Data Flow Diagrams

Introduction for organizers

The Problem

• How to model a system before building or changing it

Build an Abstraction• Molecular Model

Life Cycle

What Life Cycle?

• What does it do? – All or Part?

• Build or Buy?– Early decision for all

software systems are whether to build or buy

• WHO works on it?• WHO will run it?• HOW Long will it

last?

The Software Development Cycle1. Identify problems,

opportunities and objectives.

2. Define Information Requirements

3. Analyze Detailed Needs

4. Specify or Design the Recommended System

5. Buy or Develop the Software

6. Install and Test

7. Train

8. Deploy

9. Maintain the system

10. Evaluate and Plan for New Versions

Symbol of never-ending life

Different Points of View

Put the Parts Together

Organization’s Requirements

TechnicalExperts

User Experts

Technology

Who Does What?

Technical Assistance Provider

User Expert

Joint Effort

Who Does What?1. Identify problems,

opportunities and objectives.

2. Define Information Requirements

3. Analyze Detailed Needs

4. Specify or Design the Recommended System

5. Buy or Develop the Software

6. Install and Test

7. Train

8. Deploy

9. Maintain the system

10. Evaluate and Plan for New Versions

Technical Assistance Provider

User Expert

Joint

Data Flow Diagram Parts

• External Entity

• Process

• Data Flow

• Data Store

External Entity

EXTERNAL ENTITYEXTERNAL ENTITY

The External Entity symbol represents sources of data to the system or destinations of data from the system.

• Funder

• Politician

• Allies

• General Population

• Constituency

• Government

• Funder

• Politician

• Allies

• General Population

• Constituency

• Government

Process

PROCESS BLOCKPROCESS BLOCK

The Process symbol represents an activity that transforms or manipulates the data (combines, reorders, converts, etc.).

• Signup Member

• Plan campaign

• Communicate message

• Pay Bills

• Signup Member

• Plan campaign

• Communicate message

• Pay Bills

Data Flow

Data Flow

The Data Flow symbol represents movement of data.

• All Data Flows are defined in a data dictionary

Data Store

Data Store

The Data Store symbol represents data that is not moving (delayed data at rest).

Procedure

1. Start at the top level with external entities to organization

2. Create a context diagram with system at center and external entities sending and receiving data flows;

Community-led Organizing

GOVERNMENT

OFFICIALS

ELECTED

OFFICIALS

CONSTITUENCI

ES

FUNDERS

Official Dispoisition

Political Pressure

Bureaucratic–Control-Responses

Demands for Action

Member interest

Political Program

Disposition-of-Support-requests

Requests-for-financial-support

GENERAL

PUBLIC

General Information

Support

Context Diagram

Carry Entities and Data Flows Forward

General InformationGENERAL

PUBLIC

Member interest

CONSTITUENCI

ES

Support

Official Dispoisition

ELECTED

OFFICIALS

Demands for ActionGOVERNMENT

OFFICIALSBureaucratic–

Control-Responses

Political Program

Disposition-of-Support-requests

FUNDERS

Political Pressure

Requests-for-financial-support

Level 1• CLO Example

FUNDERS

GENERAL

PUBLIC

General Information

Member interest

CONSTITUENCI

ES

Support

Official Dispoisition

ELECTED

OFFICIALS

Demands for ActionGOVERNMENT

OFFICIALS

Bureaucratic–Control-Responses

Political Program

Political Pressure

BuildMembership

DevelopLeadership

Raise funds

Disposition-of-Support-requests

Requests-for-financial-support

ManageInfrastructure

Plan StrategyCampaign for

Results

MembershipDatabase

ORGANIZATION

LEADERS

MEMBERS

Political direction

leadership skillstraining

Interested members

new leaders

new and renewing membersmembership signup

informationmemberrecords

Requests-for-member

financial-supportmember financial support

member donation records

ideas and needsfor organization

campaign plans

Member action

Level 1• CLO Example

Exercise