The Business Connectivity Services capabilities in SharePoint 2010 on-premises and then in SharePoint (2010) Online remain consistent in SharePoint 2013. At the heart of BCS is the external content type, which has supported connectivity across a variety of external data sources, such as Web services, SQL Server databases, and custom business objects. Some of the gains for developers in this version of SharePoint include the OData connector as the basis for the ECT, REST access to external lists, broader and deeper capabilities in CSOM, and with the advent of the new cloud app model, the ability for app-level ECTs to bring LOB data into your app for SharePoint solutions — whether the app is Provider hosted, Autohosted or SharePoint hosted.
In SharePoint 2013, BCS becomes a first-class citizen in the SharePoint event infrastructure. Alerts on external lists are now available as with any other SharePoint list. Also, events can fire on external lists given that the LOB external system has a mechanism in place to detect underlying data changes and can support the ECT notification infrastructure via the exchange of information between the external system and SharePoint during the subscribe process. Given that external system notifications are in place, you can now write remote event receiver code for these external list events as described in Chapter 12.