Akka and Distributed Systems

Akka is an open-source toolkit and runtime for building highly concurrent, distributed, and resilient applications on the Java Virtual Machine (JVM), fundamentally based on the Actor Model. In the context of distributed systems, Akka provides a high-level abstraction that simplifies the inherent complexities of concurrency, parallelism, and fault tolerance. It uses lightweight, isolated processes called "actors" that communicate asynchronously through messages, enabling developers to build scalable systems that can be transparently distributed across a cluster of machines. Key features like location transparency, elastic scalability, and a "let it crash" model of self-healing through supervision hierarchies allow Akka applications to remain responsive and robust in the face of component failures, making it a powerful framework for creating modern, reactive distributed services.

1. Foundations of Concurrency and Distributed Systems
   1. Core Problems in Concurrent Programming
      1. Race Conditions
         1. Definition and Characteristics
         2. Common Scenarios and Examples
         3. Detection Techniques
         4. Prevention Strategies
         5. Testing for Race Conditions
      2. Deadlocks
         1. Necessary Conditions for Deadlock
         2. Deadlock Detection Algorithms
         3. Recovery Mechanisms
         4. Prevention Strategies
         5. Avoidance Techniques
         6. Banker's Algorithm
      3. Livelocks
         1. Definition and Characteristics
         2. Distinction from Deadlocks
         3. Common Causes
         4. Detection Methods
         5. Resolution Strategies
      4. Starvation
         1. Causes in Resource Scheduling
         2. Priority Inversion
         3. Aging Techniques
         4. Fair Scheduling Algorithms
   2. Concurrency vs. Parallelism
      1. Fundamental Definitions
      2. Key Conceptual Differences
      3. Hardware Implications
      4. Use Cases for Concurrency
      5. Use Cases for Parallelism
      6. Design Trade-offs
   3. Concurrency Models
      1. Shared-Memory Concurrency
         1. Memory Models
         2. Cache Coherence
         3. Locks and Mutexes
            1. Mutual Exclusion Principles
            2. Lock Granularity
            3. Lock Contention Issues
            4. Deadlock Potential
            5. Lock-Free Programming
         4. Semaphores and Monitors
            1. Counting Semaphores
            2. Binary Semaphores
            3. Monitor Constructs
            4. Condition Variables
         5. Atomic Operations
         6. Compare-and-Swap
      2. Message-Passing Concurrency
         1. Communicating Sequential Processes
            1. Channel-Based Communication
            2. Process Synchronization
            3. Synchronous Communication
            4. Asynchronous Communication
         2. The Actor Model
            1. Actors as Computational Units
            2. Message Passing Semantics
            3. Location Transparency
            4. Fault Isolation
   4. Challenges in Distributed Systems
      1. Network Partitions
         1. Causes of Network Splits
         2. Partition Detection
         3. Handling Split Networks
         4. Partition Recovery
      2. Latency and Network Unreliability
         1. Sources of Network Latency
         2. Jitter and Packet Loss
         3. Impact on System Design
         4. Latency Mitigation Techniques
         5. Timeout Strategies
      3. Partial Failures
         1. Types of System Failures
         2. Failure Detection Mechanisms
         3. Failure Isolation
         4. Recovery Strategies
      4. Consistency Models
         1. Strong Consistency
         2. Eventual Consistency
         3. Causal Consistency
         4. Session Consistency
         5. Monotonic Consistency
         6. Trade-offs Between Models
      5. The CAP Theorem
         1. Consistency Guarantees
         2. Availability Guarantees
         3. Partition Tolerance
         4. Practical Implications
         5. System Design Decisions
      6. ACID vs. BASE Properties
         1. ACID Properties
         2. BASE Properties
         3. Trade-offs in Distributed Systems
      7. Consensus Algorithms
         1. Raft Algorithm
         2. Paxos Algorithm
         3. Byzantine Fault Tolerance