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2026-06-21T06:24:18Z

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= OpenSimulator Internals/ROBUST Services =

All service interfaces are in OpenSim.Services.Interfaces.

ROBUST services fall into two categories: those that must run in the same process instance, and those that can be split across machines and load-balanced.

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== Must Stay in Same Instance ==

These services share state and have dependencies on each other. Running them in separate instances will cause data conflicts.

{| class="wikitable"
! Service !! Notes
|-
| [[OpenSimulator Internals/PresenceService|PresenceService]] || Who is online, which region, current session. Maintains a cache. Multiple instances would give conflicting answers.
|-
| [[OpenSimulator Internals/UserAgentService|UserAgentService]] || Manages the user agent when traveling via HyperGrid. Handles trust verification between grids.
|-
| [[OpenSimulator Internals/AgentPreferencesService|AgentPreferencesService]] || Per-user preferences such as hover height and language setting.
|-
| [[OpenSimulator Internals/GridUserService|GridUserService]] || Home region, last login location, online status. Must update atomically with PresenceService on login and logout.
|}

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== Can Be Split and Load-Balanced ==

These services are stateless and can run on separate machines behind a load balancer such as nginx.

{| class="wikitable"
! Service !! Notes
|-
| [[OpenSimulator Internals/AssetService|AssetService]] || Stores and serves asset blobs (textures, meshes, scripts, notecards, etc.). Intentionally dumb -- no referential awareness. Two storage backends: database blob (default) or FSAssets (recommended above 50GB).
|-
| [[OpenSimulator Internals/InventoryService|InventoryService]] || User inventory. Folder tree and item references. Permissions live here, not in the asset table.
|-
| [[OpenSimulator Internals/GridService|GridService]] || Region map. Handles region registration on startup and deregistration on shutdown. Answers queries for region location and coordinates.
|-
| [[OpenSimulator Internals/UserAccountService|UserAccountService]] || User account storage. Name, email, user level, flags.
|-
| [[OpenSimulator Internals/AuthenticationService|AuthenticationService]] || Login authentication. Core implementations are password and webkey.
|-
| [[OpenSimulator Internals/GroupsService|GroupsService]] || Groups. Core groups service is not enabled by default. External XmlRpc/Flotsam groups service is the common alternative.
|}

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== Additional Services ==

{| class="wikitable"
! Service !! Notes
|-
| [[OpenSimulator Internals/AvatarService|AvatarService]] || Avatar appearance, height, attached items.
|-
| [[OpenSimulator Internals/AuthorizationService|AuthorizationService]] || Always returns authorized. No database, no configuration, no logic. A stub. Actual access control (ban lists, parcel restrictions, estate settings) is handled in region code, not here.
|-
| [[OpenSimulator Internals/FriendsService|FriendsService]] || Friends list, friendship requests, permissions granted to friends.
|-
| [[OpenSimulator Internals/MapImageService|MapImageService]] || Stores and serves map tile images. Stored on filesystem, not in the database.
|-
| [[OpenSimulator Internals/LoginService|LoginService]] || Handles user login. Implements the LL login protocol.
|-
| HyperGrid services || Override normal services (asset, inventory, etc.) with HyperGrid-specific functionality.
|}

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== Simulator Services ==

These run per-simulator rather than on ROBUST. See [[OpenSimulator Internals/Data Dictionaries#Simulator_Services|Simulator Services]] for interface details.

{| class="wikitable"
! Service !! Notes
|-
| Land || Parcel data for a specific simulator. Read only.
|-
| Library || Library items and folders. Currently per-region, should be a grid service. Data from filesystem.
|-
| Simulation || General simulation functions: create agent, update agent, create object. Used for login-to-simulator and simulator-to-simulator communication (teleport, region crossing, moving objects between regions).
|}

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== See Also ==

* [[OpenSimulator Internals/Data Dictionaries]]
* [[OpenSimulator Internals/Connector Architecture]]

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