Sharepoint BDC

BDC [Business Data Catalog] is a service which part of MOSS 2007.
Its an middle man between external datasources and Sharepoint service.
It manages how the data should be passed between outside datasources are like
SQL Server and WebService using Metadata to Sharepoint service.
Example "DUET" its an collaboration software between SAP and Microsoft Office.
From SAP,Sibel or any other RDBMS data source can be used to supply the information to
SharePoint portal.
For this BDC uses the metadata to describe the APIs of business application.
This metadata model abstracts the underlying physical sources an provides a consistent and simple model of business applications to Sharepoint Service.

Runtime Object Model allows you to create,read,update and delete metadata objects in the Shared Services database.

Eventhandlers in MOSS 2007

Creating or adding extra customised features to the sharepoint components like
SharepointItems,List and WebEventReceivers is called "Features in Sharepoint/moss 2007".
usually developer create the customised action by deriving the event handler class of the sharepoints ie.SPItemEventReceiver,SPListEventReceiver and SPWebEventReceiver and attach to the sharepoint site.

Administrator installing the features and activate them on the site or web.

Synchronous Event:
Events that activate before the action occur
Example : FieldAdding event of SPListEventReceiver

Asynchronous Event
Events that activate before the action occur
Example : FiledAdded event of SPListEventReceiver