What is the Difference Between SDLC and STLC

The main difference between SDLC and STLC is that the SDLC is a process followed by software organizations to deliver a working software to the end users which involves planning, requirement gathering, and analysis, designing, implementing, testing and maintenance. Whereas, the STLC is a process followed by the testing team to ensure the quality of the software, which only involves software testing.

Software Development is a complicated process. Even though it is simple and easier to develop a small program, it is quite difficult to build enterprise level software. Therefore, it is necessary to use a proper methodology to develop the product. SDLC is the process used by software organizations to deliver working quality software to end users. It covers the entire life cycle of the software. On the other hand, STLC is the process of following the activities to ensure the quality of the software. In brief, STLC is a subset of SDLC.

Key Areas Covered

1. What is SDLC
     – Definition, Phases, Functionality
2. What is STLC
     – Definition, Phases, Functionality
3. What is the Relationship Between SDLC and STLC
     – Outline of Association
4. What is the Difference Between SDLC and STLC
     – Comparison of Key Differences

Key Terms

Software Development, SDLC, STLC

What is SDLC

SDLC stands for Software Development Life Cycle. It is a process followed from start to the delivering the software to the production environment. There are various phases in SDLC.

Figure 1: SDLC

Phases of SDLC

Planning – A basic understanding of the project is identified. This also includes recognizing risks, technical difficulties, resources.

Requirement Gathering and Analyzing –  Requirement gathering is done using various methods. Meeting the customer, meeting senior managers, observing the sales and marketing details are some of them. Then, the gathered information is analyzed and documented. This document is known as the Software Requirement Specification (SRS). It contains the requirements that need to designed and developed during the life cycle of the project.

Designing – This phase involves designing all the architectural modules, data flow representations with other modules. It also involves database designing, class diagrams, and object diagrams designing.

Development –  The project is implemented using suitable programming languages. It involves selecting programming languages, Integrated Development Environments (IDE) and tools such as code editors, debuggers, etc.

Testing –  This is the process of verifying and validating that the software has come to the expected level. There are two types of testing called functional testing and nonfunctional testing. Functional testing checks the functionalities of the software while nonfunctional testing checks the nonfunctional aspects such as performance, load, usability, etc.

Deployment and Maintenance – Finally, the product is released to the market. According to the customer feedback etc. new features are added to the product. The technical support teams provide the required services to maintain the software. This phase is also called evolution.

What is STLC

STLC stands for Software Testing Life Cycle. It is the process followed by the testing team to produce a quality software at the end. STLC is an integral part of SDLC but STLC focuses only on testing. It starts after preparing the SRS document in SDLC. The testing team prepares the test cases and start executing them to find defects of the software.

Figure 2: Testing Types

STLC involves following different phases. It is not mandatory to follow all of them. The phases in STLC can depend on the type of software, available resources and time for testing, requirements of the organization, etc.

Phases of STLC

Requirement Analysis – After preparing the SRS document, the testing team starts a high-level requirement analysis.

Test Planning – This phase is to plan the strategies and approaches for testing.

Test Case Designing – It involves developing test cases. A test case is a set of actions executed to verify a particular feature or a functionality of the software.

Test Environment Setup – It is the phase in which the integrated environment is ready to validate the product.

Test Execution – This phase performs real-time validation of the software. It actually finds the defects.

Test Closure – After completing testing, the test results are documented.

Relationship Between SDLC and STLC

• STLC is a subset of SDLC.

Difference Between SDLC and STLC

Definition

SDLC is the process followed by the development team within the software organization to develop a software product. STLC is the process of carrying out various activities to ensure the quality of the software. This is the basic difference between SDLC and STLC.

Long Form

Software Development Life Cycle is the long form of SDLC while Software Testing Life Cycle is the long form of STLC.

Involvement

Another difference between SDLC and STLC is that while SDLC covers the entire life cycle of the software,  STLC is limited only to the testing phase.

Requirement Gathering

Furthermore, in SDLC, business analyst gathers requirements and the development team analyzes them. They consider the architecture and design. In STLC, the testing team analyzes the SRS document to identify the testing requirements.

Design

We can find another difference between SDLC and STLC in their respective designing. In SDLC, designing involves developing high-level and low-level design of the software according to requirements. In STLC, designing is performed by the test architect or a test lead. He plans the test strategies to identify testing points.

Development

In SDLC, development team starts developing the software in the development phase. In STLC, the testing team writes test scenarios to validate the quality of the software. They write test cases for all modules with the expected outputs. This is also an important difference between SDLC and STLC.

Testing

In SDLC, the testing such as unit testing, integrated testing, system testing etc. is performed by testers in the testing phase. The test report is sent to the developers. They fix the defects and sends it back to the testing team for retesting. Therefore, STLC is a part of SDLC. Hence, the same tasks mentioned in SDLC is performed in STLC.

Deploying the Software to Production

Moreover, in SDLC, after the testing phase, the software is released to the real end users. In STLC, smoke and sanity testing are performed after deploying the software. Furthermore, test reports, matrixes and other documents are prepared by the testing team. We can say this as the main difference between SDLC and STLC.

Maintenance

In SDLC, the technical team provides support to update and maintain the software. In STLC, the test cases and automation scripts are maintained for updates.

Conclusion

SDLC is the process followed by the software organization to deliver a working software to the end users which involves planning, requirement gathering, and analysis, designing, implementing, testing and maintenance. STLC is the process followed by the testing team to ensure the quality of the software, which only involves software testing. That is the difference between SDLC and STLC.

Reference:

1. “SDLC Overview.” Www.tutorialspoint.com, Tutorials Point, Available here.
2. “STLC Overview.” Www.tutorialspoint.com, Tutorials Point, Available here.

Image Courtesy:

1. “SDLC – Software Development Life Cycle” By Cliffydcw – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Services stlc new” By Effone software inc – Own work (CC BY-SA 4.0) via Commons Wikimedia