A dfd shows ____.

CIS 321 Case Study ‘Employee Benefits System (ECS)’

MILESTONE 5 – PROCESS MODELING - Part II (Exploded DFD)
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Part 1

Synopsis

1. Level 0 Data flow Diagram

T

he requirements analysis phase answers the question, ‘What does the user need and want from a new system?’ The requirements analysis phase is critical to the success of any new information system! In this milestone we need to identify what information systems requirements need to be defined from the system users’ perspectives.

The Data Flow Diagram (DFD) is a graphical representation of system which shows systems structure and components. The DFD shows how the data transforms in the system, what the source of the input is and what is the destination. Also, the DFD presents data structure and how it’s stored.

In this milestone you will explode the Context level DFD to Level 0 DFD to show sub-systems (processes). The Level 0 DFD shows internal data stores and how data flows through the processes.

2. Child diagram definition

C

hild level diagrams show details and are built till needed level of details is reached. First, we show the information system as a single process on the Context diagram. Then, we decompose and show more details until all processes are functional primitives. Not all processes are exploded to the same number of levels- it’s not required to explode all processes to the same level. The main target is to reach the functional primitive which will be translated into units of program code.

Objectives

After completing this milestone, you should be able to:

1. Create a Level 0 (System) Data Flow Diagram

2. Create a Child Data Flow Diagram

Prerequisites

Before starting this milestone, the following topics should be covered:

• Process Modeling - Chapter 9

Assignment

As a systems analyst or knowledgeable end-user, you must learn how to draw data flow diagrams to model business process requirements. The preliminary investigation and problem analysis phases of the methodology have been completed and you understand the current system’s strengths, weaknesses, limitations, problems, opportunities, and constraints. You have already built the Context models (Milestone 3) to document business requirements for the new system. You now need to build the Level 0 (System) DFD and corresponding process models.

Activities

1. Develop Level 0 DFD. Make assumptions where necessary.

2. Draw one Child Diagram using the Level 0 diagram.

3. Continue decomposition of one process up to primitive processes (Level 2, Level 3, etc.)

Deliverable format and software to be used are according to your instructor’s specifications. Deliverables should be neatly packaged in a binder, separated with a tab divider labeled “Milestone 5-Part II”.

References

• Context Data Flow Diagram Narrative – Exhibit 5.1

Deliverables:
Level 0 Data flow Diagram
Due:__/__/__

Time:______

Child level diagrams: Due: __/__/__ Time:_______
ADVANCED OPTIONS
Advanced option is to develop Child diagrams for all processes in Level 0 DFD.
Child level diagrams: Due: __/__/__ Time: _______
Milestone’s Point Value: ____
Part 2
Synopsis
Each process from primitive DFD may be developed as the individual module.
The software design technique which is based on the composing software from separate, interchangeable components is known as the module.

Modular design is a way to organize the complex system as a set of distinct components. Components may be developed, tested independently and then plugged together.

Modular design is supported by three types of logic:

· Sequential;

· Decision making or control;

· Iteration or repetition.

Sequential – execution of steps one after another.

Decision making - execution of step depends on results of condition or set of conditions. Decision making is also called the selection or control.

Iteration – execution of steps is repeated until the specific condition changes. Iteration is also called as repetition or looping.

In this milestone you will write the Structured English for primitive process.

Objectives
After completing this milestone, you should be able to:

1. Write the Structured English for primitive process.

Prerequisites
Before starting this milestone the following topics should be covered:

1. Child level DFD – Chapter 9

2. Physical level DFD – Chapter 9 and12

3. Structured English – Chapter 9

4. Fact-finding results – Chapter 6

Assignment
The goal of this part of project is to write Structured English.

Activities
1. Write the Structured English for one-two primitive processes. Include sequential, decision making and iteration logics. Your instructor will indicate what specific processes to document.

References:
Previous narratives and supplied forms
Templates
See on-line learning center website for the textbook.

Deliverables:
Structured English: Due: __/__/__ Time:_______