System Analysis and Implementation. MIS 1 - 1 Systems Analysis and Implementation Management Information System

System Analysis and Implementation. MIS1 - 1

Systems Analysis Systems Analysis and Implementationand Implementation

Management Information System


System

The term system, is derived — the Greek word systeme (to combine). which means an organized relationship among functioning units or components. A collection of components organized to accomplish a specific function or a set of functions.


CHARACTERISTICS OF A SYSTEM

Basically there are three major components in every system, namely

Input,Processing Output.


THE SYSTEMS THE SYSTEMS DEVELOPMENT LIFE DEVELOPMENT LIFE CYCLECYCLE


SDLC

It is an organizational process of developing and maintaining systems. It helps in establishing a system project plan, because it gives overall list of processes and sub-processes required developing a system. Also called software development life cycle.


Phases of software development cycle

System study Feasibility study System analysis System design Coding Testing Implementation Maintenance


Phases of system development cycle


The system study is done in two phases.The preliminary survey of the system is done which helps in identifying the scope of the system. More detailed and in-depth study in which the identification of user’s requirement and the limitations and problems of the present system are studied. A system proposal is prepared by the System Analyst.

System Study


The system study phase passes through the following steps: problem identification and project initiationbackground analysisinference or findings


5

Present the

ProjectAnd plan

1

List Problems, Opportunities, and directives

2

NegotiatePreliminary

Scope

3

AssessProjectworth4

Plan theProject

Repository

Project RequestOr Assignment

Preliminary Problem Statement

Preliminary Problem Statement Scope

Statements of Project

Problem Statements with Scope

Statement of work Project Schedule and resource Assignments

Project Charter

Business Community

Problem Statements

Project is worthy

Project Plan


It is basically the test of the proposed system in the light of its workability, meeting user’s requirements, effective use of resources and of course, the cost effectiveness. The main goal of feasibility study is not to solve the problem but to achieve the scope. In the process of feasibility study, the cost and benefits are estimated with greater accuracy.

Feasibility Study


Types of Feasibility Study

Technical EconomicMotivationalScheduleOperational


System AnalysisAnalysis is a detailed study of various operations performed by a system and their relationships within and outside the system. During analysis, data are collected on the available files, decision points and transactions handled by the present system. Interviews, on-site observation and questionnaire are the tools used for system analysis.


The main points to be discussed in system analysis are:

Specification of what the new system is to accomplish based on the user requirements.Functional hierarchy showing the functions to be performed by the new system and their relationship with each other.Function network which are similar to function hierarchy but they highlight the those functions which are common to more than one procedure.List of attributes of the entities - these are the data items which need to be held about each entity (record)


Cont…

All procedures, requirements must be analyzed and documented in the form of detailed data flow diagrams (DFDs), data dictionary, logical data structures and miniature specifications. System Analysis also includes sub-dividing of complex process involving the entire system, identification of data store and manual processes.


System Design

Most crucial phase in the development of a system. Normally, the design proceeds in two stages :

preliminary or general designStructure or detailed design


Preliminary or general design

The features of the new system are specified. The costs of implementing these features and the benefits to be derived are estimated. If the project is still considered to be feasible, we move to the detailed design stage.


Structure or Detailed design

At this stage, the design of the system becomes more structured. Structure design is a blue print of a computer system solution to a given problem having the same components and inter-relationship among the same components as the original problem. Input, output and processing specifications are drawn up in detail. The programming language and the platform in which the new system will run are also decided.


Tools and techniques used for designing are

Data flow diagram (DFDs)Entity relationship diagramContext diagramSystem flow chartingInput–Output chart


After designing the new system, the whole system is required to be converted into computer understanding language. programmer converts the program specifications into computer instructions, which we refer as programs. The programs coordinate the data movements and control the entire process in a system.

Coding


Testing

A test run of the system is done removing all the bugs, if any. It is an important phase of a successful system. The output of the test run should match the expected results.


Implementation

Implementation is the stage of a project during which theory is turned into practice. During this phase, all the programs of the system are loaded onto the user's computer. After loading the system, training of the users starts.


How to execute the packageHow to enter the dataHow to process the data (processing details)How to take out the reports

Topics for training are

System Analysis and Implementation. MIS

Strategies for running the system

Parallel runPilot run

1 - 25


Parallel runBoth the systems i.e. computerized and manual are executed in parallel.Advantage

Manual results can be compared with the results of the computerized system.Failure of the computerized system at the early stage, does not affect the working of the organization, because the manual system continues to work, as it used to do.

1 - 26


Pilot runThe new system is installed in parts. Some part of the new system is installed first and executed successfully for considerable time period. When the results are found satisfactory then only other parts are implemented. This strategy builds the confidence and the errors are traced easily.

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MaintenanceIt is necessary to eliminate errors in the system during its working life and to tune the system to any variations in its working environment. The review of the system is done for:

knowing the full capabilities of the systemknowing the required changes or the additional requirementsstudying the performance


SYSTEM DEVELOPMENT SYSTEM DEVELOPMENT METHODOLOGIESMETHODOLOGIES


What Is a Methodology?

A formalized approach to implementing the SDLC

A series of steps and deliverables

Methodology CategoriesProcess-

CenteredData-CenteredObject-

Oriented

Structured DesignRapid Application

DevelopmentAgile Development


Prototyping

It is a comprehensive system , and does not include all requirements of the user.Prototyping-based methodologies perform the analysis, design and implementation phases concurrently.All three phases are performed repeatedly in a cycle until the system is completed.

System Analysis and Implementation. MIS1 -

When identification of requirements is difficult.

When requirements may change during the development process.

Prototyping- When it is used


Prototyping-based Methodology


Steps

Identify the user’s basic information requirements.Develop the initial prototype system.Use of the prototype system, to refine the user’s requirements.Revise and enhance the prototype system.

The steps 3 & 4 are repeated again and again till the prototype is refined to the satisfaction of the user.


Advantages

Ability to ‘try out’ ideas without incurring large costs.Lower overall development costs when requirements change frequently.The ability to get a functioning system onto the hands of the user quickly.

Disadvantages

Because its iterative nature , it requires too much time, effort and money.They are not complete systems and many details are not built in the prototype.Due to frequent changes, management of the development process also becomes difficult.


Waterfall Development Methodology


Pros and Cons of the Waterfall Methodology

Pros ConsIdentifies systems requirements long before programming begins

Minimizes changes to requirements asproject progresses

Design must be specified on paper before programming beginsLong time between system proposal and delivery of new system


Parallel Development Methodology


Pros and Cons of Parallel Development Methodology

Pros Cons

Reduces Schedule Time

Less Chance ofRework

Still Uses Paper

Documents

Sub-projects May BeDifficult to Integrate


Tools and techniques used for designing are

Data flow diagram (DFDs)Entity relationship diagramContext diagramSystem flow chartingInput–Output chart


Data Flow Diagrams (DFDs)

Data flow diagram (DFD) is a graphical representation of logical flow of dataHelps in expressing the system’s requirements ina asimple and understandable form.

1.0

CheckStatus

2.0

IssueStatus

Messages

3.0

GenerateShipping

Order

ACCOUNTING

CUSTOMER WAREHOUSE

4.0

Manage Accounts

Receivable5.0

ProduceReports

Order In-Stock Request

Status Data

Status Message

PendingOrdersD1

Order Data

Order Data

Shipping Order

Shipping Confirmation

Invoice

Payment

Accounts ReceivableD2

Accounting Data Accounts Receivable Data

Order Data

Inventory Reports


DFD Symbols

Process

Data Flow

Data Store

Source/Sink (External Entity)

Or Or


Process

Work or actions performed on data (inside the system) Labels should be verb phrasesReceives input data and produces output

1.0

ProduceGradeReport

Grade DetailGrade Report


Rule 1: Process

Can have more than one outgoing data flow or more than one incoming data flow

1.0

GradeStudent

Work

Submitted WorkGraded Work

Student Grade

3.0

Calculated Gross Pay

Hours Worked

Pay RateGross Pay


Rule 2: Process

Can connect to any other symbol (including another process symbol)

1.0

VerifyOrder

2.0

Assemble Order

Order Accepted OrderInventory Change


Process: Correct/Incorrect?

5.0

Create Invoice

Services Perfomed Invoice

Apply InsurancePremium

Payment AmountPolicy Number

2.1

Calculate Gross Pay

Hours Worked Pay Rate


Data Flow

Is a path for data to move from one part of the IS to anotherArrows depicting movement of dataCan represent flow between process and data store by two separate arrows

Deposit

2.1

Post Payment

Accounts Receivable

D1

Payment Detail

Invoice Detail


Data Flow: Correct/Incorrect?

Courses

Students

ClassList

5.0

PostPayment

Customer Payment

D2 Daily Payments

6.0

Prepare Deposit

DailyPayment


Data Store

Is used in a DFD to represent data that the system storesLabels should be noun phrases

StudentsD1


Rule: Data Store

Must have at least one incoming and one outgoing data flow

Daily Payments

D1

Customer Payment

Daily Payment


Data Store: Correct/Incorrect?

2.0

BookFlight

Passengers

FightRequest

D2 AccountsReceivable

PaymentDetail

3.0

PostPayment

InvoiceDetail


Source/Sink (External Entity)

External entity that is origin or destination of data (outside the system)Is the singular form of a department, outside organization, other IS, or personLabels should be noun phrases.Source – Entity that supplies data to the systemSink – Entity that receives data from the system

CUSTOMER

1.0

VerifyOrder

Order

Invoice


Rule: Source/Sink

Must be connected to a process by a data flow

BANK

2.0

Prepare Deposit

BankDeposit


Source/Sink: Correct/Incorrect?

PAYROLLDEPARTMENT

EMPLOYEE

Paycheck

3.0

ApplyPayment

CUSTOMER

Payment

CUSTOMER

AccountsReceivable

Payment


Rules for Using DFD Symbols

Data Flow That ConnectsYES NO

A process to another process

A process to an external entity

A process to a data store

An external entity to another external entity

An external entity to a data store

A data store to another data store


List the errors of this DFD

E1

E1

P2

P1

1.0

2.0

DS1

DF2

DF2

DF6

DF4

DF3

DF1

DF5


Context Diagram

Top-level view of ISShows the system boundaries, external entities that interact with the system, and major information flows between entities and the system.Example: Order system that a company uses to enter orders and apply payments against a customer’s balance


0

Order System

SALESREP

CUSTOMER WAREHOUSE

BANKACCOUNTING

Order

OrderReject Notice

PickingList

CompletedOrder

Payment Invoice

Commission Bank Deposit

CashReceiptsEntry

Context Diagram of Order System


Level-0 DFD

Shows the system’s major processes, data flows, and data stores at a high level of abstractionWhen the Context Diagram is expanded into DFD level-0, all the connections that flow into and out of process 0 needs to be retained.


Lower-Level Diagrams

Functional DecompositionAn iterative process of breaking a system description down into finer and finer detailUses a series of increasingly detailed DFDs to describe an IS

BalancingThe conservation of inputs and outputs to a data flow process when that process is decomposed to a lower levelEnsures that the input and output data flows of the parent DFD are maintained on the child DFD


Entity-Relationship (E-R) Diagram

A detailed, logical representation of the entities, associations and data elements for an organization or business.Entity relationship diagramming is a technique that is widely used in the world of business and information technology to show how information is, or should be, stored and used within a business system. The success of any organization relies on the efficient flow and processing of information.


Entity Relationship Diagram Notations

EntityAn entity is an object or concept about which you want to store information.


Attributes

Attributes are the properties or characteristics of an entity.

Attribute


Key attribute

A key attribute is the unique, distinguishing characteristic of the entity. For example, an employee's social security number might be the employee's key attribute.


Relationships

Relationships illustrate how two entities share information in the database structure.


CardinalityCardinality specifies how many instances of an entity relate to one instance of another entity.Ordinality is also closely linked to cardinality. While cardinality specifies the occurrences of a relationship, ordinality describes the relationship as either mandatory or optional. In other words, cardinality specifies the maximum number of relationships and ordinality specifies the absolute minimum number of relationships. When the minimum number is zero, the relationship is usually called optional and when the minimum number is one or more, the relationship is usually called mandatory.


An E-R Diagram


Recursive relationship

In some cases, entities can be self-linked. For example, employees can supervise other employees.


Multivalued attribute

A multivalued attribute can have more than one value. For example, an employee entity can have multiple skill values.


Derived attribute

A derived attribute is based on another attribute. For example, an employee's monthly salary is based on the employee's annual salary.


Example relationships of different degrees


System Flowchart

A system flowchart explains how a system works using a diagram. The diagram shows the flow of data through a system.


Different shaped symbols are used....


The symbols are linked with directed lines (lines with arrows) showing the flow of data through the system.


An example of a system flowchart is shown below...