Exam Review.md

Exam Review Exercises

Exercise 1: UML Use-Case Diagram

Remote content provider using an existing third-party content provider.

// 'existing' makes the third party an actor

Actors:

• regular users
• premium users
• third-party content provider

Regular users:

• can browse video content from external content provider [detailed]
• can steam video content from external content provider [detailed]

Premium users:

• can browse video content from external content provider [detailed]
• can steam video content from external content provider [detailed]
• can download video content from external content provider [detailed]
• can browse video content locally [detailed]
• can steam video content locally [detailed]

Tips

• better not to split up high-level use-case based on users
• best local + remote content

High-level

Access Local Content

• premium initiates

Access Remote Content

• regular initiates
• premium initiates
• third-party participates
  • this implies they participate with all derived use-cases

Detailed

Access Local Content

• includes browse local video
• includes stream local video
• includes download + store video
  • third-party participates

Access Remote Content

• includes browse remote video
  • extends connection error
• includes stream remote video
  • extends connection error

Sequence Diagram: Download + Store Video

Exercise 2: UML Use-Case Diagram

• social media service with API for other remote social media sites
  • allows users of remote sites to:
    • manage newsfeed [high-level]
      • by retrieving other users' posts [detailed]
      • modifying newsfeed settings [detailed]
    • mange posts [high-level]
      • post new status updates [detailed]
      • upload photos / videos [detailed]

High-level

Manage Newsfeed

• third-party site user initiates
• includes retrieve newsfeed posts
  • extends connection error
• includes modify settings
  • extends connection error

Manage Posts

• third-party site user initiates
• includes retrieve post new status updates
  • extends connection error
• includes upload photos / videos
  • extends connection error

Sequence Diagram: Retrieve Newsfeed

Sequence Diagram Steps

1. figure out which actor initiates use-case
2. select boundary object used to initiate use-case
   • named with a noun-phrase
   • e.g. candidates: download option, submit form request
3. boundary object creates control object
   • named with a verb-phrase
     • e.g. DownloadMusicControl
4. control object dictates logic
   • entity object may be created then saved
   • information may be saved directly
   • new boundary object may be created
     • reply / notification to initial actor
     • to communicate with third-party actor
5. all created objects are destroyed
   • original boundary object remains

Types of Design Problems

• creational: object creation [mechanisms]
  • abstract factory
• structural: simplification of object associations / relationships
  • adapter
  • bridge
  • composite
  • façade
  • proxy
• behavioural: communication patterns between objects
  • command
  • observer
  • strategy