24 createdfd Lemonade Good

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Creating Data Flow Diagrams

Data Flow Diagrams Symbols

Source/ Sink

DeMarco & Yourdon

System Analysis and Design

System – a group of interrelated procedures

used for a business function, with an identifiable boundary, working together for

Sink

0.0 Process

Ph i l D t Fl Di h h

y, g g

some purpose.

Analysis – separation of a whole into its

component parts

Design – to create, fashion, execute, or

construct according to plan

DATA STORE

Data Flow Lines Logical Data Flow Diagrams – show the data

flow, structure, and requirements of a new

Physical Data Flow Diagrams – show how

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Data Flow Diagrams Symbols

Source/ Sink

DeMarco & Yourdon

Source/Sink – help to establish the

boundaries of the system. A source identifies the origin of data inflow to the system. A sink Sink

0.0 Process

g y

identifies the outflow of a system, many times as information.

Sometimes referred to an entity, a source may be a customer, vendor, employee, or even another system. A single entity can be both a source and a sink.

DATA STORE

Data Flow Lines

Data Flow Diagrams Symbols

Source/ Sink

DeMarco & Yourdon

Processes – are the activities (manual and

automated) that transform the inputs, transport data from process to process,

Sink

0.0 Process

p p p ,

stores the data, and produce the outputs of a system.

Processes are used on every DFD starting with an over all process on the context level diagram, the system. The system is then decomposed until a primitive level is obtained. The primitive level is the point in

DATA STORE

Data Flow Lines

p p

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Data Flow Diagrams Symbols

Source/ Sink

DeMarco & Yourdon

Data Store – is the resting place of the data

in a system. A data store can be in the form of paper, a disk file or any other media.

Sink

0.0 Process

p p , y

Normally the word ‘data’ does not appear in the title of a data store. Some examples of data stores are Customer Order, Payment, Invoice, Time Card……

DATA STORE

Data Flow Lines

Data Flow Diagrams Symbols

Source/ Sink

DeMarco & Yourdon

Data Flow – is the data in motion. Data can

move from the outside (source) into a process. Once the inside of a system data

Sink

0.0 Process

p y

must flow from place to place through a process, the flow lines show this movement.

The lines are labeled to provide clarity and meaning to the data moving through the system.

DATA STORE

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Data Flow Diagrams Levels

Source/ Sink

DeMarco & Yourdon

0.0

Process Source/ Sink Source/ Sink

Data Flow Data Flow

Context Level DFD

Sink

0.0 Process

Data Flow Data Flow

1.0 Process

Data Flow Data Flow

Data Flow

Level 0 DFD

DATA STORE

Data Flow Lines

2.0 Process

Data Flow Source/ Sink Source/ Sink

Data Flow

3.0 Process Data Flow

Data Flow

Data Flow Diagrams Levels

Source/ Sink

DeMarco & Yourdon

Data Flow

Level 1 DFD (and on)

Source

Sink

0.0 Process

1.2 Process 1.1

Process DATA STORE

Data Flow

Source

DATA STORE

Data Flow Lines Data Flow

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Prepared by: yourname Date: 01/01/2002

Level 1 DFD Project Name

1.1

Data Flow

DATA STORE

Data Flow Diagrams Levels

Context Level DFD Project Name 1.2 Process Process Data Flow DATA STORE Data Flow

Level 1 DFD Project Name 1.2 Process 1.1 Process Data Flow DATA STORE Data Flow

Level 1 DFD Project Name 0.0

Process Source/ Sink Source/ Sink

Data Flow Data Flow

Data Flow

Level 0 DFD Project Name 1.0 Process Data Flow 1.2 Process 1.1 Process Data Flow Data Flow DATA STORE Data Flow 2.0 Process Data Flow Source/ Sink Source/ Sink Data Flow 3.0 Process Data Flow Data Flow Data Flow Data Flow Data Flow

Creating Data Flow Diagrams

Steps:

1. Create a list of activities

2. Construct Context Level DFD (identifies sources and sink)

3. Construct Level 0 DFD

(identifies manageable sub process )

4. Construct Level 1- n DFD

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Creating Data Flow Diagrams

Lemonade Stand Example

Steps:

2. Construct Context Level DFD

Example

The operations of a simple lemonade stand will be used to demonstrate the creation

(identifies sources and sink)

(identifies manageable sub processes )

(identifies actual data flows and data stores )

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Example

Think through the activities that take place at a lemonade stand

stand.

Customer Order Serve Product Collect Payment Produce Product Store Product

Creating Data Flow Diagrams

Example

Also think of the additional activities needed to support the basic activities

the basic activities.

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Example

Group these activities in some logical fashion, possibly functional areas

possibly functional areas.

Customer Order Serve Product Collect Payment

Produce Product Store Product

Order Raw Materials Pay for Raw Materials

Pay for Labor

Creating Data Flow Diagrams

Context Level DFD

Example

Create a context level diagram identifying the sources and sinks (users)

2. Construct Context Level DFD (identifies sources and sink)

0.0 Lemonade

System

EMPLOYEE CUSTOMER

Pay Payment

Order

sources and sinks (users).

Customer Order Serve Product Collect Payment

Produce Product Store Product

Payment

Purchase Order Production Schedule

Received Goods

Time Worked Sales Forecast

Product Served

Store Product

Pay for Labor

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Creating Data Flow Diagrams

Level 0 DFD

Example

Create a level 0 diagram identifying the logical subsystems that may exist

(identifies manageable sub processes )

subsystems that may exist.

Customer Order Serve Product Collect Payment Produce Product Store Product 2.0 Production EMPLOYEE Production Schedule 1.0 Sale Sales Forecast Product Ordered CUSTOMER Payment Customer Order

Received Goods Inventory Product Served

Store Product

Pay for Labor

3.0 Procure-ment Pay VENDOR Payment

Purchase Order Order Decisions Received Goods Time Worked y 4.0 Payroll

Creating Data Flow Diagrams

Level 1 DFD

Example

Create a level 1

decomposing the processes in level 0 and identifying

(identifies actual data flows and data stores )

in level 0 and identifying data stores. 1.3 Produce Sales Forecast Sales Forecast Payment Customer Order Serve Product Collect Payment Produce Product Store Product 1.1 Record Order Customer Order ORDER Severed Order

Request for Forecast CUSTOMER

Store Product

1.2 Receive Payment

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Creating Data Flow Diagrams

Level 1 DFD

Example

Create a level 1

4. Construct Level 1 (continued)

in level 0 and identifying data stores. Customer Order Serve Product Collect Payment Produce Product Store Product 2.1 Serve Product Product Order ORDER 2.2 Produce Quantity Severed Production Schedule RAW MATERIALS Quantity Used Store Product

Pay for Labor

Produce Product INVENTORTY 2.3 Store Product

Quantity Produced & Location Stored Quantity Used

Production Data

Creating Data Flow Diagrams

Level 1 DFD

Example

Create a level 1

O d D i i

in level 0 and identifying data stores. Customer Order Serve Product Collect Payment Produce Product Store Product 3.1 Produce Purchase Order Order Decision PURCHASE ORDER 3.2 Receive Items Received Goods RAW MATERIALS Quantity Received Quantity On-Hand Store Product

Order Raw Materials Pay for Raw Materials

Pay for Labor

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Creating Data Flow Diagrams

Level 1 DFD

Example

Create a level 1

Time Worked

in level 0 and identifying data stores. Time Worked Customer Order Serve Product Collect Payment Produce Product Store Product 4.1 Record Time Worked TIME CARDS 4.2 Calculate Payroll Payroll Request EMPLOYEE Employee ID

Unpaid time cards

Store Product

Pay for Labor

Payroll 4.3 Pay Employe e PAYROLL PAYMENTS Payment Approval

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Creating Data Flow Diagrams

Lemonade Stand Example