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Wikipedia defines a distributed system as a “software system in which components located on networked computers communicate and coordinate their actions by passing messages.”

In modern world, more and more systems become distributed. Yet, surprisingly few authors write about practical architecture of distributed systems. As our Hare have architected all kinds of distributed systems, from a stock exchange to a billion-messages-a-day game, we’re in a very good position to fill this gap.

Distributed Systems, page 1:

Gradual OLTP DB Development – from Zero to 10 Billion Transactions per Year and Beyond

Quote: “to make an efficient representation usable for OLAP – we need to modify our data on its way to OLAP replicas”
Another Quote: “Each of the DB Server Apps is a replica master, but all replica targets are within the same Replica DB”

Deterministic Components for Distributed Systems

Quote: “Then you can recover from any single server failure in a perfectly transparent manner”
Another Quote: “after the program fails in production, we can get the input log and run it in the comfort of a developer’s machine, under a debugger, as many times as we want, and get exactly the same variables at exactly the same points as happened in production”

Network Programming: Socket Peculiarities, Threads, and Testing

Quote: “I am not saying that this architecture is the only viable one, but it does work for TCP for sure (and performs reasonably well too)”
Another Quote: “The whole task of optimizing performance beyond, say, 20-50K packets/second per box tends to be Quite Elaborated, and involves quite a few things which are platform- and hardware-dependent.”

Unity 5 vs UE4 vs Photon vs DIY for MMO

Quote: “You can still use HLAPI despite its shortcomings”
Another Quote: “If you’re using one of the engines above (and not your own one), and your game requires Client-Driven Development Flow, you may want to start with a single-player Unity 5, or with a single-player UE4.”

IDL: Encodings, Mappings, and Backward Compatibility

Quote: “Modifying generated code usually qualifies as a Really Bad Idea”
Another Quote: “How much can be gained by each of such specialized encodings – still depends on the game, but if you can try-and-test a dozen of different encodings within a few hours – it will usually allow you to learn quite a few things about your traffic (and to optimize things both visually and traffic-wise too).”

MMOG. Point-to-Point Communications and non-blocking RPCs

Quote: “In other words, you can write your code ‘as if’ all-your-code-within-the-same-FSM executed within the same thread”
Another Quote: “As soon as we have these two parts of processing – we can say that our Server-to-Server communication is tolerant to all kinds of transient inter-server disconnects”

MMOG: World States and Reducing Traffic

Quote: “In practice, for most classical RPGs you can get away with simulating each of your PCs and NPCs as a box (parallelepiped), or as prism (say, hexagonal or octagonal one)”
Another Quote: “Mathematically speaking, without Interest Management, the amount of data on our servers will need to send (to all players combined), is O(N^2). Interest Management reduces this number to O(N)”