Lecture 32: Factoring Use Cases - Managing Complexity with Relationships - 4 | Object-Oriented Analysis and Design - Core UML Diagrams | Software Engineering Micro Specialization
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4 - Lecture 32: Factoring Use Cases - Managing Complexity with Relationships

Practice

Interactive Audio Lesson

Listen to a student-teacher conversation explaining the topic in a relatable way.

Introduction to Factoring Use Cases

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0:00
Teacher
Teacher

Welcome, everyone! Today we will explore the concept of Factoring Use Cases. Can anyone tell me what they think 'factoring' means in this context?

Student 1
Student 1

Is it about breaking down something into smaller pieces?

Teacher
Teacher

Exactly! Factoring involves breaking down large use cases into smaller, more manageable chunks. This helps us avoid redundancy and makes it easier to manage complexities. Why do we want to avoid redundancy?

Student 2
Student 2

To make our models clearer?

Teacher
Teacher

Correct! Clarity is key. If we keep repeating ourselves in multiple use cases, it can lead to confusion. Let’s remember: β€˜Less repetition, more clarity!’

Student 3
Student 3

How do we actually factor the use cases?

Teacher
Teacher

Great question! We can use two specific relationships: <<include>> and <<extend>>. Let's dive into those!

<<include>> Relationship

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Teacher
Teacher

First, let’s talk about the <<include>> relationship. Can someone remind me about its purpose?

Student 2
Student 2

It shows a use case that must be included in another one?

Teacher
Teacher

Exactly! The behavior of the included use case is mandatory for the base use case. For example, if we have 'Place Order' as a use case, what included use case might we need?

Student 4
Student 4

Probably 'Log In' because you need to be logged in to place an order.

Teacher
Teacher

Right! We might say: 'Place Order <<include>> Log In'. This way, we don’t repeat 'Log In' in both use cases. Can anyone summarize why using <<include>> is beneficial?

Student 1
Student 1

It avoids repeating details and makes it clear that 'Log In' is necessary!

<<extend>> Relationship

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Teacher
Teacher

Next, let's move to the <<extend>> relationship. Does anyone know what that signifies?

Student 2
Student 2

It’s for optional behaviors that get added under certain conditions?

Teacher
Teacher

Very well said! For instance, when might we use an <<extend>> relationship in our online shopping example?

Student 3
Student 3

When applying a discount coupon, right? That wouldn't happen every time someone places an order.

Teacher
Teacher

Correct! We can write: 'Place Order <<extend>> Apply Discount Coupon' with the extension point defined after cart total calculation. How is this beneficial for us?

Student 4
Student 4

It keeps our primary use case simple while allowing for flexibility!

Generalization for Actors

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Teacher
Teacher

Now, let's talk about using generalization for actors. Let’s define what generalization means in this context.

Student 1
Student 1

It’s about showing how one actor is a specific type of another actor?

Teacher
Teacher

Exactly! For instance, if we say 'Manager ---|> Employee', what does this imply?

Student 2
Student 2

A manager is a type of employee and inherits the roles or capabilities of an employee.

Teacher
Teacher

Right! Generalization helps us capture common behaviors in actors efficiently. Any thoughts on when you would use this?

Student 3
Student 3

In systems where several roles share similar functionalities, it can reduce complexity!

Best Practices for Factoring Use Cases

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Teacher
Teacher

To wrap up our session, let's discuss best practices for factoring use cases. What do you think we should keep in mind?

Student 4
Student 4

Don’t over-factor! We should only do it when it really helps.

Teacher
Teacher

Absolutely! We should ensure that even factored use cases represent complete goals for the users. Also, what about extension points when using <<extend>>?

Student 2
Student 2

They should be clearly defined so it's understandable where additional behavior fits in.

Teacher
Teacher

Exactly! So remember: 'Clarity, reusability, and goal orientation' are our keys in maintaining effective use cases.

Introduction & Overview

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Quick Overview

This section introduces 'Factoring Use Cases' by discussing the concepts of include and extend relationships to enhance clarity, promote reusability, and manage complexity in Use Case Models.

Standard

The lecture covers the necessity and benefits of factoring use cases, explaining how the include and extend relationships can simplify large use cases and promote code reusability. Students will learn to differentiate between these relationships and understand the implications of generalization for actors.

Detailed

Detailed Summary

This lecture builds upon foundational concepts in Use Case Modeling, specifically by introducing the idea of Factoring Use Cases through relationships defined in the Unified Modeling Language (UML). The main need for factoring use cases arises from common issues such as redundancy and complexity in large use cases. Factoring helps in reusing common functionalities, distinguishing between core and optional behaviors, and ultimately enhancing the overall clarity of the Use Case Models.

Key Concepts:

  1. The Need for Factoring Use Cases:
  2. Avoid redundancy by allowing common functionalities to be captured only once.
  3. Help manage complexity by breaking down large use cases into more manageable segments.
  4. Promote reusability of common or optional behaviors.
  5. Relationships Between Use Cases:
  6. The <> Relationship: Mandatory inclusion of one use case within another, indicated by a dashed arrow and used to avoid redundancy.
  7. The <> Relationship: Represents optional or conditional behavior that adds new functionality into a base use case, allowing for specific conditions to direct the flow.
  8. Generalization for Actors: Useful for representing commonalities among various roles in the system.
  9. Best Practices of Factoring Use Cases: Emphasize clarity and balance in the Use Case Model without over-factoring.

Understanding these relationships gives developers tools to create clearer, more maintainable software requirements.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • The Need for Factoring Use Cases:

  • Avoid redundancy by allowing common functionalities to be captured only once.

  • Help manage complexity by breaking down large use cases into more manageable segments.

  • Promote reusability of common or optional behaviors.

  • Relationships Between Use Cases:

  • The <> Relationship: Mandatory inclusion of one use case within another, indicated by a dashed arrow and used to avoid redundancy.

  • The <> Relationship: Represents optional or conditional behavior that adds new functionality into a base use case, allowing for specific conditions to direct the flow.

  • Generalization for Actors: Useful for representing commonalities among various roles in the system.

  • Best Practices of Factoring Use Cases: Emphasize clarity and balance in the Use Case Model without over-factoring.

  • Understanding these relationships gives developers tools to create clearer, more maintainable software requirements.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • A user must 'Log In' before they can 'Place Order'; hence, we factor 'Log In' into both using the <> relationship.

  • Applying a 'Discount Coupon' is optional and can be added after calculating the total in the 'Place Order' use case using the <> relationship.

  • In an organization, a Manager is an actor that inherits roles from the general Actor 'Employee' showcasing generalization.

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎡 Rhymes Time

  • If things are too big, break them down,

πŸ“– Fascinating Stories

  • Imagine a chef making a grand meal. If he includes a common recipe for sauces in every dish, he saves time and avoids confusion. This is like using <> in use cases!

🧠 Other Memory Gems

  • I.E. (Include - Extend) - 'Include to add necessary depth, Extend to add the optional breadth.'

🎯 Super Acronyms

F.C.R. - 'Factoring Cuts Redundancy' to remember that factoring helps avoid repetition.

Flash Cards

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Glossary of Terms

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  • Term: <<include>> Relationship

    Definition:

    A mandatory inclusion where one use case's behavior must be incorporated into another use case.

  • Term: <<extend>> Relationship

    Definition:

    An optional extension of a use case behavior that occurs under specific conditions.

  • Term: Factoring Use Cases

    Definition:

    The process of breaking down larger use cases into smaller, reusable components to avoid redundancy and manage complexity.

  • Term: Generalization

    Definition:

    A relationship that shows how one actor (subclass) is a specialized form of another actor (superclass).

  • Term: Extension Point

    Definition:

    A defined location in a use case that allows for the inclusion of extending behavior.