries…………………………………………………………?
?????

29. Thank Us