Systems Development Life-cycle
   HOME

TheInfoList



OR:

In
systems engineering Systems engineering is an interdisciplinary field of engineering and engineering management that focuses on how to design, integrate, and manage complex systems over their enterprise life cycle, life cycles. At its core, systems engineering util ...
,
information system An information system (IS) is a formal, sociotechnical, organizational system designed to collect, process, store, and distribute information. From a sociotechnical perspective, information systems are composed by four components: task, people ...
s and
software engineering Software engineering is a systematic engineering approach to software development. A software engineer is a person who applies the principles of software engineering to design, develop, maintain, test, and evaluate computer software. The term '' ...
, the systems development life cycle (SDLC), also referred to as the application development life cycle, is a process for planning, creating, testing, and deploying an
information system An information system (IS) is a formal, sociotechnical, organizational system designed to collect, process, store, and distribute information. From a sociotechnical perspective, information systems are composed by four components: task, people ...
. The systems development life cycle concept applies to a range of hardware and software configurations, as a system can be composed of hardware only, software only, or a combination of both. There are usually six stages in this cycle: requirement analysis, design, development and testing, implementation, documentation, and evaluation.


Overview

A systems development life cycle is composed of a number of clearly defined and distinct work phases which are used by systems engineers and systems developers to plan for, design, build, test, and deliver
information system An information system (IS) is a formal, sociotechnical, organizational system designed to collect, process, store, and distribute information. From a sociotechnical perspective, information systems are composed by four components: task, people ...
s. Like anything that is manufactured on an assembly line, an SDLC aims to produce high-quality systems that meet or exceed customer expectations, based on customer requirements, by delivering systems that move through each clearly defined phase, within scheduled time frames and cost estimates. Computer systems are complex and often (especially with the recent rise of
service-oriented architecture In software engineering, service-oriented architecture (SOA) is an architectural style that focuses on discrete services instead of a monolithic design. By consequence, it is also applied in the field of software design where services are provide ...
) link multiple traditional systems potentially supplied by different software vendors. To manage this level of complexity, a number of SDLC models or methodologies have been created, such as
waterfall A waterfall is a point in a river or stream where water flows over a vertical drop or a series of steep drops. Waterfalls also occur where meltwater drops over the edge of a tabular iceberg or ice shelf. Waterfalls can be formed in several wa ...
,
spiral In mathematics, a spiral is a curve which emanates from a point, moving farther away as it revolves around the point. Helices Two major definitions of "spiral" in the American Heritage Dictionary are:Agile software development In software development, agile (sometimes written Agile) practices include requirements discovery and solutions improvement through the collaborative effort of self-organizing and cross-functional teams with their customer(s)/ end user(s), ad ...
,
rapid prototyping Rapid prototyping is a group of techniques used to quickly fabricate a scale model of a physical part or assembly using three-dimensional computer aided design (CAD) data. Construction of the part or assembly is usually done using 3D printin ...
,
incremental Increment or incremental may refer to: *Incrementalism, a theory (also used in politics as a synonym for gradualism) *Increment and decrement operators, the operators ++ and -- in computer programming *Incremental computing *Incremental backup, wh ...
, and synchronize and stabilize. SDLC can be described along a spectrum of agile to iterative to sequential methodologies. Agile methodologies, such as XP and
Scrum Scrum may refer to: Sport * Scrum (rugby), a method of restarting play in rugby union and rugby league ** Scrum (rugby union), scrum in rugby union * Scrum, an offensive melee formation in Japanese game Bo-taoshi Media and popular culture * M ...
, focus on lightweight processes which allow for rapid changes (without necessarily following the pattern of SDLC approach) along the development cycle.
Iterative Iteration is the repetition of a process in order to generate a (possibly unbounded) sequence of outcomes. Each repetition of the process is a single iteration, and the outcome of each iteration is then the starting point of the next iteration. ...
methodologies, such as
Rational Unified Process The Rational Unified Process (RUP) is an iterative software development process framework created by the Rational Software Corporation, a division of IBM since 2003. RUP is not a single concrete prescriptive process, but rather an adaptable proce ...
and
dynamic systems development method Dynamic systems development method (DSDM) is an agile project delivery framework, initially used as a software development method. First released in 1994, DSDM originally sought to provide some discipline to the rapid application development (R ...
, focus on limited project scope and expanding or improving products by multiple iterations. Sequential or big-design-up-front (BDUF) models, such as waterfall, focus on complete and correct planning to guide large projects and risks to successful and predictable results. Other models, such as anamorphic development, tend to focus on a form of development that is guided by project scope and adaptive iterations of feature development. In
project management Project management is the process of leading the work of a team to achieve all project goals within the given constraints. This information is usually described in project documentation, created at the beginning of the development process. Th ...
a project can be defined both with a
project life cycle Project management is the process of leading the work of a team to achieve all project goals within the given constraints. This information is usually described in project documentation, created at the beginning of the development process. Th ...
(PLC) and an SDLC, during which slightly different activities occur. According to Taylor (2004), "the project life cycle encompasses all the activities of the
project A project is any undertaking, carried out individually or collaboratively and possibly involving research or design, that is carefully planned to achieve a particular goal. An alternative view sees a project managerially as a sequence of even ...
, while the systems development life cycle focuses on realizing the product
requirement In product development and process optimization, a requirement is a singular documented physical or functional need that a particular design, product or process aims to satisfy. It is commonly used in a formal sense in engineering design, includi ...
s". The SDLC is not a methodology per se, but rather a description of the phases in the life cycle of a software application. In a broad sense, these phases are: investigation, analysis, design, build, test, implement, and maintenance and support. All software development methodologies follow the SDLC phases but the method of doing that varies vastly between methodologies. In the Scrum framework, for example, one could say a single user story goes through all the phases of the SDLC within a single two-week sprint. Contrast this to the waterfall methodology, as another example, where every business requirement (recorded in the analysis phase of the SDLC in a document called the Business Requirements Specification) is translated into feature/functional descriptions (recorded in the design phase in a document called the Functional Specification) which are then all built in one go as a collection of solution features typically over a period of three to nine months, or more. These methodologies are different approaches, yet they both contain the SDLC phases in which a requirement is born, then travels through the life cycle phases ending in the final phase of maintenance and support, after which the whole life cycle typically starts again for a subsequent version of the software application.


History and details

The
product life cycle In industry, Product Lifecycle Management (PLM) is the process of managing the entire lifecycle of a product from its inception through the engineering, design and manufacture, as well as the service and disposal of manufactured products. PLM ...
describes the process of building information systems in a very deliberate, structured, and methodical way, reiterating each stage of the product's life. The systems development life cycle, according to Elliott & Strachan & Radford (2004), "originated in the 1960s, to develop large scale functional
business systems Business is the practice of making one's living or making money by producing or buying and selling products (such as goods and services). It is also "any activity or enterprise entered into for profit." Having a business name does not separa ...
in an age of large scale
business conglomerate A conglomerate () is a multi-industry company – i.e., a combination of multiple business entities operating in entirely different industries under one corporate group, usually involving a parent company and many subsidiaries. Conglomerates ...
s. Information systems activities revolved around heavy
data processing Data processing is the collection and manipulation of digital data to produce meaningful information. Data processing is a form of ''information processing'', which is the modification (processing) of information in any manner detectable by an ...
and number crunching routines".Geoffrey Elliott & Josh Strachan (2004) ''Global Business Information Technology''. p.87. Several systems development frameworks have been partly based on SDLC, such as the
structured systems analysis and design method Structuring, also known as smurfing in banking jargon, is the practice of executing financial transactions such as making bank deposits in a specific pattern, calculated to avoid triggering financial institutions to file reports required by law ...
(SSADM) produced for the UK government
Office of Government Commerce The Office of Government Commerce (OGC) was a UK Government Office established as part of HM Treasury in 2000. It was moved into the Efficiency and Reform Group of the Cabinet Office in 2010, before being closed in 2011. Overview A ''Review of ...
in the 1980s. Ever since, according to Elliott (2004), "the traditional life cycle approaches to systems development have been increasingly replaced with alternative approaches and frameworks, which attempted to overcome some of the inherent deficiencies of the traditional SDLC".


Phases

The system development life cycle framework provides a sequence of activities for system designers and developers to follow. It consists of a set of steps or phases in which each phase of the SDLC uses the results of the previous one.US Department of Justice (2003)
INFORMATION RESOURCES MANAGEMENT
Chapter 1. Introduction.
The SDLC adheres to important phases that are essential for developers—such as
planning Planning is the process of thinking regarding the activities required to achieve a desired goal. Planning is based on foresight, the fundamental capacity for mental time travel. The evolution of forethought, the capacity to think ahead, is consi ...
,
analysis Analysis ( : analyses) is the process of breaking a complex topic or substance into smaller parts in order to gain a better understanding of it. The technique has been applied in the study of mathematics and logic since before Aristotle (38 ...
,
design A design is a plan or specification for the construction of an object or system or for the implementation of an activity or process or the result of that plan or specification in the form of a prototype, product, or process. The verb ''to design'' ...
, and
implementation Implementation is the realization of an application, or execution of a plan, idea, model, design, specification, standard, algorithm, or policy. Industry-specific definitions Computer science In computer science, an implementation is a realiza ...
—and are explained in the section below. This includes evaluation of the currently used system, information gathering, feasibility studies, and request approval. A number of SDLC models have been created, including waterfall, fountain, spiral, build and fix, rapid prototyping, incremental, synchronize, and stabilize. The oldest of these, and the best known, is the
waterfall model The waterfall model is a breakdown of project activities into linear sequential phases, meaning they are passed down onto each other, where each phase depends on the deliverables of the previous one and corresponds to a specialization of tasks. ...
, a sequence of stages in which the output of each stage becomes the input for the next. These stages can be characterized and divided up in different ways, including the following: * Preliminary analysis: Begin with a preliminary analysis, propose alternative solutions, describe costs and benefits, and submit a preliminary plan with recommendations. :# Conduct the preliminary analysis: Discover the organization's objectives and the nature and scope of the problem under study. Even if a problem refers only to a small segment of the organization itself, find out what the objectives of the organization itself are. Then see how the problem being studied fits in with them. :# Propose alternative solutions: After digging into the organization's objectives and specific problems, several solutions may have been discovered. However, alternate proposals may still come from interviewing employees, clients, suppliers, and/or consultants. Insight may also be gained by researching what competitors are doing. :# Cost-benefit analysis: Analyze and describe the costs and benefits of implementing the proposed changes. In the end, the ultimate decision on whether to leave the system as is, improve it, or develop a new system will be guided by this and the rest of the preliminary analysis data. * Systems analysis, requirements definition: Define project goals into defined functions and operations of the intended application. This involves the process of gathering and interpreting facts, diagnosing problems, and recommending improvements to the system. Project goals will be further aided by the analysis of end-user information needs and the removal of any inconsistencies and incompleteness in these requirements. : A series of steps followed by the developer include: :# Collection of facts: Obtain end-user requirements through documentation, client interviews, observation, and questionnaires. :# Scrutiny of the existing system: Identify the pros and cons of the current system in place, so as to carry forward the pros and avoid the cons in the new system. :# Analysis of the proposed system: Find solutions to the shortcomings described in step two and prepare the specifications using any specific user proposals. * Systems design: At this step, desired features and operations are described in detail, including screen layouts,
business rule A business rule defines or constrains some aspect of business. It may be expressed to specify an action to be taken when certain conditions are true or may be phrased so it can only resolve to either true or false. Business rules are intended to ass ...
s, process diagrams,
pseudocode In computer science, pseudocode is a plain language description of the steps in an algorithm or another system. Pseudocode often uses structural conventions of a normal programming language, but is intended for human reading rather than machine re ...
, and other documentation. Role in system design: client,ux designer, project manager, business analyst, software developer, QA specialist * Development: The real code is written here. * Integration and testing: All the modules are brought together into a special testing environment, then checked for errors, bugs, and interoperability. * Acceptance, installation, deployment: This is the final stage of initial development, where the software is put into production and runs actual business. * Maintenance: During the maintenance stage of the SDLC, the system is assessed/evaluated to ensure it does not become obsolete. This is also where changes are made to the initial software. * Evaluation: Some companies do not view this as an official stage of the SDLC, while others consider it to be an extension of the maintenance stage, and may be referred to in some circles as post-implementation review. This is where the system that was developed, as well as the entire process, is evaluated. Some of the questions that need to be answered include if the newly implemented system meets the initial business requirements and objectives, if the system is reliable and fault-tolerant, and if it functions according to the approved functional requirements. In addition to evaluating the software that was released, it is important to assess the effectiveness of the development process. If there are any aspects of the entire process (or certain stages) that management is not satisfied with, this is the time to improve. * Disposal: In this phase, plans are developed for discontinuing the use of system information, hardware, and software and making the transition to a new system. The purpose here is to properly move, archive, discard, or destroy information, hardware, and software that is being replaced, in a manner that prevents any possibility of unauthorized disclosure of sensitive data. The disposal activities ensure proper migration to a new system. Particular emphasis is given to the proper preservation and archiving of data processed by the previous system. All of this should be done in accordance with the organization's security requirements. In the following diagram, these stages of the systems development life cycle are divided into ten steps, from definition to creation and modification of IT work products: Not every project will require that the phases be sequentially executed; however, the phases are interdependent. Depending upon the size and complexity of the project, phases may be combined or may overlap.


System investigation

First, the IT system proposal is investigated. During this step, consider all current priorities that would be affected and how they should be handled. Before any system planning is done, a
feasibility study A feasibility study is an assessment of the practicality of a project or system. A feasibility study aims to objectively and rationally uncover the strengths and weaknesses of an existing business or proposed venture, opportunities and threats pr ...
should be conducted to determine if creating a new or improved system is a viable solution. This will help to determine the costs, benefits, resource requirements, and specific user needs to be required for completion. The development process can only continue once management approves the recommendations from the feasibility study. The following represent different components of the feasibility study: * Operational feasibility * Financial feasibility * Technical feasibility * Human factors feasibility * Legal/Political feasibility


Analysis

The goal of
analysis Analysis ( : analyses) is the process of breaking a complex topic or substance into smaller parts in order to gain a better understanding of it. The technique has been applied in the study of mathematics and logic since before Aristotle (38 ...
is to determine where the problem is, in an attempt to fix the system. This step involves
breaking down "Breaking Down" is a song by American rock band I Prevail, released as the second single from their second studio album ''Trauma''. In July 2019, it peaked at number three on the '' Billboard'' Mainstream Rock Songs chart. Background The song w ...
the system in different pieces to analyze the situation, analyzing project goals, breaking down what needs to be created, and attempting to engage users so that definite requirements can be defined.


Design

In
systems design Systems design interfaces, and data for an electronic control system to satisfy specified requirements. System design could be seen as the application of system theory to product development. There is some overlap with the disciplines of system a ...
, the design functions and operations are described in detail, including screen layouts, business rules, process diagrams, and other documentation. The output of this stage will describe the new system as a collection of modules or subsystems. The design stage takes as its initial input the requirements identified in the approved requirements document. For each requirement, a set of one or more design elements will be produced as a result of interviews, workshops, and/or prototype efforts. Design elements describe the desired system features in detail, and they generally include functional hierarchy diagrams, screen layout diagrams, tables of business rules, business process diagrams, pseudo-code, and a complete entity-relationship diagram with a full data dictionary. These design elements are intended to describe the system in sufficient detail, such that skilled developers and engineers may develop and deliver the system with minimal additional input design.


Environments

Environments are controlled areas where systems developers can build, distribute, install, configure, test, and execute systems that move through the SDLC. Each environment is aligned with different areas of the SDLC and is intended to have specific purposes. Examples of such environments include the: * ''development environment'', where developers can work independently of each other before trying to merge their work with the work of others; * ''common build environment'', where merged work can be built, together, as a combined system; * ''systems integration testing environment'', where basic testing of a system's integration points to other upstream or downstream systems can be tested; * ''user acceptance testing environment'', where business stakeholders can test against their original business requirements; and * ''production environment'', where systems finally get deployed for final use by their intended end users.


Testing

The code is tested at various levels in
software testing Software testing is the act of examining the artifacts and the behavior of the software under test by validation and verification. Software testing can also provide an objective, independent view of the software to allow the business to apprecia ...
. Unit, system, and user acceptance tests are often performed. This is a grey area as many different opinions exist as to what the stages of testing are and how much, if any iteration occurs. Iteration is not generally part of the waterfall model, but the means to rectify defects and validate fixes prior to deployment is incorporated into this phase. The following are types of testing that may be relevant, depending on the type of system under development: * ''Defect testing'' the failed scenarios, including * Path testing * Data set testing *
Unit testing In computer programming, unit testing is a software testing method by which individual units of source code—sets of one or more computer program modules together with associated control data, usage procedures, and operating procedures&md ...
*
System testing System testing is testing conducted on a complete integrated system to evaluate the system's compliance with its specified requirements. System testing takes, as its input, all of the integrated components that have passed integration testing. ...
*
Integration testing Integration testing (sometimes called integration and testing, abbreviated I&T) is the phase in software testing in which individual software modules are combined and tested as a group. Integration testing is conducted to evaluate the complianc ...
*
Black-box testing Black-box testing is a method of software testing that examines the functionality of an application without peering into its internal structures or workings. This method of test can be applied virtually to every level of software testing: unit, ...
*
White-box testing White-box testing (also known as clear box testing, glass box testing, transparent box testing, and structural testing) is a method of software testing that tests internal structures or workings of an application, as opposed to its functionality ...
*
Regression testing Regression testing (rarely, ''non-regression testing'') is re-running functional and non-functional tests to ensure that previously developed and tested software still performs as expected after a change. If not, that would be called a '' regre ...
* Automation testing *
User acceptance testing In engineering and its various subdisciplines, acceptance testing is a test conducted to determine if the requirements of a specification or contract are met. It may involve chemical tests, physical tests, or performance tests. In systems en ...
*
Software performance testing In software quality assurance, performance testing is in general a testing practice performed to determine how a system performs in terms of responsiveness and stability under a particular workload. It can also serve to investigate, measure, valid ...


Training and transition

Once a system has been stabilized through adequate testing, the SDLC ensures that proper training on the system is performed or documented before transitioning the system to its support staff and end users. Training usually covers operational training for those people who will be responsible for supporting the system as well as training for those end users who will be using the system after its delivery to a production operating environment. After training has been successfully completed, systems engineers and developers transition the system to its final production environment, where it is intended to be used by its end users and supported by its support and operations staff.


Operations and maintenance

The
deployment Deployment may refer to: Engineering and software Concepts * Blue-green deployment, a method of installing changes to a web, app, or database server by swapping alternating production and staging servers * Continuous deployment, a software en ...
of the system includes various changes and enhancements before the decommissioning or sunset of the system.
Maintaining ''Maintaining'' is a 2007-2009 comic strip by cartoonist Nate Creekmore. Creekmore is a two-time winner of the Scripps College Cartoonist of the Year and an Associated Press award for achievement in college cartooning. Creekmore's strip first a ...
the system is a very important aspect of SDLC. As key personnel change positions in the organization, new changes will be implemented. There are two approaches to system development: the traditional approach (structured) and
object oriented Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of pro ...
. Information engineering includes the traditional system approach, which is also called the structured analysis and design technique. The object-oriented approach views an information system as a collection of objects that are integrated with each other to make a full and complete information system.


Evaluation

The final phase of the SDLC is to measure the effectiveness of the system and evaluate potential enhancements.


Systems analysis and design

Systems analysis and design (SAD) is the process of developing information technology systems (ITS) that effectively use hardware, software, data, processes, and people to support the company's business objectives. It is a process of planning a new business system or replacing an existing system by defining its components or modules to satisfy specific requirements. System analysis and design can be considered the meta-development activity, which serves to set the stage and bound the problem. SAD can be leveraged to set the correct balance among competing high-level requirements in the functional and non-functional analysis domains. System analysis and design interact strongly with distributed enterprise architecture, enterprise I.T. Architecture, and business architecture, and relies heavily on concepts such as partitioning, interfaces, personae and roles, and deployment/operational modeling to arrive at a high-level system description. This high-level description is then further broken down into the components and modules which can be analyzed, designed, and constructed separately and integrated to accomplish the business goal. SDLC and SAD are cornerstones of full life cycle product and system planning.


Object-oriented analysis

Object-oriented analysis (OOA) is the process of analyzing a task (also known as a
problem domain Problem solving is the process of achieving a goal by overcoming obstacles, a frequent part of most activities. Problems in need of solutions range from simple personal tasks (e.g. how to turn on an appliance) to complex issues in business an ...
), to develop a conceptual
model A model is an informative representation of an object, person or system. The term originally denoted the Plan_(drawing), plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin ''modulus'', a mea ...
that can then be used to complete the task. A typical OOA model would describe computer software that could be used to satisfy a set of customer-defined requirements. During the analysis phase of problem-solving, a programmer might consider a written requirements statement, a formal vision document, or interviews with stakeholders or other interested parties. The task to be addressed might be divided into several subtasks (or domains), each representing a different business, technological, or other areas of interest. Each subtask would be analyzed separately. Implementation constraints, (e.g.,
concurrency Concurrent means happening at the same time. Concurrency, concurrent, or concurrence may refer to: Law * Concurrence, in jurisprudence, the need to prove both ''actus reus'' and ''mens rea'' * Concurring opinion (also called a "concurrence"), a ...
,
distribution Distribution may refer to: Mathematics *Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations * Probability distribution, the probability of a particular value or value range of a vari ...
, persistence, or how the system is to be built) are not considered during the analysis phase; rather, they are addressed during object-oriented design (OOD). The conceptual model that results from OOA will typically consist of a set of
use cases In software and systems engineering, the phrase use case is a polyseme with two senses: # A usage scenario for a piece of software; often used in the plural to suggest situations where a piece of software may be useful. # A potential scenario i ...
, one or more
UML The Unified Modeling Language (UML) is a general-purpose, developmental modeling language in the field of software engineering that is intended to provide a standard way to visualize the design of a system. The creation of UML was originally m ...
class diagram In software engineering, a class diagram in the Unified Modeling Language (UML) is a type of static structure diagram that describes the structure of a system by showing the system's classes, their attributes, operations (or methods), and the rela ...
s, and a number of
interaction diagram The Unified Modeling Language (UML) is a general-purpose, developmental modeling language in the field of software engineering that is intended to provide a standard way to visualize the design of a system. The creation of UML was originally m ...
s. It may also include some kind of
user interface In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine f ...
mock-up. The input for object-oriented design is provided by the output of object-oriented analysis. Realize that an output artifact does not need to be completely developed to serve as input of object-oriented design; analysis and design may occur in parallel, and in practice the results of one activity can feed the other in a short feedback cycle through an iterative process. Both analysis and design can be performed incrementally, and the artifacts can be continuously grown instead of completely developed in one shot. Some typical (but common to all types of design analysis) input artifacts for object-oriented: *
Conceptual model A conceptual model is a representation of a system. It consists of concepts used to help people knowledge, know, understanding, understand, or simulation, simulate a subject the model represents. In contrast, physical models are physical object su ...
: Conceptual model is the result of an object-oriented analysis, it captures concepts in the problem domain. The conceptual model is explicitly chosen to be independent of implementation details, such as concurrency or data storage. *
Use case In software and systems engineering, the phrase use case is a polyseme with two senses: # A usage scenario for a piece of software; often used in the plural to suggest situations where a piece of software may be useful. # A potential scenario ...
: Use case is a description of sequences of events that, taken together, lead to a system doing something useful. Each use case provides one or more
scenarios In the performing arts, a scenario (, ; ; ) is a synoptical collage of an event or series of actions and events. In the ''commedia dell'arte'', it was an outline of entrances, exits, and action describing the plot of a play, and was literally pi ...
that convey how the system should interact with the users called actors to achieve a specific business goal or function. Use case actors may be end users or other systems. In many circumstances use cases are further elaborated into use case diagrams. Use case diagrams are used to identify the actor (users or other systems) and the processes they perform. *
System Sequence Diagram A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and expressed ...
: System Sequence diagram (SSD) is a picture that shows, for a particular scenario of a use case, the events that external actors generate, their order, and possible inter-system events. * User interface documentations (if applicable): Document that shows and describes the
look and feel In software design, the look and feel of a graphical user interface comprises aspects of its design, including elements such as colors, shapes, layout, and typefaces (the "look"), as well as the behavior of dynamic elements such as buttons, boxes ...
of the end product's user interface. It is not mandatory to have this, but it helps to visualize the end-product and therefore helps the designer. *
Relational data model The relational model (RM) is an approach to managing data using a structure and language consistent with first-order predicate logic, first described in 1969 by English computer scientist Edgar F. Codd, where all data is represented in terms of tu ...
(if applicable): A data model is an abstract model that describes how data is represented and used. If an
object database An object database or object-oriented database is a database management system in which information is represented in the form of objects as used in object-oriented programming. Object databases are different from relational databases which ar ...
is not used, the relational data model should usually be created before the design, since the strategy chosen for object-relational mapping is an output of the OO design process. However, it is possible to develop the relational data model and the object-oriented design artifacts in parallel, and the growth of an artifact can stimulate the refinement of other artifacts.


Life cycle


Management and control

The SDLC phases serve as a programmatic guide to project activity and provide a flexible but consistent way to conduct projects to a depth matching the scope of the project. Each of the SDLC phase objectives are described in this section with key deliverables, a description of recommended tasks, and a summary of related control objectives for effective management. It is critical for the project manager to establish and monitor control objectives during each SDLC phase while executing projects. Control objectives help to provide a clear statement of the desired result or purpose and should be used throughout the entire SDLC process. Control objectives can be grouped into major categories (domains), and relate to the SDLC phases as shown in the figure. To manage and control any SDLC initiative, each project will be required to establish some degree of a
work breakdown structure A work-breakdown structure (WBS) in project management and systems engineering is a deliverable-oriented breakdown of a project into smaller components. A work breakdown structure is a key project deliverable that organizes the team's work into ...
(WBS) to capture and schedule the work necessary to complete the project. The WBS and all programmatic material should be kept in the "project description" section of the project notebook. The WBS format is mostly left to the project manager to establish in a way that best describes the project work. There are some key areas that must be defined in the WBS as part of the SDLC policy. The following diagram describes the three key areas that will be addressed in the WBS in a manner established by the project manager. The diagram shows that coverage spans numerous phases of the SDLC but the associated MCD has a subset of primary mappings to the SDLC phases. For example, Analysis and Design is primarily performed as part of the Acquisition and Implementation Domain, and System Build and Prototype is primarily performed as part of delivery and support.


Work breakdown structured organization

The upper section of the work breakdown structure (WBS) should identify the major phases and milestones of the project in a summary fashion. In addition, the upper section should provide an overview of the full scope and timeline of the project, and will be part of the initial project description effort leading to the project approval. The middle section of the WBS is based on the seven systems development life cycle phases as a guide for WBS task development. The WBS elements should consist of milestones and "tasks" as opposed to "activities" and have a definitive period (usually two weeks or more). Each task must have a measurable output (e.g. document, decision, or analysis). A WBS task may rely on one or more activities (e.g. software engineering,
systems engineering Systems engineering is an interdisciplinary field of engineering and engineering management that focuses on how to design, integrate, and manage complex systems over their enterprise life cycle, life cycles. At its core, systems engineering util ...
) and may require close coordination with other tasks, either internal or external to the project. Any part of the project needing support from contractors should have a
statement of work A statement of work (SOW) is a document routinely employed in the field of project management. It is the narrative description of a project's work requirement. It defines project-specific activities, deliverables and timelines for a vendor providin ...
(SOW) written to include the appropriate tasks from the SDLC phases. The development of a SOW does not occur during a specific phase of SDLC but is developed to include the work from the SDLC process that may be conducted by external resources such as contractors.


Baselines

Baselines are an important part of the systems development life cycle. These baselines are established after four of the five phases of the SDLC, and are critical to the
iterative Iteration is the repetition of a process in order to generate a (possibly unbounded) sequence of outcomes. Each repetition of the process is a single iteration, and the outcome of each iteration is then the starting point of the next iteration. ...
nature of the model . Each baseline is considered as a milestone in the SDLC. * functional baseline: established after the conceptual design phase. * allocated baseline: established after the preliminary design phase. * product baseline: established after the detail design and development phase. * updated product baseline: established after the production construction phase.


Complementary methodologies

Complementary software development methods to systems development life cycle are: *
Software prototyping Software prototyping is the activity of creating prototypes of software applications, i.e., incomplete versions of the software program being developed. It is an activity that can occur in software development and is comparable to prototyping as ...
*
Joint applications development Joint application design (JAD) is a process used in the life cycle area of the dynamic systems development method (DSDM) to collect business requirements while developing new information systems for a company. "The JAD process also includes approa ...
(JAD) *
Rapid application development Rapid application development (RAD), also called rapid application building (RAB), is both a general term for adaptive software development approaches, and the name for James Martin's method of rapid development. In general, RAD approaches to ...
(RAD) *
Extreme programming Extreme programming (XP) is a software development methodology intended to improve software quality and responsiveness to changing customer requirements. As a type of agile software development,"Human Centred Technology Workshop 2006 ", 2006, PD ...
(XP); * Open-source development *
End-user development End-user development (EUD) or end-user programming (EUP) refers to activities and tools that allow end-users – people who are not professional software developers – to program computers. People who are not professional developers can use EUD ...
*
Object-oriented programming Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of pr ...


Strengths and weaknesses

Few people in the modern computing world would use a strict
waterfall model The waterfall model is a breakdown of project activities into linear sequential phases, meaning they are passed down onto each other, where each phase depends on the deliverables of the previous one and corresponds to a specialization of tasks. ...
for their SDLC as many modern methodologies have superseded this thinking. Some will argue that the SDLC no longer applies to models like Agile computing, but it is still a term widely in use in technology circles. The SDLC practice has advantages in traditional models of systems development that lends itself more to a structured environment. The disadvantage to using the SDLC methodology is when there is need for iterative development or (i.e. web development or e-commerce) where stakeholders need to review on a regular basis the software being designed. A comparison of the strengths and weaknesses of SDLC: An alternative to the SDLC is the rapid application development (RAD), which combines prototyping, joint application development, and implementation of CASE tools. The advantages of RAD are speed, reduced development cost, and active user involvement in the development process.


System lifecycle

The system lifecycle in
systems engineering Systems engineering is an interdisciplinary field of engineering and engineering management that focuses on how to design, integrate, and manage complex systems over their enterprise life cycle, life cycles. At its core, systems engineering util ...
is a view of a system or proposed system that addresses all phases of its existence to include system conception, design and development, production and/or construction, distribution, operation, maintenance and support, retirement, phase-out, and disposal.


Conceptual design

The
conceptual design Conceptual design is an early phase of the design process, in which the broad outlines of function and form of something are articulated. It includes the design of interactions, experiences, processes, and strategies. It involves an understanding of ...
stage is the stage where an identified need is examined, requirements for potential solutions are defined, potential solutions are evaluated, and a system specification is developed. The system specification represents the technical requirements that will provide overall guidance for system design. Because this document determines all future development, the stage cannot be completed until a conceptual
design review A design review is a milestone within a product development process whereby a design is evaluated against its requirements in order to verify the outcomes of previous activities and identify issues before committing to—and, if need be, to re-pr ...
has determined that the system specification properly addresses the motivating need. Key steps within the conceptual design stage include: *Need identification *Feasibility analysis *System requirements analysis *System specification *Conceptual design review


Preliminary system design

During this stage of the system lifecycle, subsystems that perform the desired system functions are designed and specified in compliance with the system specification. Interfaces between subsystems are defined, as well as overall test and evaluation requirements. At the completion of this stage, a development specification is produced that is sufficient to perform detailed design and development. Key steps within the preliminary design stage include: *Functional analysis *Requirements allocation *Detailed trade-off studies *Synthesis of system options *Preliminary design of engineering models *Development specification *Preliminary design review For example, as the system analyst of Viti Bank, you have been tasked to examine the current information system. Viti Bank is a fast-growing bank in
Fiji Fiji ( , ,; fj, Viti, ; Fiji Hindi: फ़िजी, ''Fijī''), officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists ...
. Customers in remote rural areas are finding difficulty to access the bank services. It takes them days or even weeks to travel to a location to access the bank services. With the vision of meeting the customers' needs, the bank has requested your services to examine the current system and to come up with solutions or recommendations of how the current system can be provided to meet its needs.


Detail design and development

This stage includes the development of detailed designs that brings initial design work into a completed form of specifications. This work includes the specification of interfaces between the system and its intended environment, and a comprehensive evaluation of the systems logistical, maintenance and support requirements. The detail design and development is responsible for producing the product, process and material specifications and may result in substantial changes to the development specification. Key steps within the detail design and development stage include: *Detailed design *Detailed synthesis *Development of engineering and
prototype A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototyp ...
models *Revision of development specification *Product, process, and material specification *Critical design review


Production and construction

During the production and/or construction stage the product is built or assembled in accordance with the requirements specified in the product, process and material specifications, and is deployed and tested within the operational target environment. System assessments are conducted in order to correct deficiencies and adapt the system for continued improvement. Key steps within the product construction stage include: *Production and/or construction of system components *Acceptance testing *System distribution and operation *Operational testing and evaluation *System assessment


Utilization and support

Once fully deployed, the system is used for its intended operational role and maintained within its operational environment. Key steps within the utilization and support stage include: *System operation in the user environment *Change management *System modifications for improvement *System assessment


Phase-out and disposal

Effectiveness and efficiency of the system must be continuously evaluated to determine when the product has met its maximum effective lifecycle. Considerations include: Continued existence of operational need, matching between operational requirements and system performance, feasibility of system phase-out versus maintenance, and availability of alternative systems.


See also

*
Application lifecycle management Application lifecycle management (ALM) is the product lifecycle management (governance, development, and maintenance) of computer programs. It encompasses requirements management, software architecture, computer programming, software testing, so ...
*
Decision cycle A decision cycle is a sequence of steps used by an entity on a repeated basis to reach and implement decisions and to learn from the results. The "decision cycle" phrase has a history of use to broadly categorize various methods of making decision ...
* IPO model *
Software development methodologies In software engineering, a software development process is a process of dividing software development work into smaller, parallel, or sequential steps or sub-processes to improve design, product management. It is also known as a software devel ...


References


Further reading

* Cummings, Haag (2006). ''Management Information Systems for the Information Age''. Toronto, McGraw-Hill Ryerson * Beynon-Davies P. (2009). ''Business Information Systems''. Palgrave, Basingstoke.
Computer World, 2002
Retrieved on June 22, 2006, from the World Wide Web:
Management Information Systems, 2005
Retrieved on June 22, 2006, from the World Wide Web:


External links




Pension Benefit Guaranty Corporation – Information Technology Solutions Lifecycle Methodology
* DoD Integrated Framework Chart IFC
frontback

FSA Life Cycle Framework

HHS Enterprise Performance Life Cycle Framework

The Open Systems Development Life Cycle

System Development Life Cycle Evolution Modeling

Zero Deviation Life Cycle

Integrated Defense AT&L Life Cycle Management Chart
the U.S. DoD form of this concept. {{Authority control Systems engineering Computing terminology Software development process Software engineering