Codebase overview

Revision as of 18:18, 4 July 2008

Coding restrictions

Because OpenSim has to run on both Windows and Mono (usually on Linux or Mac), we are limited to the parts of .net that Mono supports. That means you can't go and use fancy .net 3.0 stuff if you're planning on contributing code - see source such as Wikipedia's mono article for more details.

Codebase overview

OpenSim is already a fairly large and intricate project, so patience is required to start understanding it.

At the top level, OpenSim code is broken up into seven sections. There's also a bit more detail on the most significant packages within those sections.

• OpenSim. This contains the classes which launch the OpenSim region server and handle the console
• OpenSim.ApplicationPlugins. Each package is an individual application plugin - an application plugin is a modular piece of code that has an effect on the entire region server. See RegionModules for more details or one of justincc's blogposts for a higher level overview (which should really be in this wiki).
• OpenSim.Data. This is all the low level database manipulation stuff. In here, you'll see packages for SQLite, MySQL and MSSQL (which tends to lag), as well as code for NHibernate which will hopefully reduce our reliance on manipulation code for specific databases.
• OpenSim.Framework. General framework code used by the rest of OpenSim which is felt to be not specific to a region.
  • OpenSim.Framework.Communications. Contains asset and inventory caching code (to cut down on communication with a remote asset or inventory service), and contains CAPS code, a Linden approach to splitting some aspects of the Second Life protocol into independent, secured services. See a blog post from Tao for more background on this.
  • OpenSim.Framework.Servers. Contains generic server code, such as the base OpenSim server and http servers.
  • OpenSim.Framework.Stats. Collects statistical information on OpenSim operations.
• OpenSim.Grid. Each separate package in here contains a grid server (grid servers are used when running OpenSim in grid mode, and handle services such as assets, inventories and grid management. See Grid Architecture Diagram to get a graphical idea, or this blog post for a more textual overview. By the way, the OpenSim.Grid.ScriptServer is not currently useable.
• OpenSim.Region. Contains most of the meaty code that it specifically concerned with region manipulation.
  • OpenSim.Region.ClientStack.LindenUDP. The code necessary for communicating with clients using the Second Life protocol.
  • OpenSim.Region.Communications.Local. Code used for communicating with non-region services (user, asset, grid, etc.) when OpenSim is running in standalone mode.
  • OpenSim.Region.Communications.OGS1. Code for communicating with remote UGAI services using the Open Grid Services 1 protocol.
  • OpenSim.Region.Environment. A large package containing both the vast majority of the region modules (categorized under modules) and the central scene manipulation code (under Scenes, appropriately enough). Modules here do everything from handling region chat to loading and saving terrain.
  • OpenSim.Region.Modules. More region module code. Actually, I'm not too sure why these aren't in the OpenSim.Region.Environment package.
  • OpenSim.Region.Physics. General physics framework code and plugins for specific engines (BulletX, ODE, etc). The ODE code is by far the most reliable and stable.
  • OpenSim.Region.ScriptEngine. Script engine code that powers the scripts run within OpenSim. Currently there are two engines, the classic DotNetEngine and the relatively new XEngine.
• OpenSim.Tests. Test code. Really, we don't actually have much of this (yet).