Dfd t2s39

DFD Examples

Creating Data Flow Diagrams Steps: 1. Create a list of activities 2. Construct Context Level DFD (identifies external entities and processes) 3. Construct Level 0 DFD (identifies manageable sub process ) 4. Construct Level 1- n DFD (identifies actual data flows and data stores ) 5. Check against rules of DFD

DFD Naming Guidelines

• External Entity  Noun • Data Flow  Names of data • Process  verb phrase – a system name – a subsystem name

• Data Store  Noun

Example : Restaurant

Creating Data Flow Diagrams Example

Steps: 1. Create a list of activities

• Old way: no Use-Case Diagram The operations of a simple stand will be used to • New way: use Use-Case Diagram demonstrate the creation of 2. Construct Context Level DFD dataflow diagrams. (identifies sources and sink) 3. Construct Level 0 DFD (identifies manageable sub processes ) 4. Construct Level 1- n DFD (identifies actual data flows and data stores )

Creating Data Flow Diagrams Example Think through the activities that take place.

1. Create a list of activities Customer Order Serve Product Collect Payment Produce Product Store Product

Creating Data Flow Diagrams Example 1. Create a list of activities Also think of the additional activities needed to the basic activities.

Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor

Creating Data Flow Diagrams Example Group these activities in some logical fashion, possibly functional areas.

1. Create a list of activities Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor

Creating Data Flow Diagrams Example

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

Create a context level diagram identifying the sources and sinks (s). Customer Order Serve Product Collect Payment Produce Product Store Product

Context Level DFD Order CUSTOMER

Sales Forecast 0.0 Restaurant Production Schedule EMPLOYEE Pay System

Product Served Payment Received Goods Payment

Order Raw Materials Pay for Raw Materials VENDOR

Pay for Labor

Time Worked Purchase Order

Creating Data Flow Diagrams 3. Construct Level 0 DFD (identifies manageable sub processes )

Example

Level 0 DFD

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

1.0 Sale

Sales Forecast

Customer Order

Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor

Payment CUSTOMER

Product Served Received Goods

VENDOR

Purchase Order

2.0 Production Product Ordered Production Schedule

EMPLOYEE

Inventory 3.0 Procurement

Payment

Order Decisions Pay

4.0 Payroll

Time Worked

4. Construct Level 1- n DFD (identifies actual data flows and data stores )

Example Create a level 1 decomposing the processes in level 0 and identifying data stores.

Level 1 DFD CUSTOMER

Customer Order ORDER 1.1 Record Order

Customer Order Serve Product Collect Payment

Severed Order

Produce Product Store Product Order Raw Materials Pay for Raw Materials

Pay for Labor

Payment 1.2 Receive Payment

PAYMENT

Request for Forecast

1.3 Produce Sales Forecast

Sales Forecast

4. Construct Level 1 (continued)

Example

Create a level 1 decomposing the processes in level 0 and identifying data stores. Customer Order Serve Product Collect Payment Produce Product Store Product

Order Raw Materials Pay for Raw Materials Pay for Labor

Level 1 DFD Product Order ORDER 2.1 Serve Product

Quantity Severed RAW MATERIALS

Production Schedule 2.2 Produce Product

Production Data 2.3 Store Product

Quantity Used INVENTORTY

Quantity Produced & Location Stored

4. Construct Level 1 (continued)

Example Create a level 1 decomposing the processes in level 0 and identifying data stores. Customer Order Serve Product Collect Payment

Level 1 DFD Order Decision 3.1 Produce Purchase Order

Quantity On-Hand Quantity Received

Received Goods 3.2 Receive Items

Produce Product Store Product Order Raw Materials Pay for Raw Materials

PURCHASE ORDER

Payment Approval 3.3 Pay Vendor

Pay for Labor Payment

RAW MATERIALS

RECEIVED ITEMS

VENDOR

4. Construct Level 1 (continued)

Example Create a level 1 decomposing the processes in level 0 and identifying data stores. Customer Order Serve Product Collect Payment

Level 1 DFD

Time Worked 4.1 Record Time Worked

TIME CARDS

Employee ID EMPLOYEE

Payroll Request 4.2 Calculate Payroll

Produce Product Store Product

Unpaid time cards PAYROLL

Payment Approval

Order Raw Materials Pay for Raw Materials

4.3 Pay Employe e

Pay for Labor Payment

PAYMENTS

Process Decomposition Level 0 Context Level

1.0 Sale

0.0 Lemonade System

2.0 Production

3.0 Procurement

4.0 Payroll

Level 1 1.1 Record Order

1.2 Receive Payment

2.1 Serve Product

2.2 Produce Product

3.1 Produce Purchase Order

3.2 Receive Items

4.1 Record Time Worked

4.2 Calculate Payroll

2.3 Store Product

3.3 Pay Vendor

4.3 Pay Employe e

Bus Garage Context Diagram Mechanical problem to be repaired

Helper

Labor

Fixed mechanical problems

Bus

Bus Repair Process System

Labor

Mechanic

Labor, parts cost details

Repair summary List of parts used

Supervisor

Inventory Management System

ing

Burger’s Order Processing System

• Draw the Burger’s context diagram – System • Order processing system

– External entities • Kitchen • Restaurant • Customer

– Processes • • • •

Customer order Receipt Food order Management report

Item Record

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