Datat Flow Context Diagram Computer Science Essay

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In business, system analysis and design refers to the process of examining a business situation with the intent of improving it through better procedures and methods. System development can generally be thought of as having two major components, that are system analysis and system design. System design is the process of planning a new business system or one to replace or complement an existing system. But before this planning can be done, we must thoroughly understand the old system and determine how computers can best be used to make its operation more effective. System analysis, then, is the process of gathering and interpreting facts, diagnosing problems and using the information to recommend improvements to the system. This is the job of the systems analyst.

Define Question 1

A data flow diagram is a graphic description of a system or portion of a system. It consists of data flows, processes, external entities and data stores that are all described through the use of easily understood symbols. An entire system can be described from the viewpoint of the data it processes with only four symbols. At the same time, data flow diagrams are powerful enough to show parallel activities.

The function of data dictionary is to store descriptions of data items and structures as well as system processes. It is intended to be used to understand the system by analysts, who retrieve the details and descriptions it. The data dictionary also stores validation information to guide the analysts in specifying controls for the system’s acceptance of data. Data dictionary systems are important for five reasons that are to manage the details in large systems, to communicate a common meaning for all system elements, to document the feature of the system, to facilitate analysis of the details in order to evaluate the characteristics and determine where systems changes should be made and lastly to locate errors and omissions in the system.

Question 1

Context Diagram

Software Update

Status Report

Maintain Machine

Check Status

Money

Receipt Paper

Command

Verification Status

Password

ATM Card

Money

Receipt

Account Information

Maintenance

Security

ATM

User

Level 0 Diagram

Verification Status

User Account Information

1

Verify Account

User

Password

User Database

D1

ATM Card

Money

Receipt Paper

2

Output System

Receipt

Money

Security

User Account Information

Account Information

3

Information System

User Activity

D2

Command

Log Database

Hardware & Software Maintenance Activity

Maintenance

Maintenance Database

D3

Hardware & Software Check Status

Hardware & Software Maintenance Information

Maintain Machine

4

Hardware & Software System

Hardware & Software Status Report

Software Update

Level 1 Diagram

Maintenance Information

4.1

Hardware System

Status Report

Maintenance Database

D3

Maintenance Activity

Check Status

Maintenance

Maintenance Information

Maintain Machine

Log Database

D2

Check Status

Maintenance Activity

Status Report

4.2

Software System

Software Update

Data Dictionary

External Entity Name: User

Description: Individuals that use the system for personal purpose

Inbound Data Flows: Verification Status, Money, Receipt, Account Information

Outbound Data Flows: Password, ATM Card, Command

From Processes: Verify Account, Output System, Information System

To Processes: Verify Account, Information System

External Entity Name: Security

Description: Manages the output items in the system

Inbound Data Flows: -

Outbound Data Flows: Receipt Paper, Money

From Processes: -

To Processes: Output System

External Entity Name: Maintenance

Description: Manages the condition of the hardware and software system

Inbound Data Flows: Hardware & Software Status Report

Outbound Data Flows: Hardware & Software Check Status, Maintain Machine, Software Update

From Processes: Hardware & Software System

To Processes: Hardware & Software System

Process Name: Verify Account

Description: Verify user account to prevent unauthorized access

Process Number: 1

Process Name: Output System

Description: Draw or print out receipt or money

Process Number: 2

Process Name: Information System

Description: Hold data or information of the system

Process Number: 3

Process Name: Hardware & Software System

Description: The condition of the hardware and software of the system

Process Number: 4

Data Store Name: User Database

Description: Holds data and information of users

Inbound Data Flows: User Account Information

Outbound Data Flows: User Account Information

From Processes: Information System

To Processes: Verify Account

Data Store Number: D1

Data Store Name: Log Database

Description: Holds record of activities in the system

Inbound Data Flows: User Activity

Outbound Data Flows: -

From Processes: Information System

To Processes: -

Data Store Number: D2

Data Store Name: Maintenance Database

Description: Holds record of system maintenance information

Inbound Data Flows: Hardware & Software Maintenance Information

Outbound Data Flows: -

From Processes: Hardware & Software System

To Processes: -

Data Store Number: D3

Data Flow Name: Verification Status

Description: Verify user account

From Processes: Verify Account

To Processes: -

Data Flow Name: Password

Description: Input of password

From Processes: -

To Processes: Verify Account

Data Flow Name: ATM Card

Description: Input of ATM Card

From Processes: -

To Processes: Verify Account

Data Flow Name: User Account Information

Description: System data of user account

From Processes: Information System

To Processes: Verify Account

Data Flow Name: Money

Description: Money in cash

From Processes: Output System

To Processes: Output System

Data Flow Name: Receipt Paper

Description: Refill of blank receipt paper

From Processes: -

To Processes: Output System

Data Flow Name: Receipt

Description: Print out receipt of transaction

From Processes: Output System

To Processes: -

Data Flow Name: Command

Description: Input of instruction

From Processes: -

To Processes: Information System

Data Flow Name: Account Information

Description: Display of account information

From Processes: Information System

To Processes: -

Data Flow Name: User Activity

Description: Record of user activities

From Processes: Information System

To Processes: -

Data Flow Name: Hardware & Software Maintenance Activity

Description: Record of hardware & software maintenance activity

From Processes: Hardware & Software System

To Processes: -

Data Flow Name: Hardware & Software Check Status

Description: Status checking of hardware & software system

From Processes: -

To Processes: Hardware & Software System

Data Flow Name: Hardware & Software Maintenance Information

Description: Maintenance information of hardware & software system

From Processes: Hardware & Software System

To Processes: -

Data Flow Name: Maintain Machine

Description: Maintain machine in good condition

From Processes: -

To Processes: Hardware & Software System

Data Flow Name: Hardware & Software Status Report

Description: Print out report of hardware & software status

From Processes: Hardware & Software System

To Processes: -

Data Flow Name: Software Update

Description: Update the existing software version

From Processes: -

To Processes: Hardware & Software System

Define Question 2

Requirement specification can be described as the analysis of data describing the system to determine how well it is performing, what requirements must be met and strategies for fulfilling them.

Question 2

Requirement specification is determined by the data produced during the fact-finding investigation that is then analyzed as the description of features for a new system. This activity has three interrelated parts. First part is the analysis of factual data. The analysis of factual data is the data collected during the fact-finding study and included in data flow and decision analysis documentation are examined to determine how well the system is performing and whether it will meet the organization’s demands. The next part is the identification of essential requirements. These are the features that must be included in a new system that are ranging from operational details to performance criteria which all are specified. The third part is selection of requirements fulfillment strategies. They are the methods that will be used to achieve the stated requirements are selected. These form the basis for systems design which follows requirements specification. All these three activities are important and must be performed correctly. Requirement specification places a great deal of responsibility on the systems analyst as the quality of the work performed at this point will show up later in the characteristics of the new system.

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