CH7
A data flow is data that move together, so it can be composed of many individual pieces of data that are generated at the same time and that flow together to common destinations.
TRUE
According to the DFD guidelines, the inputs to a process are different from the outputs of that process.
TRUE
An example of inconsistency would be a data flow that appears on a higher-level DFD but not on lower levels (also a violation of balancing).
TRUE
DFDs are not as good as flowcharts for depicting the details of physical systems; on the other hand, flowcharts are not very useful for depicting purely logical information flows.
TRUE
Sources/sinks are sometimes referred to as external entities because they are outside the system.
TRUE
The information system is depicted as a DFD and the highest-level view of this system is called a context diagram.
TRUE
The inputs to a process must be sufficient to produce the outputs (including data placed in data stores) from the process. Thus, all outputs can be produced, and all data in inputs move somewhere: to another process or to a data store outside the process or onto a more detailed DFD showing a decomposition of that process.
TRUE
When you decompose a DFD from one level to the next, there is a conservation principle at work and we must conserve inputs and outputs to a process at the next level of decomposition.
TRUE
Use cases written at the fish and ________ levels (sometimes called the clam level) are much more detailed and focus on sub-function goals. A) Black B) White C) Kite D) Sea
A) Black
The concept of DFD ________ refers to whether you have included in your DFDs all of the components necessary for the system you are modeling. A) Completeness B) Accuracy C) Balancing D) Processing
A) Completeness
Functional decomposition is a(n) ________ process of breaking the description of a system down into finer and finer detail, which creates a set of charts in which one process on a given chart is explained in greater detail on another chart. A) Iterative B) Never-ending C) Continuous D) Static
A) Iterative
A(n) ________ in a data flow means that exactly the same data come from any of two or more different processes, data stores, or sources/sinks to a common location. A) Join B) Fork C) Break D) Arrow
A) Join
A ________ diagram is a DFD that is generated from n nested decompositions from a level-0 diagram. A) Level-n B) Level-0 C) Level-1 D) Level-2
A) Level-n
According to Cockburn's template, ________ are those things the system must ensure are true before the use case can start. A) Preconditions B) Minimal guarantee C) Success guarantee D) Triggers
A) Preconditions
A ________ is the work or actions performed on data so that they are transformed, stored, or distributed. A) Process B) Data store C) Flowchart D) Data flow
A) Process
A(n) ________ only transfers control from the sender to the recipient without describing the details of the communication. A) Simple message B) Sequence diagram C) Synchronous message D) Asynchronous message
A) Simple message
A use-case consists of a set of possible sequences of interactions between a system and ________ in a particular environment, possible sequences that are related to a particular goal. A) User B) Procedure C) Function D) Company
A) User
A ________ is a DFD that represents a system's major processes, data flows, and data stores at a high level of detail. A) Level-1 diagram B) Level-0 diagram C) Level-2 diagram D) Level-3 diagram
B) Level-0 diagram
________ is the process of discovering discrepancies between two or more sets of DFDs or discrepancies within a single DFD. A) Timing B) Primitive DFD C) Basic analysis D) Gap analysis
D) Gap analysis
A level-0 diagram represents the primary individual processes in the system at the highest possible level.
TRUE
Because requirements determination and structuring are often parallel steps, DFDs evolve from the more general to the more detailed as current and replacement systems are better understood.
TRUE
Context DFD is one of the deliverables for process modeling.
TRUE
Once the DFDs are complete, we can examine the details of individual DFDs for such problems as redundant data flows, data that are captured but are not used by the system, and data that are updated identically in more than one location.
TRUE
A ________ in business process modeling is a way to visually encapsulate a process. A) Gateway B) Swim-lane C) Pool D) Flow
B) Swim-lane
A data flow to a data store means ________. A) Join B) Update C) Process D) Fork
B) Update
What are the procedures when constructing a decision table?
1. Name the conditions and the values that each condition can assume. Determine all of the conditions that are relevant to your problem and then determine all of the values each condition can take. 2. Name all possible actions that can occur. The purpose of creating decision tables is to determine the proper course of action given a particular set of conditions. 3. List all possible rules. When you first create a decision table, you have to create an exhaustive set of rules. Every possible combination of conditions must be represented. 4. Define the actions for each rule. Now that all possible rules have been identified, provide an action for each rule. 5. Simplify the decision table. Make the decision table as simple as possible by removing any rules with impossible actions.
What is a DFD? Why are DFDs used?
A data flow diagram (DFD) is a picture of the movement of data between external entities and the processes and data stores within a system. A context diagram shows the scope of the system, indicating which elements are inside and which are outside the system. Second, DFDs of the system specify which processes move and transform data, accepting inputs and producing outputs. These diagrams are developed with sufficient detail to understand the current system and to provide notation as well as illustrate important concepts about the movement of data between manual and automated steps, and they offer a way to depict work flow in an organization. DFDs continue to be beneficial to information systems professionals as tools for both analysis and communication.
________ is the time period during which an object performs an operation. A) Activation B) Activity C) Sequence D) Duration
A) Activation
The concept of DFD ________ refers to whether or not the depiction of the system shown at one level of a nested set of DFDs is compatible with the depictions of the system shown at other levels. A) Consistency B) Completeness C) Balancing D) Accuracy
A) Consistency
A ________ is a diagram of process logic where the logic is reasonably complicated. A) Decision table B) Decision box C) Decision column D) Decision flow
A) Decision table
With only ________ symbols, you can use DFDs to represent both physical and logical information systems. A) Four B) Three C) Five D) Six
A) Four
No process can have only ________ and if an object has only that, then it must be a sink. A) Inputs B) Procedure C) Outputs D) Arrow
A) Inputs
As seen from the clouds, as if flying in a plane at 35,000 feet, refers to which level according to Cockburn? A) White B) Kite C) Blue D) Fish
A) White
Use cases written at the ________ level focus on user goals. A) White B) Blue C) Black D) Kite
B) Blue
A ________ can be best understood as data in motion, moving from one place in a system to another. A) Process B) Data flow C) Data store D) Data source
B) Data flow
A ________ is a picture of the movement of data between external entities and the processes and data stores within a system. A) Process flow diagram B) Data flow diagram C) Data diagram D) Procedure flow diagram
B) Data flow diagram
________ is the set of behaviors or functions in a use case that follow exceptions to the main success scenario. A) Triggers B) Extension C) Preconditions D) Connections
B) Extension
A(n) ________ in business process modeling shows the sequence of action in a process. A) Graph B) Flow C) Event D) Activity
B) Flow
A(n) ________ arises when one use case uses another use case and is shown diagrammatically as a dotted-line arrow pointed toward the use case that is being used. A) Extend relationship B) Include relationship C) System boundary D) Connection
B) Include relationship
________ DFD development recognizes that requirements determination and requirements structuring are interacting, not sequential, subphases of the analysis phase of the SDLC. A) Primitive B) Iterative C) Subjective D) Consistent
B) Iterative
At the ________ level of DFDs, new data flows may be added to represent data that are transmitted under exceptional conditions. These data flows typically represent error messages or confirmation notices. A) Highest B) Lowest C) Basic D) Medium
B) Lowest
The lowest level of a DFD is called a ________ data flow diagram. A) Low-level B) Primitive C) Level-0 D) Basic
B) Primitive
A(n) ________ diagram depicts the interactions among objects during a certain period of time. A) Activity B) Sequence C) Business D) Activation
B) Sequence
According to the DFD conventions, the data flow is always depicted by a(n) ________. A) Rectangle B) Circle C) Arrow D) Triangle
C) Arrow
When two ________ have the same data flow name, you must be careful that these flows are exactly the same. A) Rectangles B) DFDs C) Arrows D) Processes
C) Arrows
________ are common in concurrent, real-time systems, in which several objects operate in parallel. A) Sequence diagrams B) Simple messages C) Asynchronous messages D) Synchronous messages
C) Asynchronous messages
________ is NOT a phase in a systems development life cycle. A) Maintenance B) Planning C) Attributes D) Design
C) Attributes
BPMN stands for ________. A) Basic Process Modeling Notation B) Business Process Multi Notation C) Business Process Modeling Notation D) Business Procedure Modeling Notation
C) Business Process Modeling Notation
The act of going from a single system to ________ component processes is called (functional) decomposition. A) Two B) Three C) Four D) Six
C) Four
A(n) ________ in business process modeling is a decision point. A) Event B) Swim-lane C) Gateway D) Flow
C) Gateway
Both the white and ________ levels provide a summary of the use case goals. A) Blue B) Black C) Kite D) Fish
C) Kite
Balancing is the conservation of inputs and outputs to a DFD process when that process is decomposed to a ________ level. A) Balanced B) Similar C) Lower D) Higher
C) Lower
An activity diagram cannot be used to ________. A) Depict the flow of control from activity to activity B) Help in identifying extensions in a use case C) Model work flow but not business processes D) Model the sequential and concurrent steps in a computation process
C) Model work flow but not business processes
A data flow cannot go directly back to the same process it leaves. There must be at least ________ other process(es) that handle(s) the data flow, produce(s) some other data flow, and return(s) the original data flow to the beginning process. A) Three B) Two C) One D) Four
C) One
A data flow has ________ direction(s) of flow between symbols. It may flow in both directions between a process and a data store to show a read before an update. A) No B) Three C) One D) Multi
C) One
Flowcharting has been criticized by proponents of structured analysis and design because it is too ________. A) Geometrically oriented B) Diagrammatic C) Physically oriented D) Methodological
C) Physically oriented
Data cannot move directly from one data store to another data store. Data must be moved by a ________. A) Flow chart B) Procedure C) Process D) Data source
C) Process
________ is NOT one of the levels of details suggested by Cockburn. A) White B) Kite C) Red D) Blue
C) Red
A ________ lists what it takes to satisfy stakeholders if the use case is completed successfully. A) Precondition B) Minimal guarantee C) Success guarantee D) Trigger
C) Success guarantee
Which characteristics of sources and sinks are of no importance?
Characteristics we do not consider include: What a source or sink does with information or how it operates. How to control or redesign a source or sink because, from the perspective of the system we are studying, the data a sink receives and often what data a source provides are fixed. How to provide sources and sinks direct access to stored data because, as external agents, they cannot directly access or manipulate data stored within the system.
Data flow repository entries typically will NOT include ________. A) The label or name for the data flow as entered on the DFDs B) A list of other repository objects grouped into categories by type of object C) The composition or list of data elements contained in the data flow D) A long description defining the data flow
D) A long description defining the data flow
A(n) ________ diagram shows the conditional logic for the sequence of system activities needed to accomplish a business process. A) Fork B) Branch C) Business D) Activity
D) Activity
A(n) ________ in business process modeling is an action that must take place for a process to be completed. A) Gateway B) Event C) Flow D) Activity
D) Activity
A(n) ________ is an external entity that interacts with a system and is someone or something that exchanges information with the systems. A) Procedure B) DFD C) User D) Actor
D) Actor
A data flow has a noun phrase label. More than one data flow noun phrase can appear on a single ________ as long as all of the flows on the same arrow move together as one package. A) Circle B) Rectangle C) Join D) Arrow
D) Arrow
________, shown as a half arrowhead in a sequence diagram, is one where the sender does not have to wait for the recipient to handle the message. A) Simple message B) Activation C) Synchronous message D) Asynchronous message
D) Asynchronous message
Data cannot move directly from a source to a sink. It must be moved by a process if the data are of any concern to our system. Otherwise, the data flow is not shown on the ________. A) Sink B) Procedure C) Flow chart D) DFD
D) DFD
________ are NOT a component of data flow diagram symbols. A) Processes B) Data stores C) Data flows D) Data programs
D) Data programs
A(n) ________ in a data flow means that exactly the same data goes from a common location to two or more different processes, data stores, or sources/sinks. (This usually indicates different copies of the same data going to different locations.) A) Arrow B) Join C) Break D) Fork
D) Fork
________ is/are NOT a deliverable for process modeling. A) Context DFD B) DFDs of the system C) Thorough descriptions of each DFD component D) Inadequately decomposed diagrams
D) Inadequately decomposed diagrams
No process can have only ________. It would be making data from nothing (a miracle). If an object has only outputs, then it must be a source. A) Sources B) Sinks C) Inputs D) Outputs
D) Outputs
________ are NOT a part of a decision table. A) Condition stubs B) Action stubs C) Rules D) Policies
D) Policies
A ________ is the origin and/or destination of the data, and these are sometimes referred to as external entities because they are outside the system. A) Data graph B) Data flow C) Process D) Source
D) Source
A ________ is used in both conventions for sources/sinks and has a name that states what the external agent is, such as Customer, Teller, EPA Office, or Inventory Control System. A) Circle B) Triangle C) Rectangle D) Square
D) Square
A(n) ________ shown as a full, solid arrowhead, is one where the caller has to wait for the receiving object to complete execution of the called operation before it itself can resume execution. A) Activation B) Simple message C) Asynchronous message D) Synchronous message
D) Synchronous message
What do each of the four symbols in a DFD represent? Explain the terms used in describing the processes in the DFD.
DFD symbols consist of four symbols that represent the same things: data flows, data stores, processes, and sources/sinks (or external entities). A data flow can be best understood as data in motion, moving from one place in a system to another. A data flow is data that move together, so it can be composed of many individual pieces of data that are generated at the same time and that flow together to common destinations. A data store is data at rest. A process is the work or actions performed on data so that they are transformed, stored, or distributed. When modeling the data processing of a system, it does not matter whether a process is performed manually or by a computer. Finally, a source/sink is the origin and/or destination of the data.
Compare and contrast DFDs and flowcharts.
DFDs are versatile diagramming tools. With only four symbols, you can use DFDs to represent both physical and logical information systems. DFDs are not as good as flowcharts for depicting the details of physical systems; on the other hand, flowcharts are not very useful for depicting purely logical information flows. In fact, flowcharting has been criticized by proponents of structured analysis and design because it is too physically oriented. Flowcharting symbols primarily represent physical computing equipment, such as terminals and permanent storage. One continual criticism of system flowcharts has been that overreliance on such charts tends to result in premature physical system design. DFDs do not share this problem of premature physical design because they do not rely on any symbols to represent specific physical computing equipment. They are also easier to use than flowcharts because they involve only four different symbols.
How can you use DFDs as an analysis tool?
DFDs can also be used in a process called gap analysis. Analysts can use gap analysis to discover discrepancies between two or more sets of DFDs, representing two or more states of an information system, or discrepancies within a single DFD. Once the DFDs are complete, you can examine the details of individual DFDs for such problems as redundant data flows, data that are captured but are not used by the system, and data that are updated identically in more than one location. These problems may not have been evident to members of the analysis team or to other participants in the analysis process when the DFDs were created. Inefficiencies can also be identified by studying DFDs, and there are a wide variety of inefficiencies that might exist. Some inefficiencies relate to violations of DFD drawing rules. Similarly, a set of DFDs that models the current logical system can be compared with DFDs that model the new logical system to better determine which processes systems developers need to add or revise when building the new system.
There are two different standard sets of DFD symbols and each set consists of three symbols that represent the same things.
FALSE
Provide an example of DFDs being used in BPR.
DFDs can be used to model the processes of the business. It is easier to see the process graphically than to read a document about the process. The DFD can assist with finding potential issues in the process. The text uses the example of IBM. IBM realized it only to 90 minutes for the entire sales process to be completed; however, days were wasted because documents were in someone's inbox. From the DFD process documents, management was able to simplify the process.
What is typically included in a data flow repository?
Data flow repository entries typically include the following: • The label or name for the data flow as entered on the DFDs • A short description defining the data flow • A list of other repository objects grouped into categories by type of object • The composition or list of data elements contained in the data flow • Notes supplementing the limited space for the description that go beyond defining the data flow to explaining the context and nature of this repository object • A list of locations (the names of the DFDs) on which this data flow appears and the names of the sources and destinations on each of these DFDs for the data flow
) Data flow diagrams are non-versatile diagramming tools and consist of only three symbols.
FALSE
A data flow consisting of several sub-flows on a level-n diagram can be split apart on a level-0 diagram for a process that accepts this composite data flow as input.
FALSE
A data flow diagram (DFD) is a picture of the movement of data between external entities and the processes and data stores within or outside a system.
FALSE
A data flow has multiple directions of flow between symbols. It may flow in both directions between a process and a data store to show a read before an update.
FALSE
A data flow to a data store means retrieve and a data flow from a data store means change.
FALSE
A data store is data at rest and may represent only one physical location for data.
FALSE
A level-1 diagram is a DFD that represents a system's major processes, data flows, and data stores at a high level of detail.
FALSE
A source/sink might not consist of a person inside or outside the business unit supported by the system you are analyzing who interacts with the system.
FALSE
DFDs do a very good job of representing time. On a given DFD, there is an indication of whether a data flow occurs constantly in real time, once per week, or once per year. There is also an indication of when a system would run.
FALSE
DFDs do not provide notation but illustrate important concepts about the movement of data between manual and automated steps.
FALSE
If your DFD contains data flows that do not lead anywhere or data stores, processes or external entities that are not connected to anything else, your DFD is not accurate.
FALSE
A data flow has a noun phrase label. More than one data flow noun phrase can appear on a single arrow as long as all of the flows on the same arrow move together as one package.
TRUE
Describe the process in knowing when to stop decomposing a DFD.
One rule is to stop drawing when you have reached the lowest logical level; however, it is not always easy to know what the lowest logical level is. Other, more concrete rules for when to stop decomposing include the following: • When you have reduced each process to a single decision or calculation or to a single database operation, such as retrieve, update, create, delete, or read • When each data store represents data about a single entity, such as a customer, employee, product, or order • When the system user does not care to see any more detail or when you and other analysts have documented sufficient detail to do subsequent systems development tasks • When every data flow does not need to be split further to show that different data are handled in different ways • When you believe that you have shown each business form or transaction, computer online display, and report as a single data flow • When you believe there is a separate process for each choice on all lowest-level menu options for the system
What is process modeling? What are the deliverables for process modeling?
Process modeling involves graphically representing the functions, or processes, that capture, manipulate, store, and distribute data between a system and its environment and between components within a system. Deliverables include: Context DFD, DFSs of the system, and thorough descriptions of each DFD component.
List the parts of a DFD diagram and at least one rule for each one.
Process: A. No process can have only outputs. It would be making data from nothing. If an object has only outputs, then it must be a source. B. No process can have only inputs (a black hole). If an object has only inputs, then it must be a sink. C. A process has a verb phrase label. Data Store: D. Data cannot move directly from one data store to another data store. Data must be moved by a process. E. Data cannot move directly from an outside source to a data store. Data must be moved by a process that receives data from the source and places the data into the data store. F. Data cannot move directly to an outside sink from a data store. Data must be moved by a process. G. A data store has a noun phrase label. Source/Sink: H. Data cannot move directly from a source to a sink. It must be moved by a process if the data are of any concern to our system. Otherwise, the data flow is not shown on the DFD. I. A source/sink has a noun phrase label. Data Flow: J. A data flow has only one direction of flow between symbols. It may flow in both directions between a process and a data store to show a read before an update. The latter is usually indicated, however, by two separate arrows because these happen at different times. K. A fork in a data flow means that exactly the same data goes from a common location to two or more different processes, data stores, or sources/sinks. L. A join in a data flow means that exactly the same data come from any of two or more different processes, data stores, or sources/sinks to a common location. M. A data flow cannot go directly back to the same process it leaves. There must be at least one other process that handles the data flow, produces some other data flow, and returns the original data flow to the beginning process. N. A data flow to a data store means update (delete or change). O. A data flow from a data store means retrieve or use. P. A data flow has a noun phrase label. More than one data flow noun phrase can appear on a single arrow as long as all of the flows on the same arrow move together as one package.
List the advanced rules governing DFDs.
Q. A composite data flow on one level can be split into component data flows at the next level, but no new data can be added and all data in the composite must be accounted for in one or more subflows. R. The inputs to a process must be sufficient to produce the outputs from the process. Thus, all outputs can be produced, and all data in inputs move somewhere: to another process or to a data store outside the process or onto a more detailed DFD showing a decomposition of that process. S. At the lowest level of DFDs, new data flows may be added to represent data that are transmitted under exceptional conditions; these data flows typically represent error messages. T. To avoid having data flow lines cross each other, you may repeat data stores or sources/sinks on a DFD. Use an additional symbol, like a double line on the middle vertical line of a data store symbol or a diagonal line in a corner of a sink/source square, to indicate a repeated symbol.
Explain the process of functional decomposition.
The act of going from a single system to four component processes is called (functional) decomposition. Functional decomposition is an iterative process of breaking the description or perspective of a system down into finer and finer detail. This process creates a set of hierarchically related charts in which one process on a given chart is explained in greater detail on another chart. Each resulting process (or subsystem) is also a candidate for decomposition. Each process may consist of several subprocesses. Each subprocess may also be broken down into smaller units. Decomposition continues until you have reached the point at which no subprocess can logically be broken down any further. The lowest level of a DFD is called a primitive DFD.
Explain the three parts of a decision table.
The table has three parts: the condition stubs, the action stubs, and the rules. The condition stubs contain the various conditions that apply to the situation the table is modeling. The action stubs contain all the possible courses of action that result from combining values of the condition stubs. The part of the table that links conditions to actions is the section that contains the rules.
What are the guidelines for drawing DFDs?
These guidelines include: (1) completeness, (2) consistency, (3) timing considerations, (4) the iterative nature of drawing DFDs, and (5) primitive DFDs. Completeness: The concept of DFD completeness refers to whether you have included in your DFDs all of the components necessary for the system you are modeling. If your DFD contains data flows that do not lead anywhere or data stores, processes, or external entities that are not connected to anything else, your DFD is not complete. DFD consistency refers to whether or not the depiction of the system shown at one level of a nested set of DFDs is compatible with the depictions of the system shown at other levels. Timing: On a given DFD, there is no indication of whether a data flow occurs constantly in real time, once per week, or once per year. There is also no indication of when a system would run. Iterative DFD development recognizes that requirements determination and requirements structuring are interacting, not sequential, subphases of the analysis phase of the SDLC. Primitive DFD: One of the more difficult decisions you need to make when drawing DFDs is when to stop decomposing processes. One rule is to stop drawing when you have reached the lowest logical level.
