Business power point templates seven steps circular process flow diagram sales ppt slides
Lec2data Flow Diagram Power Point Slides
-
Upload
raman-kumar-mehul -
Category
Documents
-
view
229 -
download
0
Transcript of Lec2data Flow Diagram Power Point Slides
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
1/24
Data Flow Diagrams
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
2/24
IntroductionSSADMWhat is a Data Flow Diagram?Why do we use DFDs?LevellingConventionsDecomposition and AbstractionThe ElementsProcess and Data StoresOutside EntityData Flow
The LevelsRulesThe Procedure for Constructing DFDsThe Document Flow DiagramThe Context DiagramDraw the external entities and data storesLevel 1 Physical DFD - Complete
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
3/24
S.S.A.D.M. S.S.A.D.M. - Structured
Systems Analysis and
Design Method Uses different techniques
to model a system
Data Flow Diagrams Entity Relational Model
(Logical Data Stores) Normalisation
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
4/24
What is a Data FlowDiagram?
Known as DFDs A way to model a real
world situation They are the interface
between the real worldactivities and anunderstanding of how thiscan be converted into acomputer system.
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
5/24
Why do we use DFDs? It is a way of taking the
physical view andconverting it into a logical
view. The physical view - all
documents involved
The logical view - the datathey contain Their main purpose is to
communicate with theuser, the analystsunderstanding of thescope of the required
system
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
6/24
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
7/24
Conventions
BalancingProcess at lower level should
have identical data flows if they flow out of a process
Modelling Data StoresOnly use DATA STORES used
within this process on thediagram
Numbering1 - 1.1 - 1.1.1
1.2 - 1.2.1
LabelsShould carry as much meaning
as possible
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
8/24
Decomposition and
Abstraction Decomposition - Divide
and subdivide intomanageable sizeproblems
Abstraction -Concentrate on theimportant issues and
ignore the irrelevant
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
9/24
The Elements
The four main elements of DFDs notation Data Flows, with a
label to indicate whatdata is flowing
Processes, that handlethe data
Data stores, within thesystem (diary, filingcabinet or computer
file) Outside entities,
outside sources of data
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
10/24
Process and Data
StoresA process is made up of
Data Stores
Process Number
Destination(Place or Name)
Processdescription Shouldbe descriptive,starting with averb.
M1Can be M for manualor D for computerbase data stores.
Name of Store
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
11/24
Outside EntityIs anything outside the
system that is of interest tothe system. Can be a
person, a company or another system .
Outside entity shows the Name and a lowercasealpha character is used touniquely identify it.
If an outside entity is
repeated for the purpose of neat layouta line is added acrossthe top .
Customer a
Customer a
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
12/24
Data FlowIs shown by a line with an
arrowhead, indicating thedirection of the flow of
data. Each data flowshould be named toindicate what data is being
passed. Nouns or adjectives only no verbsare permitted.
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
13/24
The Levels Context - Overview -
contains only one process Level 1 - Utilises all four
elements Level 2 - A breakdown of a
level 1 process Level 3 - A breakdown of a
level 2 process There is no rule as to how
many levels of DFD thatcan be used.
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
14/24
RulesSequence not important - getting the Process
correct is Context or Level 0 - Identifies
the system/ boundary/External
Links Level 1 - Overview of function Level 2 - Breakdown to
UnderstandHard to know where to stopRule of ThumbIf there are more than 8 data
flows break itProcess of Identifying major
Processes
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
15/24
The Procedure for
Constructing DFDs Draw a document flow diagram
of the current situation Draw a systems boundary
around the agencies that arepart of the system
Draw a Context Diagram Identify processes in the system Complete the level 1 Current
Physical DFD
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
16/24
The Document Flow Diagram
The task of modelling a businesssituation can be daunting at first. It isbest to start with something simplesuch as a document flow diagram.
ProductionPlanning
Stock Control
FactoryDesign
Purchasing
Supplier
Stock
NoteWithdrawal
ProductionPlan Purchase
Order
Delivery Note
Material Requirements List
Bill of Materials
Supplier Details Update Form
DeliveryNote
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
17/24
The Context Diagram
You decide which agencies are to be
part of the system that you areexamining. These agencies fall inside the system
boundary and are reduced to one box inthe centre.
This is a Context Diagram
ProductionPlanning
Stock Control
Factory
Design Purchasing
Supplier
Stock
NoteWithdrawal
ProductionPlan
Delivery Note
Material Requirements List
Bill of Materials
Supplier Details Update Form
DeliveryNote
MaintainStock System
a b
c
d
e
(Lejk & Deeks)
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
18/24
All data flows going into thesystem must be received by aprocess.
All data flows going out of thesystem must be generated byprocess.
The first task is therefore toidentify these processes:
Stock clerk
Maintain
1
2
3
Stock clerk
Stock clerk
planned call-off
Maintain
stock cards
Preparematerial reqmnts
list
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
19/24
Draw the external entities anddata stores.
Produc t ion
S tock c le rk
Main ta in
a Bi ll o f m a te r i a l sM 11
2
3
Stock c le rk
S t o c k c a r d sM 2
Stock c le rk
p lanned ca l l-o f f
Main ta ins to c k c a r d s
P r e p a r em ate r ia l r eqm nts
list
P lann ing
Supp l ie r
b
Fac to ry
c
P u r c h a s in g
d
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
20/24
Level 1 Physical DFD - Complete
F in a lly d raw in th e d a t a flo w s to g ivc o m p le te d d ia g ra m . N o te th a t a d a t am u s t h a v e a p ro c e s s a t th ee n d .
P r o d u c t i o n
S t o c k c l e rk
M a i n t a i n
aB ill o f m ate r iM 1
1
2
3
S t o c k c l e rk
S t o c k c a r d sM 2
D e l iv e r y n o t e
B O M d e t a ils
P l a n n e d c a l l- o f f
de t a i l s
S t o c k d e t a i ls
S t o c k c l e rk
p l a n n e d c a l l- o ff
M a i n t a i ns t o c k c a r d s
P r e p a r em a t e r i a l r e q m n t s
list
P l a n n i n gP r o d u c t i o n
P l a n
S u p p l i e r
b
F a c t o r y
c
S t o c kw it h d r a w a l n o t e
P u r c h a s i n g
d
M a t e r ia l re q u ir e m e n t slist
U p d a t e dsup p ly de t a i ls
D e l i v e r yn o t e
S t o c k d e t a i ls
( Lejk&
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
21/24
H a ird re s s in g S a lo n L e v
P h y s ic a l D F D
Client
Receptionist
Register
a
Client card indexM1
1
Confirm
2
Hairdresser/Rcptnst
Conduct
3
arrival
Receptionist
Appointment
Appointment diaryM2
appointment
Appointmentdetails
Change of hairstyle etc.
Appointmentdetails Confirmation
Request
ConfirmationDetails
New clientdetails
Existing clientdetails
Appointmentdetails
Confirmation of arrival
Change of hairstyle etc.
Appointment
details
(Lejk & Deeks)
(Lejk & Deeks)
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
22/24
Process 3 Level 2
3 Hair/Reception
Clie
a
Hair Details
Clienta
3.1 Hairdresser
Conduct Appointment
3.2 Hairdresser
Inform Reception
3.3 Receptionist
Complete Appointment
M2 Diary
Appointment Details
M3 Client Card
Change of Hair Details
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
23/24
Naming of DFDprocesses
L ev el 0 L ev el 1 L ev el 2 L ev el 3 L ev el 4
M a n
O v era llP ro ce ss
M a n
P ro c es s
P ro c es s
P ro c es s
2
S u bP ro c es s
S u bP ro c es s
S u bP ro c es s
S u bP ro c es sS u bP ro c es s
P ro c es s
2 .2
S u b - S uP ro c es s
S u b - S uP ro c es s
E lem e nta r y p ro ce ssd e sc ri p tio n s.
D e cisi on tre eD e ci si o n ta bS tru ct u re dE n gli s h
2 .1 .1
T here must be consistency betw een levels, w iall the data appearing on the higher level D F
If a data store is used only for one process it ip laced w ith that process. O utsid e entities arealw ays show n ou tside the boundary of a lowlevel D FD process, even if they onlycommunicate w ith that one process.
-
7/31/2019 Lec2data Flow Diagram Power Point Slides
24/24
Summary
SSADMWhat a DFD is & Whywe use themThe differentconventions
What the elements areExample
Next Week:- EntityRelational Model