The document discusses several software life-cycle models:
1) Code-and-fix model - writing code without design or requirements, fixing as needed, which leads to maintenance issues.
2) Waterfall model - phases are completed sequentially with documentation and approval between phases.
3) Rapid prototyping - an initial prototype gets feedback before completing development.
4) Open-source model - an informal process where individuals voluntarily maintain software over time through corrective, perfective and adaptive changes based on user reports.
The document discusses best practices for quality software development including defining quality code, design, and processes. It outlines common problems like poor requirements, unrealistic schedules, and miscommunication. It recommends solid requirements, realistic schedules, adequate testing, sticking to initial requirements where possible, and good communication. The document also presents 7 principles of quality development including keeping it simple, maintaining vision, planning for reuse, and thinking before acting. It concludes with tips for developers like focusing on users and tools to aid development.
The document discusses test automation in agile environments. It covers Capgemini's World Quality Report on automation, the evolution of business models and IT ecosystems, and challenges with agile automation. Key topics include testing being embedded within the Scrum process with no separate schedule for testing, the importance of test-driven development and behavior-driven development, achieving high levels of automation coverage, and using tools like Cucumber, JUnit, and Selenium to support test automation. The document emphasizes that automation is necessary to achieve faster time to market and increased productivity in agile.
6 basic steps of software development processRiant Soft
The document outlines the six basic stages of the software development life cycle: 1) Requirement gathering and analysis, 2) System analysis, 3) System design, 4) Coding, 5) Testing, and 6) Implementation. It describes each stage in the process, from gathering requirements from stakeholders to implementing the final tested software. An effective software development life cycle ensures quality and correctness through rigorous testing and design at each stage of building the software.
This document discusses Feature Driven Development (FDD), which was invented by Jeff De Luca in 1997. FDD involves modeling the domain, creating a feature list, designing by feature, building by feature, and having 6 milestones including domain walk-through, design, coding, testing and inspection. The example provided 50 people working on a 15 month project using this methodology.
The document discusses the software development process and defines key terms. It states that a software process organizes development activities and includes roles, workflows, procedures and standards. Following a defined process makes software development more orderly, predictable and repeatable. However, some view following a process as unnecessary overhead. The reality is that not following a process can lead to more rework that outweighs any initial time savings. The document also discusses software life cycle models, such as waterfall and iterative models, and how a good process is repeatable, predictable, adaptable, learnable and measurable.
Rajeswara Rao has over 3 years of experience in software testing, including 1.2 years of manual testing and 2.4 years of automation testing using Selenium. He has experience testing web applications and developing automated test scripts in Java using frameworks like Selenium WebDriver, JUnit, and TestNG. He has worked as a Software Test Engineer at Corpus Software private Ltd since 2011 where he has tested digital signage, middleware, and STB projects.
The document discusses several software development life cycle (SDLC) models: Waterfall, V-shaped, structured evolutionary prototyping, rapid application development (RAD), incremental, and spiral. For each model, it describes the key steps, strengths, weaknesses, and scenarios where the model is best applied. The Waterfall model involves sequential phases from requirements to maintenance, while the V-shaped model adds verification and validation phases. Structured evolutionary prototyping uses iterative prototyping for requirements gathering. RAD emphasizes rapid delivery through time-boxing and productivity tools. Incremental development prioritizes requirements delivery in groups. The spiral model incorporates risk analysis, prototyping, and iterative cycles.
The document discusses best practices for quality software development including defining quality code, design, and processes. It outlines common problems like poor requirements, unrealistic schedules, and miscommunication. It recommends solid requirements, realistic schedules, adequate testing, sticking to initial requirements where possible, and good communication. The document also presents 7 principles of quality development including keeping it simple, maintaining vision, planning for reuse, and thinking before acting. It concludes with tips for developers like focusing on users and tools to aid development.
The document discusses test automation in agile environments. It covers Capgemini's World Quality Report on automation, the evolution of business models and IT ecosystems, and challenges with agile automation. Key topics include testing being embedded within the Scrum process with no separate schedule for testing, the importance of test-driven development and behavior-driven development, achieving high levels of automation coverage, and using tools like Cucumber, JUnit, and Selenium to support test automation. The document emphasizes that automation is necessary to achieve faster time to market and increased productivity in agile.
6 basic steps of software development processRiant Soft
The document outlines the six basic stages of the software development life cycle: 1) Requirement gathering and analysis, 2) System analysis, 3) System design, 4) Coding, 5) Testing, and 6) Implementation. It describes each stage in the process, from gathering requirements from stakeholders to implementing the final tested software. An effective software development life cycle ensures quality and correctness through rigorous testing and design at each stage of building the software.
This document discusses Feature Driven Development (FDD), which was invented by Jeff De Luca in 1997. FDD involves modeling the domain, creating a feature list, designing by feature, building by feature, and having 6 milestones including domain walk-through, design, coding, testing and inspection. The example provided 50 people working on a 15 month project using this methodology.
The document discusses the software development process and defines key terms. It states that a software process organizes development activities and includes roles, workflows, procedures and standards. Following a defined process makes software development more orderly, predictable and repeatable. However, some view following a process as unnecessary overhead. The reality is that not following a process can lead to more rework that outweighs any initial time savings. The document also discusses software life cycle models, such as waterfall and iterative models, and how a good process is repeatable, predictable, adaptable, learnable and measurable.
Rajeswara Rao has over 3 years of experience in software testing, including 1.2 years of manual testing and 2.4 years of automation testing using Selenium. He has experience testing web applications and developing automated test scripts in Java using frameworks like Selenium WebDriver, JUnit, and TestNG. He has worked as a Software Test Engineer at Corpus Software private Ltd since 2011 where he has tested digital signage, middleware, and STB projects.
The document discusses several software development life cycle (SDLC) models: Waterfall, V-shaped, structured evolutionary prototyping, rapid application development (RAD), incremental, and spiral. For each model, it describes the key steps, strengths, weaknesses, and scenarios where the model is best applied. The Waterfall model involves sequential phases from requirements to maintenance, while the V-shaped model adds verification and validation phases. Structured evolutionary prototyping uses iterative prototyping for requirements gathering. RAD emphasizes rapid delivery through time-boxing and productivity tools. Incremental development prioritizes requirements delivery in groups. The spiral model incorporates risk analysis, prototyping, and iterative cycles.
This document discusses Behavior Driven Development (BDD), which is an agile software development methodology that focuses on defining and testing business requirements through executable specifications and acceptance criteria. The document covers the key concepts of BDD, including outside-in development, pull-based planning, and defining behavior through user stories and scenarios. It also discusses how BDD compares to other techniques like test-driven development and finite state machines. The overall goal of BDD is to facilitate collaboration between developers and business stakeholders to build the right product through living documentation of desired behaviors.
Learn how Acceptance Test Driven Development (ATDD) provides the process for capturing detailed requirements as acceptance criteria and turn them into as test cases before development begins using Behavior Driven Development (BDD). The BDD approach and Gherkin format is the language used to create easy to understand and actionable scenarios that map from the functional level to the components and units. We will discuss the different approaches to TDD including a realistic approach leveraging BDD to a purest standpoint where TDD use the tests to drive the design of the application. Finally understand how the tools in Visual Studio and Team foundation Server to support BDD such as SpecFlow (Cucumber in .NET), Refactoring tools, and Test Cases in MTM.
The document provides an overview of the Software Development Life Cycle (SDLC) including its various stages and models. The key points are:
1. SDLC is a process that consists of planning, analysis, design, implementation, testing, deployment, and maintenance phases to develop and maintain software.
2. The stages include planning, requirements analysis, design, development, testing, deployment, and maintenance.
3. Common models include waterfall, iterative, spiral, V-model, and agile. Waterfall is the earliest and most basic sequential model while iterative and agile are more flexible to changing requirements.
With Camunda 7.2, you can call Web Services (REST, SOAP) directly from BPMN. This is based on a generic mechanism that allows you to create your very own connectors. In addition with new capabilities for handling XML and JSON as well as using script languages like Javascript or Groovy and template engines like Freemarker and XSLT, this is a very powerful toolbox for system integration.
This document discusses agile software development methods. It outlines the agile manifesto which values individuals and interactions over processes, working software over documentation, and customer collaboration over contract negotiation. Some key agile principles include customer satisfaction, welcome changing requirements, and frequent delivery of working software. Common agile methods like extreme programming and scrum are also summarized. Advantages include improved customer satisfaction and responsiveness to change, while disadvantages include potential lack of documentation.
Testing software is conducted to ensure the system meets user needs and requirements. The primary objectives of testing are to verify that the right system was built according to specifications and that it was built correctly. Testing helps instill user confidence, ensures functionality and performance, and identifies any issues where the system does not meet specifications. Different types of testing include unit, integration, system, and user acceptance testing, which are done at various stages of the software development life cycle.
The quality of software systems may be expressed as a collection of Software Quality Attributes. When the system requirements are defined, it is essential also to define what is expected regarding these quality attributes, since these expectations will guide the planning of the system architecture and design.
Software quality attributes may be classified into two main categories: static and dynamic. Static quality attributes are the ones that reflect the system’s structure and organization. Examples of static attributes are coupling, cohesion, complexity, maintainability and extensibility. Dynamic attributes are the ones that reflect the behavior of the system during its execution. Examples of dynamic attributes are memory usage, latency, throughput, scalability, robustness and fault-tolerance.
Following the definitions of expectations regarding the quality attributes, it is essential to devise ways to measure them and verify that the implemented system satisfies the requirements. Some static attributes may be measured through static code analysis tools, while others require effective design and code reviews. The measuring and verification of dynamic attributes requires the usage of special non-functional testing tools such as profilers and simulators.
In this talk I will discuss the main Software Quality attributes, both static and dynamic, examples of requirements, and practical guidelines on how to measure and verify these attributes.
This document discusses end-to-end testing and why it is important for complex modern software systems with multiple interconnected subsystems. End-to-end testing ensures that all subsystems work together as expected by testing user journeys that trigger actions across systems. It recommends planning end-to-end test cases that think through scenarios from start to finish and avoid adding unnecessary tests. Automating end-to-end test cases is difficult but valuable as it can catch issues that arise from system interactions.
The document discusses several common software life cycle models: the waterfall model, rapid application development (RAD) model, prototyping model, and spiral model. The waterfall model involves sequential phases from requirements to maintenance without overlap. The RAD model emphasizes rapid delivery through iterative prototyping. The prototyping model builds prototypes to refine requirements before full development. Finally, the spiral model takes a risk-driven approach to software development through iterative planning, risk analysis, and evaluations.
This document provides an overview of test-driven development (TDD). It defines TDD as a technique for building software where tests are written before code to guide development. The key aspects of TDD covered are:
- Writing tests first before code, which helps improve design and ensures tests are written.
- The TDD mantra of Red-Green-Refactor, where tests initially fail (Red), code is written to pass tests (Green), then code is refactored to improve design.
- An example case study of a large Java project developed using TDD that has over 20,000 lines of unit tests providing over 90% test coverage.
The document presents information on the Software Development Life Cycle (SDLC), including:
1) It describes the seven main phases of the SDLC - planning, analysis, design, development, testing, implementation, and maintenance.
2) It discusses several SDLC models like waterfall, iterative, prototyping, spiral and V-model and compares their strengths and weaknesses.
3) It emphasizes the important role of testing in the SDLC and describes different testing types done during the phases.
The document provides an overview of the Software Development Lifecycle (SDLC) process. It describes the typical phases of SDLC, including planning, analysis, design, development, testing, deployment, and maintenance. It also discusses different SDLC models like waterfall, V-model, iterative, spiral, agile, and fish models. Each model follows a series of steps to ensure success in the software development process. The document aims to explain the importance of following a structured software development approach using SDLC.
The document outlines an automation testing syllabus covering software development lifecycles, the role of testers, types of testing, test techniques, test cases, test plans, bugs, Java concepts, production tools, load testing, test management tools, and real-world manual testing projects. Key topics include waterfall, agile, and scrum models; unit, integration, and regression testing; black box and white box techniques; test plans; bug tracking; Java fundamentals; and tools like JUnit, Selenium, JIRA, LoadRunner, and QTP. The syllabus aims to equip students with the skills needed for both manual and automation testing.
Priyanka Meher has over 5 years of experience in IT testing in the telecom and BFSI domains. She has expertise in manual and automation testing using tools like HP Quality Center, QTP, and UFT. She has led testing teams and been responsible for test planning, execution, and reporting. She has received several awards for her work and achievements in test automation.
This document summarizes key concepts from the first chapter of Ian Sommerville's Software Engineering textbook. It introduces software engineering as an engineering discipline concerned with all aspects of software production. It discusses the objectives of software engineering, topics covered like frequently asked questions and professional responsibility. It also summarizes concepts like the software development process, methods, costs and challenges in the field.
DRB EXP RESUME manual and selenium master copy corrected 2Dikhit Behera
Dikhit Ranjan Behera has over 2 years of experience in information technology, including 1 year of experience with automation testing using Selenium. He has skills in manual testing, automation testing with Selenium and TestNG, defect tracking with tools like HPQC and Jira, and programming languages like Java. He currently works as an Associate Software Engineer at Mphasis Limited, where he has been involved in testing projects including an asset management system and a healthcare application.
4 Nisan 2015 tarihinde Kadir Has Üniversitesi'nde yapılan 9. Yazılım Teknolojileri Seminer etkinliğinde Eralp Erat'ın yaptığı TDD (Test Driven Design) sunumu
Now-a-days the world of testing has shifted towards a Continuous Testing model. With increasing digital transformation, Agile & DevOps principles, the need to scale up quality initiatives becomes inevitable. Moreover, with increasing complexity and continuous integration cycles, the frequency of tests to release apps in a shorter time frame with continuous testing becomes the need of the hour to match the speed of Agile & DevOps.
Fast feedback loops and immediate responses allow businesses to adapt to changes in the market quicker than ever before. This is made possible with automation and continuous testing. But how do you achieve continuous testing?
In this, our specialist Sushma Nayak will discuss the present-day best practices in test automation at Knoldus and will examine the key testing trends that focus on the adoption of Continuous Delivery and the evolution of test automation in the coming year.
watch the video of this session on our website: https://www.knoldus.com/learn/webinars
What is professional software development and definition of software engineering. Who is a software engineer. Difference between Computer Science and Systems Engineering
The document provides a summary of Manoj Prabhakar's career experience in the telecom and mobile handset application industry. It outlines his 6+ years of experience testing 3G, 2G, and real-time mobile applications on Android, Symbian S60, and Ericsson Mobile Platforms. It also lists his technical skills and responsibilities on various projects for clients like Ericsson, MacroSolve, AT&T, and Motorola Mobility involving testing applications and features on different mobile platforms.
Process Model in Software Engineering.pptAtharvaBavge
Process models provide a structured approach to software engineering by defining key activities and flows. Generic process models include communication, planning, modeling, construction, and deployment activities. Process flows can be linear, iterative, evolutionary, or parallel. Prescriptive models like the waterfall model advocate an orderly approach but lack flexibility for changing requirements. The incremental and spiral models incorporate iteration and prototypes to accommodate change while still providing structure. Evolutionary approaches address changing requirements but require management of project planning and evolution speed.
Structured system analysis and design Jayant Dalvi
The document discusses four common software development models: Waterfall, Spiral, Prototyping, and RAD (Rapid Application Development). It describes the key phases and characteristics of each model. The Waterfall model follows a linear sequence of phases from requirements to maintenance without iteration. The Spiral model is iterative with a risk-analysis focus. Prototyping emphasizes early customer feedback through prototypes. RAD prioritizes rapid delivery of high priority functionality through reuse and automated tools. Each model has advantages for certain types of projects depending on requirements clarity, budget, and risks.
This document discusses Behavior Driven Development (BDD), which is an agile software development methodology that focuses on defining and testing business requirements through executable specifications and acceptance criteria. The document covers the key concepts of BDD, including outside-in development, pull-based planning, and defining behavior through user stories and scenarios. It also discusses how BDD compares to other techniques like test-driven development and finite state machines. The overall goal of BDD is to facilitate collaboration between developers and business stakeholders to build the right product through living documentation of desired behaviors.
Learn how Acceptance Test Driven Development (ATDD) provides the process for capturing detailed requirements as acceptance criteria and turn them into as test cases before development begins using Behavior Driven Development (BDD). The BDD approach and Gherkin format is the language used to create easy to understand and actionable scenarios that map from the functional level to the components and units. We will discuss the different approaches to TDD including a realistic approach leveraging BDD to a purest standpoint where TDD use the tests to drive the design of the application. Finally understand how the tools in Visual Studio and Team foundation Server to support BDD such as SpecFlow (Cucumber in .NET), Refactoring tools, and Test Cases in MTM.
The document provides an overview of the Software Development Life Cycle (SDLC) including its various stages and models. The key points are:
1. SDLC is a process that consists of planning, analysis, design, implementation, testing, deployment, and maintenance phases to develop and maintain software.
2. The stages include planning, requirements analysis, design, development, testing, deployment, and maintenance.
3. Common models include waterfall, iterative, spiral, V-model, and agile. Waterfall is the earliest and most basic sequential model while iterative and agile are more flexible to changing requirements.
With Camunda 7.2, you can call Web Services (REST, SOAP) directly from BPMN. This is based on a generic mechanism that allows you to create your very own connectors. In addition with new capabilities for handling XML and JSON as well as using script languages like Javascript or Groovy and template engines like Freemarker and XSLT, this is a very powerful toolbox for system integration.
This document discusses agile software development methods. It outlines the agile manifesto which values individuals and interactions over processes, working software over documentation, and customer collaboration over contract negotiation. Some key agile principles include customer satisfaction, welcome changing requirements, and frequent delivery of working software. Common agile methods like extreme programming and scrum are also summarized. Advantages include improved customer satisfaction and responsiveness to change, while disadvantages include potential lack of documentation.
Testing software is conducted to ensure the system meets user needs and requirements. The primary objectives of testing are to verify that the right system was built according to specifications and that it was built correctly. Testing helps instill user confidence, ensures functionality and performance, and identifies any issues where the system does not meet specifications. Different types of testing include unit, integration, system, and user acceptance testing, which are done at various stages of the software development life cycle.
The quality of software systems may be expressed as a collection of Software Quality Attributes. When the system requirements are defined, it is essential also to define what is expected regarding these quality attributes, since these expectations will guide the planning of the system architecture and design.
Software quality attributes may be classified into two main categories: static and dynamic. Static quality attributes are the ones that reflect the system’s structure and organization. Examples of static attributes are coupling, cohesion, complexity, maintainability and extensibility. Dynamic attributes are the ones that reflect the behavior of the system during its execution. Examples of dynamic attributes are memory usage, latency, throughput, scalability, robustness and fault-tolerance.
Following the definitions of expectations regarding the quality attributes, it is essential to devise ways to measure them and verify that the implemented system satisfies the requirements. Some static attributes may be measured through static code analysis tools, while others require effective design and code reviews. The measuring and verification of dynamic attributes requires the usage of special non-functional testing tools such as profilers and simulators.
In this talk I will discuss the main Software Quality attributes, both static and dynamic, examples of requirements, and practical guidelines on how to measure and verify these attributes.
This document discusses end-to-end testing and why it is important for complex modern software systems with multiple interconnected subsystems. End-to-end testing ensures that all subsystems work together as expected by testing user journeys that trigger actions across systems. It recommends planning end-to-end test cases that think through scenarios from start to finish and avoid adding unnecessary tests. Automating end-to-end test cases is difficult but valuable as it can catch issues that arise from system interactions.
The document discusses several common software life cycle models: the waterfall model, rapid application development (RAD) model, prototyping model, and spiral model. The waterfall model involves sequential phases from requirements to maintenance without overlap. The RAD model emphasizes rapid delivery through iterative prototyping. The prototyping model builds prototypes to refine requirements before full development. Finally, the spiral model takes a risk-driven approach to software development through iterative planning, risk analysis, and evaluations.
This document provides an overview of test-driven development (TDD). It defines TDD as a technique for building software where tests are written before code to guide development. The key aspects of TDD covered are:
- Writing tests first before code, which helps improve design and ensures tests are written.
- The TDD mantra of Red-Green-Refactor, where tests initially fail (Red), code is written to pass tests (Green), then code is refactored to improve design.
- An example case study of a large Java project developed using TDD that has over 20,000 lines of unit tests providing over 90% test coverage.
The document presents information on the Software Development Life Cycle (SDLC), including:
1) It describes the seven main phases of the SDLC - planning, analysis, design, development, testing, implementation, and maintenance.
2) It discusses several SDLC models like waterfall, iterative, prototyping, spiral and V-model and compares their strengths and weaknesses.
3) It emphasizes the important role of testing in the SDLC and describes different testing types done during the phases.
The document provides an overview of the Software Development Lifecycle (SDLC) process. It describes the typical phases of SDLC, including planning, analysis, design, development, testing, deployment, and maintenance. It also discusses different SDLC models like waterfall, V-model, iterative, spiral, agile, and fish models. Each model follows a series of steps to ensure success in the software development process. The document aims to explain the importance of following a structured software development approach using SDLC.
The document outlines an automation testing syllabus covering software development lifecycles, the role of testers, types of testing, test techniques, test cases, test plans, bugs, Java concepts, production tools, load testing, test management tools, and real-world manual testing projects. Key topics include waterfall, agile, and scrum models; unit, integration, and regression testing; black box and white box techniques; test plans; bug tracking; Java fundamentals; and tools like JUnit, Selenium, JIRA, LoadRunner, and QTP. The syllabus aims to equip students with the skills needed for both manual and automation testing.
Priyanka Meher has over 5 years of experience in IT testing in the telecom and BFSI domains. She has expertise in manual and automation testing using tools like HP Quality Center, QTP, and UFT. She has led testing teams and been responsible for test planning, execution, and reporting. She has received several awards for her work and achievements in test automation.
This document summarizes key concepts from the first chapter of Ian Sommerville's Software Engineering textbook. It introduces software engineering as an engineering discipline concerned with all aspects of software production. It discusses the objectives of software engineering, topics covered like frequently asked questions and professional responsibility. It also summarizes concepts like the software development process, methods, costs and challenges in the field.
DRB EXP RESUME manual and selenium master copy corrected 2Dikhit Behera
Dikhit Ranjan Behera has over 2 years of experience in information technology, including 1 year of experience with automation testing using Selenium. He has skills in manual testing, automation testing with Selenium and TestNG, defect tracking with tools like HPQC and Jira, and programming languages like Java. He currently works as an Associate Software Engineer at Mphasis Limited, where he has been involved in testing projects including an asset management system and a healthcare application.
4 Nisan 2015 tarihinde Kadir Has Üniversitesi'nde yapılan 9. Yazılım Teknolojileri Seminer etkinliğinde Eralp Erat'ın yaptığı TDD (Test Driven Design) sunumu
Now-a-days the world of testing has shifted towards a Continuous Testing model. With increasing digital transformation, Agile & DevOps principles, the need to scale up quality initiatives becomes inevitable. Moreover, with increasing complexity and continuous integration cycles, the frequency of tests to release apps in a shorter time frame with continuous testing becomes the need of the hour to match the speed of Agile & DevOps.
Fast feedback loops and immediate responses allow businesses to adapt to changes in the market quicker than ever before. This is made possible with automation and continuous testing. But how do you achieve continuous testing?
In this, our specialist Sushma Nayak will discuss the present-day best practices in test automation at Knoldus and will examine the key testing trends that focus on the adoption of Continuous Delivery and the evolution of test automation in the coming year.
watch the video of this session on our website: https://www.knoldus.com/learn/webinars
What is professional software development and definition of software engineering. Who is a software engineer. Difference between Computer Science and Systems Engineering
The document provides a summary of Manoj Prabhakar's career experience in the telecom and mobile handset application industry. It outlines his 6+ years of experience testing 3G, 2G, and real-time mobile applications on Android, Symbian S60, and Ericsson Mobile Platforms. It also lists his technical skills and responsibilities on various projects for clients like Ericsson, MacroSolve, AT&T, and Motorola Mobility involving testing applications and features on different mobile platforms.
Process Model in Software Engineering.pptAtharvaBavge
Process models provide a structured approach to software engineering by defining key activities and flows. Generic process models include communication, planning, modeling, construction, and deployment activities. Process flows can be linear, iterative, evolutionary, or parallel. Prescriptive models like the waterfall model advocate an orderly approach but lack flexibility for changing requirements. The incremental and spiral models incorporate iteration and prototypes to accommodate change while still providing structure. Evolutionary approaches address changing requirements but require management of project planning and evolution speed.
Structured system analysis and design Jayant Dalvi
The document discusses four common software development models: Waterfall, Spiral, Prototyping, and RAD (Rapid Application Development). It describes the key phases and characteristics of each model. The Waterfall model follows a linear sequence of phases from requirements to maintenance without iteration. The Spiral model is iterative with a risk-analysis focus. Prototyping emphasizes early customer feedback through prototypes. RAD prioritizes rapid delivery of high priority functionality through reuse and automated tools. Each model has advantages for certain types of projects depending on requirements clarity, budget, and risks.
The document discusses several software development life cycle (SDLC) models:
1. The waterfall model involves sequential phases from requirements to maintenance.
2. The spiral model adds risk analysis and prototyping to the waterfall model in iterative cycles.
3. Evolutionary prototyping builds prototypes to refine requirements through user feedback before full development.
4. The incremental model prioritizes requirements and delivers them in groups to provide early functionality.
This document discusses the software development life cycle (SDLC) model. It defines the SDLC as a detailed plan for creating, developing, implementing, and eventually retiring software. The SDLC involves phases such as concept development, planning, requirements analysis, design, development, testing, implementation, and maintenance. Two common SDLC models are the waterfall model and iterative model. Following an SDLC is important for health IT systems to ensure software meets needs, integrates properly, and has appropriate documentation for maintenance.
Software development life cycle (SDLC) ModelsAOmaAli
The document discusses various software development life cycle (SDLC) models. It describes the waterfall model process with distinct phases of requirements, design, implementation, testing and maintenance. It also covers the V-model which incorporates testing at each phase. Other models discussed include prototyping, iterative/incremental and when each may be used based on project characteristics and requirements stability.
The document discusses various approaches for selecting a project methodology, including whether to build a system in-house or outsource it. It covers the waterfall model, spiral model, prototyping, and incremental delivery. The key aspects addressed are identifying project characteristics and risks to determine the most appropriate software process model. Structured versus agile approaches are weighed in terms of balancing requirements specification with delivery speed.
The document provides an overview of various software engineering process models including waterfall, rapid prototyping, incremental, evolutionary, spiral, and agile models like XP. It discusses the main characteristics, advantages, and disadvantages of each model. It also covers the Rational Unified Process (RUP) in detail including its iterative nature, use case driven approach, architecture centricity, and use of UML. Finally, it discusses process improvement frameworks like the Capability Maturity Model (CMM).
This document provides an overview of software engineering concepts including different types of software, software classification, software attributes, and common software development process models. It describes system software and application software, and distinguishes between generic/off-the-shelf software and custom software. Popular process models covered include waterfall, prototyping, and rapid application development (RAD). The waterfall model and its stages are explained in detail.
The document discusses different prescriptive process models for software engineering projects. It describes the waterfall model as the oldest and most basic sequential model. Incremental process models like the incremental model and RAD model deliver functionality in increments to get early user feedback. Evolutionary models like prototyping and the spiral model are iterative and allow for changes through repeated prototype revisions or spiral loops of risk analysis, development and validation.
The document discusses different software development models:
- The classical waterfall model divides development into sequential phases: feasibility study, requirements, design, coding/testing, integration/testing, and maintenance. It lacks mechanisms to handle errors between phases.
- The iterative waterfall model and V-model are more suitable for well-defined problems with clear requirements. The evolutionary model is suitable for large problems developed incrementally.
- The prototyping model uses initial toy implementations to refine requirements before full development. Different models suit different types of projects based on factors like size, risks, and requirements stability.
This document discusses software engineering and the software development life cycle. It defines software engineering as applying engineering principles to software development using systematic techniques, methodologies and guidelines based on past experiences. It also discusses factors that previously contributed to software crises like products failing to meet requirements. The document contrasts older ad hoc development approaches with modern practices emphasizing error prevention over correction through techniques like reviews and testing. Finally, it defines software life cycle models as descriptive models that identify phases and precedence of activities to systematically develop software.
The document discusses various software development process models:
- Waterfall model is characterized by feedback loops and documentation-driven. It is idealized and doesn't match reality well.
- Rapid prototyping model involves building prototypes during requirements phase for user evaluation and feedback. It allows for flexible design but may continue indefinitely.
- Spiral model is a simplified form of waterfall plus risk analysis. Each phase is preceded by risk analysis and followed by evaluation and planning.
- Incremental model divides the project into builds to slowly add functionality with each release. It delivers portions of product quickly but requires good planning.
- The conclusions state different models have their own strengths and weaknesses. The best approach is to mix and match
The document discusses the software development life cycle (SDLC) which consists of 7 stages: 1) Planning and requirements analysis, 2) Defining requirements, 3) Designing the software, 4) Coding, 5) Testing, 6) Deployment, and 7) Maintenance. It provides details about the activities in each stage. The waterfall model is introduced as one of the popular SDLC models which follows a linear sequential process where each stage must be completed before moving to the next. Some other models mentioned are iterative, spiral, V-model, and big bang. Advantages and disadvantages of the waterfall model are also outlined.
The document discusses several software development life cycle (SDLC) models including the Capability Maturity Model (CMM), Waterfall model, V-shaped model, Rapid Application Development (RAD) model, Incremental model, and Spiral model. It provides an overview of the key stages and characteristics of each model as well as their strengths and weaknesses to help determine when each model is best applied.
The document discusses various software development life cycle (SDLC) models including waterfall, V-shaped, prototyping, rapid application development (RAD), incremental, spiral, and agile models. For each model, the key steps or phases are described along with strengths and weaknesses. When each model is most applicable is also discussed. The document then covers quality assurance planning and activities that should be included like defect tracking, testing at various levels, and technical reviews.
The document discusses several software development life cycle (SDLC) models including the Capability Maturity Model (CMM), Waterfall model, V-shaped model, Rapid Application Development (RAD) model, Incremental model, and Spiral model. It provides an overview of the key stages and characteristics of each model as well as their strengths and weaknesses to help determine when each model is best applied.
The document discusses several software development life cycle (SDLC) models including the Capability Maturity Model (CMM), Waterfall model, V-shaped model, Rapid Application Development (RAD) model, Incremental model, and Spiral model. It provides an overview of the key stages and characteristics of each model as well as their strengths and weaknesses to help determine when each model is best applied.
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2. 2
Life-Cycle Model
• It specifies the various phases/workflows of the
software process, such as the requirements,
analysis (specification), design, implementation,
and postdelivery maintenance, and the order in
which they are to be carried out.
3. Software engineering
• Software engineering: the profession, practiced by
developers, concerned with creating and maintaining
software applications by applying technologies and practices
from computer science, project management, and other
fields.
4. 4
Roles of people in software
• people involved in software production
– customer / client: wants software built
• often doesn't know what he/she wants
– managers / designers: plan software
• difficult to foresee all problems and issues in advance
– developers: write code to implement software
• it is hard to write complex code for large systems
– testers: perform quality assurance (QA)
• it is impossible to test every combination of actions
– users: purchase and use software product
• users can be fickle and can misunderstand the product
5. 5
Problems with software today
• Example: Space shuttle software
– cost: $10 Billion, millions of dollars more than planned
– time: 3 years late
– quality: first launch of Columbia was cancelled because of a
synchronization problem with the Shuttle's 5 onboard computers
• error was traced back to a change made 2 years earlier when a
programmer changed a delay factor in an interrupt handler from 50 to 80
milliseconds
• the likelihood of the error was small enough, that the error caused no harm
during thousands of hours of testing
• substantial errors still exist in the code
– astronauts are supplied with a book of known software problems "Program
Notes and Waivers"
– reusability: shuttle software cannot be reused
• Have to develop each software product from scratch
6. 6
Ad-hoc software development
• ad-hoc development: creating software without
any formal guidelines or process
• what are some disadvantages of ad-hoc
development?
some important actions (testing, design) may go ignored
not clear when to start or stop doing each task
does not scale well to multiple people
not easy to review or evaluate one's work
7. 7
The software lifecycle
• software lifecycle: series of steps / phases, through which
software is produced
– can take months or years to complete
• goals of each phase:
– mark out a clear set of steps to perform
– produce a tangible document or item
– allow for review of work
– specify actions to perform in the next phase
• common observation: The later a problem is found in
software, the more costly it is to fix
8. 8
Lifecycle phases
• standard phases
1. Requirements Analysis & Specification
2. Design
3. Implementation, Integration
4. Testing, Profiling, Quality Assurance
5. Operation and Maintenance
• other possible phases
– risk assessment: examining what actions are critical and
performing them first (part of Spiral model)
– prototyping: making a quick version of the product and using it
to guide design decisions
9. 9
One view of SW cycle phases
Subsystems
Structured By
class...
class...
class...
Source
Code
Implemented
By
Solution
Domain
Objects
Realized By
System
Design
Object
Design
Implemen-
tation
Testing
Application
Domain
Objects
Expressed in Terms
Of
Test
Cases
?
Verified
By
class.... ?
Requirements
Elicitation
Use Case
Model
Analysis
10. 10
Some software models
• Several models for developing software (besides ad-
hoc) have been attempted:
– code-and-fix: write some code, debug it, repeat until
finished
– evolutionary: build initial requirement spec, write it, then
"evolve" the spec and code as needed
– waterfall: perform the standard phases (requirements,
design, code, test) in sequence
– rapid prototyping: write an initial "throwaway" version of the
product, then design, code, test
– spiral: assess risks at each step, and do the most critical
action immediately
12. 12
Software Development in Practice
• In the real world, software development is totally
different and is more chaotic
– Software professionals make mistakes
– The client’s requirements change while the software
product is being developed
– A software product is a model of the real world, and
the real world is continually changing.
13. 13
1. Code-and-Fix Life-Cycle Model
The easiest way to develop software
The most expensive way for maintenance (i.e.,
maintenance nightmare)
• No design
• No specifications
14. 14
Code-and-Fix Life-Cycle Model (Cont.)
• The product is implemented without requirements or
specifications, or any attempt at design.
• The developers simply throw code together and
rework it as many times as necessary to satisfy the
client.
• It is used in small project and is totally unsatisfactory
for products of any reasonable size.
15. 15
2. Waterfall Life-Cycle Model
• The linear life cycle
model with feedback
loops
– The waterfall model
cannot show the order of
events
16. 16
Waterfall Life-Cycle Model
(Cont.)
• No phase is complete until the documentation for that
phase has been completed and the products of that phase
have been approved by the software quality assurance
(SQA) group.
• If the products of an earlier phase have to be changed as a
consequence of following a feedback loop, that earlier
phase is deemed to be complete only when the
documentation for the phase has been modified and the
modifications have been checked by the SQA group.
17. 17
Waterfall Life-Cycle Model
(Cont.)
• Advantages:
– Documentation is provided at each phase
– All the products of each phase (including the
documentation) are meticulously checked by SQA.
Maintenance is easier
• Disadvantages:
– Specification documents are long, detailed, and boring
to read.
19. 19
Rapid-Prototyping Life-Cycle Model (Cont.)
• A rapid prototype is a working model that is functionally
equivalent to a subset of the product.
• The first step is to build a rapid prototype and let the client
and future users interact and experiment with the rapid
prototype.
• Strength:
– The development of the product is essentially linear, proceeding
from the rapid prototype to the delivered product.
– The feedback loops of the waterfall model are less likely to be
needed in the rapid prototyping model.
– It is built rapidly and modified rapidly to reflect the client’s needs.
Speed is of the essence.
20. 20
Rapid-Prototyping Life-Cycle Model (Cont.)
• Weakness:
–One the client’s real needs have been
determined, the rapid prototype
implementation is discarded.
• The lessons learned from the rapid
prototype implementation are retained and
used in subsequent development phases.
22. 22
Open-Source Life-Cycle Model
(Cont.)
• The first informal phase
– One individual builds an initial version and makes it
available via the Internet (e.g., SourceForge.net)
– If there is sufficient interest in the project, the initial version
is widely downloaded; users become co-developers; and
the product is extended
• Key point: Individuals generally work voluntarily on an
open-source project in their spare time
23. 23
Open-Source Life-Cycle Model
(Cont.)
• The second Informal Phase
– Reporting and correcting defects
• Corrective maintenance
– Adding additional functionality
• Perfective maintenance
– Porting the program to a new environment
• Adaptive maintenance
• The second informal phase consists solely of
postdelivery maintenance
– The word ―co-developers‖ on the previous slide should
rather be ―co-maintainers‖
24. 24
Open-Source Life-Cycle Model
(Cont.)
• An initial working version is produced using the rapid-
prototyping model, the code-and-fix model, and the open-
source life-cycle model.
• The initial version of the rapid-prototyping model is then
discarded. The initial versions of Code-and-fix model and
open-source life-cycle model become the target product
• There are generally no specifications and no design.
However, open-source software production has attracted
some of the world’s finest software experts. They can
function effectively without specifications or designs
25. 25
Open-Source Life-Cycle Model (Cont.)
• A point will be reached when the open-source product is no
longer maintainable
• The open-source life-cycle model is restricted in its applicability
– It can be extremely successful for infrastructure projects, such as :
Operating systems (Linux, OpenBSD, Mach, Darwin), Web browsers
(Firefox, Netscape), Compilers (gcc), Web servers (Apache), and
Database management systems (MySQL)
– There cannot be open-source development of a software product to be
used in just one commercial organization
– The open-source life-cycle model is inapplicable unless the target
product is viewed by a wide range of users as useful
26. 26
Open-Source vs. Closed-Source
• Closed-source software is maintained and tested by employees
– Users can submit failure reports but never fault reports
• Open-source software is generally maintained by unpaid
volunteers
– Users are strongly encouraged to submit defect reports, both failure
reports and fault reports
• Core group: Small number of dedicated maintainers with the inclination, the
time, and the necessary skills to submit fault reports (―fixes‖); They take
responsibility for managing the project; They have the authority to install
fixes
• Peripheral group: Users who choose to submit defect reports from time to
time
27. 27
Open-Source vs. Closed-Source
(Cont.)
• New versions of closed-source software are typically
released roughly once a year
– After careful testing by the SQA group
• The core group releases a new version of an open-source
product as soon as it is ready
– Perhaps a month or even a day after the previous version was
released
– The core group performs minimal testing
– Extensive testing is performed by the members of the peripheral
group in the course of utilizing the software
– ―Release early and often‖
29. 29
Evolution-Tree Life-Cycle Model (Cont.)
• The explicit order of events is shown
• At the end of each episode
– We have a baseline, a complete set of artifacts (a
constitute component of a software product)
30. 30
Moving Target Problem
• Moving Target Problem: The requirements change while the software
product is being developed. This change is inevitable
– Growing companies are always going to change
– If the individual calling for changes has sufficient clout, nothing can be done
to prevent the changes being implemented.
• The software product can be adversely impacted
– Numerous changes can induce dependencies within the code.
• Any change made to a software product can potentially cause a
regression fault. That is, a change to one part of the software induces a
fault in an apparently unrelated part of the software
• If there are too many changes, the entire product may have to be
redesigned and reimplemented
• There is no solution to the moving target problem!!
31. 31
6. Iterative and Incremental
Life-Cycle Model: Iteration
• In the real life, we cannot speak about ―the analysis phase‖
– Instead, the operations of the analysis phase are spread out over
the life cycle as a consequence of both the moving target problem
and the need to correct the inevitable mistakes
• The basic software development process is iterative
– Each successive version is intended to be closer to its target than
its predecessor
32. Iterative and Incremental
Life-Cycle Model: Incrementation
• Miller’s Law: At any one time, we can concentrate on only
approximately seven chunks (units of information) ( The Law is
often interpreted to argue that the number of objects an
average human can hold in working memory is 7 ± 2.)
• To handle larger amounts of information, use stepwise
refinement
– Concentrate on the aspects that are currently the most important
– Postpone aspects that are currently less critical
– Every aspect is eventually handled, but in the order of current
importance
• This is an incremental process
33. 33
Iterative-and-Incremental Model
Iteration and incrementation are used in conjunction with one another
1) There is no single ―requirements phase/workflow‖ or ―design phase/workflow‖
2) Instead, there are multiple instances of each phase/workflow. However, only one
phase/workflow predominates at most times.
34. 34
Workflows
• All five core workflows are performed over the entire life
cycle
• However, at most times one workflow predominates
• Examples:
– At the beginning of the life cycle
• The requirements workflow predominates
– At the end of the life cycle
• The implementation and test workflows predominate
• Planning and documentation activities are performed
throughout the life cycle
37. 37
Combine the Evolution-Tree and the Iterative-
and-Incremental Models (Cont.)
• Each episode corresponds to an increment
• Not every increment includes every workflow
• Increment B was not completed
• Dashed lines denote maintenance
– Episodes 2, 3: Corrective maintenance
– Episode 4: Perfective maintenance
38. 38
Risks and Other Aspects of Iteration and
Incrementation
• We can consider the project as a whole as a set of mini
projects (increments)
• Each mini project extends the
– Requirements artifacts, Analysis artifacts, Design artifacts,
Implementation artifacts, Testing artifacts
• During each mini project, we
– Extend the artifacts (incrementation);
– Check the artifacts (test workflow); and
– If necessary, change the relevant artifacts (iteration)
• The final set of artifacts is the complete product
39. 39
Risks and Other Aspects of Iteration and
Incrementation (Cont.)
• Each iteration can be viewed as a small but complete
waterfall life-cycle model
• During each iteration we select a portion of the software
product
• On that portion we perform the
– Classical requirements phase
– Classical analysis phase
– Classical design phase
– Classical implementation phase
40. 40
Strength of the Iterative-and-Incremental
Model
• There are multiple opportunities for checking that the
software product is correct
– Every iteration incorporates the test workflow
– Faults can be detected and corrected early
• The robustness of the architecture can be determined early
in the life cycle
– Architecture — the various component modules and how they fit
together
– Robustness — the property of being able to handle extensions
and changes without falling apart
41. 41
Strength of the Iterative-and-Incremental
Model (Cont.)
• We can mitigate (resolve) risks early
– Risks are invariably involved in software development
and maintenance
• We always have a working version of the software
product
– Variation: Deliver partial versions to smooth the
introduction of the new product in the client organization
• There is empirical evidence that the life-cycle model
works
42. 42
Managing Iteration and Incrementation
• The iterative-and-incremental life-cycle model is as regimented
as the waterfall model since developing a software product
using the iterative-and-incremental model is equivalent to
developing a series of smaller software products, all using the
waterfall model.
– The project as a whole is broken up into a series of waterfall mini
projects.
– During each mini-project, iteration is performed as needed.
– For each increment, the requirements, analysis, design, and
implementation phases are repeatedly performed until it is clear that no
further iteration is needed. That is: each increment is a waterfall mini
project.
• The iterative-and-incremental life-cycle model is the
waterfall model, applied successively
43. 43
7. Agile Processes:
Extreme Programming
• Extreme programming is a somewhat controversial
new approach to software development based on
the iterative-and-incremental model.
• The software development team determines the
various features (stories) the client would like the
product to support.
44. 44
Agile Processes:
Extreme Programming (Cont.)
• Based on the features (stories) the client wants:
– The development team estimates the duration and cost
of each feature
– The client selects the features for next build using cost-
benefit analysis
– The proposed build is broken down into smaller pieces
termed tasks
– The programmer draws up test cases for a task Test-
driven development (TDD)
45. 45
Agile Processes:
Extreme Programming (Cont.)
• Pair Programming: The programmer works together with a
partner on one screen to implement the task and ensure
that all the test cases work correctly.
• Continuous integration of tasks since a number of pairs
implement tasks in parallel
• The TDD test cases used for the task are retained and
utilized in all further integration testing.
46. 46
Unusual Features of
Extreme Programming (XP)
• The computers of the XP team are put in the center of a
large room lined with cubicles.
• A client representative works with the XP team at all times.
• Software professionals cannot work overtime for 2
successive weeks.
• There is no specialization. Instead, all members of the XP
team work on analysis, design, code, and testing.
• There is no overall design step before the various builds
are constructed. Instead, the design is modified while the
product is being built. This procedure is termed
refactoring.
47. 47
Agile Processes
• Extreme programming is one of a number of new
paradigms that are collectively referred to as agile
processes.
• Agile processes are characterized by
– Less emphasis on analysis and design
– Earlier implementation (working software is considered
more important than detailed documentation)
– Responsiveness to change in requirements
– Close collaboration with the client
48. 48
Agile Processes (Cont.)
• A principle in the Manifesto is
– Deliver working software frequently
– Ideally every 2 or 3 weeks
• One way of achieving this is to use timeboxing
– Used for many years as a time-management technique
• A specific amount of time is set aside for a task
– Typically 3 weeks for each iteration
– The team members then do the best job they can during that time
• Agile processes demand fixed time, not fixed features
49. 49
Agile Processes (Cont.)
• Another common feature of agile processes is stand-up
meetings
– Short meetings held at a regular time each day
– Attendance is required
• Participants stand in a circle
– They do not sit around a table
– To ensure the meeting lasts no more than 15 minutes
• The aim of a stand-up meeting is
– To raise problems, not solve them
• Solutions are found at follow-up meetings, preferably held
directly after the stand-up meeting
50. 50
Agile Processes (Cont.)
• Stand-up meetings and timeboxing are both
– Successful management techniques
– Now utilized within the context of agile processes
• Both techniques are instances of two basic
principles that underlie all agile methods:
– Communication; and
– Satisfying the client’s needs as quickly as possible
51. 51
Evaluating Agile Processes
• Agile processes have had some successes with
small-scale software development
– However, medium- and large-scale software development
is very different
• The key decider: The impact of agile processes on
postdelivery maintenance
– Refactoring is an essential component of agile processes
– Refactoring continues during maintenance
– Will refactoring increase the cost of postdelivery
maintenance?
52. 52
Evaluating Agile Processes (Cont.)
• Agile processes are good when requirements are vague or
changing
• It is too soon to evaluate agile processes
– There are not enough data yet
• Even if agile processes are proven to be disappointing
– Some features (such as pair programming) may be adopted as
mainstream software engineering practices
53. 53
8. Synchronize-and-Stabilize
Life-Cycle Model
• Microsoft’s life cycle model
• Requirements: Interview numerous potential clients for the
package and extract a list of features of highest priority to
the clients.
• Draw up specifications
• Divide the work into three or four builds.
– The 1st build: Most critical features.
– The 2nd build: The next most critical features.
– Each build is carried out by a number of small teams working in
parallel.
54. 54
Synchronize-and-Stabilize
Life-Cycle Model (Cont.)
• Synchronize at the end of each day: Put the
partially completed components together and test
and debug the resulting product.
• Stabilize at the end of each build: Fix remaining
faults and no further changes will be made to the
specifications
55. 55
Synchronize-and-Stabilize
Life-Cycle Model (Cont.)
• Advantages:
– The repeated synchronization step ensures that the
various components always work together.
– The regular execution of the partially constructed
product makes the developers gain early insight into the
operation of the product and modify the requirements if
necessary during the course of a build.
56. 56
9. Spiral Life-Cycle Model
• Simplified form
– Rapid prototyping model
plus risk analysis
preceding each phase
• If all risks cannot be
mitigated, the project is
immediately terminated
58. 58
Full Spiral Life-Cycle Model
Radial dimension: cumulative costs to date
Angular dimension: progress through the spiral.
• Precede each phase by
– Alternatives
– Risk analysis
• Follow each phase by
– Evaluation
– Planning of the next phase
59. 59
Spiral Life-Cycle Model (Cont.)
• Minimize risk via the use of prototypes and other
means.
• Two types of risk:
– Analyzable Risk: Time and cost
– Un-analyzable Risk:
• Personnel turnover
• Difference between small-scale and large-scale software
• Evaluate the delivery promises of a hardware supplier
60. 60
Spiral Life-Cycle Model (Cont.)
• Precede each phase by determining:
– Objective of the phase;
– Alternatives for achieving the objectives;
– Constraints imposed on those alternatives.
• Strategy is analyzed from the viewpoint of risk. Attempts
are made to resolve every potential risk.
• Follow each phase by:
– The results of the phase are evaluated.
– The next phase is planned.
61. 61
Spiral Life-Cycle Mode (Cont.)
• Strengths
– The emphasis on alternatives and constraints supports
the reuse of existing software and the incorporation of
software quality as a specific objective.
– There is essentially no distinction between development
and maintenance since maintenance is another cycle of
the spiral.
• Weaknesses
– For large-scale software only
– For internal (in-house) software only
62. 62
Comparison of Life-Cycle Models
• Different life-cycle models have been presented
– Each with its own strengths and weaknesses
• Criteria for deciding on a model include:
– The organization
– Its management
– The skills of the employees
– The nature of the product
• Best suggestion
– ―Mix-and-match‖ life-cycle model
65. 65
Some software models
• Several models for developing software (besides ad-
hoc) have been attempted:
– code-and-fix: write some code, debug it, repeat until
finished
– evolutionary: build initial requirement spec, write it, then
"evolve" the spec and code as needed
– waterfall: perform the standard phases (requirements,
design, code, test) in sequence
– rapid prototyping: write an initial "throwaway" version of the
product, then design, code, test
– spiral: assess risks at each step, and do the most critical
action immediately
67. 67
Problems with code-and-fix
• What are some reasons not to use the code-and-fix
model?
code becomes expensive to fix (bugs are not found until
late in the process)
code didn't match user's needs (no requirements phase!)
code was not planned for modification, not flexible
68. 68
Evolutionary model
For each build:
Perform detailed
design, implement.
Test. Deliver.
Requirements
Verify
Retirement
Operations
Verify
Arch. Design
69. 69
Problems with evolutionary
• The evolutionary model is similar to code-and-fix, but it
assumes the repetitions are "evolutions" of the code, not
necessarily bug fixes. Problems with this?
difficult to distinguish from code-and-fix
assumes user's initial spec will be flexible; fails for:
separate pieces that must then be integrated
"information sclerosis": temporary fixes become permanent constraits
bridging; new software trying to gradually replace old
wrong order: makes lots of hard-to-change code
70. 70
Waterfall model (Royce, 1970)
Requirements
Verify
Retirement
Operations
Test
Implementation
Verify
Design
Req. Change
72. 72
Waterfall / Prototyping issues
• The waterfall models (with or without prototyping)
are perhaps the most common model for software
development
– we will use waterfall in this course!
• What are some positives and negatives about this
method?
+ formal, standard, has specific phases with clear goals
+ good feedback loops between adjacent phases
- rigid, too linear; not very adaptable to change in the product
- requires a lot of planning up front (not always easy / possible)
- assumes that requirements will be clear and well-understood
74. 74
Another view of spiral model
Requirements
Verify
Retirement
Operations
Test
Implementation
Verify
Design
Req. Change
Adds a Risk Analysis
step to each phase
(phases may not be
completed in this order
any more!)
Risk Assessment
Risk Assessment
Risk Assessment
75. 75
Spiral model problems
• What are some positives and negatives about this
method?
+ focuses attention on reuse
+ accommodates changes, growth
+ eliminates errors and unattractive choices early
+ limits to how much is enough (not too much design, reqs, etc)
+ treats development, maintenance same way
- matching to contract software (doesn't work well when you're bound to a fixed inflexible contract)
- relying on developers to have risk-assessment expertise
- need for further elaboration of project steps (clearer milestones)
76. 76
Tools for software engineers
• CASE (Computer-Aided Software Engineering)
– requirements / spec generation software
– design diagram (UML) software
– integrated development environments (IDEs)
– test suites (JUnit) and benchmarking / profiling software