Use case diagram is the pictorial representation of how a user interacts with the system. Use case diagram typically contains ‘Actors’ and ‘Events’. Actors are the entities who trigger the events. Event is a set of rules or a transaction that will occur by an actor’s action.
I would love to say,Use case is a high Level diagram and it is a mother of all the diagram(People laugh most of times,when i use the word “Mother of all Diagram’s”) ,the main focus of the use case diagram,how the external interface (i.e. EndUser, Support System, Special Database and internet connectivity etc ) is interacting with purposed IT solution. The interaction is initiated with a distinct business case called “Use-case”.
Use case Diagram describes functionality of the system in a horizontal way and it is also show all the list of availability of functions.
Use Case diagram is the graphical representation describing the functionality of a system. It consists of actors and use cases. A use case describes a sequence of actions that provide something of measurable value to an actor.
An actor is a person, organization, or external system that plays a role in one or more interactions with your system. Actors are drawn as stick figures.
Use case diagram basically used in requirement gathering phase to collect the requirement from the end user and these use case are fed in design in design phase to define the technical road map.
Use case diagram describe what system will do ?
- Use case capture functional or behavior requirement of the system.
- In other case use case tells us what system should do .
- Use case describes interaction b/w various actors and systems .
- Use case capture all the different goals using various actors have in system.
- Primary Actor (Primary actors are active participant and they are responsible for triggering event )
- Secondary actor (Secondary Actors are passively participant in the use case)
- Positive Flow (Happy Path)
- Alternative Flow
- Extension(optional) Flow
Use Case Document Consist of fallowing
- Use Case No#
- Use Case Name
- Use Case description
- Primary Actors ,Secondary Actors
- Basic Flow and Alternative Flow
- Pre Condition
- Main Scenario
- Success and Failed Scenario
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