Unit 2: Analysis Modeling@VV - WordPress.com€¦ · Draw Diagram 0, Draw Diagram 0, the next level. Show processes, but keep them general. Show data stores at this level. 44

Analysis ModelingAnalysis Modeling

•• What is Analysis Modeling ?What is Analysis Modeling ?

–– Analysis modeling uses a combination of text and Analysis modeling uses a combination of text and

diagrammatic forms to depict(represent) diagrammatic forms to depict(represent)

requirements for data, function, and behavior requirements for data, function, and behavior

–– These text and diagrammatic forms are represent These text and diagrammatic forms are represent

in a way that is relatively easy to understand, and in a way that is relatively easy to understand, and

it is also more straightforward to review for it is also more straightforward to review for it is also more straightforward to review for it is also more straightforward to review for

correctness, completeness and consistency.correctness, completeness and consistency.

–– In other words, Data modeling is a method used In other words, Data modeling is a method used

to define and analyze data requirements needed to define and analyze data requirements needed

to support and to develop the new to support and to develop the new

system/software.system/software.

by:-Assit. Prof. Vijay Vora

(SOOADM) MCA-III(Murlidhar Group of Institutions,Bhavnagar Road , Rajkot)

3

–– The analysis model consists of a wide variety of The analysis model consists of a wide variety of

diagrammatic forms used to bridge an important diagrammatic forms used to bridge an important

gap.gap.

Purpose:

•• Describe what the customer wants builtDescribe what the customer wants built

•• Establish the foundation for the software Establish the foundation for the software

•• Provide a set of validation requirementsProvide a set of validation requirements



4

–– Analysis Analysis Model consist three types of ModelsModel consist three types of Models

•• Data ModelData Model

––ER modelER model

––Object modelObject model

•• Functional modelFunctional model

––Data flow modelData flow model

•• Behavioral modelBehavioral model•• Behavioral modelBehavioral model

––State transition modelState transition model

––System behavior modeling with sequence diagramSystem behavior modeling with sequence diagram



5

Data Flow DiagramData Flow DiagramData Flow DiagramData Flow Diagram(Data Flow Approach)(Data Flow Approach)

(Process Model)(Process Model)

(Data Flow (Data Flow GGraphsraphs) )

•• What is The Data Flow Diagram?What is The Data Flow Diagram?–– A Data Flow Diagram is a graphically A Data Flow Diagram is a graphically

representation of the flow of data.representation of the flow of data.

–– A Data Flow Diagram (DFD) is a diagrammatic A Data Flow Diagram (DFD) is a diagrammatic representation of the information flows within a representation of the information flows within a system, that shows:system, that shows:

• how information enters and leaves the system, • how information enters and leaves the system,

• what changes the information,

• where information is stored.

–– So, one can said that ,The DFD tracks the data So, one can said that ,The DFD tracks the data from an original source, carries it through a from an original source, carries it through a process, then flows it to a final destination.process, then flows it to a final destination.



7

–– In the DFD, flow is shown as an arrowed line with In the DFD, flow is shown as an arrowed line with

the arrowthe arrow--head showing the direction of flow. head showing the direction of flow.

–– Each data flow should be uniquely identified by a Each data flow should be uniquely identified by a

meaningful descriptive name (caption).meaningful descriptive name (caption).

–– Generally, DFD are commonly used during Generally, DFD are commonly used during

problem analysis.problem analysis.

–– DFD DFD DepictDepict::–– DFD DFD DepictDepict::

• System inputs

• Processes

• outputs



8

•• Purpose of Data Flaw Diagram?Purpose of Data Flaw Diagram?

[[self study]self study]



9

•• Advantages of Data Flaw DiagramAdvantages of Data Flaw Diagram–– A data flow diagram is an excellent tool for A data flow diagram is an excellent tool for

summarizing the information of systemsummarizing the information of system

–– DFD organize a detailed information about a DFD organize a detailed information about a system’s boundaries, processes, and data entities.system’s boundaries, processes, and data entities.

–– It also provide the analyst with a logical map of It also provide the analyst with a logical map of the system.the system.the system.the system.

–– Documenting the system’s boundaries by drawing Documenting the system’s boundaries by drawing a context diagram helps the analyst, the user, and a context diagram helps the analyst, the user, and the responsible managers to visualize alternative the responsible managers to visualize alternative highhigh--level logical system designs.level logical system designs.

–– The elements of a data flow diagram lead directly The elements of a data flow diagram lead directly into physical design.into physical design.



10

•• Disadvantages of Data Flaw DiagramDisadvantages of Data Flaw Diagram

[Self study][Self study]



11

Symbols of Data Flow DiagramSymbols of Data Flow Diagram(Elements of Data Flow (Elements of Data Flow Diagrams)Diagrams)

((Components Components of Data Flow of Data Flow Diagrams)Diagrams)((Components Components of Data Flow of Data Flow Diagrams)Diagrams)

(Data Flow Diagram Icons)(Data Flow Diagram Icons)

–– FFour primary symbols are used to create a data our primary symbols are used to create a data

flow diagramflow diagram

•• External External entitiesentities

•• ProcessesProcesses

•• Data storesData stores

•• Data flowsData flows•• Data flowsData flows



13

1.1. External External entitiesentities

–– it shows source or destination it shows source or destination

–– Sources and destinations define the system’s Sources and destinations define the system’s

boundariesboundaries

Where/whoWhere/who



14

Entity identifierEntity identifier

EntityEntity namename

–– A shape of external entity (source or destination) is A shape of external entity (source or destination) is

represented by a shaded square.represented by a shaded square.

–– They are often beyond the area of influence of the They are often beyond the area of influence of the

developer.developer.

–– These can represent another system or subsystem. These can represent another system or subsystem.

–– These go on margins/edges of data flow diagram. These go on margins/edges of data flow diagram.

–– External entities are named with appropriate name.External entities are named with appropriate name.–– External entities are named with appropriate name.External entities are named with appropriate name.

–– Thus , the Thus , the external entities either input information external entities either input information

to the system, output information from the system to the system, output information from the system

or both. or both.

–– Typically Typically they may represent job titles or other they may represent job titles or other

systems that interact with the system to be built. systems that interact with the system to be built.



15

22.. ProcessesProcesses

–– Processes are work or actions performed on incoming Processes are work or actions performed on incoming data flows to produce outgoing data flows.data flows to produce outgoing data flows.

–– A shape of Process is represented by a roundA shape of Process is represented by a round--cornered cornered

Process identifierProcess identifier

ProcessProcess namename

–– A shape of Process is represented by a roundA shape of Process is represented by a round--cornered cornered rectangle.rectangle.

–– These show data transformation or change. These show data transformation or change.

–– Data coming into a process must be "worked on" in some Data coming into a process must be "worked on" in some way.way.

–– Thus, all processes must have inputs and outputs.Thus, all processes must have inputs and outputs.

–– Major functions of processes are computations and Major functions of processes are computations and making decisions.making decisions.



16

–– Process Naming conventionProcess Naming convention

• Processes are named with one carefully chosen verb and an object of the verb. There is no subject.

• Name is not to include the word "process".

• Each process should represent one function or action

• If there is an "and" in the name, then process • If there is an "and" in the name, then process have more than one function



17

3.3. Data storesData stores

–– Data Stores are repository(storage area) for data Data Stores are repository(storage area) for data that are temporarily or permanently recorded within that are temporarily or permanently recorded within the system.the system.

––

Data Store identifierData Store identifier

Data StoreData Store DescriptionDescription

–– A shape of Data Stores is represented by an openA shape of Data Stores is represented by an open--ended, horizontal rectangle.ended, horizontal rectangle.

–– It is an "inventory“(record) of data. It is an "inventory“(record) of data.

–– These are common link between data and process These are common link between data and process models. models.

–– Only processes may connect with data stores.Only processes may connect with data stores.



18

–– Data Stores Naming conventionData Stores Naming convention

• Data stores are named with an appropriate name, not to include the word "file“.

• Names should consist of plural nouns describing the collection of data.

for e.g. - customers, orders, and products.

• These may be duplicated.

• These are detailed in the data dictionary.• These are detailed in the data dictionary.



19

4.4. Data flowsData flows

–– Data flow represents the input or output of data to Data flow represents the input or output of data to or from a process ("data in motion").or from a process ("data in motion").

–– A shape of Data Flow is represented by an arrow in A shape of Data Flow is represented by an arrow in any direction.any direction.

–– Data flows only data, not controlData flows only data, not control

––

Data flowData flow

–– Data flows must begin and/or end at a process.Data flows must begin and/or end at a process.

–– Data Flow Naming conventionData Flow Naming convention• Data flows are always named.

• Name is not to include the word "data".

• Should be given unique names.

• Names should be some identifying noun. For example, order, payment, complaint.



20



21

Steps to develop Steps to develop data flow diagrams data flow diagrams (Different Levels (Different Levels of Data Flow of Data Flow Diagrams)Diagrams)(Different Levels (Different Levels of Data Flow of Data Flow Diagrams)Diagrams)

•• Steps to draw Steps to draw Data flow diagramData flow diagram–– TopTop--Down approach is use to draw DFD.Down approach is use to draw DFD.

1.1. Make a List of business activity Make a List of business activity and use it to determine various� External entities

� Data flows

� Process

� Data stores

2.2. Create a Create a Context Diagram Context Diagram � this shows external entities and data flows to and from the system,

� Do not show any detailed processes or data stores.

3.3. Draw Diagram 0, Draw Diagram 0, the next level. � Show processes, but keep them general. � Show processes, but keep them general.

� Show data stores at this level.

4.4. Create a child diagram Create a child diagram for each of the processes in Diagram 0.

5.5. Check for errors Check for errors and make sure the labels that assign to each process and data flow are meaningful.

6.6. Develop a physical data flow diagram Develop a physical data flow diagram from the logical data flow diagram.� Distinguish between manual and automates process.

� Describe actual files and reports by name

� Add controls to indicate when processes are complete or error occur.

7.7. Partition the physical data flow diagram Partition the physical data flow diagram by separating or grouping parts of the diagram in order to facilitate programming and implementation.



23

�� Create a Create a Context Diagram Context Diagram (step(step--2)2)

–– The highest level (i.e. the 0 level) in a data flow diagramThe highest level (i.e. the 0 level) in a data flow diagram

–– Context diagram is to explain current or proposed system Context diagram is to explain current or proposed system as summaryas summary

–– A context diagram documents the system’s boundaries A context diagram documents the system’s boundaries by highlighting its sources and destinationsby highlighting its sources and destinations

–– Generally, it Contains only one process to represent the Generally, it Contains only one process to represent the entire systementire system

–– Documenting the system’s boundaries by drawing a Documenting the system’s boundaries by drawing a –– Documenting the system’s boundaries by drawing a Documenting the system’s boundaries by drawing a context diagram helps the analyst, the user, and the context diagram helps the analyst, the user, and the responsible managers visualize alternative highresponsible managers visualize alternative high--level level logical system designs.logical system designs.

–– All external entities, as well as Major data flows are All external entities, as well as Major data flows are shownshown

–– The diagram does not contain any data stores.The diagram does not contain any data stores.



24

–– Figure shows the context level diagramFigure shows the context level diagram



25

�� Drawing Drawing Diagram 0 Diagram 0 (step(step--3)3)

–– The explosion of the context diagramThe explosion of the context diagram

–– May include up to nine processesMay include up to nine processes

–– Each process is numberedEach process is numbered

–– Major data stores and all external entities are Major data stores and all external entities are includedincluded

–– DData flow diagram 0 shows the system’s ata flow diagram 0 shows the system’s primaryprimaryprocesses, data stores, sources, and destinations processes, data stores, sources, and destinations linked by data flows.linked by data flows.linked by data flows.linked by data flows.

–– Start with the data flow from an entity on the input Start with the data flow from an entity on the input sideside

–– Examine the data flow to or from a data storeExamine the data flow to or from a data store

–– Analyze a wellAnalyze a well--defined processdefined process

–– Take note of any fuzzy(unclear) areasTake note of any fuzzy(unclear) areas



26

–– Figure shows the Diagram 0Figure shows the Diagram 0



27

–– Each process start from context level diagram Each process start from context level diagram

and it may be explode to a next lower leveland it may be explode to a next lower level

–– The lower level diagram number is the same as The lower level diagram number is the same as

the parent process numberthe parent process number

–– Processes that do not create a child diagram are Processes that do not create a child diagram are

called primitivecalled primitive



28

�� Creating Creating Child Diagrams Child Diagrams (step(step--4)4)

–– Each process on diagram 0 may be exploded to Each process on diagram 0 may be exploded to create a child diagramcreate a child diagram

–– A child diagram cannot produce output or A child diagram cannot produce output or receive input that the parent process does not receive input that the parent process does not also produce or receivealso produce or receive

–– The child process is given the same number as The child process is given the same number as the parent processthe parent process

–– The child process is given the same number as The child process is given the same number as the parent processthe parent process

• Below given figure shows the child Diagram, in which Process 3(in Diagram 0) would explode to next level diagram i.e. Diagram 3



29



30

–– Entities are usually not shown on the child Entities are usually not shown on the child diagramsdiagrams

–– If the parent process has data flow connecting If the parent process has data flow connecting to a data store, the child diagram may include to a data store, the child diagram may include the data store as wellthe data store as well

–– In addition, the lowerIn addition, the lower--level diagram may level diagram may contain data stores that are not shown on the contain data stores that are not shown on the parent process.parent process.parent process.parent process.



31

�� Checking the Diagrams for Errors Checking the Diagrams for Errors (step(step--5)5)

–– Checking errors like…Checking errors like…

•• Forgetting to include a data flow or pointing Forgetting to include a data flow or pointing an arrow in the wrong directionan arrow in the wrong direction



32

•• Connecting data stores and external entities Connecting data stores and external entities directly to each otherdirectly to each other



33

•• Incorrectly labeling processes or data flowIncorrectly labeling processes or data flow

–Each object or data flow is properly labeled

–Data flow described with a verb.

–Processes should indicate the system name or use the verb-adjective-noun format.

•• Try to not include more than nine processes Try to not include more than nine processes on a data flow diagramon a data flow diagramon a data flow diagramon a data flow diagram– Because having too many processes creates a

cluttered diagram that is confusing to read and understand.

–– The next figure shows the payroll example, in The next figure shows the payroll example, in that the typical errors can occur in a data flow that the typical errors can occur in a data flow diagramdiagram



34



35

Logical Data Flow Diagrams Logical Data Flow Diagrams

and and

Physical Data Flow DiagramsPhysical Data Flow DiagramsPhysical Data Flow DiagramsPhysical Data Flow Diagrams

(types of DFD)(types of DFD)

•• Logical Logical Data Flow DiagramsData Flow Diagrams–– Focuses on the business and how the business Focuses on the business and how the business

operatesoperates

–– Not concerned with how the system will be Not concerned with how the system will be constructedconstructed

–– Describes the business events that take place and Describes the business events that take place and the data required and produced by each eventthe data required and produced by each eventthe data required and produced by each eventthe data required and produced by each event

•• Physical Data Flow DiagramsPhysical Data Flow Diagrams–– Shows how the system will be implementedShows how the system will be implemented

–– Depicts the systemDepicts the system



37



38

•• The The progression of models from logical progression of models from logical

to physicalto physical



39

•• Advantages of Advantages of Logical Data Flow Logical Data Flow

DiagramsDiagrams

•• Advantages of Advantages of Physical Data Flow Physical Data Flow

DiagramsDiagrams



40

•• Physical Physical data flow diagrams contain many items not found data flow diagrams contain many items not found

in logical data flow diagramsin logical data flow diagrams



41

Self study Self study

•• Event Modeling and Data Flow DiagramsEvent Modeling and Data Flow Diagrams

•• Event Response Event Response TablesTables

•• Use Cases and Data Flow Use Cases and Data Flow DiagramsDiagrams

•• Partitioning Data Flow Partitioning Data Flow DiagramsDiagrams•• Partitioning Data Flow Partitioning Data Flow DiagramsDiagrams

•• Reasons for PartitioningReasons for Partitioning



42

Data Dictionaries Data Dictionaries Data Dictionaries Data Dictionaries

•• What is Data Dictionary?What is Data Dictionary?–– Data Dictionary is a Centralized repository of Data Dictionary is a Centralized repository of

information about data such as meaning, information about data such as meaning, relationships to other data, origin, usage, and relationships to other data, origin, usage, and format.format.

–– A data dictionary allows more precise A data dictionary allows more precise descriptions of the data to be madedescriptions of the data to be madedescriptions of the data to be madedescriptions of the data to be made

–– Collects and coordinates data terms, and Collects and coordinates data terms, and

confirms what each term means to different confirms what each term means to different

people in the organizationpeople in the organization



44

•• Need Need for Understanding the Data for Understanding the Data

DictionaryDictionary–– Provide documentationProvide documentation

–– Eliminate redundancyEliminate redundancy

–– Validate the data flow diagramValidate the data flow diagram

–– Provide a starting point for developing screens Provide a starting point for developing screens and reportsand reportsand reportsand reports

–– Determine the contents of data stored in filesDetermine the contents of data stored in files

–– To develop the logic for DFD processesTo develop the logic for DFD processes



45

•• Data RepositoryData Repository–– A data repository is a large collection of project A data repository is a large collection of project

informationinformation

–– It includes:It includes:

• Information about the data maintained by the system

• Procedural logic and use cases• Procedural logic and use cases

• Screen and report design

• Data relationships

• Project requirements and final system deliverables

• Project management informationby:-Assit. Prof. Vijay Vora


46

•• How How data dictionaries relate to data flow data dictionaries relate to data flow diagramsdiagrams



47

•• Category Category of Data Dictionaryof Data Dictionary

––Data flowsData flows

––Data structuresData structures

––ElementsElements

––Data storesData stores



48

––Data flowsData flows• ID - identification number (optional)

• Unique descriptive name

• A general description of the data flow

• The source of the data flow

• The destination of the data flow

• Type of data flow

• The volume per unit time

• An area for further comments and notations



49

• An example of a data flow description from World’s Trend Catalog Division



50

––Data structuresData structures

•• Data structures are made up of smaller Data structures are made up of smaller structures and elementsstructures and elements

•• An algebraic notation is used to describe An algebraic notation is used to describe data structuresdata structures

»»Algebraic NotationAlgebraic Notation

• Equal sign, meaning “is composed of”

• Plus sign, meaning "and”

• Braces {} meaning repetitive elements

• Brackets [] for an either/or situation

• Parentheses () for an optional element



51

•• Data structure example for adding a customer order at World’s Data structure example for adding a customer order at World’s Trend Catalog DivisionTrend Catalog Division



52

•• AAnother example of Data Structurenother example of Data Structure

Student record= student ID +

Student name+

Address +

Date of birth +

Gender +

Course record= course name +

Course number+

Grade



53

Gender +

Nationality +

Telephone number +

(mobile telephone number) +

{ course record}

[Self Study][Self Study]

(this points are sub(this points are sub--points of points of Data StructuresData Structures))

»»Structural RecordsStructural Records

»»Use of Structural Records in Different SystemUse of Structural Records in Different System

»»Structural Record ExampleStructural Record Example



54

»»Logical and Physical Data StructuresLogical and Physical Data Structures

»Logical

• Show what data the business needs for its day-to-day operations

»Physical

• Include additional elements necessary for implementing the system



55

––Elements DescriptionElements Description•• Element ID Element ID

•• The name of the elementThe name of the element

•• AliasesAliases

•• A short description of the elementA short description of the element

•• Element is base or derivedElement is base or derived

•• Element lengthElement length•• Element lengthElement length

•• Type of dataType of data

•• Input and output formatsInput and output formats

•• Validation criteriaValidation criteria

•• Default valueDefault value

•• An additional comment or remark areaAn additional comment or remark areaby:-Assit. Prof. Vijay Vora


56

• Example of an element description form from World’s Trend Catalog Division



57

–– Data Stores DescriptionData Stores Description•• The Data Store IDThe Data Store ID

•• The Data Store Name The Data Store Name

•• An Alias for the tableAn Alias for the table

•• A short description of the data storeA short description of the data store

•• File formatFile format

•• The maximum and average number of The maximum and average number of records on the file as well as the growth per records on the file as well as the growth per

•• The maximum and average number of The maximum and average number of records on the file as well as the growth per records on the file as well as the growth per yearyear

•• The file or data set name specifies the file The file or data set name specifies the file name, if knownname, if known

•• Primary keysPrimary keys

•• CommentsCommentsby:-Assit. Prof. Vijay Vora


58

• An example of a data store form for World’s Trend Catalog Division



59

•• Creating Creating the Data Dictionarythe Data Dictionary

»»Data dictionary entries Data dictionary entries

• Created after the data flow diagram is

completed or

• Created as the data flow diagram is being

developed

»»Created using a topCreated using a top--down approachdown approach



60

• Two data flow diagrams and corresponding data dictionary entries

for producing an employee paycheck



61

»»Analyzing Input and OutputAnalyzing Input and Output

• A descriptive name for the input or output

• Whether the data is input or output

• The format of the data flow

• Elements indicating the sequence of the data on a report or screen

• A list of elements• A list of elements



62

• An example of an input/output analysis form for World’s Trend Catalog Division



63

»»Developing Data StoresDeveloping Data Stores

• Represent data at rest

• Contain information of a permanent or semi-permanent (temporary) nature

• When data stores are created for only one report or screen, it refer to as an“user views”



64

•• Using Using the Data Dictionarythe Data Dictionary

–– To have maximum power, the data dictionary To have maximum power, the data dictionary

should be tied into a number of systems should be tied into a number of systems

programsprograms

––May be used toMay be used to

• Create screens, reports, and forms

• Generate computer language source code

• Analyze the system design, detecting flaws and

areas that need clarification



65

[Self Study][Self Study]

��Using Data Dictionaries to Create X M LUsing Data Dictionaries to Create X M L



66

Process Specifications Process Specifications

•• What is Process Specifications ?What is Process Specifications ?

–– Process Specification is a deep clarification or Process Specification is a deep clarification or

explanation of primitive processes.explanation of primitive processes.

–– Sometimes it called miniSometimes it called mini--specs, because they are specs, because they are

a small portion of the total product specificationsa small portion of the total product specifications

–– Created for primitive processes as well as for Created for primitive processes as well as for

some higher level processes on a data flow some higher level processes on a data flow some higher level processes on a data flow some higher level processes on a data flow

diagramdiagram

–– Process Specifications explain the decisionProcess Specifications explain the decision--

making logic and formulas that transform process making logic and formulas that transform process

input data into output.input data into output.



68

•• Purpose/Goal of Process Specifications ?Purpose/Goal of Process Specifications ?

–– Reduce process ambiguityReduce process ambiguity

• make the analyst to learn details about

how the process works.

–– Obtain a precise description of what is Obtain a precise description of what is

accomplishedaccomplishedaccomplishedaccomplished

–– Validate the system designValidate the system design



69

•• WWhen to not create Process Specifications ?hen to not create Process Specifications ?

((Process Specifications Process Specifications are not createdare not created……))

–– Processes that represent physical input and/or Processes that represent physical input and/or

outputoutput

–– Processes that represent simple data validationProcesses that represent simple data validation

–– Processes that use prewritten codeProcesses that use prewritten code–– Processes that use prewritten codeProcesses that use prewritten code



70

•• How Process Specifications How Process Specifications relate to the data flow relate to the data flow

diagram?diagram?



71

•• Process Process Specification Format InformationSpecification Format Information��The process numberThe process number

�Must match the process ID on the data flow diagram�Allows the analyst to work on or review any process, and to locate

the data flow diagram containing the process easily

��The process name The process name �The same as displays within the process symbol on the DFD

��Description of what the process accomplishes (achieve)Description of what the process accomplishes (achieve)��A list of input data flowA list of input data flow��Output data flowsOutput data flows��Type of process Type of process ��Type of process Type of process

�Batch�Online�Manual

��Uses prewritten codeUses prewritten code�Include the name of the subprogram or function containing the

code

��Process logic descriptionProcess logic description��Logic method reference Logic method reference ��List any unresolved issuesList any unresolved issues by:-Assit. Prof. Vijay Vora


72

•• example example of a completed process specificationof a completed process specification



73

••Method of writing process specifications LogicMethod of writing process specifications Logic••Tools of process specifications Logic/ Tools of process specifications Logic/

Structured Decision Analysis Structured Decision Analysis

1. Structured English1. Structured English2. Decision Tables 3. Decision Trees

Structured English Structured English

•• WWhat is hat is Structured English Structured English ??

–– Structured English is a method of writing process Structured English is a method of writing process

specifications which is combination of English specifications which is combination of English

language and structured programming.language and structured programming.

–– This is the only method which provides This is the only method which provides

environment for representing program logic with environment for representing program logic with

the natural English language.the natural English language.the natural English language.the natural English language.

–– In short, Structured English is a description of In short, Structured English is a description of

processes in simple English processes in simple English



75

•• The The objective of using structured objective of using structured EnglishEnglish

–– Expand a DFD so that a user can understand it Expand a DFD so that a user can understand it

–– Develop algorithms corresponding to processes Develop algorithms corresponding to processes

in a DFD in a DFD

–– Ease writing programs for DFDs Ease writing programs for DFDs



76

•• Writing Writing Structured EnglishStructured English–– Structured English uses 3 basic types of statements to Structured English uses 3 basic types of statements to

describe processes namely: describe processes namely: --

1.1. Sequential structure.Sequential structure.– The sequential structured are single declarative

statements denoting single step or action in a process.

2.2. Decision structure.Decision structure.– The decision structured allows branching instructions

providing YES / NO type decisions.

– For these decision structures keywords like – For these decision structures keywords like IF…THEN…ELSE are used

3.3. Looping or repetitive structureLooping or repetitive structure– The repetitive structure allows to specify group of

instructions which in to be executed until given conditions are satisfied.

– Some of the ways of writing repetitive structures are: -

DO……….. WHILE……….

REPEAT………. UNTIL……….etcby:-Assit. Prof. Vijay Vora


77

–– Structured English uses 3 basic types of Structured English uses 3 basic types of

statements to describe processes namelystatements to describe processes namely

–– Use and capitalize accepted keywords such as IF, Use and capitalize accepted keywords such as IF,

THEN, ELSE, DO, REPETE etc…THEN, ELSE, DO, REPETE etc…

–– Indent blocks of statements to show their Indent blocks of statements to show their

hierarchy (nesting) clearlyhierarchy (nesting) clearly

–– Clarify the logical statementsClarify the logical statements–– Clarify the logical statementsClarify the logical statements



78

–– Examples of logic expressed in a sequential structure, a decision Examples of logic expressed in a sequential structure, a decision

structure, a case structure, and an iterationstructure, a case structure, and an iteration



79

•• Advantages Advantages of Structured Englishof Structured English

–– Clarifying the logic and relationships found in Clarifying the logic and relationships found in

human languageshuman languages

–– An effective communication tool, it can be taught An effective communication tool, it can be taught

to and understood by users in the organizationto and understood by users in the organization



80

••Method of writing process specificationsMethod of writing process specifications••Tools of process specificationsTools of process specifications

1. Structured English22. Decision Tables . Decision Tables 3. Decision Trees

Decision Tables Decision Tables

•• What is What is Decision TablesDecision Tables

–– Decision table is one of those method which is Decision table is one of those method which is

use for writing process specifications in which use for writing process specifications in which

shows how a rule or set of rules are applied for shows how a rule or set of rules are applied for

repetitive situations. repetitive situations.

–– A table of rows and columns, separated into four A table of rows and columns, separated into four

quadrantsquadrantsquadrantsquadrants

• Conditions

• Condition alternatives

• Actions to be taken

• Rules for executing the actions



82

•• The The standard format used for presenting a decision standard format used for presenting a decision

tabletable



83

•• Example of Example of decision decision tabletable

–– Constructing a decision table for deciding which catalog Constructing a decision table for deciding which catalog

to send to customers who order only from selected to send to customers who order only from selected

catalogscatalogs



84

•• Second Example of Second Example of decision decision tabletable



85

•• Developing Developing Decision TablesDecision Tables–– Determine conditions that affect the decisionDetermine conditions that affect the decision

–– Determine possible actions that can be takenDetermine possible actions that can be taken

–– Determine condition alternatives for each conditionDetermine condition alternatives for each condition

–– Calculate the maximum number of columns in the Calculate the maximum number of columns in the decision tabledecision table

–– Fill in the condition alternativesFill in the condition alternatives

–– Complete table by inserting an X where rules suggest Complete table by inserting an X where rules suggest actionsactionsactionsactions

–– Combine rules where it is apparent Combine rules where it is apparent

–– Rearrange to make more understandableRearrange to make more understandable



86

•• Checking Checking for Completeness and Accuracyfor Completeness and Accuracy–– Four main problemsFour main problems

• Incompleteness

• Impossible situations

• Contradictions

• Redundancy



87

•• Example shows Contradiction & RedundabcyExample shows Contradiction & Redundabcy



88

•• Decision Decision Table AdvantagesTable Advantages–– Help the analysis ensure completenessHelp the analysis ensure completeness

–– Easy to check for possible errorsEasy to check for possible errors

• Impossible situations

• Contradictions

• Redundancy• Redundancy



89

••Method of writing process specificationsMethod of writing process specifications••Tools of process specificationsTools of process specifications

1. Structured English2. Decision Tables 3. Decision Trees3. Decision Trees

Decision Trees Decision Trees

•• What is Decision Trees ?What is Decision Trees ?––Decision Tree is a tool of process Decision Tree is a tool of process

specification which is used when complex specification which is used when complex branching occurs in a structured decision branching occurs in a structured decision processprocess

––Decision trees are superior to decision Decision trees are superior to decision tables when sequence of testing conditions tables when sequence of testing conditions is particularly importantis particularly importanttables when sequence of testing conditions tables when sequence of testing conditions is particularly importantis particularly important



91

•• Drawing Drawing Decision TreesDecision Trees–– Identify all conditions and actions and their Identify all conditions and actions and their

order and timing (if they are critical)order and timing (if they are critical)

––Begin building the tree from left to right, Begin building the tree from left to right, making sure you list all possible alternatives making sure you list all possible alternatives before moving to the rightbefore moving to the right



92

•• Example of decision Example of decision tree to show the noncash tree to show the noncash

purchase approval actions for a department storepurchase approval actions for a department store



93

•• Decision Decision Tree AdvantagesTree Advantages––The order of checking conditions and The order of checking conditions and

executing actions is immediately noticeableexecuting actions is immediately noticeable

––Conditions and actions of decision trees are Conditions and actions of decision trees are found on the same branches but not on found on the same branches but not on othersothers

––Compared to decision tables, decision trees Compared to decision tables, decision trees ––Compared to decision tables, decision trees Compared to decision tables, decision trees are more readily understood by others in are more readily understood by others in the organizationthe organization



94

•• Which Technique,user have to Select for Which Technique,user have to Select for

Structured Structured Decision Decision Analysis or for Analysis or for

Process SpecificationProcess Specification––Use structured English when there are many Use structured English when there are many

repetitious actions or when communication repetitious actions or when communication to end users is importantto end users is important

––Use decision tables when complex Use decision tables when complex ––Use decision tables when complex Use decision tables when complex combination of conditions, actions and rules combination of conditions, actions and rules are found, or system require a method that are found, or system require a method that effectively avoids impossible situations, effectively avoids impossible situations, redundancies, and contradictionsredundancies, and contradictions

––Use decision trees when the sequence of Use decision trees when the sequence of conditions and actions is criticalconditions and actions is critical



95

––To download To download material Visitmaterial Visitwww.vijayvorafrommgi.wordpress.com



96

Documents

Unit 2: Analysis Modeling@VV - WordPress.com€¦ · Draw Diagram 0, Draw Diagram 0, the next level. Show processes, but keep them general. Show data stores at this level. 44