Major Models used in SDLC

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Good afternoon! How we doing today? PAUSE
Good? Fantastic!
Today’s topic is SDLC, its importance and How important is our job!
So I will speak for 20 odd minutes, pause, and then open it up for Q&A, not in
between though. PAUSE
Sounds good?
pause
Cool!
I am going to speak about the process of developing software. It will not include the
tools used for developing software. Essentially in software terminology, the process
is called SDLC (Software/System Development Life Cycle).
Now imagine, the life cycle of a human being. Pause. Likewise there is a lifecycle of
software, right?
For us humans - a baby is planned by parents based on what purpose it would serve
in the world and for itself. Like 40 years back in India more kids meant more bread
winners. Then there is the stage of analysis/conception, then the architect of the
world designs in darkness the baby by choosing the right design and there starts
the development of the baby in darkness for 9 months, by Lords army of invisible
experts who we call demi-gods and then the baby is released to the world and then
follows the growth and maintainance, upgradation of new modules added in the
form of lifelong education & training to serve different purpose of the world, and
somewhere towards the end a steady stage of maturity and then finally comes
death. Same process is true for other animals also, right?

Likewise software is planned, analysed/conceived, designed, developed, tested,
accepted, operated & maintained, and disposed.
Now why do we need to know about the software development process at the client
site? Same reason, why we need to know about the birthing process of humans.
Because it gives us an understanding of what happens in the field where we send
our visible soldiers i.e consultants, unlike Gods invisible soldiers. :) It enables us to
make informed decision on finding the right soldier with the right skill and attach
them to the right position.
Know this though, the right fit is always a 2 attribute match. One is the technical fit
and the other one is adaptability fit. We will speak mainly on the technical fit and its
component today. Adaptability fit is a very important criteria, but we will keep it for

another time for another speaker, maybe Rupa Thakur. ;). I will touch the tip of the
iceberg on the adaptability. My Manager Moumita is a VERY GOOD source to run by,
for adaptability fit of a candidate for a position.

Now the technical fit mainly comprises of 2 main attributes. Process knowledge and
tools knowledge. Process knowledge is the SDLC part of it and tools knowledge is
the plethora of tools you see in the JD of the position. Eg: IBM Requisite Pro, MSProject, MS-Visio, IBM ClearCase, ClearQuest, IntelliJ, NetBeans, WebLogic,
Websphere, Ant, LoadRunner, Installshield, Sharepoint etc. On tools, what we look
for is a high tech high skilled person with an ability and/or prior expertise of using
these tools without much error.
On Process knowledge, the SDLC process has given rise to different variants of it
depending on the type of software to be build like for inhouse use as in Dell's/EMC's
machine programming or for building software to be sold off the shelf to many
different companies. To add to that IBM mainframes like TPF and all has very
different process.
Now a little bit about the geographic location of the clients from where the project is
off-shored. This will be the tip of the iceberg about the adaptability I mentioned a
little while earlier. most of us place candidates for projects coming from USA, Right.
Now as per my knowledge, speaking to people who lived in USA for a decade or
more - there are mainly two different variants of SDLC used, although there are
many and the use is based on the type of project undertaken.
So, today I am going to cover some topics which will be really important for we
recruiters to find the right technical talent - whichever client we are working for.
Please understand, my intention is not to make you a software engineer, for which
you will need to go back to school for 4 years. Rather I will try to cover topic on how
a set or multiple sets of software engineers, qa's, project teams work together to
deliver a product or project. This will kind of give you a 10 thousand feet view of
what happens in that software engineering kitchen and therefore enable you to find
the right chef, helpers, food testers analogous to software engineering.
So essentially, its SDLC and its different variants that have emerged over time.
One thing to remember though, in the beginning is, One kind is used in east coast of
USA and it primarily extends from extreme east to central part of USA, down south
and up north, and the second variant is used in silicon valley i.e north California
primarily and maybe some part of Seattle and Los Angeles. Remember east coast
companies are other businesses who produce software to be used particularly for
their businesses, whereas west coast companies are mainly off the shelf software
only businesses, although there are exceptions.

The thing to know if courage permits, from which location in USA the project is offshored from, or which time zone people your candidate will be working with. That
will give you an idea of what kind of candidate is good fit. For instance, I currently
work with client EMC, which is primarily based out of east coast of USA. Therefore I
try to find candidates who have already worked on projects from east coast, in
similar sized company, and of course same skills.

My experience has been it is hard for a guy who worked on projects from only
Silicon valley, California to adjust to projects from east coast. It just requires 2
different kind of energy levels, you know!

Having said that, lets see what SDLC is and how they are applied to the different
projects.
Most of you are familiar with this term. Its the Software Development Life Cycle.

So to sum it all, essentially what we are looking for, is a technician who knows the
process and based on his role, expertise on a particular set of tools out of a group of
tools, selected by the client which best fits the chosen process to accomplish a
project.

Project Initiation and Monitoring team (top management)
Project Management team (contains business analyst, business experts, solution
architects,
project manager)
Engineering team (engg mgmt, all hieranchy of software hands on professionals like
principle engg, design/architecture team, team lead, sr. s/w engg, s/w engg)
QA team (QA Management, principal QA, QA Architect, QA lead, load testing team,
benchmarking team, etc)

Release management team (build team, installation team)
Systems Maintainance team (for installation/rebuilding machines of entire team
Production support team (includes sr. technical team from Engineering and
Customer support)
Customer support team (has a whole hieranchy)
Now how does all these team work in tandem to deliver a release, month after
month, year after year?

So the basic framework that is followed is SDLC (System/Software Development Life
Cycle). "Cloud computing" also uses SDLC with slight variation, more by using
SCRUM.

Software Development Life Cycle

SDLC is a process followed for a software project, within a software organization. It
consists of a detailed plan describing how to develop, maintain, replace and alter or
enhance specific software. The life cycle defines a methodology for improving the
quality of software and the overall development process.
This figure is a graphical representation of the various stages of a typical SDLC.

A typical Software Development life cycle consists of the following stages:
Stage 1: Planning and Requirement Analysis : Requirement analysis is the most
important
and fundamental stage in SDLC. It is performed by the senior members of the team
with inputs
from the customer, the sales department, market surveys and domain experts in
the industry.
This information is then used to plan the basic project approach and to conduct
product
feasibility study in the economical, operational, and technical areas.
Planning for the quality assurance requirements and identification of the risks
associated with
the project is also done in the planning stage. The outcome of the technical
feasibility study is
to define the various technical approaches that can be followed to implement the
project
successfully with minimum risks.

Stage 2: Defining Requirements : Once the requirement analysis is done the next
step is to
clearly define and document the product requirements and get them approved from
the
customer or the market analysts. This is done through ‘SRS’ – Software Requirement
Specification document which consists of all the product requirements to be
designed and
developed during the project life cycle.
Stage 3: Designing the product architecture : SRS is the reference for product
architects to
come out with the best architecture for the product to be developed. Based on the
requirements specified in SRS, usually more than one design approach for the
product
architecture is proposed and documented in a DDS - Design Document
Specification. This DDS
is reviewed by all the important stakeholders and based on various parameters as
risk assessment, product robustness, design modularity , budget and time
constraints , the best
design approach is selected for the product.
A design approach clearly defines all the architectural modules of the product along
with its
communication and data flow representation with the external and third party
modules (if
any). The internal design of all the modules of the proposed architecture should be
clearly
defined with the minutest of the details in DDS.
Stage 4: Building or Developing the Product : In this stage of SDLC the actual
development
starts and the product is built. The programming code is generated as per DDS
during this
stage. If the design is performed in a detailed and organized manner, code
generation can be

accomplished without much hassle.
Developers have to follow the coding guidelines defined by their organization and
programming tools like compilers, interpreters, debuggers etc are used to generate
the code.
Different high level programming languages such as C, C++, Pascal, Java, and PHP
are used for
coding. The programming language is chosen with respect to the type of software
being
developed.
Stage 5: Testing the Product : This stage is usually a subset of all the stages as in
the modern
SDLC models, the testing activities are mostly involved in all the stages of SDLC.
However this
stage refers to the testing only stage of the product where products defects are
reported,
tracked, fixed and retested, until the product reaches the quality standards defined
in the SRS.
Stage 6: Deployment in the Market and Maintenance : Once the product is tested
and ready
to be deployed it is released formally in the appropriate market. Sometime product
deployment happens in stages as per the organizations’ business strategy. The
product may
first be released in a limited segment and tested in the real business environment
(UAT- User
acceptance testing).
Then based on the feedback, the product may be released as it is or with suggested
enhancements in the targeting market segment. After the product is released in the
market,
its maintenance is done for the existing customer base.
SDLC Models

There are various software development life cycle models defined and designed
which are
followed during software development process. These models are also referred as
"Software
Development Process Models". Each process model follows a Series of steps unique
to its type,
in order to ensure success in process of software development. Following are the
most
important and popular SDLC models followed in the industry:
 Waterfall Model
 Iterative Model
 Spiral Model
 V-Model
 Big Bang Model
The other related methodologies are Agile Model, RAD Model – Rapid Application
Development and Prototyping Models.

Waterfall Model design
Waterfall approach was first SDLC Model to be used widely in Software Engineering
to
ensure success of the project. In "The Waterfall" approach, the whole process of
software
development is divided into separate phases. In Waterfall model, typically, the
outcome
of one phase acts as the input for the next phase sequentially.
Following is a diagrammatic representation of different phases of waterfall model.

The sequential phases in Waterfall model are:
 Requirement Gathering and analysis All possible requirements of the system to
be
developed are captured in this phase and documented in a requirement
specification
doc.
 System Design: The requirement specifications from first phase are studied in
this
phase and system design is prepared. System Design helps in specifying hardware
and
system requirements and also helps in defining overall system architecture.
 Implementation: With inputs from system design, the system is first developed in
small programs called units, which are integrated in the next phase. Each unit is
developed and tested for its functionality which is referred to as Unit Testing.
 Integration and Testing: All the units developed in the implementation phase are
integrated into a system after testing of each unit. Post integration the entire
system

is tested for any faults and failures.
 Deployment of system: Once the functional and non functional testing is done,
the
product is deployed in the customer environment or released into the market.
 Maintenance: There are some issues which come up in the client environment. To
fix
those issues patches are released. Also to enhance the product some better
versions
are released. Maintenance is done to deliver these changes in the customer
environment.

Iterative Model design
Iterative process starts with a simple implementation of a subset of the software
requirements and iteratively enhances the evolving versions until the full system is
implemented. At each iteration, design modifications are made and new functional
capabilities are added. The basic idea behind this method is to develop a system
through
repeated cycles (iterative) and in smaller portions at a time (incremental).
Following is the pictorial representation of Iterative and Incremental model:

Iterative and Incremental development is a combination of both iterative
design or iterative method and incremental build model for development. "During
software development, more than one iteration of the software development cycle
may
be in progress at the same time." and "This process may be described as an
"evolutionary acquisition" or "incremental build" approach."
In incremental model the whole requirement is divided into various builds. During
each
iteration, the development module goes through the requirements, design,
implementation and testing phases. Each subsequent release of the module adds
function
to the previous release. The process continues till the complete system is ready as
per
the requirement.
The key to successful use of an iterative software development lifecycle is rigorous
validation of requirements, and verification & testing of each version of the software
against those requirements within each cycle of the model. As the software evolves
through successive cycles, tests have to be repeated and extended to verify each
version
of the software.

V- Model design
Under V-Model, the corresponding testing phase of the development phase is
planned in

parallel. So there are Verification phases on one side of the ‘V’ and Validation
phases on
the other side. Coding phase joins the two sides of the V-Model.
The below figure illustrates the different phases in V-Model of SDLC.

What is Agile?
Agile model believes that every project needs to be handled differently and the
existing
methods need to be tailored to best suit the project requirements. In agile the tasks
are
divided to time boxes (small time frames) to deliver specific features for a release.
Iterative approach is taken and working software build is delivered after each
iteration.
Each build is incremental in terms of features; the final build holds all the features
required by the customer.

The most popular agile
methods include Rational Unified Process (1994), Scrum (1995), Crystal Clear,
Extreme
Programming (1996), Adaptive Software Development, Feature Driven
Development,
and Dynamic Systems Development Method (DSDM) (1995).

Agile Vs Traditional SDLC Models
Agile is based on the adaptive software development methods where as the
traditional
SDLC models like waterfall model is based on predictive approach.
Predictive teams in the traditional SDLC models usually work with detailed planning
and
have a complete forecast of the exact tasks and features to be delivered in the next
few
months or during the product life cycle. Predictive methods entirely depend on the

requirement analysis and planning done in the beginning of cycle. Any changes to
be
incorporated go through a strict change control management and prioritization.
Agile uses adaptive approach where there is no detailed planning and there is
clarity on
future tasks only in respect of what features need to be developed. There is feature
driven development and the team adapts to the changing product requirements
dynamically. The product is tested very frequently, through the release iterations,
minimizing the risk of any major failures in future.
Customer interaction is the backbone of Agile methodology, and open
communication
with minimum documentation are the typical features of Agile development
environment.
The agile teams work in close collaboration with each other and are most often
located in
the same geographical location.

Then there is RAD where software prototyping goes alongwith the development.
Mainly used in off-shored projects to a 3rd party company which does not have a
proven brand name.
---------------------------How are we important. We provide the right match not the devilish match which
could throw the project in hay.

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