guidelines use case analysis interaction diagrams

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INTERACTION DIAGRAMS BY SYED FEROZ ZAINVI WRITING FROM: HTTP://WWW.COMPUTER-SCIENCE-NOTES.BLOGSPOT.COM Guidelines Use Case Analysis

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This presentation gives an overview of interaction diagrams, their types, contents, guidelines about how to draw them and choosing when to use which one.

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Page 1: Guidelines Use Case Analysis Interaction Diagrams

INTERACTION DIAGRAMS

BYSYED FEROZ ZAINVI

WRITING FROM:HTTP://WWW.COMPUTER-SCIENCE-NOTES.BLOGSPOT.COM

Guidelines Use Case Analysis

Page 2: Guidelines Use Case Analysis Interaction Diagrams

Recap

Create the Use-Case Realization Supplement the Use-Case Description Find Analysis Classes – Boundary, Control,

Entity Distribute Behavior to Analysis Classes Describe Responsibilities Describe Attributes and Associations

Page 3: Guidelines Use Case Analysis Interaction Diagrams

INTERACTION DIAGRAMS

Object Interaction Diagrams (OID) model scenario Scenario An instance of a use-case

Primary Represents normal flow Secondary Represents alternate flow

OID Types: Collaboration Diagram: Message oriented dynamic

behavior OBJECT ROLES

Sequence Diagram: Time oriented dynamic behavior WHAT MESSAGE & WHEN

Page 4: Guidelines Use Case Analysis Interaction Diagrams

Collaboration Diagram

Contents Actors: Invoke interaction-Keep

at periphery Objects: Objectname:Classname(classname unspecified, object

named/unnamed, only classname)

Links: Relationship, instance of association-may be unspecified- veh for messages

Messages: Communication-arrow points towards target object-shown with name, parmaters, sequence-temporary: later mapped to operation

Page 5: Guidelines Use Case Analysis Interaction Diagrams

Sequence Diagram

ContentsObjects with lifelineActorsMessages with

durationNo linksScripts: Textual

description for lifelines or messages

Rules same as for Collaborations Diagrams

[condn]

*

Page 6: Guidelines Use Case Analysis Interaction Diagrams

Control Flow in Sequence Diagrams

Centralized Control FlowFew objects steer the flow

by sending messages to, and receiving messages from other objects

These controlling objects decide the order in which other objects will be activated in the use case

Interaction among the rest of the objects is very minor or does not existFORK SHAPED

Page 7: Guidelines Use Case Analysis Interaction Diagrams

Control Flow in Sequence Diagrams

Decentralized Control Flow

Participating objects communicate directly with one another, not through one or more controlling objects

STAIR-WAY SHAPED

Page 8: Guidelines Use Case Analysis Interaction Diagrams

Centralized Vs Decentralized Control Flow

A decentralized structure is appropriate: If the sub-event phases are tightly coupled.

This will be the case if the participating objects: Form a part-of or consists-of hierarchy,

such as Country - State - City; Form an information hierarchy, such as

CEO - Division Manager - Section Manager;

Represent a fixed chronological progression (the sequence of sub-event phases will always be performed in the same order), such as Advertisement - Order - Invoice -Delivery - Payment; or

Form a conceptual inheritance hierarchy, such as Animal - Mammal - Cat.

If you want to encapsulate, and thereby make abstractions of, functionality. This is good for someone who always wants to use the whole functionality, because the functionality can become unnecessarily hard to grasp if the behavior structure is centralized.

A centralized structure is appropriate:

If the order in which the sub-event phases will be performed is likely to change.

If you expect to insert new sub-event phases.

If you want to keep parts of the functionality reusable as separate pieces.

Page 9: Guidelines Use Case Analysis Interaction Diagrams

Similarities between Collaboration & Sequence Diagram

Both determine class responsibilities & interfaces

Both express similar information but in different ways

Make either or both of them for: a use case part of use case each flow of events each sub-flow of events

Page 10: Guidelines Use Case Analysis Interaction Diagrams

Collaboration Diagram

Unlike sequence diagram, shows relationship among objects

Provides understanding of all the effects on a given object and for procedural design

Better suited for analysis activities Good for depicting simpler interactions of smaller

numbers of objects- Hard to read when number of objects or messages

increase- Timing, decision points, unstructured information

can be added as easily as in sequence diagram

Page 11: Guidelines Use Case Analysis Interaction Diagrams

Sequence Diagram

Unlike a collaboration diagram, includes chronological sequences

But does not include object relationshipsSuited when the explicit sequence of

messages has to be shown when it is important to visualize the time ordering of

messages

But for structural relationships among the instances in an interaction, use a collaboration diagram

Page 12: Guidelines Use Case Analysis Interaction Diagrams

Further Guidelines

Choices can be shown on OIDs (demonstrating slightly different scenarios)

Keep OIDs simple – so limit No limit on no. of scenarios that can be produced produce

more OIDs rather than make more complex Sequence Or Collaboration: No definitive rule—Easier to

understand & should be used for communicating with customers

When used: Identification of use case Implementation Details may vary: In analysis, no message signatures and no design objects Inspect behavior of several objects within a single use-case

Page 13: Guidelines Use Case Analysis Interaction Diagrams

ALSO LINKED THROUGH:

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For more notes, keep visiting:

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