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Tips ,Tricks notes and Quizes

What is UML

What is UML

  • UML stands for “Unified Modeling Language”
  • It is a industry-standard graphical language for specifying, visualizing, constructing, and documenting the artifacts of software systems
  • The UML uses mostly graphical notations to express the OO analysis and design of software projects.
  • Simplifies the complex process of software design

Types of UML Diagrams

  • Use Case Diagram
  • Class Diagram
  • Sequence Diagram
  • Collaboration Diagram
  • State Diagram

This is only a subset of diagrams … but are most widely used

  1. Use Case Diagram

Used for describing a set of user scenarios

Mainly used for capturing user requirements

Work like a contract between end user and software developers

      Use Case Diagram (core components)

Actors:  A role that a user plays with respect to the system,including human users and other systems. e.g.,inanimate physical objects (e.g. robot); an external system that needs some information from the current system.

Use case: A set of scenarios that describing an interaction  between a user and a system, including alternatives.


System boundary: rectangle diagram representing the boundary between the actors and the system.

Association:  communication between an actor and a use case; Represented by a solid line. uml3Generalization: relationship between one general use case and a special use case (used for defining special alternatives)

Represented by a line with a triangular arrow head toward the parent use case.



Include: a dotted line labeled <<include>> beginning at base use case and ending with an arrows pointing to the include use case.  The include relationship occurs when a chunk of behavior is similar across more than one use case. Use “include” in stead of copying the description of that behavior.


Extend: a dotted line labeled <<extend>>  with an arrow toward the base case. The extending use case may add behavior to the base use case. The base class declares “extension points








  1. Class diagram

Used for describing structure and behavior in the use cases

Provide a conceptual model of the system in terms of entities and their relationships

Used for requirement capture, end-user interaction

Detailed class diagrams are used for developers

Class representation


  • Each class is represented by a rectangle subdivided into three compartments
    • Name
    • Attributes
    • Operations
  • Modifiers are used to indicate visibility of attributes and operations.
    • ‘+’ is used to denote Public visibility (everyone)
    • ‘#’ is used to denote Protected visibility (friends and derived)
    • ‘-’ is used to denote Private visibility (no one)
  • By default, attributes are hidden and operations are visible.


  • Sequence Diagram


  • Collaboration Diagram


  1. State Diagrams
    (Billing Example)

State Diagrams show the sequences of states an object goes through during its life cycle in response to stimuli, together with its responses and actions; an abstraction of all possible behaviors.

Updated: January 28, 2019 — 4:02 am


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