Software Development Life Cycle (SDLC): Lecture 3

Department : MCA

Semester     : IV

Subject        : Principles of Software Engineering                                             

Paper           : 21

Faculty        : Avinash Kumar

Syllabus covered in  this blog:

SDLC: Phases and History

Software Development Life Cycle (SDLC)

The software development life cycle (SDLC) is a key part of information technology practices in today's enterprise world. SDLC has undergone many changes and evolved throughout the ages of big data, cloud delivery and AI/ML automation, but it is still a key framework for understanding the delivery of software products.

The entire process of software development isn’t as simple as its definition, it’s a complicated process. Accordingly, it requires an efficient approach from the developer in the form of the Software Development Life Cycle (SDLC).

Proper planning and execution are the key components of a successful software development process. The entire software development process includes 6 stages. Software Development Life Cycle (SDLC) is the common term to summarize these 6 stages.

SDLC specifies the task(s) to be performed at various stages by a software engineer/developer. It ensures that the end product is able to meet the customer’s expectations and fits in the overall budget. Hence, it’s vital for a software developer to have prior knowledge of the software domain.

Stage-1: Planning and Requirement Analysis:

Planning is the crucial step in everything and so as in software development. In this same stage, requirement analysis is also performed by the developers of the organization. This is attained from the inputs from the customers, sales department/market surveys.

The information from this analysis forms the building block of a basic project. The quality proof of the project is a result of planning. Thus, in this stage, the basic project is designed with all the available information.

Stage-2: Defining Requirements:

In this stage, all the requirements for the target software are specified. These requirements get approval from the customers, market analysts, and stakeholders.
This is fulfilled by utilizing SRS (Software Requirement Specification). This is a sort of a document that specifies all those things that need to be defined and created during the entire project cycle.

Stage-3: Designing Architecture:

SRS is a reference for software designers to come out with the best architecture for the software. Hence, with the requirements defined in SRS, multiple designs for the product architecture are present in the Design Document Specification (DDS).
This DDS is assessed by market analysts and stakeholders. After evaluating all the possible factors, the most practical and logical design is chosen for the development.

Stage-4: Developing Product:

At this stage, the fundamental development of the product starts. For this, developers use a specific programming code as per the design in the DDS. Hence, it is important for the coders to follow the protocols set by the association. Conventional programming tools like compilers, interpreters, debuggers, etc. are also put into use at this stage. Some popular languages like C/C++, Python, Java, etc. are put into use as per the software regulations.

Stage-5: Product Testing and Integration:

After the development of the product, testing of the software is necessary to ensure its smooth functioning. Since minimal testing is conducted at every stage of SDLC therefore at this stage, all the probable flaws are tracked, fixed, and retested. This ensures that the product confronts the quality requirements of SRS.

Stage 6: Deployment and Maintenance Of Product:

After detailed testing, the conclusive product is released as per the organization’s strategy. After that it is tested in a real industrial environment to ensure its smooth performance. If it performs well, the organization sends out the product as a whole. After retrieving beneficial feedback, the company releases it as it is or with auxiliary improvements to make it further helpful for the customers.

History of the SDLC

The consensus is that the SDLC as a framework developed in the 1950s and 1960s as computer science itself evolved quickly.

Prior to the second half of the 1900s, when the ENIAC and various other innovations moved the computing world forward quickly, computing really wasn't elaborate enough to need something like the SDLC. The first implementations of software technologies involved simple tools, like basic go-to lines and if/then statements.

Over time, the concept of structured programming brought in the need for developmental models and the SDLC was born.

The first early models were mainly defined by the stages.

Examine the diagram below to know the evolution of

Software Development Strategies 

Iterative and incremental practices led to prototyping in the 1980s, which led to various different types of innovations like spiral and V-model frameworks, and then into agile in the 1990s.

There are numerous ways to describe these changes over time, but the bottom line is that the software development life cycle began as a carefully staged process.

The waterfall remains the dominant model for these early software development life cycle frameworks. In the waterfall model, everything in one stage is completed before you move to the next stage. All planning gets completed before the project moves to implementation. All implementation is completed before the process moves to testing.

Then, as these frameworks evolved into agile, this idea broke down into a system where collaborative work changed workflows, and previously monolithic staging was sliced and diced into its composite parts. For example, testing could go on in different phases in different environments.

As a side note, testing was increasingly becoming automated as well.

In any case, the move from waterfall to other models, to agile and DevOps, brings us up to the current day, where the DevOps mentality is leveraging cloud architectures, micro-services and more to redefine what software development life cycle work means.