I'm writing this blog to list the new BCS features and enhancements in SharePoint 2013. SharePoint 2013 is released with great features for developers and IT Admins in terms of ease of use connecting to external sources and the ability to develop self-contained SharePoint applications that connect to external sources. In this article i will describe the new features and enhancements when building solutions on top of SharePoint 2013.
BCS enhancements in on-premise SharePoint 2013:
1) Automatic generation for BDC Models for OData data sources:
In SharePoint 2013, you are able to connect to OData endpoints and generate BDC models. You must use Visual Studio 2010 to create BDC models for OData data sources.
Then you can import these models in BDC Catalog on your farm-scoed external content types or added on a SharePoint App. VS 2010 will generate BCS operations for all OData Operations (Get, Put, Post and Delete).
2) The ability to create SharePoint App-Scoed External Content Type:
When creating BDC models in VS 2010, you will be able to add App-Scoped external content types that will be used only on the associated SharePoint App.
3) Performance improvements in external lists:
SharePoint 2013 has introduced new enhancements and improvements to minimize the load on the database servers in the SharePoint farm and by increasing the speed of list rendering.
The ability to perform paging, filtering, and sorting of the external list data before it is sent to SharePoint is a great feature.
4) Limiting the records returned by external system:
In the BDC model, users can specify the number of records in the list that they want displayer per page.
5) Data Source Filtering, Sorting and export to excel:
In SharePoint 2013 you are able to filter and sort the data exposed through the an external list. So, in this case the external system filter and sort the data before send it back to the external list.
Also, you can export an external list to excel and in this case you get all list content and structure it shows in the browser.
BCS enhancements in SharePoint Online:
1) REST (CSOM): REST Api is available for web and mobile devlopers to consume SharePoint data using Client Obect Model for the REST Api.
2) BCS Client runtime supports side by side Office 2010 and Office 2013 installaion.
Hope this helps.