Business Data Catalog - Using the BDC Object Model

There are a few good MSDN entries with samples on using the Business Data Catalog, aka the ApplicationRegistry namespace.

BDC

http://msdn.microsoft.com/en-us/library/ms563661.aspx

BDC - Using the runtime object model

http://msdn.microsoft.com/en-us/library/ms568510.aspx

BDC - Get a LobSystem and an Entity

http://msdn.microsoft.com/en-us/library/ms501019.aspx

BDC - Executing a Finder to retrieve a collection

http://msdn.microsoft.com/en-us/library/ms560143.aspx

BDC - Executing a SpecificFinder to retrieve an item in a collection

http://msdn.microsoft.com/en-us/library/ms545953.aspx

BDC - Call a method on an entity

http://msdn.microsoft.com/en-us/library/ms559510.aspx

BDC - Building a BDC Search Web Part

http://msdn.microsoft.com/en-us/library/ms558854.aspx

SDK

http://msdn.microsoft.com/en-us/library/microsoft.office.server.applicationregistry.runtime.aspx

Some parts of the SDK are incomplete, but this part is about done and it’s the main one to use.