Models In Software Engineering

1. WATERFALL MODEL AND SPIRAL MODEL
A. D. PATEL INSTITUTE OF TECHNOLOGY
SOFTWARE ENGINEERING(2160701) : A.Y. 2018-19
DEPARTMENT OF INFORMATION TECHNOLOGY
A D PATEL INSTITUTE OF TECHNOLOGY (ADIT)
NEW VALLABH VIDYANAGAR, ANAND, GUJARAT
GUIDED BY:
PROF.RAVI PATEL
(DEPT OF IT, ADIT)
PREPARED BY:
KADAM PRAJAPATI (160010116050)
DHRUV SHAH (160010116053)
RUSHIL PATEL (160014116001)
B.E. (IT) SEM - 6
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2. Outline
 Waterfall Model
oHistory of waterfall model.
oFeatures of water fall model.
oPhase of water fall model.
oBrief description of phases.
oAdvantages & Disadvantages.
 Spiral Model
oFig. Of Spiral Model.
oPhase of water fall model.
oWhen to use the Waterfall Model?
oAdvantages & Disadvantages.
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3. Waterfall Model
o History of waterfall model :
The first formal description of the waterfall model is often cited as a 1970 article by
Winston W. Royce. Royce presented this model as an example of a flawed, non-working
model.
The waterfall model is the classic lifecycle model – it is widely known, understood
and used. In some cases, waterfall is considered ”common sense” approach.
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4. o Features :
• A Water Fall Model is easy to flow.
• It can be implemented for any size of project.
• Every stage has to be done separately at the right time so you cannot jump
stages.
• Documentation is produced at every stage of a waterfall model allowing people
to understand what has been done.
• Testing is done at every stage.
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5. Waterfall Model Fig.
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6. o Phase of water fall model :
Waterfall model has 5 different phases, Which are following.
1)Requirement gathering and Analysis.
2)Design.
3)Coding.
4)Testing.
5)Maintenance.
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7. o Requirement gathering and Analysis :
• This is the first phase of waterfall model which includes a meeting with the
customer to understand his requirements.
• This is the most crucial phase as any misinterpretation at this stage may give rise
to validation issues later.
• The software definition must be detailed and accurate with no ambiguities.
• Documentation is produced at every stage of a waterfall model allowing people
to understand what has been done.
• It is very important to understand the customer requirements and expectations
so that the end product meets his specifications.
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8. o Design :
• The customer requirements are broken down into logical modules for the ease of
implementation. Hardware and software requirements for every module are
Identified and designed accordingly.
• Also the inter relation between the various logical modules is established at this
stage. Algorithms and diagrams defining the scope and objective of each logical
model are developed.
• In short, this phase lays a fundamental for actual programming and
implementation.
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9. o Coding :
• Coding is a step in which design is translated
• into machine-readable form.
• If design is done in sufficient detail then coding can be done effectively.
• Programs are created in this phase.
• In this phase all software divided into small module then after doing coding for that
small module rather than do coding whole software.
• According to design programmers do code and make class and structure of whole
software.
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10. o Testing :
• In this stage, both individual components and the integrated whole are Methodically
verified to ensure that they are error-free and fully meet the requirements outlined in
the first step.
• In this phase testing whole software into two parts 1) HARDWARE & 2) SOFTWARE.
• Type of testing is 2-types
• Inside test.
• Outside test.
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11. o Maintenance :
• This is the final phase of the waterfall model, in which the completed software
product is handed over to the client after alpha, beta testing.
• After the software has been deployed on the client site, it is the duty of the software
development team to undertake routine maintenance activities by visiting the client
site.
• If the customer suggests changes or enhancements the software process has to be
followed all over again right from the first phase i.e requirement analysis.
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12. Spiral Model
oFig. Of Spiral
Model:
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13. Phase of Spiral model
• The spiral model, also known as the spiral lifecycle model, is a systems
development model used in information technology (IT).
• This model of development combines the features of the Prototype model and
the Waterfall model.
• The spiral model is favored for large, expensive, and complicated projects.
• Steps in Spiral Model:
1) Communication.
2) Planning and Identification.
3) Risk Analysis.
4) Engineering.
5) Construction.
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14. o Communication :
• This is the first phase of spiral model which includes a meeting with the customer to
understand his requirements.
• This is the most crucial phase as any misinterpretation at this stage may give rise to
validation issues later.
• The software definition must be detailed and accurate with no ambiguities.
• It is very important to understand the customer requirements and expectations so that the
end product meets his specifications.
• Requirement gathering and Analysis phase the basic requirements of the system must be
understood by software engineer, who is also called ANALYST.
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15. o Planning and Identification :
• This phase starts with gathering the business requirements in the baseline spiral.In the
subsequent spirals as the product matures, identification of system requirements, subsystem
requirements and unit requirements are all done in this phase.
• This phase also includes understanding the system requirements by continuous
communication between the customer and the system analyst. At the end of the spiral, the
product is deployed in the identified market.
• Determining objectives,alternatives,constraints
• Objectives: functionality,performance,hardware/software interface,critical success factor
• Alternatives: build,reuse,buy,sub-contract etc.
• Constraints:cost,schedule,interface etc.
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16. o Risk Analysis :
• Study alternatives related to objective and constraints.
• Requirements are studied and brain storming sessions are done to identify the potential risks
(lack of experience,new technology,tight schedules,poor process).
• Once the risks are identified , risk mitigation strategy is planned and finalized.
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17. o Engineering & Construction :
• Coding is a step in which design is translated into machine-readable form.
• If design is done in sufficient detail then coding can be done effectively. Programs are created in this
phase.
• In this phase all software divided into small module then after doing coding for that small module
rather than do coding whole software.According to design programmers do code and make class and
structure of whole software.
• In this stage, both individual components and the integrated whole are methodically verified to
ensure that they are error-free and fully meet the requirements outlined in the first step.
• If the customer suggests changes or enhancements the software process has to be followed all over
again right from the first phase i.e. requirement analysis.
• The usually the longest stage of the software. In this phase the software is updated to:
• Meet the changing customer needs, Enhancing the efficiency of the software.
• Adapted to accommodate changes in the external environment.
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18. o When to use the Waterfall Model?
• Requirements are very well known
• Product definition is stable
• Technology is understood
• New version of an existing product
• Porting an existing product to a new platform.
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19. o Advantages :
• Easy to understand, easy to use
• Provides structure
• Milestones are clear
• Good for management control (plan, staff, track)
• Works well when quality is more important than cost or schedule
o Disadvantages :
• All requirements must be known upfront
• Deliverables created for each phase are considered frozen – inhibits flexibility.
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