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| Introduction: |
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| UML is Unified Modelling
Language used to create models of application before its development.
Modelling of application is as similar as creating model of a objects
before its development in our real life say railway bridge, which
results in analyzing risk factors, Constraints, advantages. These
models are GUI based and is reviewed by different stakeholders of
application as per their requirement say Higher Level management review
GUI model for all functional and Non Functional requirements Status.
The main benefit of reviewing Model at design time is to find out
limitations, constraint which can delay the successful completion
and deployment of the application. |
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| UML supports different components for
different stages of SDLC using which analysts and designers create
self explanatory models of application, which are used later on by
different teams of project say developers, Testing Team, Reviewers,
and Client. |
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| UML supports Iterative SDLC in which
we work in each stage of SDLC percentage wise. |
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| The major Components of UML are: |
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| 1.
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Use Case Diagram |
| 2. |
Sequence Diagram |
| 3. |
Collabration Diagram |
| 4. |
Activity Diagram |
| 5. |
Class Diagram |
| 6. |
State Transition Diagram |
| 7. |
Component Diagram |
| 8. |
Deployment Diagram |
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| 1. Use Case Diagram |
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| Before I discuss Use Case diagram in
details, I am giving brief introduction of different components of
Use Case Diagram i.e. Use Case, Actor. |
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| Actor: Actors are
the various users of an application having different access rights
based on their category. Actors are represented as: |
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Use Case: Use Case
represents the different major functionalities of the system. These
are of two types: Business Use Case and System Use Case.
Business use case represents the functionalities related to the existing
business where as System Use case represents the functionalities available
in the application. E.g. Online Order Placement use case in Banking
Solution. Use cases are represented as follows: |
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| The different parts of a use case are: |
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Basic Flow: Represents the main
flow of execution for the use case. |
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Alternative Flows: Represents
Secondary/Optional flows that get executed depending upon various
scenarios and get executed in parallel to basic Flow. |
| 3. |
Pre Conditions: This gets executed
before the execution of use case. |
| 4. |
Post conditions: These get executed
just after the completion of use case execution. |
| 5. |
Validations: These are check
points, which ensures execution of use case with correct data. |
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| Coming back to Use Case Diagram, this
diagram shows relationship of actors with use cases, which helps in
finding involvement of various Actors with different use cases. Use
case Diagrams are represented as follows: |
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| There are two types of Relations between
use cases Uses & Extends. |
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| Uses: Means One use
case is dependant on another use case. It is dependent relation i.e.
First use case can’t execute itself independently, it will execute
after the execution of second one. As in our case Online order Placement
can‘t execute independently, it will execute after execution
of Chk Authentication. |
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| Extends: Means One
use case extends functionality of another use case i.e. Online Order
Placement can execute independently and it can extend functionality
of Chk authentication use case also. |
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| 2. Sequence Diagram: |
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| Sequence Diagram shows detailed flow
of execution of a use case with respect to Time. Sequence Diagram
is initiated by an actor. Sequence Diagram shows sequence of message
generated during use case execution. Considering above use case Online
Order Placement, sequence diagram will show all steps required to
timely execute the use case. |
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| I will discuss rest of Components of
UML in next article. |
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