Bug fixes may not flow through the entire cycle, however, at least an abbreviated process is necessary to ensure that the fix does not introduce other problems known as a regression. Below is a brief explanation and how they relate to the SDLC.
The Waterfall method of software development follows a rigid, predetermined path through a set of phases. This method was adapted from traditional engineering. Ironically, the paper credited as the origin of the Waterfall method, describes it as being fundamentally flawed. Despite that fact, Waterfall became a very common, even standard methodology for large projects around the world. Waterfall methodology begins with long planning and design phases.
Once developed, the software then goes through phases of testing, and is finally deployed for use. Waterfall is considered by many to be too rigid to adapt to changing requirements. It does not support feedback throughout the process, leading to the implementation of requirements that may have changed during the development effort. This weakness in Waterfall led to the development of more flexible methodologies, such as Agile.
The Manifesto for Agile Software Development was drafted and signed by a group of software developers in Reading the manifesto, you can see clearly the contrast between Waterfall, then the de-facto standard for development methods, and Agile, the newer method.
The Manifesto addresses key problems with Waterfall that led to challenges in software delivery. Agile emphasizes teamwork, prototyping, and feedback loops that can change the direction of the development effort in response to changing requirements. Several variants of Agile have emerged since the signing of the Manifesto. Scrum defines specific roles and events, known as ceremonies , as part of its practice.
Kanban is simpler, with fewer prescriptions and more flexibility. Agile teams often combine these together to adapt a bespoke process that fits them best. Waterfall is still used by many companies around the world, however, Agile is rapidly gaining ground. Regardless of the method used, there are practices that reduce risk and increase the chances of success. The importance of a central source control repository cannot be overstated. Development teams that do not use source control are taking risks, both with the code, and their process.
Using source control reduces risk by ensuring that work code is gathered together in a single place, on a regular basis. If a developer workstation or file server fails, the central repository saves the day. Modern Source control systems also support Continuous Integration. The purpose of Continuous Integration CI is to keep the software in a functional state. Prior to the common use of CI, development teams would write thousands of lines of code, then attempt to integrate them.
This integrating that much work all at once is tedious, painful, and prone to error. CI is an automation that builds software every time the code changes. If there is a problem, the CI system alerts the developers. Following proper CI practices, no further work is done until the build is successful.
This prevents errors and defects from progressing into software that should be as bug-free as possible. Large, complex software development efforts can be unwieldy and difficult to track. An entire class of software systems has grown around this problem: Application Life Cycle Management. The larger the effort, the more indispensable these systems become. They offer features in work management, bug tracking, and analytics to assist in decision making.
Implementation Phase. In the implementation phase, the organization configures and enables system security features, tests the functionality of these features, installs or implements the system, and obtains a formal authorization to operate the system.
Design reviews and system tests should be performed before placing the system into operation to ensure that it meets all required security specifications. This approach ensures that new controls meet security specifications and do not conflict with or invalidate existing controls. The organization should continuously monitor performance of the system to ensure that it is consistent with pre-established user and security requirements, and that needed system modifications are incorporated.
Configuration management CM and control activities should be conducted to document any proposed or actual changes in the security plan of the system. Information systems are in a constant state of evolution with upgrades to hardware, software, firmware, and possible modifications in the surrounding environment. Documenting information system changes and assessing the potential impact of these changes on the security of a system are essential activities to assure continuous monitoring, and prevent lapses in the system security accreditation.
Disposal Phase. In this phase, plans are developed for discarding system information, hardware, and software and making the transition to a new system. The information, hardware, and software may be moved to another system, archived, discarded, or destroyed.
If performed improperly, the disposal phase can result in the unauthorized disclosure of sensitive data. When archiving information, organizations should consider the need for and the methods for future retrieval. Usually, there is no definitive end to a system. Systems normally evolve or transition to the next generation because of changing requirements or improvements in technology.
System security plans should continually evolve with the system. Much of the environmental, management, and operational information for the original system should still be relevant and useful when the organization develops the security plan for the follow-on system. The disposal activities ensure the orderly termination of the system and preserve the vital information about the system so that some or all of the information may be reactivated in the future, if necessary.
Particular emphasis is given to proper preservation of the data processed by the system so that the data is effectively migrated to another system or archived in accordance with applicable records management regulations and policies for potential future access.
Other projects are facility-oriented, such as the establishment of a data center or a hot site. Organizations developing projects such as these should follow the principles for integrating security into the SDLC, as they examine and address the additional security considerations involved in these projects.
Publications developed by NIST help information management and information security personnel in planning and implementing a comprehensive approach to information security. The general security of information systems depends upon attention to basic issues such as security planning, certification and accreditation, risk management, categorization of systems, and use of security controls.
NIST SP also provides further detail on additional activities that are valuable for consideration in different system and agency settings. This publication is being revised. It is often used and followed when there is an IT or IS project under development. The SDLC highlights different stages phrases or steps of the development process.
The life cycle approach is used so users can see and understand what activities are involved within a given step. It is also used to let them know that at any time, steps can be repeated or a previous step can be reworked when needing to modify or improve the system. This is the first phase in the systems development process. It identifies whether or not there is the need for a new system to achieve a business"s strategic objectives. This is a preliminary plan or a feasibility study for a company"s business initiative to acquire the resources to build on an infrastructure to modify or improve a service.
The company might be trying to meet or exceed expectations for their employees, customers and stakeholders too. The purpose of this step is to find out the scope of the problem and determine solutions. Resources, costs, time, benefits and other items should be considered at this stage. The second phase is where businesses will work on the source of their problem or the need for a change.
In the event of a problem, possible solutions are submitted and analyzed to identify the best fit for the ultimate goal s of the project. This is where teams consider the functional requirements of the project or solution. Systems analysis is vital in determining what a business"s needs are, as well as how they can be met, who will be responsible for individual pieces of the project, and what sort of timeline should be expected.
The third phase describes, in detail, the necessary specifications, features and operations that will satisfy the functional requirements of the proposed system which will be in place. This is the step for end users to discuss and determine their specific business information needs for the proposed system.
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