Editing OpenSimulator Internals/Package Overview

= Package Overview =

OpenSimulator's source tree is organized into a hierarchy of packages (C# projects).
This page gives a top-level map. For detailed internals of individual classes,
see the [[OpenSimulator_Internals/Code_Map|Code Map]] pages.

== OpenSim ==

The top-level package launches the region server and manages the console.

* '''Entry point:''' <code>OpenSim/Region/Application/Application.cs</code> — <code>Main()</code>
  instantiates an <code>OpenSim</code> object, calls <code>Startup()</code> (which spins
  up worker threads), then blocks the initial thread on the main console prompt.
* <code>OpenSim.Startup()</code> is inherited from
  <code>OpenSim.Framework.Servers.BaseOpenSimServer</code>; it delegates to
  <code>StartupSpecific()</code>.

== OpenSim.Addons ==

'''Note: not actively maintained. Use with caution.'''

* '''OpenSim.Addons.Groups''' — group support.
* '''OpenSim.Addons.OfflineIM''' — offline IM support.

== OpenSim.ApplicationPlugins ==

Application plugins: modular code that affects the entire region server
(as distinct from [[OpenSimulator_Internals/Package_Overview#OpenSim.Region.CoreModules|region modules]],
which affect individual regions).

== OpenSim.Capabilities ==

Basic data structures for capability (HTTPS/event-queue) support.

== OpenSim.ConsoleClient ==

REST console client for remote connection to a running OpenSimulator instance.
Not widely deployed; most operators use a <code>screen</code> session on Linux
or separate terminals on Windows.

== OpenSim.Data ==

All low-level database access code. Contains per-backend packages:

* '''OpenSim.Data.MySQL''' — MySQL/MariaDB backend (primary for grid deployments).
* '''OpenSim.Data.SQLite''' — SQLite backend (common for standalone/testing).

Each backend implements the <code>IAssetData</code> and sibling interfaces defined here.
The interface hierarchy is: <code>OpenSim.Data</code> defines the interfaces;
per-DB packages provide the implementations.

See also: [[OpenSimulator_Internals/Useful_Queries|Useful Queries]].

== OpenSim.Framework ==

General framework code shared across the simulator and ROBUST. Not region-specific.

Subpackages of note:

{| class="wikitable"
|-
! Subpackage !! Purpose
|-
| OpenSim.Framework.AssetLoader.Filesystem || Loads library assets from the local filesystem.
|-
| OpenSim.Framework.Console || Console infrastructure.
|-
| OpenSim.Framework.Monitoring || Statistics gathering and monitoring.
|-
| OpenSim.Framework.RegionLoader.FileSystem || Loads region config from filesystem (e.g. <code>bin/Regions/Regions.ini</code>).
|-
| OpenSim.Framework.RegionLoader.Web || Loads region config from a remote URL.
|-
| OpenSim.Framework.Serialization || OAR and IAR read/write infrastructure.
|-
| OpenSim.Framework.Servers || Generic server base classes, HTTP server infrastructure.
|}

Two subpackages handle configuration loading from HTTP and XML respectively;
neither is a current deployment path.

== OpenSim.Region ==

Most of the region-specific code lives here.

=== OpenSim.Region.ClientStack ===

Infrastructure for pluggable UDP client stacks. In practice only one stack exists
(LLUDP); the abstraction remains in case alternatives are ever needed.

* '''OpenSim.Region.ClientStack.LindenCaps''' — HTTP/capability side of the Second Life
  protocol. Glues cap requests to region modules.
* '''OpenSim.Region.ClientStack.LindenUDP''' — UDP side of the Second Life protocol.
  Glues UDP packets to scene and region module code.

Future Code Map page: [[OpenSimulator_Internals/Code_Map/LLUDPServer|LLUDPServer]] (planned).

=== OpenSim.Region.CoreModules ===

The bundled region modules. This is a large package covering a wide range of
functionality. Key modules documented in the Code Map:

* [[OpenSimulator_Internals/Code_Map/AttachmentsModule|AttachmentsModule]] — avatar attachment lifecycle.
* [[OpenSimulator_Internals/Code_Map/EntityTransferModule|EntityTransferModule]] — region crossings and teleports.
* [[OpenSimulator_Internals/Code_Map/HGEntityTransferModule|HGEntityTransferModule]] — Hypergrid teleport handling.
* [[OpenSimulator_Internals/Code_Map/InventoryAccessModule|InventoryAccessModule]] — inventory access during rez/derez.
* [[OpenSimulator_Internals/Code_Map/AvatarFactoryModule|AvatarFactoryModule]] — avatar appearance management.

=== OpenSim.Region.DataSnapshot ===

Generates an XML summary of region contents; can be exposed to external search engines.

=== OpenSim.Region.Framework ===

The core of the simulator: scene graph, [[OpenSimulator_Internals/Code_Map/ScenePresence|ScenePresence]],
scene object classes, inventory structures, and the [[OpenSimulator_Internals/Code_Map/Scene|Scene]] itself.

=== OpenSim.Region.OptionalModules ===

Region modules not considered core; could in principle be removed while retaining
a functional Second Life-compatible simulator.

=== OpenSim.Region.Physics ===

Physics framework and engine plugins: BulletSim, ubODE, ODE.

=== OpenSim.Region.ScriptEngine ===

Script engine infrastructure. Current engines: XEngine (older), YEngine (current).

=== OpenSim.Region.UserStatistics ===

Exposes simulator statistics via a web page.

== OpenSim.Server ==

Server infrastructure shared between the region simulator and ROBUST.

* '''OpenSim.Server.Base''' — common server infrastructure.
* '''OpenSim.Server.Handlers''' — translates raw incoming HTTP requests to
  service calls. Used primarily in grid mode for ROBUST instances.
  Example: <code>Asset/AssetServerGetHandler</code> translates an asset fetch
  request into a call to the asset service and returns the result.

== OpenSim.Services ==

Service implementations and the connectors that invoke them remotely over HTTP.

* In '''grid mode''': service implementations run inside ROBUST instances.
* In '''standalone mode''': service implementations are instantiated directly
  inside OpenSim.exe.

<code>OpenSim.Services.Connectors</code> contains the HTTP client code that
region simulators use to talk to remote ROBUST services.

See [[OpenSimulator_Internals/Connector_Architecture|Connector Architecture]]
for the full connector and service table.

== OpenSim.Tests ==

Test infrastructure and some standalone client test code.
Actual regression tests live in <code>*.Tests</code> subpackages throughout
the tree (e.g. <code>OpenSim.Region.Framework.Tests</code>).

== OpenSim.Tools ==

Utility tools associated with OpenSimulator but not used in normal operation.

== See Also ==

* [[OpenSimulator_Internals/Code_Map|Code Map]] — per-class internals
* [[OpenSimulator_Internals/Connector_Architecture|Connector Architecture]] — service/connector table
* [[OpenSimulator_Internals/Useful_Queries|Useful Queries]] — database reference
* [[OpenSimulator_Internals/Walkthroughs|Walkthroughs]] — runtime flow documentation

[[Category:OpenSimulator Internals]]