SDLC Software Development Life Cycle

SDLC Acronym for system development life cycle. Acronym for system development life cycle. Is the process of developing information systems through: Is the process of developing information systems through: –Investigation –Analysis –Design –Implementation –Maintenance

SDLC Also known as: Also known as: –information systems development or –application development Is a systems approach to problem solving Is a systems approach to problem solving Is made up of several phases, each comprised of multiple steps …. Is made up of several phases, each comprised of multiple steps ….

The Software Concept Identifies and defines a need for the new system Identifies and defines a need for the new system –The existing system is evaluated –Deficiencies are identified –This can be done by: »Interviewing users of the system »Consulting with support personnel

A Requirements Analysis Analyses the information needs of the end users Analyses the information needs of the end users –The new system requirements are defined –The deficiencies in the existing system must be addressed with specific proposals for improvement

The Architectural Design Creates a blueprint for the design with the necessary specifications for: Creates a blueprint for the design with the necessary specifications for: –the hardware –the software –the people –the data resources –the security issues –the physical construction

Coding and Debugging Creates and programs the final system Creates and programs the final system The new components and programs must be obtained and installed The new components and programs must be obtained and installed

System Testing Evaluates the system's actual functionality in relation to expected or intended functionality Evaluates the system's actual functionality in relation to expected or intended functionality –Users of the system must be trained in its use –All aspects of performance must be tested –If necessary, adjustments must be made at this stage

System Put to Use Can be done in various ways: Can be done in various ways: –The new system can be phased in, according to application or location, and the old system gradually replaced –In some cases, it may be more cost-effective to shut down the old system and implement the new system all at once

System Evaluation Once the new system is up and running for a while, it should be exhaustively evaluated Once the new system is up and running for a while, it should be exhaustively evaluated Maintenance must be kept up rigorously at all times Maintenance must be kept up rigorously at all times Users of the system should be kept up-to- date concerning the latest modifications and procedures Users of the system should be kept up-to- date concerning the latest modifications and procedures

Various SDLC Approaches The waterfall model, the original SDLC method The waterfall model, the original SDLC method Rapid Application Development (RAD) Rapid Application Development (RAD) Joint Application Development (JAD) Joint Application Development (JAD) The fountain model The fountain model The spiral model The spiral model Build and fix Build and fix Synchronize-and-stabilize Synchronize-and-stabilize Frequently, several models are combined into some sort of hybrid process Frequently, several models are combined into some sort of hybrid process

Documentation Is crucial regardless of the type of model chosen or devised for any application Is crucial regardless of the type of model chosen or devised for any application Is usually done in parallel with the development process. Is usually done in parallel with the development process.

Waterfall Model Linear and sequential Linear and sequential Distinct goals for each phase of development Distinct goals for each phase of development Development moves from concept, through design, implementation, testing, installation, troubleshooting, and ends up at operation and maintenance with no overlapping or going over previous steps Development moves from concept, through design, implementation, testing, installation, troubleshooting, and ends up at operation and maintenance with no overlapping or going over previous steps

Waterfall Model Does not allow for much reflection or revision Does not allow for much reflection or revision Once an application is in the testing stage, it is very difficult to go back and change something that was not well-thought out in the concept stage Once an application is in the testing stage, it is very difficult to go back and change something that was not well-thought out in the concept stage

Joint Application Development A methodology that involves the client or end user in the design and development of an application, through a succession of collaborative workshops called JAD sessions A methodology that involves the client or end user in the design and development of an application, through a succession of collaborative workshops called JAD sessions Is thought to lead to faster development times and greater client satisfaction, because the client is involved throughout the development process Is thought to lead to faster development times and greater client satisfaction, because the client is involved throughout the development process

Rapid Application Development A concept that products can be developed faster and of higher quality through: A concept that products can be developed faster and of higher quality through: –Gathering requirements using workshops or focus groups –Prototyping and early, reiterative user testing of designs –The re-use of software components –A rigidly paced schedule that defers design improvements to the next product version –Less formality in reviews and other team communication Is a variation of JAD Is a variation of JAD

Build A build is a version of a program A build is a version of a program As a rule, a build is a pre-release version and as such is identified by a build number, rather than by a release number As a rule, a build is a pre-release version and as such is identified by a build number, rather than by a release number Reiterative (repeated) builds are an important part of the development process Reiterative (repeated) builds are an important part of the development process

Build Throughout development, application components are collected and repeatedly compiled for testing purposes, to ensure a reliable final product Throughout development, application components are collected and repeatedly compiled for testing purposes, to ensure a reliable final product Build tools, such as Make or Ant, enable developers to automate some programming tasks Build tools, such as Make or Ant, enable developers to automate some programming tasks As a verb, to build can mean either to write code or to put individual coded components of a program together As a verb, to build can mean either to write code or to put individual coded components of a program together

Synchronise and Stabilise Is a systems development life cycle model in which teams work in parallel on individual application modules Is a systems development life cycle model in which teams work in parallel on individual application modules They frequently synchronise their code with that of other teams They frequently synchronise their code with that of other teams They debug (stabilise) code regularly throughout the development process. They debug (stabilise) code regularly throughout the development process.

Synchronise and Stabilise The sync-and-stabilize model offers advantages over the older waterfall model, which is strictly sequential in nature The sync-and-stabilize model offers advantages over the older waterfall model, which is strictly sequential in nature –Sync-and-stabilize development allows for changes at any point in the process –It can be flexible, and more easily able to respond to market requirement changes