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SDK 0.10
SDK 0.10
  • Welcome
  • Overview
    • What is coherence?
    • How does coherence work?
    • Rooms and Worlds
    • Features and Roadmap
    • Release Notes
    • Known Issues and Troubleshooting
  • Learning coherence
    • First Steps tutorial
      • 1. Basic syncing
        • 1.2. Animation parameters
        • 1.3. Sending commands
      • 2. Physics / Authority transfer
      • 3. Areas of interest
      • 4. Parenting entities
      • 5. Complex hierarchies
      • 6. Persistence
    • How to network...
      • Racing
      • Turn-based
      • First-Person Shooter
      • MMO
      • Fighting
  • Get started
    • Installation
    • Scene Setup
      • Sample UI
    • Prefab Setup: CoherenceSync
    • Local Development
      • Tips and Recommendations
    • coherence Cloud
      • Create a Free Account
      • Deploy a Replication Server
      • Share Builds
  • coherence SDK for Unity
    • Components
      • CoherenceSync
      • CoherenceMonoBridge
      • CoherenceLiveQuery
      • CoherenceTagQuery
      • Order of execution
    • Networking State Changes
      • Messaging with Commands
      • Hierarchies & Child Objects
        • Child GameObjects
        • Child CoherenceSyncs
        • Deep Child CoherenceSyncs
      • Animations
      • CoherenceSync References
      • [Sync] and [Command] Attributes
      • [OnValueSynced] Attribute
      • Supported Types
      • Player Name (Sample UI)
    • Baking (Code Generation)
    • Authority
      • Authority transfer
      • Server-authoritative setup
    • Lifetime
      • Persistence
      • Example – a global counter
    • Optimization
      • Simulation Frequency
      • Areas of Interest
      • Level of Detail (LOD)
    • Interpolation
    • Settings
    • Simulation Frame
    • Replication Server
    • Simulators
      • Scripting: Client vs Simulator
      • Local Development
      • World Simulators
      • Room Simulators
      • Simulator Slugs
      • Multi-Room Simulators
      • Build and Publish
      • Command-line arguments
      • Load Balancing
      • Network Connectivity
    • Client Connections
    • Rollback Networking Support
    • Floating Origin
    • CLI
  • coherence API
    • Worlds
    • Rooms
    • PlayResolver
    • DescriptorProvider
  • Developer Portal
    • Overview
    • Dashboard
    • Worlds
    • Rooms
    • Game Services
      • Account
      • Key-Value Store
      • API
        • Game account
        • Key-value store
  • Schema explained
    • Overview
    • Specification
    • Field settings
    • Archetypes
  • Additional resources
    • Community
    • SDK Upgrade Guide
    • Video Tutorials
    • Quick Samples
    • Continuous Integration
    • Unreal Engine Support
    • WebGL Support
    • Peer-to-Peer Support (P2P)
    • Pricing
    • SLA
    • Glossary
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  • Basic terms
  • State Replication

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  1. Overview

How does coherence work?

Last updated 2 years ago

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Basic terms

Replication Server ("Replicator")

A lean and performant server that keeps the state of the world and replicates it efficiently between various Simulators and Game Clients. The Replicator usually runs in the coherence Cloud, but developers can start it locally from the command line or the Unity Editor.

Game Client

A build of the game. To connect to coherence, it will use the coherence SDK.

Simulation Server ("Simulator")

A version of the Game Client without the graphics ("headless client") optimized and configured to perform server-side simulation of the game world. When we say something is simulated on the server, we mean it is simulated on one or several Simulators.

Schema

A text file defining the structure of the world from the network's point of view. The schema is shared between the Replicators, Simulators and Game Clients. The world is generally divided in components and archetypes.

Code generation

The process of generating code specific to the game engine that takes care of network synchronization and other network-specific code. This is done using a CLI tool called Protocol Code Generator that takes the schema file and generates code for various engines (e.g. C# for Unity).

State replication

The process of making sure the state of the world is eventually the same on the Replicator, Simulators and Game Clients, depending on their areas of interest.

State Replication

coherence works by sharing game world data via a Replication Server in the cloud and passing it to the connected Clients.

The Clients and Simulators can define areas of interest (LiveQueries), levels of detail, varying simulation and replication frequencies and other optimization techniques to control how much bandwidth and CPU power is used in different situations.

The game world can be run using multiple Simulators that split up simulation functions or areas of the world accordingly.

The platform handles scaling, synchronization, persistence and load balancing automatically.

Fast authority transfer and remote commands allow different authority models, including Client authority, Server authority, distributed authority and combinations like Client prediction with .

Peer-to-peer support (without a Replicator) is planned in a future release. Please see the for updates.

input queues
Peer-to-peer page