What Are External Content Types?
Published: May 2010
A core concept of Microsoft Business Connectivity Services (BCS) is the external content type. Used throughout the functionality and services offered by Business Connectivity Services, external content types are reusable metadata descriptions of connectivity information and data definitions plus the behaviors you want to apply to a certain category of external data. External content types enable you to manage and reuse the metadata and behaviors of a business entity such as Customer or Order from a central location, and enable users to interact with that external data and processes in a more meaningful way.
For example, consider a business entity such as Customer. You might want to interact with items of type Customer inside a SharePoint list or work on them offline in Microsoft Outlook. Or, you might want to enable the user to pick a customer from a list of customers in an Orders contract document inside Microsoft Word. You can create an external content type once and then reuse it anywhere you need it.
Business Connectivity Services (BCS) is included in Microsoft SharePoint Foundation 2010, Microsoft SharePoint Server 2010, and Microsoft Office 2010 applications. However, the feature set and the capabilities differ in each. See What Is Included in Business Connectivity Services? for details.
External content types offer the following benefits:
Enable reusability An external content type is a reusable data definition of a business entity. After you create it, you can use it with any of the Presentation Features in BCS to provide a rich user experience to interact with external data.
Encapsulate complexities of external systems External content types enable information workers to assemble business solutions without having to handle the complexities of the external systems, for example, without needing to know the connectivity information or learn their programmability interfaces. After an experienced user or a developer creates an external content type, it is available to any user for use in any way they need (provided they have the permissions to perform that operation and access the external data). However, the user does not need to know anything about the location of the external data or how to connect to it.
Provide built-in Office and SharePoint behavior External content types provide Office item-type behaviors (such as contacts, tasks, calendars in Microsoft Outlook, documents in Microsoft Word, and lists in Microsoft SharePoint Workspace); SharePoint behaviors (such as lists, Web Parts, and profile pages); and capabilities (such as the ability to search or work offline) to external data and services, so users can work in their familiar work environments without having to hunt for data or learn and interact with different (and proprietary) user interfaces.
Ensure secure access External content types adhere to the security put in place by both the external system and SharePoint Products and Technologies. You can have full control of who accesses what data by configuring security in SharePoint.
Simplify maintenance. Because external content types can be created once and used by multiple solutions in various scenarios, you can manage them easily. For example, you can manage their access permissions and connection and data definitions in one central location.
Enable external data search You can use SharePoint Server search from an intranet portal to look up information about a specific external content type such as a Customer. SharePoint Server search retrieves the data directly from the external system. Consequently, users can get the information they need without having to get approval or install a separate application.
Enable working offline You can take external content types offline in Outlook 2010 and SharePoint Workspace 2010. Business Connectivity Services provides rich cache and offline work features, and supports cache-based operations. Users can manipulate external data seamlessly and efficiently, even when they are offline or if the server connectivity is slow, intermittent, or unavailable. The read/write operations performed against cached business entities are synchronized when connection to the server becomes available.