OpenSimulator Internals/Simulator Services

Simulator Services

Simulator services run inside OpenSim.exe and are scoped to the simulator process, not the grid. They are distinct from ROBUST services, which run in ROBUST.exe and serve the entire grid.

Each simulator service follows the same local/remote connector pattern used by grid services: a local connector handles in-process calls; a remote connector makes HTTP calls to another simulator. See Connector Architecture for the general pattern.

Config key for all three services is in the [Modules] section of OpenSim.ini.

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Land Service

Interface: ILandService (OpenSim.Services.Interfaces)
Config key: LandServices

Purpose

Retrieves parcel land data by region handle and coordinates. Used when a simulator needs land data for a region it does not itself host -- for example, to resolve access rules at a region border before a crossing completes.

Interface

ILandService exposes a single method:

LandData GetLandData(UUID scopeID, ulong regionHandle, uint x, uint y, out byte regionAccess)

Connectors

Connector	Class	Used when
Local	LocalLandServicesConnector	Destination region is hosted by this simulator. Walks the local scene list, matches by world coordinates, returns LandData plus access level and dwell count.
Remote	RemoteLandServicesConnector	Destination region is on another simulator. Tries local first; falls back to HTTP call via LandServicesConnector base class.

Notes

• The local connector iterates m_Scenes and matches by world coordinate

 bounds, not by region UUID. This matters for varregions where a single scene
 covers a range of coordinates.

• Dwell count is retrieved via IDwellModule if present; not part of

 the core land data.

• Returns null if no local scene matches and no remote call is

 configured.

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Library Service

Interface: ILibraryService (OpenSim.Services.Interfaces)
Implementation: OpenSim.Services.InventoryService.LibraryService
Config section: [LibraryService]

Purpose

Provides the shared library inventory -- the read-only content visible to all users under the Library folder. Backed by XML files on the local filesystem, not the database.

Config

[LibraryService]
DefaultLibrary = inventory/Libraries.xml
LibraryName = OpenSim Library

Both keys are optional; the values above are the defaults.

Interface

InventoryFolderImpl LibraryRootFolder { get; }
Dictionary<UUID, InventoryFolderImpl> GetAllFolders()
InventoryItemBase GetItem(UUID itemID)
InventoryItemBase[] GetMultipleItems(UUID[] itemIDs)

Notes

• Not a region module. Instantiated as a ServiceBase directly by

 the service infrastructure. No [Modules] config key.

• Singleton per process: static instance, initialized once regardless of how

 many regions the simulator hosts.

• Loaded from XML files under the inventory/ directory at startup.

 Root folder UUID is a fixed constant (00000112-000f-0000-0000-000100bba000);
 all library UUIDs are fixed and do not vary between installations.

• No remote connector. No ROBUST equivalent. Library content is local to each

 simulator.

• The source explicitly notes this is a stopgap: "basically a hack to give us

 an Inventory library while we don't have an inventory server." Architecturally
 it should be a grid service with shared content across simulators; it has
 never been converted.

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Simulation Service

Interface: ISimulationService (OpenSim.Services.Interfaces)
Config key: SimulationServices

Purpose

Handles simulator-to-simulator communication: creating and updating agents on remote simulators, moving objects across region boundaries, and closing agents when they leave. Used for teleports, region crossings, child agent maintenance, and object crossings.

This is not a ROBUST service. It runs entirely between simulators.

Interface

Agent operations:

Method	Purpose
CreateAgent(source, destination, aCircuit, flags, ctx, out reason)	Creates a new agent circuit on the destination simulator. Entry point for teleport and login-to-region.
UpdateAgent(destination, AgentData, ctx)	Full child agent update: position, appearance, animation state.
UpdateAgent(destination, AgentPosition)	Lightweight position-only update for child agents.
QueryAccess(destination, agentID, homeURI, viaTeleport, position, features, ctx, out reason)	Checks whether the destination will accept this agent. Called before CreateAgent.
ReleaseAgent(originRegion, agentID, uri)	Destination notifies origin that the client has connected. Origin clears its teleport-pending state.
CloseAgent(destination, agentID, auth_token)	Closes an agent circuit on the destination simulator.

Object operations:

Method	Purpose
CreateObject(destination, newPosition, sog, isLocalCall)	Sends a scene object to the destination simulator. Used for prim crossings and object teleport. If isLocalCall is true, the object is cloned before transfer; if false, it is used as received from the wire.

Connectors

Connector	Class	Used when
Local	LocalSimulationConnectorModule	Destination region is hosted by this simulator. Dispatches directly to the target Scene by UUID lookup.
Remote	RemoteSimulationConnectorModule	Destination region is on another simulator. Tries local first; falls back to HTTP via SimulationServiceConnector.

Notes

• The local connector maintains a Dictionary<UUID, Scene> keyed

 by region UUID. GetScene() has a fallback that returns the first
 available scene if the requested UUID is not found -- this masks bugs and is
 noted as a known issue in the source.

• QueryAccess enforces a version check: if the requesting simulator

 is running protocol version below 0.3 and the destination is a varregion
 (non-256x256), the request is denied. Older viewers crash on varregions.

• RemoteSimulationConnectorModule wraps a

 LocalSimulationConnectorModule instance as its local backend.
 All calls try local first, then fall through to HTTP only if the destination
 is confirmed not-local via IsLocalRegion().

• source in CreateAgent may be null if the user logged

 in directly or arrived from an older simulator that does not send it.

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See Also

• ROBUST Services
• Connector Architecture
• Walkthrough: Avatar Transfer Between Regions
• Walkthrough: Avatar Goes HG