SYSTEM DEVELOPMENT Introduction; Fulfilling the role of system development, a no. of diff. situations arise, which must be understood to facilitate decisions on the approach, strategy, technology & development. The user in the business org has become more literate in terms of knowledge, use of IT & its application in the mgt of business. The problem of meeting the changing information needs is solved by keeping the DB, & the knowledge base at Back end. There are a variety of systems where system analysis would be required.

Data processing systems TPS Functional systems Integrated systems enterprise mgt

The role of system analyst is a, business analyst, technology expert & a consultant, giving a solution to the business needs of the inform. Requirement.

Need for System Analysis;

System objective System boundaries System importance Nature of the system Role of the system as an interface Participation of user Understanding of resource needs Assessment feasibility

System Analysis; Study of end-user information requirements that is needed before the design of a new inform system can be completed.

System Design; SD describe what a system should do to meet the inform needs of users. The strategy specifies how the system will accomplish the objectives

System Analysis of the Existing System;

Understanding the existing system Understanding the objectives achieved by the existing

system Knowing whether the system is feasible in technically

& operationally Evaluate the system for computerization & its

placement in the total MIS design

System Analysis of a new requirements;

Definition of the system & its objectives Development of the system Installation of the system & testing Operations of the system Review & evaluation

• INTRODUCTION

• The details of the waterfall model vary but two things remain constant there are boxes going from left downward to the right and there are arrow connecting each to its succesor.

•

Water fall model

DEFINITION

• The water fall model is a popular version of the system development lifecycle model for software engineering.

• It is often considered the classic approach to the system development life cycle.

• In order to design a good system, traditionally, the development have used the waterfall model.

• This model describes a development method that is linear and sequential.

• Waterfall development has distinct goals for each phase of development.

Information needsspecifications

Analysis

Systemdesign

Mission &Goal

Process design

Testing

Implementation

Maintenance

Water fall modelWater fall model

ADVANTAGES

It allows for departmentalization and managerial control.

Each phase of department proceeds in strict order without any overlapping.

DISADVANTAGES

• It doesn’t allow for much reflection or revision.

• Once an application is in the testing stage, it is very difficult to go back and change.

• Something that was not well though out in the concept stage.

The RAD Model

Rapid application development is an incremental S/W development process model that emphasizes an extremely short development cycle. The RAD model is a “high-speed” adaptation of the linear sequential model in which rapid development is achieved by using component-based construction.

If the requirement are well understood & project scope is constrained, the RAD process enables a development team to create a “fully functional system”within very short time period.

The RAD approach encompasses the following phases;

Business modeling The information flow among businesses function is molded in a way that answers the following questions:

1. What information drives the business processes/2. What information is generated?3. Who generates it?

4. where does the information go? 5. Who process it

Data Modeling; The information flow defined as part of the business modeling phase is refined into a set of data objects that are needed to support the business. The characterizes (called attributes) of the each object are identified & the relationships b/w these objects defined

Process modeling; The data objects defined in the data modeling phase are transformed to achieve the information flow necessary to implement a business function. Processing description are created for adding, modifying, deleting, or retrieving a data object.

Application Generation; RAD assumes the use of the 4th generation techniques. Rather than creating S/W using conventional 3rd generation programming languages the RAD process works to reuse existing program components or create reusable components. In all cases, automated tools are used to facilitate construction of the S/W.

Testing & Turnover; Since the RAD process emphasize reuse, many of the program components have been tested. This re3dusede overall testing time. However, new components must be tested & all interfaces must be fully exercised.

Advantages of RAD modelTime constraints imposed on a RAD project demand “scalable scope” Each major function to be completed in less than 3 months Each major function can be addressed by a separate RAD team & then integrated to form a whole

Disadvantages of RAD model RAD requires sufficient human resources to create a right number of RAD team RAD require developers & customers for rapid-fire activates Not all type of applications are appropriate for RAD RAD is not appropriate when technical risks are high

Business modeling

Data modeling

Process modeling

Testing & Turnover

Application generation

60 – 90 days

PROTO TYPE

• It typically involves user and developer• The developer interviews the user and

develops an initial system using a DBMS• The user works with the proto type and

suggest changes• Process will repeats until the user or

developer is satisfied

Steps in system development by proto type:

System development initiated

Investigate and analyze problem sufficiently to develop workable solution

Develop prototype

Put proto type into operation

Refine and modify proto type

Complete component of system

PROCESS OF PROTO TYPE

Initial interview

MIS designer user

Build initial proto type

New version

Use proto type

Modify proto type

Request changes

Eg: Proto type of an auto-mobile-----subsequent developments made

PROCESS REPEATS UNTILL:

User is satisfied Formal system is built by proto type Need for application is removed Process never ends ADVANTAGES: Accessible than SDLC Users wills and wishes are satisfied Designed to be modified from the starting Using case tools and DBMS error free code can be generated Helps heavily in user interactionDIS-ADVANTAGES : Several users involves When the project will be finished? Un capability of analyst No predefined targets

SPIRAL MODEL

Spiral model proposed by Boehm1. It is evolutionary S/W process model2. Spiral have couple of iterative in nature of prototyping with the controlled & systematic aspects of the linear sequential model3. It provides the potential for rapid development of incremental versions of the software4. During early iteration, the incremental release might be paper model or prototype5. In later iterations increasingly complete versions of the engineered system are produced Spiral model dividing into no. of framework activities, also called task Regions. Spiral model guiding the risk levels in the projects Spiral model that contains six task regions;1. Customer communication2. Planning3. Risk analysis4. Engineering5. Construction & release6. Customer evaluation

Data Flow Diagram

• A graphical system model that shows all of the main requirements for an information system: inputs, outputs, processes and data storage They are primarily used in the systems development process. A data flow diagram is often the diagram of choice for modern entities.

Context Diagram

A DFD that summarizes all processing activity within the system in single process symbol. Describes highest level view of a system All external agents and all data flows into and out

of a system are shown in the diagram The whole system is represented as one process The data flows that pass between the external

entities and the system.

Purpose

To identify and examine the interface between the external entities and the system.

For Example A Context Data Flow Diagram for Payroll

Processing shows a context diagram for a Payroll Processing that

interacts with 5 agents: Employee, Management, Government Agencies, Human Resources, Time keeping.

Symbols used in Context Diagram

A square represents an external data

source or data destination.

A Vowel indicates a internal entity or

transformation process.

A line with an arrow indicates the direction of the flow of data.

Guidelines for drawing a Context Diagram

List potential external entities (people, places). Look for entities that

Give data to the system without explaining the process that creates that data

Take data from the system without explaining what it does with that data

Establish what flows are sent to and from the system from the external entities Draw the context diagram

Structured systems Analysis & Design [SSAD]

Symbols;

Flow of data process of Storage of Entity Transforming Data DataExample;

CustomerProcess

Customerorder

Order acceptance

Product data

Customer data

CustomerorderOrderacceptance

Computer Systems Design;

Input Design Output Design Processing Design Data Specifications Procedure Design

MIS & Systems Analysis

• Systems analysis plays a central role in the development of the MIS

• MIS lies in the information needs of the various personnel in the org across all levels of the mgt

• The MIS development process largely relies on the SAD as a source of the scientific development

• The modern MIS largely depends on how these technologies are blended with the main systems

• The SA begins with the O/P design• The SA with its structural analysis ensures an appropriate

coverage of the sub-systems• MIS methodology may be the conventional design of data, DB

& file approach• MIS may call for an open system design• Systematic approach in development helps in achieving the

objectives of the MIS

BUSINESS PROCESS REENGINEERING [BPR]

BPR is a methodology for introducing a fundamental change in specific business process & usually supported by an IS.

Business Process; A business process is a collection of activities that --- takes one or more kinds of I/P --- create an O/P of value to the customers BPR combines a strategy of promoting business innovation with a strategy of making major improvements to business processes, so that a company canBecome a much stronger & more successful competitor in the marketplace. Restructuring & transforming a business process by a fundamental rethinking & redesign to achieve dramatic improvements in the cost, quality, & speed.Example; Order Mgt Proposal Commitment Configuration

Creditchecking

delivery

BillingCollections

Duties & Responsibilities of DBA

• Design of the conceptual & physical schemas

• Security & Authorization

• Data availability

• Recovery the data from failure

• Database tuning

Definition of System Analyst

A system analyst is the person who selects and configures computer systems for an organization or business.

The analyst must understand the general objectives of the business, as well as what each individual user's job requires.

ROLES OF SYSTEM ANALYST

Change AgentInvestigator and MonitorArchitectPsychologistSalespersonMotivatorPolitician

Change Agent The analyst may be viewed as an agent of

change.

Investigator and Monitor

In defining a problem a analyst pieces together the information gathered to determine why the present system does not work well and what changes we correct the problem.

ArchitectThe architect ‘s primary function as liaison

between the client’s abstract design requirements and contractor detailed building plan may be compare to analyst’s role as liaison between the users logical design requirements in details and physical system design.

Psychologist The analyst plays the role of a

psychologist in the way he/she reaches people, interprets their thoughts, assesses their behavior and draws conclusions from these interactions.

SalespersonThe analyst is also playing a role as a

sales persons.

Motivator A candidate system must be well designed

and acceptable to the user. The analyst’s roles as a motivator becomes obvious during the first few weeks after implementation.

Politician Related to the role of motivator is that of

politician.

RESPONSIBILTIES OFSYSTEM ANALYST

Assists current or potential application users in identifying and describing problems or opportunities that might be addressed either:

a) by implementing a new (automated or manual) system, or b) by changing an existing application system.

Investigates such problems and opportunities to determine the feasibility of a system solution.

Analyzes users’ business requirements in detail. Assists and guides prospective users of a proposed new or changed system in: a) quantifying the benefits of having the system, and b) assessing the impact of the system on their organization and on the operation of their

business. Obtains rough estimates of the cost of operating and maintaining a proposed new or changed system.

Assists the project manager in identifying the resources needed to implement a new system:

a) the cost of developing or changing the system, b) the duration of a project to do so.

It analyze the costs, benefits, risks, and return-on-investment of the proposed new system.

Deciding whether to proceed with the implementation.

Prepares, in consultation with users, implementers and operations representatives, the acceptance test plan for any new or changed system.

Assists the users in preparing for the installation and start-up of any new system being implemented.

Ditties & Responsibilities of DB Designer

• Identifying the data to be stored in the DB & for choosing appropriate structures to represent & store this data

• DB designer to comm. With all prospective DB users

• In many cases, the designers are on the staff of the DBA

• DB designers typically interact with each potential group of users