Incremental lifecycle model

8/7/2019 Incremental lifecycle model

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Experiment No.2

Incremental lifecycle modelIt is an evolution of waterfall model. The product is designed,

implemented, integrated and tested as a series of incremental

builds .It is a popular model software evolution used many

commercial software companies and system vendor.

Applications

Incremental software development model may be applicable to

projects where:

Software Requirements are well defined, but realization may

be delayed.

The basic software functionality are required early


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Advantages

Generates working software quickly and early during the

software life cycle.

More flexible - less costly to change scope and requirements.

Easier to test and debug during a smaller iteration.

Easier to manage risk because risky pieces are identified and

handled during its iteration.

Disadvanta

ges

Each phase of an iteration is rigid and do not overlap each

other.

Problems may arise pertaining to system architecture because

not all requirements are gathered up front for the entire

software life cycle.


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Spiral lifecycle modelSpiral model is an evolutionary version of incremental

prototyping, developed by Boehm in 1988. Each iteration of the

prototype represented as a cycle in the spiral. The Spiral

software development model is a risk-oriented.

ApplicationsSpiral software development model may be applicable to

projects where:

The projects requirements are very difficult

Where new technologies are used


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The aim ofcustomer communication is to establish effective

communication between developer and customer.

The planning objectives are to define resources, project

alternatives, time lines and other project related information.

The purpose of the risk analysis phase is to assess both

technical and management risks.

The engineering task is to build one or more representations of

the application.

The construction and release taskto construct, test, install

and provide user support (e.g., documentation and training).

The customer evaluation task - to obtain customer feedback


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based on the evaluation of the software representation created

during the engineering stage and implemented during the install

stage.

Advantages

High amount of risk analysis

Good for large and mission-critical projects.

Software is produced early in the software life cycle.

Disadvantages

Can be a costly model to use.

Risk analysis requires highly specific expertise.

Project's success is highly dependent on the risk analysis

phase.

Doesnt work well for smaller projects


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Rapid Application Development

RAD is a linear sequential software development process model

that emphasis an extremely short development cycle using a

component based construction approach. If the requirements are

well understood and defines, and the project scope is constraint,

the RAD process enables a development team to create a fully

functional system with in very short time period.

RAD model has the following phases:

1. Business Modeling: The information flow among business

functions is defined by answering questions like what

information drives the business process, what information is

generated, who generates it, where does the information go,

who process it and so on.

2. Data Modeling: The information collected from business

modeling is refined into a set of data objects (entities) that are

needed to support the business. The attributes (character of

each entity) are identified and the relation between these data

objects (entities) is defined.


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3. Process Modeling: The data object defined in the data

modeling phase are transformed to achieve the information

flow necessary to implement a business function. Processingdescriptions are created for adding, modifying, deleting or

retrieving a data object.

4. Application Generation: Automated tools are used to

facilitate construction of the software; even they use the 4th

GL techniques.5. Testing and Turn over: Many of the programming

components have already been tested since RAD emphasis

reuse. This reduces overall testing time. But new components

must be tested and all interfaces must be fully exercised.


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Advantages

RAD reduces the development time and reusability of

components help to speed up development.

All functions are modularized so it is easy to work with.


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Disadvantages

For large projects RAD require highly skilled engineers in the

team.

Both end customer and developer should be committed to

complete the system in a much abbreviated time frame.

If commitment is lacking RAD will fail.

RAD is based on Object Oriented approach and if it is

difficult to modularize the project the RAD may not work

well.


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What is Requirements Elicitation?

Requirements elicitation is the process of identifying the sources

of requirements for a new system and obtaining those

requirements from those sources.

Potential sources of requirements include users, documents,

regulators and even legacy software code.

Requirements elicitation is a crucial part of the Requirements

Gathering, Documentation and Analysis Process.

It is a very challenging activity that requires focus and skill from

the business analyst.

Whatever elicitation technique you choose and however you

implement the technique, you need to do whatever it takes to

understand what the real needs of your customers are.

There are many requirements elicitation techniques that may be

used in various situations depending on the level ofrequirements as well as the type of stakeholder.

Each requirements elicitation technique has its advantages and

disadvantages.


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It is a good idea to gain a mastery of many different elicitation

techniques so that you can use a combination of them on thejob

to successfully draw out your stakeholder needs.

Preparing to Elicit Requirements

Planning your elicitation activities ensures that you:

1. Understand your stakeholders.

2. Use the right elicitation techniques for each stakeholder or

stakeholder group.

3. Accurately prioritize the stakeholders and assign the right

level of involvement.

4. Allocate adequate time and resources to the requirements

gathering activities.

5. Adequately prepare the stakeholders for the elicitation

sessions.

6. Gain the trust and cooperation of your stakeholders.
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Requirements Elicitation Techniques

Brainstorming

Brainstorming sessions are used to let the stakeholders come up

with creative ideas or new approaches to a problem

Workshops

Workshops are facilitated meetings with multiple stakeholders.


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Interviewing

Interviews are in-person, one-on-one meetings where the

business analyst asks questions to get information from the

stakeholder.

With an interview you can quickly obtain a lot of requirements

from one person. However, you still need to examine those

requirements to make sure they do not conflict with other

stakeholder needs.

Surveys

Surveys are used to gather information anonymously from the

stakeholders.

Documentation Review

This is the process of obtaining requirements from written

documentation such as manuals.

Prototyping

This is the use of partially finished versions of the software that

have been created to help validate requirements.


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Focus Groups

Focus Groups are group interviews with potential and/or actual

users where the business analyst raises issues and questions to

obtain information from the stakeholders.

Focus groups are a collaborative technique that lets you gather a

lot of information. It includes a measure of brainstorming which

is good when the users dont know what they really want or

need from the system.

Observation

Observation is when the business analyst watches the users

performing their daily tasks and asks questions about the tasks

and work. This technique gives you the advantage of actually

seeing what the users do as they work as opposed to what they

tell you they do.

Observation helps the analyst develop a real understanding of

the users on thejob issues.

A good business analyst should have excellent skills choosing

and using the right elicitation technique for each situation.


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Documents

Incremental lifecycle model