How do distributed systems manage messaging?

1 Message passing

Message passing is the basic mechanism of communication in distributed systems. It involves sending and receiving messages between nodes using a network layer, such as TCP/IP or UDP. Message passing can be synchronous or asynchronous, depending on whether the sender and the receiver are blocked or not until the message is delivered or acknowledged. Message passing can also be reliable or unreliable, depending on whether the network layer guarantees the delivery or not of the message. Message passing can be implemented using various APIs, such as sockets, RPC, RMI, or REST.

2 Message ordering

Message ordering is the problem of ensuring that messages are received and processed in a consistent and logical order by the nodes in a distributed system. Message ordering is important for maintaining the consistency and correctness of the system state and behavior. However, message ordering is difficult to achieve in distributed systems, as messages may be delayed, duplicated, or lost by the network. Message ordering can be classified into different types, such as FIFO, causal, total, or logical. Message ordering can be enforced using different algorithms, such as vector clocks, Lamport timestamps, or Paxos.

3 Message delivery

Message delivery is the problem of ensuring that messages are delivered to the intended recipients in a distributed system. Message delivery is essential for achieving the availability and reliability of the system services and functions. However, message delivery is challenging to guarantee in distributed systems, as nodes may crash, fail, or leave the system. Message delivery can be classified into different modes, such as at-most-once, at-least-once, or exactly-once. Message delivery can be achieved using different protocols, such as acknowledgment, retransmission, or idempotency.

4 Message routing

Message routing is the problem of finding the optimal paths for sending messages between nodes in a distributed system. Message routing is crucial for optimizing the performance and scalability of the system operations and resources. However, message routing is complex to optimize in distributed systems, as the network topology, traffic, and conditions may change dynamically. Message routing can be classified into different strategies, such as direct, indirect, multicast, or broadcast. Message routing can be implemented using different algorithms, such as Dijkstra, Bellman-Ford, or gossip.

5 Message filtering

Message filtering is the problem of selecting the relevant messages for processing by the nodes in a distributed system. Message filtering is useful for reducing the overhead and noise of the system communication and computation. However, message filtering is tricky to implement in distributed systems, as the nodes may have different interests, preferences, and capabilities. Message filtering can be classified into different models, such as content-based, topic-based, or type-based. Message filtering can be realized using different techniques, such as publish-subscribe, message queues, or event-driven.