ALLNotes

Software characteristic

2019-06-25T19:34:00.002+05:45

Software characteristic

The nature and behavior of a software is quite different than other products of human life.

Some of the important characteristics.

· Software does not wear out

Unlike hardware products software becomes reliable overtime instead of wearing out due to testing and fixing faults, failure intensity will come down initially and stabilize after certain time.

· Software is flexible

A program can be developed to do almost anything. Sometime, this characteristics almost anything may be the best and may help us to accommodate any kind of change.

· Software is not manufactured

Development of a software is a one time effort but it requires a continuous maintenance effort in order to keep use it operational. However making 100 copies is not issue and it does not involved any cost.

· Re-usability of components

For hardware products we purchase every unit and components from the market and produce the finished products. But in software, every project is a new project we start from the scratch and design of every of a software product which requires huge effort and increased cost. However efforts have been made to design standard components that may be used in new projects.

Software process & characteristics

2019-06-25T10:39:00.002+05:45

Software process

It is the way in which we produce software they are five generic framework activities that can be used during the development of programs.

Construction (code generation and testing)
Development (delivered to the customer as a complete entity a as a partially completed)
Communication (heavy interaction and collaboration with the customer)
Planning (establish a plan for the software engineering work that follows)
Modeling (creation of models to help developer & customer to better understand software requirements)

The software process is the set of activities and associate results that produced a software product.

Following are the fundamental process activities

Software Specifications

The functionality of the software and constrains on its operation must be defined

Software development

The software must be developed that meet the specifications

Software Validation

The software must be validated to ensure that it performs what the customer needs

Software Evolution

The software must evolve to meet the changing customer requirements

Following are the software process characteristics

·   Understand ability
·        Visibility
·        Robustness
·        Reliability
·        Acceptability
·        Maintainability
·        Rapidity

Deliverables,Product and process

2019-06-25T09:44:00.003+05:45

Deliverable

A deliverable is a tangible or intangible good or service produced as a result of a project that is intended to be delivered to a customer (either internal or external). A deliverable could be a report, a document, a software product, a server up-grade or any other building block of an overall project. A deliverable may be composed of multiple smaller deliverable. Some deliverable are dependent on other deliverable being completed first, this is common in projects with multiple successive milestone.

Product and process

A software process specifies a method of developing software. A software project on the other hand is a development projects in which a software process is used.

And software products are the outcomes of a software projects.

Measure Metrics and Measurements

2019-06-25T09:26:00.000+05:45

Measure Metrics and Measurements

measure

A software is measure to:

1. Establish the quality of the current product or process

2. To predict the future quality of the product or process

3. To improve the quality of a product process

4. To determine the state of the project in relation to budget and schedule

Measurement

A measurement is an indication of the size quality amount or dimension of a particular attribute of a product or process

For example

The number of errors in a system is measurement

Metrics

A metric is a measurement of the degree that any attribute belongs to a system, product or process

For example

The number of errors per person/hour would be metric

Thus software measurement gives ries to software metrices are related to the four functions of management

· Planning

· Organizing

· Controlling

· Improving

Software metric can be divided into two categories

Product metrices

Product metrics are used to assess the state of the product, tracking ricks and discovering potential (problem areas). The terms ability to control quality is assessed

Process metrics

Process metric focus on improving the long term of the team or organization.

Differences between Computer Organization & Computer Architecture

2019-06-24T13:34:00.000+05:45

Computer Organization	Computer Architecture
1. Computer Organization is concerned with the way the hardware components operate and the way they are connected together to form computer system.	1. Computer Architecture is concerned with the structure and behavior of comp system as seen by the user.
2. It includes Hardware details transparent to the programmer such as control signal and peripheral.	2. It includes information, formats, instruction set and techniques for addressing memory.
3. It describes how the computer performs. 4.Example: circuit design, control signals, memory types this all are under Computer Organization.	3. It describ what the computer does.

Different Types of Software Application

2019-06-24T13:25:00.001+05:45

Applications Of Software

The most significant factor in determining which software engineering methods and techniques are most important is the type of application that is being developed.

Different Types of Software Application

System Software

A collection of programs written to service other programs. Compiler, device driver, editors, file management. for example
compilers, Editors, File Drivers etc.
Real Time software
It monitors /analyze /control real hardware events as they occur is called real time software.It includes a separate data gathering components,an analysis, components and control output components that responds to the external environment and a monitoring component that co-ordinates all other components so that real time response can be maintained.

Application software

It solves a specific Business needs. It is needed to convert the business function in real time. Example -point of sale, Transaction processing, real time manufacturing control.

Scientific or Engineering Software

Applications like based on astronomy, automative stress analysis, molecular Biology, space Shuttle orbital dynamic, automated manufacturing.

Embedded Software

There are software control systems that control and manage hardware devices. Example- software in mobile phone, software in Anti lock Braking in car, software in microwave oven to control the cooking process.

Web based application

It is also called " web apps ", are evolving into sophisticated computing environment that not only provide stand alone features, computing functions, and content to the end user but also are integrated with corporate database and business applications.

Artificial intelligence software

This include- robotic, expert system, pattern recognition, image and voice, artificial neural network, game playing, theorem proving ... It solves Complex problems.

Software Characteristics of good software

2019-06-21T13:05:00.002+05:45

Software Characteristics of good software

Software characteristics are classified into 6 major components there are

Functionality

It refers to the degree of performance of the software against its intended purpose. It basically means are the required functions.

Reliability

A set of attribute that Bear on the capability of software to maintain its level of performances understated conditions for a stated period of time.

Efficiency

It refers to the ability of the software to use System Resources in the most Effective and Efficient Manner. The software should make effective use of storage space and executive commands as per desired timing requirement.

Usability

It refers to the extent to which the software can be used with ease. Or the amount of effort or time required to learn how to use the software should be less.

Maintainability

Refers to the ease with which the modifications can be made in a software system to extend its functionality, improvement, performance or correct errors.

Portability

A set of attributes that bears on the ability of the software to be transferred from one environment to another, without or minimum change.

Empirical estimation technique

2019-06-21T12:55:00.005+05:45

Empirical estimation technique

Empirical estimation technique are based on the data taken from the previous project and some based on guesses and assumptions.

There are many empirical estimation technique but most popular are

Expert Judgement Technique
Delphi Cost Technique

Expert judgement technique

An expert makes an educated guess of the problem size after analyzing the problem thoroughly. Expert estimate the cost of different components that is modules and sub modules of the system.

Disadvantages

Human error, considering not all factors and aspects of the project, individual bias, more chances of failure.

Estimation by group of experts minimize factors such as individual oversight, lack of familiarity with a particular aspect of a project, personal bias and desired to win a contract through overly optimistic estimates.

Delphi cost estimation:

Role of Members: Coordinator provide a copy of Software Requirement Specification (SRS) document and a form of recording it cost estimate to each estimator.
Estimator: It complete their individual estimate anomalously and submit to the coordinator with mentioning, if any, unusual characteristics of product which has influenced his estimation.

The coordinator and distribute the summary of the response to all estimator and they re-estimate them.

different between program and software

2019-06-21T12:45:00.004+05:45

Program	Software
1 They are usually small in size. They are lines of code or maybe 100 to 2000 lines codes on little more.	Very big inside. The lines of codes are in thousands To lac maybe more, depends on Software Product.
2 There is no documentation or lack in documentation.	Proper documentation and well documented and user manual prepared.
3 Developer himself is sole user.	Large or vast number of users
4 Single developer or maybe 2 developer make a program.	A proper and well trained team of developer indulge in development.
5 There is no or lacks proper user interface.	There is proper and full well designed user interface

program

1 They are usually small in size. They are lines of code or maybe 100 to 2000 lines codes on little more.
2 There is no documentation or lack in documentation.
3 Developer himself is sole user.

4 Single developer or maybe 2 developer make a program.

5 There is no or lacks proper user interface.

software

1 Very big inside. The lines of codes are in thousands To lac maybe more, depends on Software Product.

2 Proper documentation and well documented and user manual prepared.

3 Large or vast number of users.

4 A proper and well trained team of developer indulge in development.

5 There is proper and full well designed user interface.

Advantages & Disadvantages Of Spiral Model

2019-06-20T14:46:00.000+05:45

Advantages Of Spiral Model:

Later Stage Changes: Addition functionality or changes can be done at a later stages as proper planning is done at each Iteration.

Easy Cost Estimation: As Prototype building is done in small fragments by which cost estimation becomes easy.

Good Risk Management: As Risk Analysis Stage comes in very early stages and continuous or repeated development helps in Risk Management.

Systematic Development: Development is fast and features can be added in a systematic way.

Space For Customer Feedback: There is continuous feedback is taken at each ITERATION.

Large Project Oriented: It is very good model for handling large and Mission Critical Projects.

Better Project Monitoring: Project Monitoring is very "Easy And Effective". Each Phase as well as "Each Loop, requires a Review from concerned people. This makes people model more Transparent.

Disadvantages Of Spiral Model:

High Cost: Cost involved in this model is quite "HIGH" as more planning, prototype version, risk management has to be done.

Need well expertise: Skills required to evaluate and review project from time to time, need expertise.

No Reusablity of prototype: Due to various customization from client, using same prototype for the other project in future is difficult.

Not suitable for small project: It is quite difficult to follow this strategy for Small Projects due to

Prototype Model

2019-06-19T18:42:00.000+05:45

Prototype Model:

Prototype model is generally used when the requirements are unclear. It is used

when the customer is unclear about the details of the input, process and the output needs of the software.

It is usually built using several "shortcuts". The shortcuts might involve using inefficient, inaccurate, or dummy functions.

In this prototyping quick iterations are planned and quick modelling occurs.

The prototype is implemented and then accessed by customer or user for their feedback to refine requirements for the software.

That prototyping is turned and iterated till the customer satisfaction

Step Wise Approach to Design a Software Prototype

Requirement gathering:

Understanding the very basic product requirement especially in terms of user interface.

Quick design:

After requirement gathering, a quick design is made that is work on flow diagram, languages etc.

Building prototype:

In this basic requirements are showcaseed and user interfaces are provided. This prototype gives some look and feel to the customer in what will be exactly product.

Evaluate / review of the prototype:

The Prototype developed is then presented to the customer and the other stakeholder in the project. Feedback is collected and used for further enhancements.

Refine prototype:

Feedback and comment are discussed and some negotiation happen with customer based on time and budget constraints. The changes accepted again incorporated in new prototype. This cycle repeats until customer expectations are met.

Waterfall Model OR Classical Waterfall Model(Advantages &Disadvantages )

2019-06-19T17:49:00.000+05:45

Waterfall Model OR Classical Waterfall Model:

• Waterfall model is a simplest model of software development paradigm.

• All the phases of sdlc will function one after in linear manner. That is, when the first phase is finished then only the second phase will start and so on.

The Waterfall model was first process model to be introduce and also called "Linear- Sequential Life Cycle Model.

At the end of a phase, a review take place to determine if the project is on the right path and whether or not to continue or discard the project.

In this testing starts only after the development is completed and phases do not overlap.

Advantages of WaterFall Model:

1) Discipline: This staged development cycle enforces discipline. Every phase has a start and end point, and progress can be conclusively identified( through the use of milestones) by both vendor and client.

2) minimal wastage:- the emphasis on requirement and design before writing a single line of code ensure minimal wastage of time and efforts and reduces the risk of schedule slippage.

3) improves quality:- It is much easier to catch and correct possible flows at the design stage then at the testing stage after all the component have been integrated and tracking down specific error is more complex.

Disadvantages of WaterFall Model:

Uncertain Nature of Customer Needs:- due to this estimating time and costs with any degree of accuracy(as the model subjects) is often extremely difficult.

Implicit Assumption to Roadblock: Implicit assumption that designs can be feasibly translated into real products, they sometimes runs into roadblock when developer begin implementation.

No Good Model: Not a good model for Complex and object oriented project as world changing fast as technology changes.

• It haas High amount of risk and uncertainty.

• It is somewhere poor model for long and ongoing projects.

Advantages & Disadvantages of TDMA

2019-06-17T19:14:00.000+05:45

Time Division Multiple Access (TDMA) is a digital cellular telephone communication technology. It facilitates many users to share the same frequency without interference. Its technology divides a signal into different timeslots, and increases the data carrying capacity.

Advantages of TDMA

Here is a list of few notable advantages of TDMA −

· Permits flexible rates (i.e. several slots can be assigned to a user, for example, each time interval translates 32Kbps, a user is assigned two 64 Kbps slots per frame).

· Can withstand gusty or variable bit rate traffic. Number of slots allocated to a user can be changed frame by frame (for example, two slots in the frame 1, three slots in the frame 2, one slot in the frame 3, frame 0 of the notches 4, etc.).

No guard band required for the wideband system

Disadvantages of TDMA

The disadvantages of TDMA are as follow −

· High data rates of broadband systems require complex equalization.

· Due to the burst mode, a large number of additional bits are required for synchronization and supervision.

· Call time is needed in each slot to accommodate time to inaccuracies (due to clock instability).

· Electronics operating at high bit rates increase energy consumption.

· Complex signal processing is required to synchronize within short slots.

Advantages & Disadvantages of FDMA

2019-06-17T19:10:00.002+05:45

Frequency Division Multiple Access (FDMA) is one of the most common analogue multiple access methods. The frequency band is divided into channels of equal bandwidth so that each conversation is carried on a different frequency

Advantages of FDMA

As FDMA systems use low bit rates (large symbol time) compared to average delay spread, it offers the following advantages −

· Reduces the bit rate information and the use of efficient numerical codes increases the capacity.

· It reduces the cost and lowers the inter symbol interference (ISI)

· Equalization is not necessary.

· An FDMA system can be easily implemented. A system can be configured so that the improvements in terms of speech encoder and bit rate reduction may be easily incorporated.

Disadvantages of FDMA

Although FDMA offers several advantages, it has a few drawbacks as well, which are listed below −

· It does not differ significantly from analog systems; improving the capacity depends on the signal-to-interference reduction, or a signal-to-noise ratio (SNR).

· The maximum flow rate per channel is fixed and small.

· Guard bands lead to a waste of capacity.

Advantages & Disadvantages of CDMA(CDMA)

2019-06-17T17:17:00.002+05:45

Code Division Multiple Access (CDMA) is a sort of multiplexing that facilitates various signals to occupy a single transmission channel. It optimizes the use of available bandwidth. The technology is commonly used in ultra-high-frequency (UHF) cellular telephone systems, bands ranging between the 800-MHz and 1.9-GHz.

Advantages of CDMA

CDMA has a soft capacity. The greater the number of codes, the more the number of users. It has the following advantages −

· CDMA requires a tight power control, as it suffers from near-far effect. In other words, a user near the base station transmitting with the same power will drown the signal latter. All signals must have more or less equal power at the receiver

· Rake receivers can be used to improve signal reception. Delayed versions of time (a chip or later) of the signal (multipath signals) can be collected and used to make decisions at the bit level.

· Flexible transfer may be used. Mobile base stations can switch without changing operator. Two base stations receive mobile signal and the mobile receives signals from the two base stations.

Disadvantages of CDMA

The disadvantages of using CDMA are as follows −

· The code length must be carefully selected. A large code length can induce delay or may cause interference.

· Time synchronization is required.

· As the sum of the power received and transmitted from a base station needs constant tight power control. This can result in several handovers.

Differences Between TDM and FDM(abut TDM and FDM)

2019-06-16T11:43:00.000+05:45

Time-division multiplexing (TDM)
is considered to be a digital procedure which can
be employed when the transmission medium data rate quantity is higher than the data
rate requisite of the transmitting and receiving devices.

Frequency-division multiplexing (FDM)
is an analog technique which is implemented only when the bandwidth of the link is higher than the merged bandwidth of the signals to be transmitted.
Each sending device produces signals which modulate at distinct carrier frequencies.
To hold the modulated signal, the carrier frequencies are isolated by adequate bandwidth

Time Division Multiplexing (TDM)	Frequency-Division Multiplexing (FDM)
The time-division multiplexing (TDM) includes sharing of the time through utilizing time slots for the signals.	frequency-division multiplexing (FDM) involves the distribution of the frequencies, where the channel is divided into various bandwidth ranges (channels).
Analog signal or Digital signal any could be utilized for the TDM	FDM works with Analog signals only.
Framing bits (Sync Pulses) are used in TDM at the start of a frame in order to enable synchronization	FDM uses Guard bands to separate the signals and prevent its overlapping
The utilization of physical link in case of TDM is more efficient than in FDM.	FDM system divides the link in multiple channels which does not make use of full channel capacity