What is BCS and BDC in SharePoint?

BCS (Business Connectivity Services)

BCS Overview:

BCS allows the integration of external data into SharePoint through an (ORM) Object relational map, known as ECT (External Content Type).
ETC maps external data fields to business entities.
ECT defines the operations to perform on the external data. i.e. like (Creating, rereading, Updating, Deleting items.)
Creating ECT is the primary development activity while working with BCS.

BCS = Combination of ( BDC + “Some Other Services”)

Connecters:

Connecters will help to connect with external Systems through Out-of-box. We can connect with “OData, WCF, SQL Servers”.
We can use .NET code to connect with other Data-Bases Servers.

BDC:

BDC (Business Data Connectivity).
BDC (Business Data Catalog) introduced in MOSS(2007). Which allow you to upload an XML-file, which define a Metadata to describe how to connect External-Data-Base in Read-Only mode?
In SP-2010 BCS allows us to upload same XML-file but, it will allow us to read and also perform the Full-Crawl operation on the external data base.
We can say BDC is the Core-System/Engine.
BDC is a Service application and installed in SharePoint server and can be Administered through Central-Admin website.

Secure Store Service (SSS):

SSS is a credential mapping system that allows (BCS) Business Connectivity Service to access external data.

We can use the External-Data in SharePoint several ways.

o Search

o Columns

o Web-Parts

o CSOM (Client Side Object Model)

o Profiles

Using of External-Data in SharePoint Site/Apps:

SharePoint Sites and Apps can use external data.
We can use external data with External-List. This look like normal SharePoint-List but it’s packed by External Content type instead of Standard Content type.

Other BCS Enhancements:

BCS is also support SharePoint Online.
BCS improved "Sorting and Filtering" capabilities for External-List to improve query efficiency.

Note: "Sorting" is Only possible in "OData & SQL Server". WCF doesn't support "Sorting".

Filtering is support in all external data base systems.

OData Sources:

OData (Open Data Protocol) for performing CRUD operations on Web Data. i.e. {Query and Updating the data.}
OData uses standard HTTP GET, POST, PUT and DELETE operations.
OData returns "ATOM" and "JSON" results.
OData Provides easy Cross-Platform data access.
OData support REST (Representational State Transfer).
OData will allows us to connect verity of External-Data Sources.

OData is an important protocol for services, that was not previously support by BCS.
Visual Studio supports for automatically generating BDC MetaData models from an OData Source.

Siva Kakarla