Business Connectivity Services - Architecture

Before comparing BDC vs BSC, one should know that BDC is still a part of SP 2010. It is integral part of Business Connectivity Services (BCS).

One should understand BSC Architecture, before practically implementing it. So, as usually MSDN has everything, and let me bring it on to a post.

A: The Business Data Connectivity service (BDC service) provides a means for storing and securing external content types and related objects. An external content type defines the following:

• A named set of fields of data, such as "customer."
  
• The operations for interacting with the data's external system, such as read, write, and create.
  
• The connectivity information that lets solutions that use the external content type connect to the external system.
  

B: External content types are stored in a dedicated Business Data Connectivity service database.
C: The Secure Store Service securely stores credential sets for external systems and associates those credential sets with identities of individuals or with group identities. A common scenario for the Secure Store Service is a solution that authenticates against an external system in which the current user has a different account for authentication on that external system. When used with Business Data Connectivity service, the Secure Store Service provides a way to authenticate users and groups on external data sources.
D: Credential sets that the Secure Store Service uses are stored in a dedicated, secure database.
E: The Business Data Connectivity Server Runtime on front-end SharePoint servers uses the Business Data Connectivity data to connect to external systems and execute operations on the external systems for access by thin clients such as Web browsers.
F: The BCS Package Store holds the deployable Microsoft Business Connectivity Services packages that contain information that Microsoft Business Connectivity Services and Office applications need to interact with the external systems from rich clients.
G: The Business Data Connectivity service supports connecting to relational databases, Web services, Windows Communication Foundation (WCF) services, .NET connectivity assemblies, and custom data connectors that comply with the requirements of Microsoft Business Connectivity Services.
H: SharePoint Web sites use Business Data Web parts and SharePoint external lists to interact with external data that Microsoft Business Connectivity Services expose.
I: When users connect to an external list, a BCS package is downloaded to the client computers.
J: On supported Office clients (Microsoft SharePoint Workspace, Microsoft Outlook, and Microsoft Word), the Office Integration Client Runtime acts as a connector between Microsoft Business Connectivity Services running on the client and Office applications.
K: The Business Data Connectivity Client Runtime, on client computers, uses the Business Data Connectivity service data and Secure Store Service data to connect to and execute operations on external systems for access by supported rich clients.
L: Business Data Connectivity service data and Secure Store Service data is cached on client computers.

M: The Business Data Connectivity Runtime, on client computers, supports connecting to SQL Server and other relational databases, Web services, and custom data connectors that comply with the requirements of the Microsoft Business Connectivity Services.
N: The client cache refresh synchronizes the cache with the Microsoft Business Connectivity Services data and Secure Store Service data.
O: The Client Secure Store enables end users to configure their client mappings in the credential database.
P: Solution developers can use Microsoft SharePoint Designer 2010 and Visual Studio 2010 to create external content types and BDC models.

 Is it helpful for you? Kindly let me know your comments / Questions.