Low-Level Design is an important aspect in which software developers can demonstrate the validate design of the modules that they are going to develop.

1. LOW LEVEL DESIGN
(LLD)

2. LOW LEVEL DESIGN
• It’s a component level design process
• It gives the internal logical design of the software being developed
• It defines the class diagrams that has attributes and methods, defining
relationships between them etc
• It helps to develop the code directly with LLD document with minimal debugging
& testing.

3. OOAD
• Object Oriented Analysis & Design
• OOA – Its an investigation of the objects needed to develop a system
• OOD – Collaboration of identified objects during the analysis
• Purpose of OOAD
• identifying the objects,
• recognizing the relationship between them
• make design out of it
• convert it to code using OO languages

4. UML
• Unified Modelling Language
• It’s a pictorial language used to make software blueprints
• It’s used to define, specify, visualize and document the artifacts of a software
systems
• The output from OOAD is the input to UML diagrams

5. COMMON TERMS IN UML
• Class
• Interface
• Collaboration
• Use Case
• Component
• Node
• Dependency
• Association
• Aggregation
• Composition
• Generalization
• Realization

6. UML DIAGRAMS
• Class diagram
• Object diagram
• Use case diagram
• Sequence diagram
• Collaboration diagram
• Activity diagram
• Statechart diagram
• Deployment diagram
• Component diagram

7. CLASS DIAGRAM
• It represents the static view of the module/application
• It defines the attributes and operations of a class
• It can be directly mapped to Object Oriented Programming languages (C++, Java,
Swift, Kotlin etc)
• Class diagram shows a collection of classes, interfaces, associations,
collaborations, and constraints.

8. IMPORTANT CONNECTIONS (CONTD…2)
• Association: It’s a structural relationship that defines how different objects are
connected or associated with each other. It also represents the data flow between
them
Below are treated as special case of association.
• Aggregation: It’s a kind of relationship in which one object can exist independent
of other. (Example: A student in a class)
• Composition: It’s a relationship where the child cannot exist independent of the
parent. (Example: A room in a house)

9. EXAMPLE
Composition Aggregation

10. GENERALIZATION & SPECIALIZATION
• Its a mechanism for combining similar classes of objects into a single, more general class.
• Generalization is Top-Down approach, where as Specialization is Bottom-Up approach

11. IMPORTANT CONNECTIONS

12. REPRESENTATION OF CLASS DIAGRAM

13. Example & Questions