Business Connectivity Services

Business Connectivity Services
Business Connectivity Services (BCS) formerly known as Business Data Catalog (BDC) in a SharePoint 2010 enables easier integration with Line Of Business systems. This allows developers to perform CRUD operations on data they need for a particular business process in one place regardless whether data is housed in SharePoint or otherwise.
The idea behind this functionality is to expose Line of Business data from your back end services (such as People Soft, SAP, custom databases etc.) to business analysts so they can use them within SharePoint. Each piece of information (for example a table in a database that has your Customers information) can be exposed as an External Content Type (ECT) by an IT professional or a developer using SharePoint Designer 2010. Then a business analyst can use SharePoint through the web browser to make an External List which uses this ECT. The result will be that they have a list now showing information straight from the Customers table. When anyone manipulates the information in that External List, it will actually be written back to that table in the database.
Benefits of ECTs:
1. Reusability
2. Enabling working offline Mode
3. Secure Access
4. Encapsulate complexities of external systems.
5. Allows user to perform CRUD operations easily.
6. Integrated with SharePoint provides built in Office and SharePoint behavior.
After you create an external content type, you can use any of the presentation features of Microsoft Business Connectivity Services (BCS) to provide a rich experience to the user, without writing any code.
Presentation Features on the SharePoint 2010 Server
1. External Lists in SharePoint 2010 exposes BCS entities to the end user through familiar SharePoint List UI.
2. External Data Columns: The Business Data list column type is now renamed External Data column, and it enables users to add data from external content types to standard SharePoint lists.
3. External Data Web Parts: BCS continues to offer Web Parts: External Data List, External Data Item, External Data Item Builder, External Data Related List, and External Data Connectivity Filter.
4. External Content Type Picker: An External Content Type Picker provides picking and resolving functionality to the user. You can embed a picker in a form or page for scenarios where a user should be able to pick an external content type from the list of available external content types.
5. Profile Pages: Profile Pages are SharePoint pages on the server that display the details about an external item. Just like any other SharePoint Web Part page, you can customize this page to show details of an external item.