Software products, which don’t happen to be user friendly just, don’t find any place in a highly competitive market of this modern era, although they might have been developed with the help of the best available technology. The ease of use of the product is of paramount importance compared to its internal technology, which the customer is not going to see.
Thus for the creation of Innovative Software products, the Development Life Cycle undergoes six phases like:
1) Initial Phase
2) Analysis Phase
3) Design phase
4) Coding Phase
5) Testing Phase
6) Delivery and Maintenance phase
Phase – 1: Initial Phase: Involves Interaction with the customer and capturing all the requirements.
Personnel Involved: 1) Business Annalist – BA & 2) Engagement Manager - EM
Process Involved: This phase begins with a technical meeting between the Business Analyst & the customer. The Business Analyst (BM) understands all the requirements from the customer & prepares comprehensive requirements document with the help of standard templates & check sheets used by the company. The requirements document forms the basis for further study & action by the Engagement Manager (EM).
The Engagement Manager tries to hunt for extra requirements if any, which might not be apparent immediately but might involve extra cost. To resolve ambiguous requirements if any, the Engagement Manager organizes demonstration of a prototype if necessary. Such action of quick demonstration of a prototype, which is nothing but a rapidly developed model for the customer is found extremely helpful to remove ambiguities from the requirements on one hand & help winning the confidence of the customer on the other.
Ultimate objective of this phase is to prepare a most comprehensive customer requirements document. Many companies call it with different names like:
# BRS: Business Requirement Specification.
# FRS: Functional Requirement Specification.
# URS: User Requirement Specification.
# CRS: Client / Customer Requirement Specification.
# BDD: Business Design Document.
# BD : Business Document.
Depending upon the system followed by various companies, sometimes a single document is maintained, while some companies may go in for two documents. In this case, Broad / outlining information is recorded in the BRS (Business Requirement Specification), while detailed information is recorded in FRS (Functional Requirement Specification).
Phase – 2: Analysis Phase: Involves Feasibility Study, Broad Planning, Technology selection, Requirement analysis etc.
Personnel Involved: 1) System Annalist – SA, 2) Project Manager – PM & 3) Team Manager -TM
Process Involved: To understand the nature of the program to be developed, the System Annalist focuses on understanding the information domain of the software, its necessary functions, behaviors, performance and necessary interfaces etc. The major objective of the analysis phase is to find out the need and to define the problem, which needs to be solved.
The process covers four distinct analytical operations like:
1) Feasibility Study: Involves detailed study of all the requirements to ascertain as to whether it is possible to meet all the requirements or not. There may be a need for the development team to visit the customer place for study of their system. They development team may investigate the need for possible software automation within the boundaries of the given system.
2) Broad Planning: Involves an outline document on planning of all resource and time wise planning.
3) Technology Selection: Involves identification, analysis & compilation of various tools & technologies, which would be needed to accomplish the project successfully.
4) Requirement analysis: Involves identification & compilation of various requirements of human resources, hardware & software, which would be needed to accomplish the project successfully.
Ultimate objective of this phase is to prepare a most comprehensive document called SRC or Software Requirement Specification.
Phase – 3: Design Phase: Involves hard core design activities like 1) HLD - High Level Designing & 2) LLD - Low Level Designing
Personnel Involved: 1) Chief Architect – CA is responsible for High Level Designing, 2) Technical Lead – TL is responsible for Low Level Designing
Process Involved: The Chief Architect – CA, starts The entire designing process. This involves subdivision of the entire project into various modules & the process is adequately explained with the help of flow charts & diagrams. Thereafter, the Technical Lead – TL further subdivides these main Modules into sub modules with the help of Unified Modeling Language - UML. The technical lead is responsible for creating the Pseudo Code which is a comprehensive set of instructions written in English language & are meant for guiding the actual code developers.
Ultimate objective of this phase is to prepare a Technical Design Document - TDD.
Phase – 4: Coding Phase: Involves actual Programming or Coding.
Personnel Involved: Code Developers or Programmers
Process Involved: The design needs to be translated into a machine-readable form. There comes the process of code generation. With the help of Pseudo Code written by the Technical Lead – TL during the Design Phase, Developers carry out the development of the actual source code. The entire coding process is bound by stipulated coding standards defined by the company.
Ultimate objective of this phase is to prepare a Source Code Document - SCD.
Phase – 5: Testing Phase: Involves rigorous testing of the application developed by the programmers.
Personnel Involved: Testing Engineers.
Process Involved: Different testing methodologies are practiced to detect the software bugs, which happen to take birth during the previous phases. Various testing tools and methodologies are available these days. Some companies create their own testing tools, which are custom made to suit their own development functions.
# In fact the testing process begins right from the customer requirement document. A good test engineer starts his work by thorough study of the requirement document. In case of any doubt arising during understanding of customer requirements, the test engineer raises a Review Report –RR, which contains details of all the doubts.
# Having clarified all the doubts & ambiguities, and after having a thorough understanding of the requirements, the test engineer shall write the test cases with the help of company specific test case templates.
# Execution of the test cases upon the release of the first build by the developers. This follows recording of defects in a defect profile document.
# The defect profile document is transferred to the developers for improvements / eradication of defects found by them. The testing process halts here till next build with improvements is released by the developers.
# The entire testing process involving execution of test cases is repeated on the new build. This process of code improvement, subsequent testing on new builds & finding of defects continues again and again till the product is free from defects.
# The testing process is decided to be stopped after gaining reasonable confidence of product being defect free
Ultimate objective of this phase is to produce a Quality Product.
Phase – 6: Delivery and Maintenance phase: Involves Installing the newly developed application under the client environment.
Personnel Involved: Senior Testing Engineers who are entrusted the task of Deployment Engineers.
Process Involved:
# Delivery: After the code is appropriately tested, it is approved for release, it is deployed into a production environment. The deployment of application is done with the help of guidelines provided in the application deployment document.
# Maintenance: After the deployment of the application, client may encounter many task-based problems.
Maintaining and enhancing the software to cope up with newly discovered problems or new requirements can take far more time than the initial development of the software. It may be necessary to add some code, which does not fit the original design to correct an unforeseen problem. It may be that the customer is requesting more functionality, and some code can be added to take care of his requests.
Showing posts with label SDLC. Show all posts
Showing posts with label SDLC. Show all posts
Friday, September 9, 2011
Monday, December 20, 2010
Different Types of SDLC
System Development Life Cycle (SDLC) Model:
The software development life cycle (SDLC) is the entire process of formal, logical steps taken to develop a software product. The systems development life cycle (SDLC) is a conceptual model used in project management that describes the stages involved in an information system development project, from an initial feasibility study through maintenance of the completed application.
Software Development Models
The following are some basic popular models that are adopted by many software development firms
A. Waterfall Model
B. Prototyping Model
C. Rapid Application Development Model
D. Component Assembly Model
A. Waterfall Model
This is also known as Classic Life Cycle Model (or) Linear Sequential Model (or) Waterfall Method. This model has the following activities.
1. System/Information Engineering and Modelling
As software is always of a large system (or business), work begins by establishing the requirements for all system elements and then allocating some subset of these requirements to software. This system view is essential when the software must interface with other elements such as hardware, people and other resources. System is the basic and very critical requirement for the existence of software in any entity. So if the system is not in place, the system should be engineered and put in place. In some cases, to extract the maximum output, the system should be re-engineered and spruced up. Once the ideal system is engineered or tuned, the development team studies the software requirement for the system.
2. Software Requirement Analysis
This process is also known as feasibility study. In this phase, the development team visits the customer and studies their system. They investigate the need for possible software automation in the given system. By the end of the feasibility study, the team furnishes a document that holds the different specific recommendations for the candidate system. It also includes the personnel assignments, costs, project schedule, target dates etc.... The requirement gathering process is intensified and focussed specially on software. To understand the nature of the program(s) to be built, the system engineer or "Analyst" must understand the information domain for the software, as well as required function, behavior, performance and interfacing. The essential purpose of this phase is to find the need and to define the problem that needs to be solved .
3. System Analysis and Design
In this phase, the software development process, the software's overall structure and its nuances are defined. In terms of the client/server technology, the number of tiers needed for the package architecture, the database design, the data structure design etc... are all defined in this phase. A software development model is thus created. Analysis and Design are very crucial in the whole development cycle. Any glitch in the design phase could be very expensive to solve in the later stage of the software development. Much care is taken during this phase. The logical system of the product is developed in this phase.
4. Code Generation
The design must be translated into a machine-readable form. The code generation step performs this task. If the design is performed in a detailed manner, code generation can be accomplished without much complication. Programming tools like compilers, interpreters, debuggers etc... are used to generate the code. Different high level programming languages like C, C++, Pascal, Java are used for coding. With respect to the type of application, the right programming language is chosen.
5. Testing
Once the code is generated, the software program testing begins. Different testing methodologies are available to unravel the bugs that were committed during the previous phases. Different testing tools and methodologies are already available. Some companies build their own testing tools that are tailor made for their own development operations.
6. Maintenance
The software will definitely undergo change once it is delivered to the customer. There can be many reasons for this change to occur. Change could happen because of some unexpected input values into the system. In addition, the changes in the system could directly affect the software operations. The software should be developed to accommodate changes that could happen during the post implementation period.
B. Prototyping Model
This is a cyclic version of the linear model. In this model, once the requirement analysis is done and the design for a prototype is made, the development process gets started. Once the prototype is created, it is given to the customer for evaluation. The customer tests the package and gives his/her feed back to the developer who refines the product according to the customer's exact expectation. After a finite number of iterations, the final software package is given to the customer. In this methodology, the software is evolved as a result of periodic shuttling of information between the customer and developer. This is the most popular development model in the contemporary IT industry. Most of the successful software products have been developed using this model - as it is very difficult (even for a whiz kid!) to comprehend all the requirements of a customer in one shot. There are many variations of this model skewed with respect to the project management styles of the companies. New versions of a software product evolve as a result of prototyping.
C. Rapid Application Development (RAD) Model
The RAD modelis a linear sequential software development process that emphasizes an extremely short development cycle. The RAD model is a "high speed" adaptation of the linear sequential model in which rapid development is achieved by using a component-based construction approach. Used primarily for information systems applications, the RAD approach encompasses the following phases:
1. Business modeling
The information flow among business functions is modeled in a way that answers the following questions:
What information drives the business process?
What information is generated?
Who generates it?
Where does the information go?
Who processes it?
2. Data modeling
The information flow defined as part of the business modeling phase is refined into a set of data objects that are needed to support the business. The characteristic (called attributes) of each object is identified and the relationships between these objects are defined.
3. Process modeling
The data objects defined in the data-modeling phase are transformed to achieve the information flow necessary to implement a business function. Processing the descriptions are created for adding, modifying, deleting, or retrieving a data object.
4. Application generation
The RAD model assumes the use of the RAD tools like VB, VC++, Delphi etc... rather than creating software using conventional third generation programming languages. The RAD model works to reuse existing program components (when possible) or create reusable components (when necessary). In all cases, automated tools are used to facilitate construction of the software.
5. Testing and turnover
Since the RAD process emphasizes reuse, many of the program components have already been tested. This minimizes the testing and development time.
D.Component Assembly Model
Object technologies provide the technical framework for a component-based process model for software engineering. The object oriented paradigm emphasizes the creation of classes that encapsulate both data and the algorithm that are used to manipulate the data. If properly designed and implemented, object oriented classes are reusable across different applicationsand computer based system architectures. Component Assembly Model leads to software reusability. The integration/assembly of the already existing software components accelerate the development process. Nowadays many component libraries are available on the Internet. If the right components are chosen, the integration aspect is made much simpler.
The software development life cycle (SDLC) is the entire process of formal, logical steps taken to develop a software product. The systems development life cycle (SDLC) is a conceptual model used in project management that describes the stages involved in an information system development project, from an initial feasibility study through maintenance of the completed application.
Software Development Models
The following are some basic popular models that are adopted by many software development firms
A. Waterfall Model
B. Prototyping Model
C. Rapid Application Development Model
D. Component Assembly Model
A. Waterfall Model
This is also known as Classic Life Cycle Model (or) Linear Sequential Model (or) Waterfall Method. This model has the following activities.
1. System/Information Engineering and Modelling
As software is always of a large system (or business), work begins by establishing the requirements for all system elements and then allocating some subset of these requirements to software. This system view is essential when the software must interface with other elements such as hardware, people and other resources. System is the basic and very critical requirement for the existence of software in any entity. So if the system is not in place, the system should be engineered and put in place. In some cases, to extract the maximum output, the system should be re-engineered and spruced up. Once the ideal system is engineered or tuned, the development team studies the software requirement for the system.
2. Software Requirement Analysis
This process is also known as feasibility study. In this phase, the development team visits the customer and studies their system. They investigate the need for possible software automation in the given system. By the end of the feasibility study, the team furnishes a document that holds the different specific recommendations for the candidate system. It also includes the personnel assignments, costs, project schedule, target dates etc.... The requirement gathering process is intensified and focussed specially on software. To understand the nature of the program(s) to be built, the system engineer or "Analyst" must understand the information domain for the software, as well as required function, behavior, performance and interfacing. The essential purpose of this phase is to find the need and to define the problem that needs to be solved .
3. System Analysis and Design
In this phase, the software development process, the software's overall structure and its nuances are defined. In terms of the client/server technology, the number of tiers needed for the package architecture, the database design, the data structure design etc... are all defined in this phase. A software development model is thus created. Analysis and Design are very crucial in the whole development cycle. Any glitch in the design phase could be very expensive to solve in the later stage of the software development. Much care is taken during this phase. The logical system of the product is developed in this phase.
4. Code Generation
The design must be translated into a machine-readable form. The code generation step performs this task. If the design is performed in a detailed manner, code generation can be accomplished without much complication. Programming tools like compilers, interpreters, debuggers etc... are used to generate the code. Different high level programming languages like C, C++, Pascal, Java are used for coding. With respect to the type of application, the right programming language is chosen.
5. Testing
Once the code is generated, the software program testing begins. Different testing methodologies are available to unravel the bugs that were committed during the previous phases. Different testing tools and methodologies are already available. Some companies build their own testing tools that are tailor made for their own development operations.
6. Maintenance
The software will definitely undergo change once it is delivered to the customer. There can be many reasons for this change to occur. Change could happen because of some unexpected input values into the system. In addition, the changes in the system could directly affect the software operations. The software should be developed to accommodate changes that could happen during the post implementation period.
B. Prototyping Model
This is a cyclic version of the linear model. In this model, once the requirement analysis is done and the design for a prototype is made, the development process gets started. Once the prototype is created, it is given to the customer for evaluation. The customer tests the package and gives his/her feed back to the developer who refines the product according to the customer's exact expectation. After a finite number of iterations, the final software package is given to the customer. In this methodology, the software is evolved as a result of periodic shuttling of information between the customer and developer. This is the most popular development model in the contemporary IT industry. Most of the successful software products have been developed using this model - as it is very difficult (even for a whiz kid!) to comprehend all the requirements of a customer in one shot. There are many variations of this model skewed with respect to the project management styles of the companies. New versions of a software product evolve as a result of prototyping.
C. Rapid Application Development (RAD) Model
The RAD modelis a linear sequential software development process that emphasizes an extremely short development cycle. The RAD model is a "high speed" adaptation of the linear sequential model in which rapid development is achieved by using a component-based construction approach. Used primarily for information systems applications, the RAD approach encompasses the following phases:
1. Business modeling
The information flow among business functions is modeled in a way that answers the following questions:
What information drives the business process?
What information is generated?
Who generates it?
Where does the information go?
Who processes it?
2. Data modeling
The information flow defined as part of the business modeling phase is refined into a set of data objects that are needed to support the business. The characteristic (called attributes) of each object is identified and the relationships between these objects are defined.
3. Process modeling
The data objects defined in the data-modeling phase are transformed to achieve the information flow necessary to implement a business function. Processing the descriptions are created for adding, modifying, deleting, or retrieving a data object.
4. Application generation
The RAD model assumes the use of the RAD tools like VB, VC++, Delphi etc... rather than creating software using conventional third generation programming languages. The RAD model works to reuse existing program components (when possible) or create reusable components (when necessary). In all cases, automated tools are used to facilitate construction of the software.
5. Testing and turnover
Since the RAD process emphasizes reuse, many of the program components have already been tested. This minimizes the testing and development time.
D.Component Assembly Model
Object technologies provide the technical framework for a component-based process model for software engineering. The object oriented paradigm emphasizes the creation of classes that encapsulate both data and the algorithm that are used to manipulate the data. If properly designed and implemented, object oriented classes are reusable across different applicationsand computer based system architectures. Component Assembly Model leads to software reusability. The integration/assembly of the already existing software components accelerate the development process. Nowadays many component libraries are available on the Internet. If the right components are chosen, the integration aspect is made much simpler.
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