Chapter 7 Using Data Flow Diagrams SAD Exam

Short Answer: List three of the five advantages of a logical data flow diagram.

1. Better communication with users 2. More stable systems 3. Better understanding of the business by analysts 4. Flexibility and maintenance 5. Elimination of redundancies and easier creation of the physical model

Short Answer: What are the four advantages of using a data flow approach over narrative explanations of data movement?

1. Freedom from committing to the technical implementation of the system too early 2. Further understanding of the interrelatedness of systems and subsystems 3. Communicating current system knowledge to users through data flow diagrams 4. Analysis of a proposed system to determine if the necessary data and processes have been defined

Short Answer: Describe each of the four data items that can be symbolized on a data flow diagram?

A double square is used to depict an external entity. An arrow shows movement of data. A rectangle with rounded corners is used to show the occurrence of a transforming process. An open ended rectangle is used to represent a data store.

Short Answer: What is the difference between a logical and physical data flow diagram?

A logical data flow diagram focuses on the business and how the business operates; while a physical data flow diagram shows how the system will be implemented.

Which of the following is not an advantage of using a logical model?

A logical model clarifies which processes are automated.

________ depict the broadest possible overview of system inputs, processes, and outputs.

Data flow diagrams

An arrow is used to depict an external entity that can give and receive data from the system. T/F

False

Linear data flow from process to process is normal in higher level data flow diagrams. T/F

False

Processes in a rectangle with rounded corners sometimes denote something other than a change in or transformation of data or a system/subsystem. T/F

False

Processes that transform data should be named with a noun which indicates the data that has been transformed. T/F

False

Which of the following is not an advantage of using a physical model?

It is easier to create compared with the logical model.

Short Answer: Why is partitioning useful when designing a Web site?

Partitioning is useful when designing a Web site because it allows the designer to separate the site into a series of pages that will increase the site's usability, the speed of human processing, and the ease of maintaining the site.

The biggest advantage of the data flow approach lies in the conceptual freedom found in the use of the four symbols. T/F

TRUE

The data flow diagram graphically characterizes data processes and flows in a business system. T/F

TRUE

A primitive process is:

a process that is not exploded to a child diagram.

What should be created each time data must be obtained from an external partner?

a unique Web form and DFD process to validate and process the data

In a CRUD matrix, each row represents the data stores used for each:

activity.

Which is not one of the four basic symbols used to chart data movement on data flow diagrams?

an oval

Which is the biggest advantage of the data flow approach over narrative explanations?

conceptual freedom found in the use of the four symbols

When the first ________ diagram is made, inputs and outputs are specified and these remain constant throughout all of the following diagrams.

context

While the first ________ diagram helps the systems analyst grasp basic data movement, its general nature limits its usefulness.

context

A method that provides conceptional freedom for representing processes and flows in a business system is the ________.

data flow diagram

Which graphically characterize(s) data processes and flows through a business system?

data flow diagrams

Which of the following is not an error when drawing a data flow diagram?

data flow on a child diagram that has only one end connected to a process, the other end is a point in space

An external entity is called a source or ________ of data, and is considered to be external to the study.

destination

By using combinations of only four symbols, the systems analyst is able to create a pictorial depiction of data flows that eventually can provide solid system ________.

documentation

The process of creating a simple data flow diagram fragment for each unique system trigger is called:

event modeling.

Which of the following is a goal of dividing a Web site into a series of Web pages?

improve the ease of maintaining the Web site

Physical data flow diagrams:

include processes for adding, updating, changing and deleting records.

A logical data flow diagram:

is a model of how the business operates.

Transaction files:

may be used to link processes that execute at different times.

Ajax is used to:

obtain data from a Web server and update the current Web form.

Data flows occurring simultaneously can be depicted doing just that through the use of ________ arrows.

parallel

What is the middle of the process symbol used for?

process description

The data store symbol is simply showing a depository for data which allows addition or ________ of data.

retrieval

Partitioning on a data flow diagram for an ecommerce Web site may be used to show:

security.

A use case:

summarizes an activity, its trigger, input, and output.

The data flow approach enables the systems analyst to better understand the interrelatedness of ________ and ________.

systems; subsystems

Having separate Web forms to collect transaction data means that:

the forms are less complex and easier to fill out.

Each time an external company or system is involved:

the process involved needs to be partitioned into a separate program.

Which of these are reasons for partitioning a system?

to keep transactions secure

Which of the following is not a reason for partitioning processes into separate programs?

to maintain consistency of data

With a ________ approach, the diagrams move from general to specific.

top-down

When the data flow in and out of a parent process do not match the data flow in or out of a child diagram, it is called:

unbalanced decomposition.

The advantage of building data flow diagrams based on events is that:

users are familiar with the events within their business and know how the events drive other activities.

A CRUD matrix is used to show:

where records are updated, added, deleted or used.

In logical data flow diagrams, the type of physical storage is unspecified. T/F

True

Partitioning data flow diagrams is the process of deciding which processes are manual procedures and which processes should be grouped into which computer programs. T/F

True

The name of the data flow coming out of a process should be different than the name of the data flow going into the process. T/F

True

A rectangle with rounded corners is used to show the occurrence of a transforming process. T/F

True