In Iterative model, iterative process starts with a simple implementation of a small set of the software requirements and iteratively enhances the evolving versions until the complete system is implemented and ready to be deployed.

1. Experiment: - 2
Model
Software developmentmodel used
Iterative Waterfall model
The waterfall model is a sequential design
process, often used in software development processes, in which progress is seen as
flowing steadily downwards (like a waterfall) through the phases of Conception,
Initiation, Analysis, Design, Construction, Testing, Production/Implementation, and
Maintenance.
The waterfall development model originates in the manufacturing and construction
industries; highly structured physical environments in which after-the-fact changes
are prohibitively costly, if not impossible. Since no formal software development
methodologies existed at the time, this hardware-oriented model was simply adapted
for software development
DATE: -

2. Software Requirements Specifications:
This is the most crucial
phase for the whole project, here project team along with the customer makes a
detailed list of user requirements. The project team chalks out the functionality and
limitations (if there are any) of the software they are developing, in detail. The
document which contains all this information is called SRS, and it clearly and
unambiguously indicates the requirements. A small amount of top-level analysis
and design is also documented. This document is verified and endorsed by the
customer before starting the project. SRS serves as the input for further phases.
REQIREMENTS
DESIGN
IMPLEMENTATION
VERIFICATION
MAINTENANCE

3. System Design and Software Design:
Using SRS as input, system
design is done. System design included designing of software and hardware i.e.
functionality of hardware and software is separated-out. After separation design of
software modules (see whatmodularityis)is done. The design process translates
requirements into representation of the software that can be assessed forquality
before generation of codebegins. At the same time test plan is prepared, test plan
describes the various tests which will be carried out on the system after completion
of development.
Implementation and Unit Testing:
Now that we have system design,
code generation begins. Code generation is conversion of design into machine-
readable form. If designing ofsoftware and system is donewell, codegeneration can
be done easily. Software modules are now further divided into units. A unit is a
logically separable part of the software. Testing of units can be done separately. In
this phase unit testing is done by the developer itself, to ensure that there are no
defects.
Integration and System testing:
Now the units of the software are
integrated together and a system is built. So we have complete software at hand
which is tested to check if it meets the functional and performance requirements of

4. the customer. Testing is done, as per the steps defined in the test plan, to ensure
defined input produces actual results which agree with the required results. A test
report is generated which contains test results.
Operation & maintenance:
Now that we have completed the tested
software, we deliver it to the client. His feed-backs are taken and any changes, if
required, are made in this phase. This phase goes on till the software is retired.
DATA FLOW DIAGRAMS:
A DFD describes what data flow (logical) rather than
how they are processed, so it does not depend on hardware, software, data
structure or file organization. It is also known as ‘bubble chart’. A Data Flow
Diagrams is a structured analysis and design tool that can be used for flowcharting
in place of, or in association with, information-oriented and process-oriented
systems flowcharts. A DFD is a network that describes the flow of data and the
processes that change, or transform, data throughout a system. This network is
constructed by using a setof symbols thatdo not imply a physicalimplementation.
It has the purpose of clarifying system requirements and identifying major
transformations that will become programs in system design.

5. The four basic
symbols used to construct data flow diagrams are shown below: A rectangle
represents a data sourceor destination. A directed line represents the flow of data
thatis data stream. Anenclosed figure,usuallya circleor an ovalbubble, represents
a process that transforms data streams.
An open-ended rectangle represents data storage. These is symbols thatrepresent
data flows, data sources, data transformations and data storage. The points at
which data are transformed are represented by enclosed figures, usually circles,
which are called nodes. The principle processes that take place at nodes are:
1. Combining data streams
2. Splitting data streams
3. Modifying data streams.

6. Incoming
message
m
Check for new message
Is the
sender’s
no
valid?
Keep displaying the previous
message
N
Y
Is new
message
higher in
priority?
Keep displaying the previous
message
Replace old message with new one
in memory
Y
Y