Module 5: Data and Process Modeling

Alias

A term used in various data dictionaries to indicate an alternate name, or a name other than the standard data element name, that is used to describe the same data element.

Balancing

A process used to maintain consistency among an entire series of diagrams, including input and output data flows, data definition, and process descriptions.

Black Box

A metaphor for a process or an action that produces results in a non-transparent or non-observable manner. In data flow diagrams, a process appears as a _____ where the inputs, outputs, and general function of the process are known, but the underlying details are not shown.

Black Hole

A process that has no output.

Business Logic / Business Rules

Rules to determine how a system handles data and produces useful information, reflecting the operational requirements of the business. Examples include adding the proper amount of sales tax to invoices, calculating customer balances and finance charges, and determining whether a customer is eligible for a volume-based discount.

Child Diagram

The lower-level diagram in an exploded DFD.

Context Diagram

A top-level view of an information system that shows the boundaries and scope.

Context Structures / Logical Structures

Serve as building blocks for a process. Have one entry and exit point. They may be completed in sequential order, as the result of a test or condition, or repeated until a specific condition changes.

Data Dictionary

A central storehouse of information about a system’s data.

Data Element / Data Item / Field / Attribute

A single characteristic or fact about an entity. The smallest piece of data that has meaning within an information system. For example, a Social Security number or company name.

Data Flow

A path for data to move from one part of the information system to another.

Data Flow Diagram (DFD)

Shows how data moves through an information system but does not show program logic or processing steps. Uses various symbols to show how the system transforms input data into useful information.

Data Repository / Data Store

A symbol used in DFDs to represent a situation in which a system must retain data because one or more processes need to use that stored data at a later time.

Data Structures

A meaningful combination of related data elements that are included in a data flow or retained in a data store. A framework for organizing and storing data.

Decision Table

A table that shows a logical structure, with all possible combinations of conditions and resulting actions.

Decision Tree

A graphical representation of the conditions, actions, and rules found in a decision table.

Decomposing

Another way of conveying a process or system that has been broken down from a general, top-level view to more detail. The terms exploded and partitioned also can be used.

Diagram 0

A diagram depicting the first level of detail below the initial context diagram. Zooms in on the context diagram and shows major processes, data flows, and data stores, as well as repeating the external entities and data flows that appear in the context diagram.

Diverging Data Flow

A data flow in which the same data travels to two or more different locations.

Domain

The set of values permitted for a data element.

Entity

A person, a place, a thing, or an event for which data is collected and maintained. For example, an online sales system may include _____ named CUSTOMER, ORDER, PRODUCT, and SUPPLIER.

Exploding

A diagram is said to be _____ if it “drills down” to a more detailed or expanded view

Four-Model Approach

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 are all developed.

Functional Primitive

A single function that is not exploded further. The logic for _________ is documented in a data dictionary process description.

Gane and Sarson

A popular symbol set used in DFDs. Processes, data flows, data stores, and external entities all have a unique symbol. Uses rectangles with rounded corners to depict processes.

Gray Hole

A process with an input obviously insufficient to generate the shown output.

Iteration

The completion of a process step that is repeated until a specific condition changes.

Leveling

The process of drawing a series of increasingly detailed diagrams to reach the desired level of detail.

Logical Model

Shows what a system must do, regardless of how it will be implemented physically.

Looping / Repetition

Refers to a process step that is repeated until a specific condition changes. For example, a process that continues to print paychecks until it reaches the end of the payroll file is _____.

Modular Design

A design that can be broken down into logical blocks. Also known as partitioning or top-down design.

Parent Diagram

The higher or more top-level diagram in an exploded DFD.

Partioning

The breaking down of overall objectives into subsystems and modules.

Physical Model

A model that describes how a system will be constructed.

Process

Procedure or task that users, managers, and IT staff members perform. Also, the logical rules of a system that are applied to transform data into meaningful information. In data flow diagrams, a _____ receives input data and produces output that has a different content, form, or both.

Process 0

In a DFD, _____ represents the entire information system but does not show the internal workings.

Process Description

A documentation of a functional primitive’s details, which represents a specific set of processing steps and business logic.

Pseudocode

A technique for representing program logic in semi-structured prose.

Record

A collection of data elements considered as a single unit that flows through the system.

Selection

A control structure in modular design, it is the completion of two or more process steps based on the results of a test or condition.

Sequence

The completion of steps in sequential order, one after another.

Sink

An external entity that receives data from an information system.

Source

An external entity that supplies data to an information system.

Spontaneous Generation

An unexplained generation of data or information. With respect to DFDs, processes cannot ________ data flows—they must have an input to have an output.

Structured English

A subset of standard English that describes logical processes clearly and accurately.

Terminators / External Entity

A DFD symbol that indicates a data origin or final destination.

Validity Rules

Checks that are applied to data elements when data is entered to ensure that the value entered is valid. For example, a ________ might require that an employee’s salary number be within the employer’s predefined range for that position.

Yourdon

A type of symbol set that is used in DFDs. Processes, data flows, data stores, and external entities each have a unique symbol in the ______ symbol set. Circles to depict processes.