IS315 Final Exam

What is the advantage of using structured English to communicate with people in an organization?

the biggest advantage of structured English as being a communication tool.

a context level diagram is

"the highest level in a data flow diagram and contains only one process, representing the entire system"

Four reasons for compiling a complete data dictionary.

- make sure that the dataflow is complete and accurate - provide a starting point for screens and reports - determine the conents of the actual data stored in files - to develop logic for flow diagram processes

What are the four data items that can be symbolized on a data flow diagram.

-Entity: Used to depict an external entity that can send data to or receive data from a system. -Data flow arrow: shows movement of data from one point to another, with the head of the arrow pointing toward the data's destination. -Process rectangle: Used to show the occurrence of a transforming process. -Data store: The data store represents a manual store, such as a filling cabinet, or a computerized file or database.

List three reasons for creating 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.

List five characteristics of a physical data flow diagram that a logical data flow diagram does not have.

1. Clarifying which processes are performed by humans (manual) and which are automated. 2. Describing processes in more detail than logical DFD's. 3. Sequencing processes that have to be done in a particular order. 4. Identifying temporary data stores. 5. Specifying actual names of files, database tables, and printouts.

What is the difference between base and derived elements?

A base element is one that is initially keyed into the system such as a customer name, address, or city. Derived elements are created by processes as the result of a calculation or a series of decision-making statements.

What is a context-level data flow diagram? Contrast it to a level 0 DFD

A context diagram uses only one process to represent the entire system. It is the highest level in a data flow diagram. It is also known as a Level 0 diagram. The context diagram shows all entities and data flow but does not show the data sources.

Define the term data dictionary. Define metadata

A data dictionary is a referenced work of data about data (metadata) created by a systems analyst based on data flow diagrams which collects and coordinates specific data terms, confirming what each term means to different people in the organization.

What is a structural record?

A structural record is data that uses algebraic symbols. These symbols assist data analyst in understanding the elements of the data structure.

What does a use case model describe?

A use case model is the model of the system's intended functions, it describes the primary uses of the system and how it can be used and worked from a users POV.

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

According to Kendall & Kendall a logical data flow diagram focuses on the business and how the business operates. It describes the business events that take place and the data required and produced by each event.

What does an ID attribute ensure?

According to Kendall & Kendall the ID attribute is to ensure that the customer number is not repeated in a longer XML document. The attribute list definition for a customer number contains a keyword ID.

What does an activity diagram depict?

An activity diagram shows the sequence of activities in a process. This could include activities that are either sequential or parallel with each other.

How can an event table be used to create a data flow diagram?

An event table is used to create data flow diagrams by analyzing each even and the data used and produced by the event. Every row in the event table represents a unique activity and is used to create one process on the data flow diagram.

List what the diagrams included in a structural diagram.

Class diagrams Component diagrams Deployment diagrams

List three ways to use completed data flow diagrams.

Completed data flow diagrams are used in the design process to ascertain information requirements. At this stage, they aid in providing an overview of data movement through the system. They are also used to communicate with users other members of the project team. Lastly, completed data flow diagrams are used to document the system.

What are the main uses of decision trees in systems analysis?

Decision trees are used when complex branching occurs in a structured decision process. Trees provide useful when it is essential to keep a string of decisions in a particular sequence.

List the eight specific categories that each entry in the data dictionary should contain. Briefly give the definition of each category.

Element ID: optional; used to build automated data dictionary entries Element Name: descriptive and unique within the system; common name with major users for element; my include a listing of any aliases Short Description of Element: general description of what element is like/does Length of Data: for non-standard-size elements (standard=state abbreviations, postal/zip codes, telephone numbers), analysts must decide on a reasonable length for these fields to avoid truncation of data. Type of Data: base or derived; continuous or discrete; numeric,date, alphabetic, alphanumeric,character, etc. Input and Output Formats: coded symbols indicating how data is to be presented Validation Criteria: rules used to ensure data accuracy (list of fixed values or an acceptable value range); may include default value for element Comment/Remark: any additional comments or remarks, such as special validation or check-digit tests required.

Describe what "exploding" data flow diagrams means

Exploding a diagram means that more details will be able to be seen with a magnified view versus the normal view that is used. This way you will be able to see all of the processes involved within that particular entity.

What are the trade-offs involved in deciding how far data streams should be exploded?

Exploding data streams allows the analyst to take a more detailed look at how data moves within the system. While the level of complexity should ultimately be the deciding factor of whether or not to explode a given process, an analyst must carefully consider how granular to go.

List five conventions that should be followed when using structured English.

Express all logic in terms of one of these four types: sequential structures, decision structure, case structures, or iterations. Use and capitalize accepted keywords such as IF, THEN, ELSE, DO, DO WHILE, DO UNTIL, and PERFORM Indent blocks of statements to show their hierarchy (nesting) clearly. When words or phrases have been defined in a data dictionary, underline those words or phrases to signify that they have a specialized reserved meaning. Be careful when using "and" and "or," and avoid confusion when distinguishing between A and B; "A or B" means either A or B, but not both. Clarify the logical statements now rather than waiting unit the program coding stage.

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

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

What are gen/spec diagrams used for?

Generalization/Specialization (gen/spec) diagrams can be considered to enhance class diagrams. It may be necessary, in some cases, to separate out the generalizations from the specific instances.

What does an IDREF attribute validate?

IDREF is an attribute used to provide a link between one element and another element.

A data repository contains project information. Kendall lists the following as information that can be found in a data repository:

Information about the data maintained by the system, including data flows, data stores, record structures, element, entities, and messages Procedural logic and use cases Screen and report design Data relationships, such as how one data structure is linked to another Project requirements and final system deliverables Project management information, such as delivery schedules, achievement, issues that need resolving, and project users

What is a document type definition?

It is XML content that is used to determine whether the XML document content is valid. This type of software is seen alot in webpage design software and examples of when it is being used are the element formats !DOCTYPE, !ELEMENT, or !ATTLIST.

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

Logical data flow diagrams focus on the business and how the business operates. It is not concerned on how the system will be constructed. The physical data flow diagram focuses on how the system will be implemented, including hardware, software, files, and people involved in the system.

Define method overloading.

Method overloading is when a method of the same name is used to handle different data types in the arguments.

Describe the difference between a class and an object.

Objects are persons, places, or things that are relative to the systems we are analyzing. Entities can be described as objects. Classes are normally part of a group of similar item classes. According to Kendall, "a class defines the set of shared attributes and behaviors found in each object in a class"

What are the basic differences among data dictionary entries prepared for data stores, data structures, and data elements?

One of the basic differences can be found in their nature. Data elements are either base or derived, simple, and defined as a single data type (numerical, etc.). Data structures are usually defined by algebraic notation and contain elements.

List three reasons for producing process specifications.

One reason is to reduce the ambiguity of the process. Two is get a clear description of what has been done. Three is validate system design.

What is partitioning, and how is it used?

Partitioning is you divide something in to sections or when you a lot a certain amount of space for operations or memory.

Why is labeling data flow diagrams so important? What can effective labels on data flow diagrams accomplish for those who are unfamiliar with the system?

Providing accurate and detailed labels in data flow diagrams is crucial because basic all general systems models bear the configuration of input, process, and output so labels for the diagrams need to provide specific identifiable information.

How can a use case be used to create a data flow diagram?

Since a use case summarizes an event it can be used as a fragment of a data flow diagram. This is especially true since it contains an activity, trigger, input, and output.

Why are structural records used?

Structural records are used in many different systems. Those structural records allow an analyst to define things such as the street and city name, telephone number, zip code, even first and last name.

Why Are Structural Records Used?

Structural records are used when data flow base elements are grouped together to form a structural record, a data store is created for each unique structural record.

What are the two building blocks of structured English?

Structured English is base on (1) structured logic, or instructions organized into nested and grouped procedures, and (2) simple English statements such as add, multiply, and move.

Define what is meant by a structured decision.

Structured decisions use a technique known as structured English to analyze a decision process. It is based on structured logic and English statements.

In which two situations do decision tables work best?

The best time to use decision tables is when you need to eliminate impossible situations, inconsistencies and redundancies in complex situations.

How do the data dictionary entries relate to the levels in a set of data flow diagrams

The data dictionary and the data flow diagram (DFD), in many ways are quite synonymous. Kendell even explains that the two artifacts are sometimes created at the very same time

What three advantages do decision trees have over decision tables?

The first advantages that decision trees have over the tables is the sequential structure of the tree branches. The second is that conditions and actions can be isolated on just the branches themselves whereas decision tables would all of the conditions & actions on the same tables. The last advantage is that decision trees are easily read compared to decision tables.

List the four main problems that can occur in developing decision tables?

The first problem is incompleteness. The next problem is having impossible situations represented on the decision table that cannot exist and therefore presenting rules that cannot qualify in the defined condition. Contradictions can also occur in decision tables. A contradiction is a set of conditions that suggest different actions. Lastly, redundancy can occur in decision tables where different rules have the same conditions with the same actions.

What is the first step to take in developing a decision table?

The first step to take in a decision table is to determine the amount of conditions that might affect the decision. The number of conditions is the number of rows in the decision table.

List the four categories of into which classes fall.

The four categories that classes fall into are: Entity classes, Boundary or Interface classes, Abstract classes, and Control classes.

What are the four categories into which classes fall?

The four categories that the classes fall into are entity, interface, abstract, and control.

what is one of the main methods available for an analyst to use when analyzing data-oriented systems

The main method available for an analyst to use when analyzing data-oriented systems is a Data Flow Diagram (DFD).

List the major sections of a use case

The major sections of a use case include "...an actor that initiates an event, the event that triggers a use case, and the use case that performs the actions triggered by the event."

Define the top-down approach as it relates to drawing data flow diagrams.

The top-down approach starts by using the organization's story to define business activities into external entities, data flows, processes, and data stores. It's a systematic way to represent a system.

In which two situations are decision trees preferable?

The two situations where decision trees are preferred are when the sequence of conditoons and actions are critical or when not every condition is relevant to evrry action (the branches are different).

Which quadrant of the decision table is used for conditions? Which is used for condition alternatives?

The upper left quadrant contains the condition or conditions. The upper right quadrant contains the conditions alternatives.

What are four reasons for compiling a complete data dictionary?

There are several reasons for compiling a complete data dictionary. One reason is to authenticate the data flow diagrams for accuracy. This document allows a starting point to design user screens and reports. Another reason for compiling a data dictionary is that it will show what data will be stored in file as well as help produce the logic for data flow diagram processes. Also, a data dictionary can be used to build Extensible Markup Language (XML) which enables data sharing between systems.

List three ways to use completed data flow diagrams.

They are useful throughout the analysis and the design process. When ascertaining information requirements we use the original unexploded data flow diagrams. We also use them to document the system as in high and low levels of analysis and help substantiate the logic underlying the data flow of the organization. Last but not least data flow diagrams can provide and overview of the data movement through the systems.

What are the three major elements of UML?

Things Relationships Diagrams

List three ways of determining partitioning in a data flow diagram.

Timing Efficiency Security

Why is using UML for modeling important?

UML is a powerful tool that can greatly improve the quality of your systems analysis and design, and it is hoped that the improved practices will translate into higher-quality systems.

What is UML?

UML stands for Unified Modeling Language, it is an industry standard for modeling object-oriented systems. UML includes diagrams that will allow you to visualize the build of a system.

List the major sections of a use case.

Use case name Description Trigger Trigger type Input name Source Output Name Destination Steps Performed Information for Steps

What are the main benefits of using a data dictionary?

Validate the data flow diagram for completeness and accuracy Provide a starting point for developing screens and reports Determine the contents of data stored in files Develop the logic for data flow diagram processes Create XML

When are transaction files required in a system's design?

When data needs to be stored between processes. Transaction files must hold the data from one process to the next process.

What is the difference between logical and physical data structures?

When data structures are first designed, only the data elements that the user would see, such as a name, address, and balance due, are included. This stage is a logical design, showing what data the business needs for its day-to-day operations

What does Extensible Markup Language (XML) Describe?

XML is a language that is used to transfer data systems. XML is used to to transfer the data between different computer systems and software, the readings show an example of a user using Oracle and another user using IBM's DB2.

What is one of the major advantages of decision tables over other methods of decision analysis?

decision tables are advantageous over other methods because the rules for developing the table itself as well as the rules for eliminating redundancy, contradictions, and impossible situations are straight forward and manageable.

List the four major steps in building decision trees.

identify the conditions, identify the actions, identify the condition alternatives, identify the actions rules.

What are the two main types of diagrams of UML?

structural diagrams and behavioral diagrams

What is the difference between logical and physical data structures?

the logical data structure is a data structure that shows the data elements that the user would see as well as the data a business needs for its day-to-day operations. The physical model includes the logical model but has everything else the system needs in order to actually work.