1. Needs analysis
It is the most fundamental and critical stage of the SDLC. If aims or processes are unclear, this is likely to increase both the cost and the risk of the project. If a commercial software company is creating the software, this stage will require extensive market research. If it is done in-house, project leaders will need to engage with key stakeholders to understand the outcomes they want the project to deliver. In both cases, the aim is to deliver a Software Requirements Specification (SRS) document. This describes what functionality the software is planned to have; and how it is be expected to perform.
Once the needs are known, software design development can begin. This is codified in a Software Design Document (SDS) which provides the high-level architecture of the application. This should specify the hardware platform, operating system, and programming language to be used. This should also define all the key modules of the product; and dictate communication and data flows with any external or third-party elements. A prototype or proof-of-concept (PoC) might then be created to flush out any glaring problems or to firm up requirements.
3. Development and Testing
This is the point at which the actual software starts to be created. It is crucial that each member of the coding team sticks to the plans defined previously in the SDLC. This team has different types of skills. Front-end experts tackle the user interface. Database Administrators (DBAs) ensure the right data is available. And software developers write and implement the code.
Once created, it is vital to confirm that the code meets the defined requirements. This is when the Quality Assurance (QA) team takes over. They test the finished software, flagging any bugs so the coding time can fix them. This process continues until the software meets the required functional and quality threshold.
Once the code has been tested and approved, it then needs to be released into a production environment. For commercial software products, this may involve some customization and additional testing. Training and support should also be considered: software that isn’t used properly will not deliver on its full potential. All software must also continue to adapt to the real-world environment. New security issues will arise. New (or overlooked) user requirements will be discovered. Ongoing development will be necessary to ensure the continued relevance of the software. This means that the whole SDLC must be repeated on an ongoing basis, though hopefully on a much smaller scale.
For any programmer, reliable documentation is always essential. Documentation helps monitor the different aspects of the completed software. It also enhances its long-term quality by ensuring it can easily be kept up to date or enhanced. Good documentation makes information easily accessible and ensures knowledge transfer. It lowers support costs by enabling new users to quickly learn what they need to know. Documentation can include, but is not restricted to, the following: business rules; database records; server platform; and installation and deployment.
This is sometimes called a post-implementation review. Not every company considers this to be an official part of the SDLC. Some believe it to be part of the maintenance stage. While opinions vary, there is no doubt that evaluation is critical. It is how you confirm that the system maps to the initial needs and objectives. It is how you prove that the system is stable. This is also the phase when any flaws can be identified and addressed. It is also a chance to look at the effectiveness of the development process itself. Important lessons can be learned through evaluation that could have a positive impact on future projects.
Software creation is complex, so project management of the SDLC is crucial. The role of project managers is varied. They manage all the people and teams involved in the project. They ensure quality assurance so that the completed application is stable and fit for purpose. And they must keep all those with a stake in the success of the project fully up to date.
Secure SDLC (SSDLC) ensures that security is built into software creation and not bolted on at the end of the process. It gathers best practices that aim to add security to the existing SDLC approach. More than just a process, SSDLC requires a mind shift from development teams. It is no longer good enough just to think about functionality. Instead, it requires a focus on security at each phase of the SDLC. This approach ensures that security flaws are spotted earlier – and that the costs of fixing them are reduced.
Open source vs. proprietary software
For decades, all software was proprietary or ‘closed source’. This protects the intellectual property of those that created the software. On the other hand, it limits the ability of developers to adapt the code to their unique needs. Only the original authors of the code are legally allowed to copy or amend closed source software.
Their customers are asked to sign a license agreement that ensures they do not tamper with the code in any way. Microsoft Windows and the Apple macOS are both examples of closed code software.
In the mid-1990’s, Linux – an open source alternative to the Unix platforms that powered many businesses – became popular. Since then, the open source movement has grown into a widely accepted foundation for software creation. According to opensource.com, the term refers to
“Software with source code that anyone can inspect, modify, and enhance”.
It is free to use, but conditions attach to this. Any improvements you make must be given back to the open source code community that created the original code.
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