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OOD - Call Center

mediumLast edited: January 1, 2026

1. Problem Statement
2. System Requirements
3. Use Case Diagram
4. Class Diagram
5. Activity Diagrams
Incoming Call Routing
Call Escalation
Call Completion
6. Java Implementation
7. Design Patterns Applied
1. Template Method Pattern (Employee.handleCall)
2. Chain of Responsibility (Escalation)
3. Observer Pattern (Call Metrics)
4. Strategy Pattern (Queue Management)
5. Singleton Pattern (CallHandler)
6. State Pattern (Employee Free/Busy)
8. Key Design Decisions
Decision 1: Abstract Employee Base Class
Decision 2: Separate Queue Per Rank Level
Decision 3: Call Object Tracks Required Rank
Decision 4: Synchronized Employee Methods
Decision 5: Automatic Next Call Assignment
Decision 6: CallHandler Owns Employee Lists
Decision 7: Metrics with AtomicLong
Decision 8: Call Lifecycle Timestamps
Decision 9: Escalation Increments Count
Decision 10: ReentrantLock in CallHandler

Related Tags

ctci ood-object-oriented-design call-routing queue-management

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