Whats A System Life Development Cycle

Published Date: 02 Nov 2017

Task 1

What is a system life development Cycle? Identify three stages of the life cycle and their function

The software development life cycle (SDLC)  is the procedure of crafting or changing software systems, and the models and methodologies that people use to develop these systems. In each such lifecycle, people, procedure and knowledge all frolic a act in success.

SDLC is a procedure of crafting new or changing continuing systems. The SDLC can be believed of as a concept that lies beneath a number of software development methodologies presently retained across industry. From these, the framework to craft, design, and manipulation an information flows that is additionally recognized as the software development process

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Stages of SDLC

The stages of life development cycle are as follows

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Preliminary Investigation: This is one of the most important tasks to understand the real setback of the pre-installed system. The analyst has to spend a lot of time in order to fully realise the problems/fault in the system. The faults could have however overcome if the Preliminary Investigation before installing the system was correctly done. It is the First stage of the development of the system. In this stage the analyst makes a survey by gathering all the available information needed for the system elements and allocation of the requirements to the software.

Analysis of the requirement: The analyst understands the nature of the information and the functions of the software which is required for the system. The analyst then creates a survey of the main requirements then analyzes the performance of the system to which is to be developed. The analyst should also make sure to get enough information and resources for building the appropriate system.

System Design: The analyst actually makes number of designs of the system on paper or on the computer and checks that the rough image made of the system comprises of all the requirements or not. When these actions are completed, the analyst should then select and finalize the best suited design for the development of the system.

System Coding: The analyst translates the code or the programs in a way that they become in machine readable form. The next step of coding is usually time consuming and involves number of rooms for errors.

System Testing: when the analyst has completed the coding stage, he tests the systems and sees to it that it is working as per the expectations or not. The analyst then corrects the problems in the system if any are found.

System Implementation: This is one of the most vital periods as in this period the analyst truly gives the arrangement to the client and expects for a positive feedback

"The implementation stage of software development is the process of converting a system specification into an executable system. It always involves processes of software design and programming but if an evolutionary approach to develop is used, may also involve refinement of the software specification. ( Sommerville 2001)

System Maintenance: The final stage of the SDLC is for the analyst needs to maintain the system and check to see if it is working within the standards set. The analyst needs to maintain the system by removing the defects of flaws occurred.

TASK 2

Identify stages of a System Life Cycle of an organisation, product of other real life scenario you are familiar with

I previously worked in Lenco Ltd an engineering company that designed engine valves for Volkswagen cars. Due to the fact that every car model required a different valve depending on its engine specification and fuel, the system at times encountered problems and a new system was initialised to solve the problems arising.

Planning

The planning phase is the first phase of SDLC. In this phase the team that is responsible for creating the system has idenfied what is required for the company. Lenco Ltd needs a new system because the current system cannot handle the increasing changes of specifications and orders. The new system will be able to allocate orders and separate orders from petrol engine cars and diesel engine cars. The system will also save the orders. Feasibility study will also be carried out in order to check that the new system cost is within the organisation budget and the benefits in the long run. Planning needs to also include what technology and resources are required in order to complete the project. The project manager is responsible for the planning of the project.

Requirement definition:

This is the second phase of the life cycle. At this stage Lenco Ltd analysts work with the user to have better understanding of the system and collect data from the user and analyse the data for development

Gathering details about the current system will involve:

Interviewing staff at different levels of the organisation from the end-users to senior management.

Examining current business and systems documents and output. These may include current order documents, computer systems procedures and reports used by operations and senior management.

Sending out questionnaires and analysing responses. The questions have to be carefully constructed to elicit unambiguous answers.

Observation of current procedures, by spending time in various departments. A time and motion study can be carried out to see where procedures could be made more efficient, or to detect where bottlenecks occur.

The systems analyst’s report will examine how data and information flow around the organisation, and may use data flow diagrams to document the flow. It will also establish precisely and in considerable detail exactly what the proposed system will do (as opposed to how it will do it). It will include an in-depth analysis of the costs and benefits, and outline the process of system implementation, including the organisational change required. It must establish who the end-users are, what information they should get and in what form and how it will be obtained.

System Design

The design phase is the third phase of SDLC and it involves the design of the system.

System design

In Lenco Ltd the design specifies the following aspects of a system:

The hardware platform – which type of computer, network capabilities, input, storage and output devices;

The software – programming language, package or database; (visual basic / java) – provide a good user interface

The outputs – report layouts and screen designs;

The inputs – documents, screen layouts and validation procedures;

The user interface – how users will interact with the computer system;

The modular design of each program in the application;

The test plan and test data;

Conversion plan – how the new system is to be implemented

Documentation including systems and operations documentation. Later, a user manual will be produced.

Implementation

This phase includes both the coding and testing of the system, for Lenco this is the acquisition of hardware and software and the installation of the new system or conversion of the old system to the new one.

The installation phase will include:

Installing the new hardware, which may involve extensive recabling and changes in office layouts;

Training the users on the new system;

Conversion of master files to the new system, or creation of new master files.

Maintenance

This includes the maintenance of the system and any future updates or expansion of the system. For Lenco Ltd this involves maintenance and updating hardware/software for the system in use. Future expansion of the software is involved in this phase.

According to (http:databasemanagement.com) this phase us the longest phase as it has no defined endpoint, with the exception of the end of the system and its users

TASK 3

Explain two different life cycle models and make a comparison between them

Waterfall model

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Requirement Analysis and Definition

All necessities of the system to be designed are done in this phase. Necessities are a set of purposes and constraints that the end - user needs from the system. The necessities are gathered from the end - user at the onset of the software development progress phase. These necessities are next analyzed for their validity, and the potential of incorporating the necessities in the arrangement to be industrialized is additionally studied. Finally, a necessity specification document is crafted that serves the intention of guideline for the subsequent period of the model.

System and Software Design

Before commencing the actual coding period, it is exceedingly vital to comprehend the necessities of the end user and additionally have a rough idea of how the end product looks like. The necessity specifications from the early period are learned in this period and a system design is prepared. The system design aids in enumerating hardware and system requirements and additionally helps in delineating the finished system architecture. The system design specifications assist as an input for the subsequent period of the model.

Implementation and Unit Testing

Upon receiving system design documents, the work is then divided into modules/units and actual coding is started. The system is early industrialized in small programs called units that are then integrated into the next phase. Each unit is tested and developed for its functionality; referring to this as unit testing. Unit testing mainly verifies if the units/modules meet their specifications.

Integration and System Testing

Just as it is specified above, the system is at first divided into units which are then developed and tested for their functions. These units are consolidated into a finished arrangement across integration period and tested to check if all modules/units coordinate alongside every single supplementary, and the system as a whole behaves as per the specifications. Then after successfully testing the software thoroughly, it is delivered to the customer.

Operations & Maintenance

This phase of the model is nearly a never-ending phase. Generally, setbacks alongside with the system developed (which are not found during the development life cycle) come up later its useful to use starts, so the issues related to the system are resolved after the deployment of the system. Not all the setbacks come into picture directly but they arise from period to period and need to be solved; hence this procedure is denoted to as maintenance.

Advantages

One of the advantages of this model is that only after the work for a particular phase is completed, then the other phase can start, meaning there is no overlapping of phases or the product does not have to go through various iterative steps.

There is clear compartmentalization of work and control in the model. Since there is compartmentalization, it is simpler to set schedule the tasks to be done within a specific time frame.

This model is the easiest to apply in the eyes of most of the mangers, due to its linear model. As the procedures of this model are grasped out in linear manner, the price of resources is decreased to a big extent, to which in turn helps in cutting the price of the undertaking considerably.

finally, the documentation and testing occurs at the end of each phase, this in turn helps in maintaining the quality of the project.

Disadvantages

due to the fact it is crucial to gather all possible requirements during the requirement gathering and analysis phase in order to correctly design the system, not all requirements are received at once, the requirements from client carries on getting added to the list even after the end of "requirement gathering and analysis" phase, this in turn affects the system development process and its success in negative aspects.

The problems with one phase are never solved completely during that phase and in fact many problems regarding a particular phase arise after the phase is signed off, these results in badly structured system as not all the problems (related to a phase) are solved during the same phase.

The project is not partitioned in phases in a flexible way.

As the requirements of the customer go on getting added to the list, not all the requirements are fulfilled, this results in development of almost unusable system. These requirements are then met in the newer version of the system; this increases the cost of system development.

Spiral Model

The spiral model was proposed by Boehm. As the name suggests the activities in this model are organised like a spiral. Each loop in the spiral represents a phase of the software process.

The spiral model was introduced, due to the shortcomings in the waterfall and prototype models of software engineering. It is a combination of the said two models of software development. From the name of the model, it can be derived that the activities of software development are carried out like a spiral. To explain the model further, the entire software development process is broken down into small projects. The phases of the spiral model are as follows:

Planning Phase

Risk Analysis Phase

Engineering Phase

Coding and Implementation Phase

Evaluation Phase

http;//freetutes.com/systemsanalysis/sa2-spiral-model.html

Advantages

The disadvantage of the waterfall model is the advantage of the spiral model. It is a realistic model, which is often used in the development of large software. There is a systematic approach used in the spiral model, which is integrated into the iterative framework. This helps in ensuring there is no problems in the software. Since changes to the software can be made at any point of time in the software development process.

Disadvantages

In the spiral model, it is important to have a member in the team, who is an expert at risk assessment. Without correct risk assessment, there are chances that the software can utterly be a failure. The client may have to spend a lot of time with the development team to fix the issues that have cropped up in the software. This may at times become like a overhead for the both the client as well as the software development company. This also leads to the over involvement of the customer in the process of software development, which may cause the customer to ignore certain risks and cause harm to the project.

http://upload.wikimedia.org/wikipedia/en/3/33/Spiral_model_%28Boehm%2C_1988%29.png (http://upload.wikimedia.org/wikipedia/en/3/33/Spiral_model_%28Boehm%2C_1988%29.png )

Waterfall Model

Spiral model

Customer is not involved

Waterfall model is a rigid model which is easily manageble

software is not developed according to the needs of the customer

when the development process shifts to the next stage, there is no going back. This often leads to roadblocks, especially during the coding phase.

Revisiting different phases of software not available in waterfall model

Simple Model / successfully used by system developers over a long period of time

waterfall model has sequential progression, along with clear documentation of the entire process. This ensures one has a better hold over the entire process.

As this is method is a sequence of different phase, there is lack of communication between developer and client therefore the client has to be patient in this process

System results are only visible when the process has finished all its stages

customer is made aware of all the happenings in the software development,

Software is developed according to need of the customer

Since there are different iterations, it is rather easier to change the design and make the software feasible.

one can revisit the different phases of software development, as many times as one wants, during the entire development process

more complicated model due to its iterations

 in spiral model often there is no documentation involved which makes it difficult to keep a track of the entire process.

This method is not rigid thus requiring more concentration and attention during its application

This method is more suitable for large project and it is not as effective as waterfall method when it comes to managing smaller projects

http://bukisa.com/waterfallmodels

http://bukisa.com/spiralmodel