<<–2/”>a href=”https://exam.pscnotes.com/5653-2/”>p>HLD and LLD, combining the key differences, pros and cons, similarities, and FAQs in an easy-to-digest format.
Introduction
In the Software development lifecycle (SDLC), the system design phase is crucial for outlining the structure and functionality of the software. This phase is divided into two distinct levels: High-Level Design (HLD) and Low-Level Design (LLD).
- High-Level Design (HLD): Focuses on the overall architecture of the system, defining the major components, their relationships, and how they interact to fulfill the project’s requirements.
- Low-Level Design (LLD): Delves into the specifics of each component identified in the HLD. It outlines the detailed logic, algorithms, data structures, and interfaces needed to implement each component.
Key Differences: HLD vs LLD
| Feature | High-Level Design (HLD) | Low-Level Design (LLD) |
|---|---|---|
| Scope | Overall system architecture, major components, and their interactions | Specifics of each component (logic, algorithms, data structures, interfaces) |
| Level of Detail | Abstract, conceptual | Concrete, detailed |
| Focus | “What” the system will do | “How” the system will do it |
| Audience | Project managers, stakeholders, architects | Developers, testers |
| Output | Architecture diagrams, component descriptions, interface specifications | Pseudocode, class diagrams, sequence diagrams, Database schemas |
| Purpose | Define the system’s structure and high-level functionality | Provide a blueprint for implementation |
| Example | A diagram showing the main modules of an E-Commerce system and their flow | The detailed steps involved in processing a user’s order in the e-commerce system |
Advantages and Disadvantages
High-Level Design (HLD)
| Advantages | Disadvantages |
|---|---|
| Provides a big-picture view of the system, aiding understanding and decision-making. | May lack the necessary detail for developers to start implementation. |
| Facilitates Communication between stakeholders and technical teams. | Can be time-consuming to create if not done efficiently. |
| Helps identify potential issues early in the development process. | Might require revisions as the project progresses and more details become available. |
Low-Level Design (LLD)
| Advantages | Disadvantages |
|---|---|
| Provides a clear roadmap for developers, ensuring efficient implementation. | Can be overly complex and difficult to understand if not well-structured. |
| Helps identify and address technical challenges before coding begins. | May lead to tunnel vision, focusing on details and losing sight of the overall picture. |
| Ensures consistency and adherence to coding standards. | Can be time-consuming to create and maintain, especially for large systems. |
Similarities between HLD and LLD
- Both are essential: HLD and LLD are both critical phases in the SDLC, contributing to a successful project outcome.
- Iterative: Both designs may evolve and be refined as the project progresses.
- Documentation: Both designs should be well-documented to serve as a reference for the development team and stakeholders.
FAQs on HLD and LLD
Q: Which comes first, HLD or LLD?
A: HLD comes first. It sets the foundation for the LLD by defining the overall system architecture.
Q: Can HLD and LLD be done in parallel?
A: While some overlap is possible, it’s generally best to complete the HLD before starting the LLD to ensure a solid architectural base.
Q: Who is responsible for creating HLD and LLD?
A: Typically, solution architects or system designers create the HLD, while developers and technical leads create the LLD.
Q: What tools are used for HLD and LLD?
A:
- HLD: UML diagrams, architecture diagrams, flowcharts
- LLD: Class diagrams, sequence diagrams, pseudocode, database schemas
Let me know if you’d like more details on any specific aspect of HLD or LLD.