A _________ shows what the system must do, regardless of how it will be implemented physically.
Logical model
In the systems design phase, you build a _______ that describes how the system will be constructed.
Physical model
A __________ uses various symbols to show how the system transforms input data into useful information.
Data flow diagram (DFD)
(T/F) A data flow diagram (DFD) shows how data moves through an information system but does not show program logic or processing steps. A set of DFDs provides a logical model that shows what the system does, not how it does it.
True
A ______receives input data and produces output that has a different content, form, or both.
Process
Processes contain the ________, also called __________ that transform the data and produce the required results.
Business logic , Business rules
A process symbol can be referred to as a______, because the inputs, outputs, and general functions of the process arc known, but the underlying details and logic of the process are hidden.
Black box
(T/F) By showing processes as black boxes, an analyst can create DFDs that show how the system functions, but avoid unnecessary detail and clutter.
True
A _______ is a path for data to move from one part of the information system to another. A data flow in a DFD represents one or more data items.
Data flow
(T/F) A process symbol can have more than one outgoing data flow. A process also can connect to any other symbol, including another process. A data flow, therefore, must have a process symbol on at least one end.
True
The APPLY INSURANCE PREMIUM process, for instance, produces output, but has no input data flow. Because it has no input, the process is called a ___________ process.
Spontaneous generation
CALCULATE GROSS PAY is called a ___________ process, which is a process that has input, but produces no output.
Black hole
A ____________ is a process that has at least one input and one output, but the input obviously is insufficient to generate the output shown. For example, a date of birth input is not sufficient to produce a final grade output in the CALCULATE GRADE process.
Gray hole
(T/F) Spontaneous generation, black holes, and gray holes are impossible logically in a DFD because a process must act on input, shown by an incoming data flow, and produce output, represented by an outgoing data flow.
True
A _________ is used in a DFD to represent data that the system stores because one or more processes need to use the data at a later time.
Data store
(T/F) The physical characteristics of a data store are unimportant because you are concerned only with a logical model. Also, the length of time that the data is stored is unimportant - it can be a matter of seconds while a transaction is processed or a period of months while data is accumulated for year-end processing. What is important is that a process needs access to the data at some later time.
True
The _________ symbol for a data store is a flat rectangle that is open on the right side and closed on the left side.
Gane and Sarson
The symbol for an _______ is a rectangle, which may be shaded to make it look three dimensional. The name of the _________ appears inside the symbol.
Entity
DFD entities also are called ___________ because they are data origins or final destinations.
Terminators
Systems analysts call an entity that supplies data to the system a _________, and an entity that receives data from the system a sink.
Source
(T/F) During requirements modeling, you used interviews, questionnaires, and other techniques to gather facts about the system, and you learned how the various people, departments, data, and processes fit together to support business operations.
True
Guidelines for Drawing DFDs:
Draw the context diagram
Use the name of the IS
Use unique names
Do not cross lines
Provide a unique name and reference number
Obtain as much user input and feedback
A __________ is a top-level view of an information system that shows the system's boundaries and scope.
Context diagram
The symbol represents the entire information system, and you identify it as _________
Process 0
___________ zooms in on the system and shows major internal processes, data flows, and data stores. It also repeats the entities and data flows that appear in the context diagram.
Diagram 0
When you explode a DFD, the higher-level diagram is called the________, and the lower-level diagram is referred to as the __________.
Parent diagram , child diagram
A ___________ is a process that consists of a single function that is not exploded further.
Functional primitive
___________ is the process of drawing a series of increasingly detailed diagrams, until all functional primitives are identified.
Leveling
__________ maintains consistency among a set of DFDs by ensuring that input and output data flows align properly.
Balancing
__________ also is called exploding, partitioning, or decomposing.
Leveling
A_________, or___________, is a central storehouse of information about the system's data.
Data dictionary , data repository
A _________, also called a _____________, is the smallest piece of data that has meaning within an information system.
data element , data item or field
Data elements are combined into _______, also called _________.
Records , data structures
A ________ is a meaningful combination of related data elements that is included in a data flow or retained in a data store.
Record
(T/F) The more complex the system, the more difficult it is to maintain full and accurate documentation. Fortunately, modern CASE tools simplify the task.
True
Several of the DFDs and data dictionary entries were created using a popular CASE tool called __________.
Visible Analyst
Any name(s) other than the standard data element name; this alternate name is called an _____.
Alias
______ refers to whether the data element contains numeric, alphabetic, or character values.
Type
________ is the maximum number of characters for an alphabetic or character data element or the maximum number of digits and number of decimal positions for a numeric data element.
Length
The _________ is the value for the data element if a value otherwise is not entered for it.
Default value
Specification of the data element's ________, which is the set of values permitted for the data element; these values either can be specifically listed or referenced in a table, or can be selected from a specified range of values.
Domain
Some data elements have additional _______.
Validity rules
The specification for the origination point for the data element's values.
Source
Identification for the individual or department that has access or update privileges for each data element.
Security
Identification of the user(s) responsible for entering and changing values for the data element.
Responsible user(s)
This part of the documentation allows you to enter additional notes.
Description and comments.
Describes the expected number of occurrences for the data flow per unit of time.
Volume and frequency
Each data flow represents a group of related data elements called a record or data structure.
Record
The DFD ending point(s) for the data flow; the destination can be a process, a data store, or an entity.
Destination
The data flow name as it appears on the DFDs.
Data flow name or label
Describes the data flow and its purpose.
Description
Aliases for the DFD data flow name(s).
Alternate name(s)
The DFD beginning, or source, for the data flow; the origin can be a process, a data store, or an entity.
Origin
A reference number that identifies the process and indicates relationships among various levels in the system.
Process number
This section includes the input and output data flows. It also documents the processing steps and business logic.
Process description
The standard DFD names for the input data flows to the entity.
Input data flows
The standard DFD names for the data flows leaving the entity.
Output data flows
The record name as it appears in the related data flow and data store entries in the data dictionary.
Record or data structure name
A list of all the data elements included in the record. The data element names must match exactly what you entered in the data dictionary.
Attributes
The _______ serves as a central storehouse of documentation for an information system. It is created when the system is developed, and is updated constantly as the system is implemented, operated, and maintained.
Data dictionary
A __________ documents the details of a functional primitive, and represents a specific set of processing steps and business logic.
process description
________ is based on combinations of three logical structures, sometimes called control structures, which serve as building blocks for the process.
Modular design
Modular design is based on combinations of three logical structures, sometimes called _________, which serve as building blocks for the process.
control structures
The completion of steps in sequential order, one after another.
Sequence
The completion of one of two or more process steps based on the results of a test or condition.
Selection
The completion of a process step that is repeated until a specific condition changes.
Iteration
_________ is a subset of Standard English that describes logical processes clearly and accurately.
Structured English
Structured English might look familiar to programming students because it resembles _________, which is used in program design.
Pseudocode
A _________ is a logical structure that shows every combination of conditions and outcomes.
decision table
A ________ is a graphical representation of the conditions, actions, and rules found in a decision table. It shows the logic structure in a horizontal form that resembles a tree with the roots at the left and the branches to the right.
decision tree
Many analysts follow a __________, which means that they develop a physical model of the current system, a logical model of the current system, a logical model of the new system, and a physical model of the new system.
four-model approach
(T/F) The major benefit of the four-model approach is that it gives you a clear picture of current system functions before you make any modifications or improvements. That is important because mistakes made early in systems development will affect later SDLC phases and can result in unhappy users and additional costs.
