5 Data Flow Diagrams

A Data Flow diagram is a graphical technique used to abstract the operation of a system in a given environment. They explicitly show how information flows to and from the system and how this information is transformed along the way. The following Data Flow diagrams have been created to provide such an overview for IFESS.

5.1 How To Read a Data Flow Diagram

Data Flow diagrams are drawn in nested layers. They start with the most general representation of the system and work down into specific sections. In the following diagrams, there are labeled bubbles representing different components of the system. For each bubble, a more detailed description will be given in the individual diagram corresponding to the component name. For clarity, a legend of the symbols used in Data Flow diagrams is given below. In addition, the following generic rules are the main guidelines:

         - Arrowheads indicate which way the data is flowing.
         - Processes have at least one input and one output.
         - Any two data stores are never directly connected to each other.
         - Any two external entities are never directly connected to each other.
         - Transitions between processes are legal.

5.1.1 Legend

5.2 Level 0 Diagram

This high-level view shows how IFESS will interact with its environment; such a schematic is also referred to as a context diagram. The entire IFESS system is represented by a central bubble, which has directed arcs specifying its general input and output. In this diagram it is also easy to see the many entities that supply input to IFESS and its many facets for output.

5.3 Level 1 Diagram

The level one diagram is an expansion of the singular IFESS bubble in the previous schematic. It shows all of the major components of the system and indicates which of these components the input and output arcs from the level zero diagram belong to. Also, the input and output arcs are more specific, and now the label indicates what specific data is flowing. The purpose of this level is to clarify the breakdown of the entire software system into its major components.

5.4 Level 2 Diagrams

5.4.1 Level 2A: The Internet

This simple diagram describes how IFESS provides access to the Internet. Passengers input information into the IFESS Internet browsing tool, prompting IFESS to retrieve the content from the Internet and output it to the Display system.

5.4.2 Level 2B: Food Ordering

Illustrated here is the system functionality that deals with food orders and meal reservations. Passengers and pilots are able to reserve a meal from a list of available choices, as well as order individual food items. Also shown is how they can change their selection meals anytime before the cutoff. Flight attendants can both view pending orders and mark them as delivered. All information storage is done through the food data store, which gets revised regularly by the update system.

5.4.3 Level 2C: Games

Another simple diagram showing how IFESS provides the passengers with access to basic games such as hearts and FreeCell. Passengers select the game that they want to play and IFESS displays the game on the passengerís terminal. It then takes inputs from the user and outputs the visual and audio game information to the display system and headphones respectively.

5.4.4 Level 2D: Billing System

This diagram describes the comprehensive IFESS billing and account tracking system. This system accepts billing information from both the food and movie systems, and updates the passenger-specific billing information in the billing/account information data store. The diagram shows how passengers can view their individual account information and how flight attendants can access passenger information, add a payment to an account, and print a permanent account record. The arc leading to the billing/account information data store from the update system depicts this update of information.

5.4.5 Level 2E: Movies

This diagram shows the data flow to and from the movie system. The functionality includes selecting a movie, watching it, and controlling the playback. When a movie is selected, the system sends the movie and passenger information to the billing system in order to update the account balance. It also internally determines if the passenger is required to pay for watching the selected movie. From there, the movie file is found in the data store and played on the passengerís terminal, the audio information going to the headphones while the video stream goes to the display. During play, the system also handles passenger control of the movieís progress through standard stop, pause, re-wind, and fast-forward commands.

5.4.6 Level 2F: Display

Shown here is how various IFESS components access the display system to output information to the user. There are nine components accessing the display system: information update, music, food, in-flight info, billing/accounts, movies, games, Internet, and help. There is also functionality to display core information, which involves the display of core items such as the IFESS user interface.

5.4.7 Level 2G: Music

This diagram describes the data flow to and from the music system. If covers all related functionality, including listening to pre-recorded music tracks and listening to the radio. Radio stations interact with IFESS by sending the radio station stream via the web. Passengers send requests for stations or music type, which sends the appropriate audio to the headphones. For pre-recorded music tracks, track progress is also sent to the video display.

5.4.8 Level 2H: Flight Information

This diagram describes how passengers interact with the flight information system. A passenger request on the status of the flight prompts IFESS to retrieve the information from the data store and generate a status report. This report is formatted into readable display information and sent to the terminal. The data store is constantly updated by the in-flight information, so passengers can always see an up-to-date outlook of the flight status.

5.4.9 Level 2I: Update Information

This is a simple diagram that depicts how the information in all of the IFESS systemís data stores is updated. For clarity, all of the IFESS data stores have been represented as one universal data store. This is merely an abstract representation, and is not meant to imply any implementation choices. It is to this universal data store that the administrator inputs updated information. The updated information is then sent to the appropriate local data store.

5.4.10 Level 2J: Help

This straightforward diagram shows how the various IFESS users can access help files for all IFESS operations. Passengers, Flight Attendants, Pilots and Administrators can all access this system. When they input a help section to view, the system retrieves the help files from the data store, and the information is sent to the display.

5.5 Data Flow Diagrams Data Dictionary

Term

Movie Item

Location(s) of Use:

Movie, Billing/Accounts

Description:

IFESS representation of a movie.


Term:

Administrator Inputs

Location(s) of Use:

Level 0

Description:

All the possible inputs the Administrator may use.


Term:

Altitude

Location(s) of Use:

Level 0, In-flight Info

Description:

Current Altitude of the plane


Term:

Audio

Location(s) of Use:

Level 0

Description:

All sound that is output to the headphones.


Term:

Audio Signal

Location(s) of Use:

Level 0, Movies, Music

Description:

Movies and Music both generate Audio output in the form of an Audio Signal


Term:

Billing display data

Location(s) of Use:

Display

Description:

The information from Billing that is to be displayed.


Term:

Billing info

Location(s) of Use:

Level 0

Description:

All the information that is pertinent to Billing. Information such as Seat Number and Passenger ID are a couple of examples.


Term:

Billing/Account info

Location(s) of Use:

Level 0, Billing/Accounts, Display

Description:

The accumulated information from Billing/Accounts that is to be displayed.


Term:

Browsing instructions

Location(s) of Use:

Level 0, Internet

Description:

Instructions from the user to control the browsing of the Internet.


Term:

Category

Location(s) of Use:

Level 0, Help

Description:

A subsection of the Help File.


Term:

Confirmation

Location(s) of Use:

Billing/Accounts

Description:

Action to ensure correct data input.


Term:

Core Display data

Location(s) of Use:

Display

Description:

Display data corresponding to the representation of information in the data store.


Term:

Cost

Location(s) of Use:

Level 0, Food, Billing/Accounts, Movie

Description:

The price of an item.


Term:

Database output

Location(s) of Use:

Level 0

Description:

Information transferred from the plane to the airport.


Term:

Deliver Orders

Location(s) of Use:

Food

Description:

Message indicating that a food order has been delivered.


Term:

Description

Location(s) of Use:

Food, Billing/Accounts

Description:

General description of an item.


Term:

Detailed account info

Location(s) of Use:

Billing/Accounts

Description:

Account information to be processed.


Term:

Detailed account record

Location(s) of Use:

Level 0, Billing/Accounts

Description:

Account information to be printed.


Term:

Displayable flight info

Location(s) of Use:

Level 0, Display, In-Flight Info

Description:

Data required for displaying the flight status.


Term:

ETA

Location(s) of Use:

Level 0, In-Flight Info

Description:

Estimated Time of Arrival of the flight.


Term:

Fast Forward

Location(s) of Use:

Movie, Music

Description:

Fast Forward a movie or music option.


Term:

Files

Location(s) of Use:

Information Update

Description:

The physical files needed to be updated during administrative maintenance.

Term:

Flight attendant inputs

Location(s) of Use:

Level 0

Description:

All possible inputs the Flight Attendant will need to enter.


Term:

Flight Data

Location(s) of Use:

In-Flight Info

Description:

All flight data pertinent to the Flight status, such as Altitude and ETA.


Term:

Food Adjustments

Location(s) of Use:

Level 0

Description:

Adjustments made to the way food is represented on the system.


Term:

Food display data

Location(s) of Use:

Display

Description:

All data required for displaying food information.


Term:

Food info

Location(s) of Use:

Level 0, Food, Display

Description:

All data associated with Food.


Term:

Food item

Location(s) of Use:

Level 0, Food, Billing/Accounts

Description:

Individual item of food, eg. A turkey sandwich.


Term:

Food Order

Location(s) of Use:

Level 0, Food

Description:

Contains a collection of Food Items.


Term:

Game display data

Location(s) of Use:

Display

Description:

Data required to display games.


Term:

Game Info

Location(s) of Use:

Display, Information Update

Description:

All pertinent information relating to Games, eg. The name of the game.


Term:

Game List

Location(s) of Use:

Information Update

Description:

List of games available.


Term:

Game play instructions

Location(s) of Use:

Level 0

Description:

Input from user to control the game play.


Term:

Help Display data

Location(s) of Use:

Level 0, Help, Display

Description:

Data required to display Help.


Term:

Help Files

Location(s) of Use:

Help

Description:

Physical files containing the text for help.


Term:

Help request

Location(s) of Use:

Level 0

Description:

Request for help on a topic.


Term:

Help Section Request

Location(s) of Use:

Help

Description:

Section of help desired.


Term:

IFESS core data

Location(s) of Use:

Display

Description:

Main data at the heart of the IFESS system.


Term:

In-flight display data

Location(s) of Use:

Display

Description:

Data required to display the in-flight status of the plane.


Term:

Internet Content

Location(s) of Use:

Display, Internet

Description:

Visual data retrieved from the Internet.


Term:

Meal

Location(s) of Use:

Food

Description:

Prearranged grouping of Food Items.


Term:

Meal Adjustments

Location(s) of Use:

Information Update

Description:

Adding, removing, adjusting meal listings.


Term:

Meal ID

Location(s) of Use:

Food

Description:

Identification of a type of meal.


Term:

Movie

Location(s) of Use:

Movies

Description:

Data representation of a movie.


Term:

Movie audio

Location(s) of Use:

Level 0

Description:

Audio emitted from a movie.


Term:

Movie Info

Location(s) of Use:

Display

Description:

Movie description information to be displayed.


Term:

Movie Item

Location(s) of Use:

Movie, Billing/Accounts

Description:

IFESS representation of a movie.


Term:

Movie Name

Location(s) of Use:

Movie

Description:

Name of a movie.


Term:

Movie Request

Location(s) of Use:

Level 0, Movie

Description:

User request for a movie to be played.


Term:

Movie Video Stream

Location(s) of Use:

Level 0, Movie, Display

Description:

Video display generated from a movie.


Term:

Music Display data

Location(s) of Use:

Display

Description:

Information describing Music to be displayed.


Term:

Music Info

Location(s) of Use:

Information Update

Description:

Information for updating the status of the music list.


Term:

Music List

Location(s) of Use:

Information Update

Description:

List of all available music.


Term:

Music progress

Location(s) of Use:

Level 0, Music, Display

Description:

Progress of music as it is playing.


Term:

Music/Radio request

Location(s) of Use:

Level 0

Description:

User request to listen to music or to the radio.


Term:

Order

Location(s) of Use:

Food

Description:

General food/snack item order information.


Term:

Passenger ID

Location(s) of Use:

Level 0, Food, Movies, Billing/Accounts

Description:

Passengerís unique identification number within the system.


Term:

Passenger Inputs

Location(s) of Use:

Level 0

Description:

General data associated with passenger interaction with IFESS.


Term:

Pause

Location(s) of Use:

Movies, Music

Description:

User request to pause movie or music playback.


Term:

Payment

Location(s) of Use:

Billing/Accounts

Description:

Data associated with a customer payment.


Term:

Play

Location(s) of Use:

Movies, Music

Description:

User request to play a loaded movie or music option.


Term:

Playback Control Request

Location(s) of Use:

Movies, Music

Description:

User request to manipulate the playback of a song or movie, throughout the use of: play, pause, rewind, stop, and fast forward


Term:

Position

Location(s) of Use:

Level 0, In-Flight Info

Description:

Flight position as given by the onboard flight information system.


Term:

Price

Location(s) of Use:

Food, Billing/Accounts

Description:

The price of a food system item.


Term:

Quantity Change

Location(s) of Use:

Food

Description:

Integer value of change that is required.


Term:

Radio Stream

Location(s) of Use:

Music

Description:

Data stream for radio stations.


Term:

Relevant Flight Info

Location(s) of Use:

In-Flight Info

Description:

Human readable generated flight info from raw flight info data.


Term:

Request for Passenger Account Info

Location(s) of Use:

Level 0, Billing/Accounts

Description:

User request to get passenger account information.


Term:

Request Game

Location(s) of Use:

Level 0

Description:

User request to play a game.


Term:

Request Meal

Location(s) of Use:

Food

Description:

User request to reserve a meal.


Term:

Request Orders

Location(s) of Use:

Food

Description:

User request for a list of pending food orders.


Term:

Request Price

Location(s) of Use:

Food

Description:

User request for the price of an item.


Term:

Request to Cancel Meal

Location(s) of Use:

Food

Description:

User request to cancel a meal order.


Term:

Rewind

Location(s) of Use:

Movies, Music

Description:

User request to rewind movie or music selection.


Term:

Seat Number

Location(s) of Use:

Food, Billing/Accounts

Description:

The unique seat number associated with a transaction.


Term:

Song

Location(s) of Use:

Music

Description:

The playable song data.


Term:

Song Title

Location(s) of Use:

Music

Description:

The title of a playable song.


Term:

Station Data

Location(s) of Use:

Level 0, Music

Description:

Information about a radio station.


Term:

Station Identifier

Location(s) of Use:

Music

Description:

Unique identifier for a radio station.


Term:

Status Request

Location(s) of Use:

Level 0, In-Flight Info

Description:

User request for flight status information.


Term:

Stop

Location(s) of Use:

Movies, Music

Description:

User request to stop a playing movie or audio stream.


Term:

Time

Location(s) of Use:

In-Flight Info

Description:

Time of day at origin and destination.


Term:

Update Amount

Location(s) of Use:

Billing/Accounts

Description:

Information concerning transaction.


Term:

Update Feedback

Location(s) of Use:

Information Update, Display System

Description:

Feedback from a data update procedure.


Term:

Update Info Display

Location(s) of Use:

Display System

Description:

Visible feedback from information update system.


Term:

Updated Account Info

Location(s) of Use:

Level 0, Billing/Accounts

Description:

The account data that has been changed.


Term:

Updated Food List

Location(s) of Use:

Information Update

Description:

The data associated with a new/changed food list.


Term:

Updated Game List

Location(s) of Use:

Information Update

Description:

The data associated with a new/changed game list.


Term:

Updated Movie List

Location(s) of Use:

Information Update

Description:

The data associated with a new/changed movie list.


Term:

Updated Music List

Location(s) of Use:

Information Update

Description:

The data associated with a new/changed music list.


Term:

Velocity

Location(s) of Use:

Level 0, In-Flight Info

Description:

Flight velocity information.


Term:

View Orders

Location(s) of Use:

Food

Description:

Flight Attendant request to view pending orders.


Term:

Visual Data

Location(s) of Use:

Display System

Description:

Raw visual information that is to be sent to end user terminals.


Term:

Web Display Data

Location(s) of Use:

Display System

Description:

Displayable web content.