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SOFTWARE PROCESS MODELS AND PROJECT
LIFECYCLES NOTES-2026 EDITION
Project Lifecycle & Effort Estimation Sokware processes are the activities for designing, implementing, and testing a software system. The software development process is complicated and involves a lot more than technical knowledge. A software process model is an abstract representation of the development process. Software process model A sokware process model is an abstraction of the software development process. The models specify the stages and order of a process. So, think of this as a representation of the order of activities of the process and the sequence in which they are performed. A model will define the following: ● The tasks to be performed ● The input and output of each task ● The pre and post-conditions for each task ● The flow and sequence of each task ● The goal of a software process model is to provide guidance for controlling and coordinating the tasks to achieve the end product and objectives as effectively as possible. There are many kinds of process models for meeting different requirements. We refer to these as SDLC models (Software Development Life Cycle models). The most popular and important SDLC models are as follows: ● Waterfall model ● V model ● Incremental model ● RAD model ● Agile model ● Iterative model ● Prototype model ● Spiral model Factors in choosing a software process: Choosing the right software process model for your project can be difficult. If you know your requirements well, it will be easier to select a model that best matches
your needs. You need to keep the following factors in mind when selecting your software process model:
1. Project requirements Before you choose a model, take some time to go through the project requirements and clarify them alongside your organization’s or team’s expectations. Will the user need to specify requirements in detail after each iterative session? Will the requirements change during the development process? 2. Project size
generally 60 - 90 days. Rapid application development is a software development methodology that uses minimal planning in favor of rapid prototyping. A prototype is a working model that is functionally equivalent to a component of the product. In the RAD model, the functional modules are developed in parallel as prototypes and are integrated to make the complete product for faster product delivery. Since there is no detailed preplanning, it makes it easier to incorporate the changes within the development process.
RAD projects follow an iterative and incremental model and have small teams comprising of developers, domain experts, customer representatives and other IT resources working progressively on their component or prototype. The most important aspect for this model to be successful is to make sure that the prototypes developed are reusable. Following are the various phases of the RAD Model −
1. Business Modelling The business model for the product under development is designed in terms of flow of information and the distribution of information between various business channels. A complete business analysis is performed to find the vital information for business, how it can be obtained, how and when is the information processed and what are the factors driving successful flow of information. 2. Data Modelling The information gathered in the Business Modelling phase is reviewed and analyzed to form sets of data objects vital for the business. The attributes of all data sets is identified and defined. The relation between these data objects are established and defined in detail in relevance to the business model. 3. Process Modelling The data object sets defined in the Data Modelling phase are converted to establish the business information flow needed to achieve specific business objectives as per the business model. The process model for any changes or enhancements to the data object sets is defined in this phase. Process
The actual system is built and coding is done by using automation tools to convert process and data models into actual prototypes.
5. Testing and Turnover The overall testing time is reduced in the RAD model as the prototypes are independently tested during every iteration. However, the data flow and the interfaces between all the components need to be thoroughly tested with complete test coverage. Since most of the programming components have already been tested, it reduces the risk of any major issues. When to use RAD Model? o When the system should need to create the project that modularizes in a short span time (2- 3 months). o When the requirements are well-known. o When the technical risk is limited. o When there's a necessity to make a system, which modularized in 2 - 3 months of period. o It should be used only if the budget allows the use of automatic code generating tools. Advantage of RAD Model
o This model is flexible for change. o In this model, changes are adoptable. o Each phase in RAD brings highest priority functionality to the customer. o It reduced development time.
Phases of Agile Model: Following are the phases in the Agile model are as follows:
- Requirements gathering
- Design the requirements
- Construction/ iteration
- Testing/ Quality assurance
- Deployment
- Feedback 1. Requirements gathering: In this phase, you must define the requirements. You should explain business opportunities and plan the time and effort needed to build the project. Based on this information, you can evaluate technical and economic feasibility. 2. Design the requirements: When you have identified the project, work with stakeholders to define requirements. You can use the user flow diagram or the high-level UML diagram to show the work of new features and show how it will apply to your existing system. 3. Construction/ iteration: When the team defines the requirements, the work begins. Designers and developers start working on their project, which aims to deploy a working product. The product will undergo various stages of improvement, so it includes simple, minimal functionality. 4. Testing: In this phase, the Quality Assurance team examines the product's performance and looks for the bug. 5. Deployment: In this phase, the team issues a product for the user's work environment. 6. Feedback: After releasing the product, the last step is feedback. In this, the team receives feedback about the product and works through the feedback. Advantages of Agile Methodology:
- In Agile methodology the delivery of software is unremitting.
- The customers are satisfied because after every Sprint working feature of the software is delivered to them.
- Changes in the requirements are accepted even in the later stages of the development.
- An Agile/Scrum approach can improve organizational synergy by breaking down organizational barriers and developing a spirit of trust and partnership around organizational goals. Disadvantages of the Agile Methodology:
- In Agile methodology the documentation is less.
- Sometimes in Agile methodology the requirement is not very clear hence it’s difficult to predict the expected result.
- In few of the projects at the starting of the software development life cycle it’s difficult to estimate the actual effort required.
- Because of the ever-evolving features, there is always a risk of the ever-lasting project.
- For complex projects, the resource requirement and effort are difficult to estimate. Agile Testing Methods: ○ Scrum ○ Crystal ○ Dynamic Software Development Method(DSDM) ○ Feature Driven Development(FDD) ○ Lean Software Development ○ eXtreme Programming(XP) Dynamic Systems Development technique (DSDM) The Dynamic Systems Development technique (DSDM) is an associate degree agile code development approach that provides a framework for building and maintaining systems. The DSDM philosophy is borrowed from a modified version of the sociologist principle—80 % of An application is often delivered in twenty percent of the time it’d desire deliver the entire (100 percent) application. DSDM is An iterative code method within which every iteration follows the 80% rule that simply enough work is needed for every increment to facilitate movement to the following increment. The remaining detail is often completed later once a lot of business necessities are noted or changes are requested and accommodated.
DSDM life cycle defines 3 different iterative cycles, preceded by 2 further life cycle activities:
- Feasibility Study: It establishes the essential business necessities and constraints related to the applying to
Extreme Programming (XP) Extreme programming (XP) is one of the most important software development frameworks of Agile models. It is used to improve software quality and responsiveness to customer requirements. The extreme programming model recommends taking the best practices that have worked well in the past in program development projects to extreme levels. Good practices need to be practiced in extreme programming: Some of the good practices that have been recognized in the extreme programming model and suggested to maximize their use are given below: ● Code Review: Code review detects and corrects errors efficiently. It suggests pair programming as coding and reviewing of written code carried out by a pair of programmers who switch their works between them every hour. ● Testing: Testing code helps to remove errors and improves its reliability. XP suggests test- driven development (TDD) to continually write and execute test cases. In the TDD approach test cases are written even before any code is written.
● Incremental development: Incremental development is very good because customer feedback is gained and based on this development team comes up with new increments every few days after each iteration.
● Simplicity: The main principle of the XP model is to develop a simple system that will work efficiently in the present time, rather than trying to build something that would take time and may never be used. It focuses on some specific features that are immediately needed, rather than engaging time and effort on speculations of future requirements. Applications of Extreme Programming (XP): Some of the projects that are suitable to develop using the XP model are given below: ● Small projects: XP model is very useful in small projects consisting of small teams as face-to- face meeting is easier to achieve.
● Projects involving new technology or Research projects: This type of project face changing requirements rapidly and technical problems. So the XP model is used to complete this type of project. Extreme Programming (XP) is an Agile software development methodology that focuses on delivering high-quality software through frequent and continuous feedback, collaboration, and adaptation. XP emphasizes a close working relationship between the development team, the customer, and stakeholders, with an emphasis on rapid, iterative development and deployment. XP includes the following practices:
- Continuous Integration: Code is integrated and tested frequently, with all changes reviewed by the development team.
- Test-Driven Development: Tests are written before code is written, and the code is developed to pass those tests.
- Pair Programming: Developers work together in pairs to write code and review each other’s work.
- Continuous Feedback: Feedback is obtained from customers and stakeholders through frequent demonstrations of working software.
- Simplicity: XP prioritizes simplicity in design and implementation, with the goal of reducing complexity and improving maintainability.
- Collective Ownership: All team members are responsible for the code, and anyone can make changes to any part of the codebase.
- Coding Standards: Coding standards are established and followed to ensure consistency and maintainability of the code.
- Sustainable Pace: The pace of work is maintained at a sustainable level, with regular breaks and opportunities for rest and rejuvenation.
- XP is well-suited to projects with rapidly changing requirements, as it emphasizes flexibility and adaptability. It is also well-suited to projects with tight timelines, as it emphasizes rapid development and deployment. DSDM is often combined with XP to supply a mixed approach that defines a solid method model (the DSDM life cycle) with the barmy and bolt practices (XP) that are needed to create code increments. Additionally, the ASD ideas of collaboration and self-organizing groups are often tailored to a combined method model. Managing Interactive Processes: Booch suggests that there are two levels of development:
