SDLC A Brief Introduction

1. SDLC � A Brief Introduction

2. Contents Product, Process and Methods Methodologies followed in late 60�s for software Development What is SDLC? SDLC Models Classifications of SDLC Model Sequential Model Progressive Model Iterative Model Spiral model Lifecycle Models Incremental Model Differences between Exploratory & SDLC Models

3. Product, Process and Methods Product includes some of: hardware , software , documentation , installation, etc. Process Process defines a framework for a set of key process areas that must be established for effective delivery of software engineering technology. involves all of: communication (internal and external) , standards (definition and adherence) , planning and monitoring , tools and methodologies , quality assurance Role of Processes Increasingly, software suppliers recognize that software development process capability is a key source of competitive advantage. Competition forces suppliers to improve processes to meet the conflicting demands of higher quality, lower cost, and compressed schedules. Method Methods provides the technical �how to�s� for building software

4. Methodologies followed in late 60�s for software Development

5. Methodologies followed in late 60�s for software Development The Software was developed on a Trial & Error basis. No Specific Process was followed during the development of the Product. Defects were detected only after the product is delivered to the external Users. This resulted in software crisis Software fail to meet user requirements. Softwares used to crash frequently. Development of Software became expensive. Software became difficult to alter, debug, and enhance. The Software was often delivered late. Software use resources non-optimally.

6. Common Symptoms of Failed Software Development Projects Inaccurate understanding of end-user-needs Inability to deal with changing requirements Modules that do not fit together Software that is too hard to maintain or extend Late discovery of serious flaws Poor software quality Unacceptable software performance

7. Some Root Causes for Failure Ad hoc requirements management Ambiguous and imprecise communication Overwhelming complexity Undetected inconsistencies in requirements, design and implementations Insufficient testing Failure to attack risk Insufficient use of automation tools

8. Software Development Life Cycle (SDLC)

9. What is SDLC ? The various activities which are undertaken when developing software are commonly modeled as a software development lifecycle. The software development lifecycle begins with the identification of a requirement for software and ends with the formal verification of the developed software against that requirement. The software development lifecycle does not exist by itself, it is in fact part of an overall product lifecycle. Within the product lifecycle, software will undergo maintenance to correct errors and to comply with changes to requirements. The simplest overall form is where the product is just software, but it can become much more complicated, with multiple software developments each forming part of an overall system to comprise a product.

10. SDLC - Models

11. Software Life-Cycle Model Definition The series of steps through which the product progresses The models specifies the various phases of the process e.g., requirements, specification, design� the order in which they are carried out

12. SDLC Models There are a number of different models for software development lifecycles. Life cycle models describe the interrelationships between software development phases. It specifies the relationships between project phases, including transition criteria, feedback mechanisms, milestones, baselines, reviews, and deliverables. Typically, a life cycle model addresses the following phases of a software project: requirements phase, design phase, implementation, integration, testing, operations and maintenance.