1. The context diagram shows the key external entities that interact with the order system - customers, warehouse, and accounting. It displays the major information flows between these entities and the system. 2. The level-0 DFD of the order system contains 5 main processes: 1) check status, 2) issue status messages, 3) generate shipping order, 4) manage accounts receivable, and 5) produce reports. It also includes 2 data stores - pending orders and accounts receivable - and displays the high-level data flows between the entities, processes, and data stores.

1. Data Flow Diagrams (DFDs)
Mr.Somkiat Jaidee
Department Of Information Technology
Siam Dhurakit School
Reference From
Mr.Prasad Sawant
Department Of Computer Science
Prof .Ramkurshana More Arts, Commerce and Science College Akurdi.
Mobile :9665755707
Email:sawanprasad@gmail.com
Blog:http://prasadmsawant.blogspot.com/

2. Data Flow Diagrams (DFDs)
Order In-Stock Request
CUSTOMER WAREHOUSE
Data flow diagram
1.0
 Status
Message
Shipping
(DFD) is a picture of
Check
Status Data Status Order
the movement of data
Shipping
2.0
Order
Data
3.0
between externalConfirmation Issue
Status
D1
Pending
Orders
Generate
entities and the
Messages
Shipping
Order Data Order
processes and data Payment 4.0
stores with in a
Order Data
Invoice
Manage
Accounts
system
Receivable
5.0
Accounting Data Accounts Receivable Data
Produce
Accounts Reports
D2 Receivable
Inventory
Reports
ACCOUNTING

3. DFD Symbols (Gane & Sarson)
Process
Data Flow
Data Store
Source/Sink (External Entity)

4. Process
1.0
Grade Detail Grade Report
Produce
Grade
Report
 Work or actions performed on data (inside the
system)
 Labels should be verb phrases
 Receives input data and produces output

5. Rule 1: Process
 Can have more than one outgoing data flow or
more than one incoming data flow
1.0
Graded Work
Submitted Work Grade
Student Student Grade
Work
3.0
Hours Worked
Gross Pay
Calculated
Pay Rate
Gross
Pay

6. Rule 2: Process
 Can connect to any other symbol (including
another process symbol)
1.0 2.0 Inventory
Order Accepted Order Change
Verify Assemble
Order Order

7. Process: Correct/Incorrect?
5.0
Services Perfomed Invoice
Create
Invoice
Policy Number Payment Amount
Apply
Insurance
Premium
2.1
Hours Worked Pay Rate
Calculate
Gross
Pay

8. Data Store
D1 Students
 Is used in a DFD to represent data that the
system stores
 Labels should be noun phrases

9. Rule: Data Store
 Must have at least one incoming and one outgoing
data flow
Customer Payment
D1 Daily
Payments
Daily Payment

10. Source/Sink (External Entity)
1.0
Order
CUSTOMER Invoice
Verify
Order
 External entity that is origin or destination of
data (outside the system)
 Is the singular form of a department, outside
organisation, other IS, or person
 Labels should be noun phrases
 Source – Entity that supplies data to the
system
 Sink – Entity that receives data from the
system

11. Rule: Source/Sink
 Must be connected to a process by a data flow
BANK
Bank
Deposit
2.0
Prepare
Deposit

12. Rules for Using DFD Symbols
 Data Flow That Connects
YES NO
A process to another process
A process to an external entity
A process to a data store
An external entity to another external entity
An external entity to a data store
A data store to another data store

13. Context Diagram
 Top-level view of IS
 Shows the system boundaries, external entities that
interact with the system, and major information
flows between entities and the system.
 Example: Order system that a company uses to
enter orders and apply payments against a
customer’s balance

14. Level-0 DFD
 Shows the system’s major processes, data flows, and
data stores at a high level of abstraction
 When the Context Diagram is expanded into DFD
level-0, all the connections that flow into and out of
process 0 needs to be retained.

15. Lower-Level Diagrams
 Functional Decomposition
◦ An iterative process of breaking a system description
down into finer and finer detail
◦ Uses a series of increasingly detailed DFDs to
describe an IS
 Balancing
◦ The conservation of inputs and outputs to a data flow
process when that process is decomposed to a lower
level
◦ Ensures that the input and output data flows of the
parent DFD are maintained on the child DFD

16. Strategies for Developing DFDs
 Top-down strategy
◦ Create the high-level diagrams (Context
Diagram), then low-level diagrams (Level-0
diagram), and so on
 Bottom-up strategy
◦ Create the low-level diagrams, then higher-
level diagrams

17. Exercise:
Precision Tools sells a line of high-quality woodworking tools.
When customers place orders on the company’s Web site, the
system checks to see if the items are in stock, issues a status
message to the customer, and generates a shipping order to the
warehouse, which fills the order. When the order is shipped, the
customer is billed.The system also produces various reports.
 Draw a context diagram for the order system
 Draw DFD diagram 0 for the order system

18. Identify Entities,Process,Data Stores & Data Flow
 Entities - เอ็นทิต้ ี  Data Flows
◦ Customer - ลูกค้า
 Order -คาสั่งซื้ อ
◦ Warehouse - คลังสิ นค้า
 In-Stock Request –คาร้องสิ นค้าในคลัง
◦ Accounting -การบัญชี 1.0
 Order Data -ข้อมูลสั่งซื้อ
 Processes-กระบวนการ
 Status Data -สถานะข้อมูล
◦ 1.0 Check Status-ตรวจสอบสถานะ 2.0
 Status Message -สถานะข้อความ
◦ 2.0 Issue Status Messages-สถานะปั ญหา
 Shipping Order-การจัดส่งสิ นค้า
◦ 3.0 Generate Shipping Order-การจัดส่ งสิ นค้า 3.0
 Order Data
◦ 4.0 Manage Accounts Receivable-การจัดการบัญชี
ลูกค้า  Invoice-ใบกากับสิ นค้า
◦ 5.0 Produce Reports-รายการสิ นค้า  Shipping Confirmation-ยืนยันการจัดส่งสิ นค้า
4.0
 Data Stores  Payment-การชาระเงิ น
◦ D1 Pending Orders-รายการสังซื้ อ
่  Accounting Data-ข้อมูลบัญชี
◦ D2 Accounts Receivable-บัญชีลูกค้า  Accounts Receivable Data-ข้อมูลบัญชี ลูกค้า
 Order Data-ข้อมูลสั่งซื้ อ 5.0
 Inventory Reports-รายการสิ นค้าคงคลัง

19. Order
CUSTOMER In-Stock WAREHOUSE
Payment Request
Status 0 Shipping
Message Order
Order
Invoice System Shipping Confirmation
Inventory
Reports
ACCOUNTING
Context
Diagram of
Order
System

20. Order In-Stock Request
CUSTOMER WAREHOUSE
1.0
Status
Message
Check Shipping
Status Data Status Order
Order
2.0 Data
Shipping 3.0
Confirmation Pending
Issue D1 Orders
Status
Messages Generate
Shipping
Order Data Order
Payment 4.0
Order Data
Invoice
Manage
Accounts
Receivable
5.0
Accounting Data Accounts Receivable Data
Produce
Accounts Reports
D2 Receivable
Inventory
Level-0 of Reports
Order
System ACCOUNTING