To create a new BDC model, start Visual Studio 2010 and create a new project based on the “Business Data Connectivity Model” project template, as shown in Figure 9-9. Give the project a meaningful name and connect to a SharePoint website that you want to use for debugging. Notice that you can only create BDC model projects as farm solutions. When you build a BDC model by using Visual Studio, you create a .bdcm file and an assembly. The assembly is deployed to the BDC service application database, which requires full trust and hence, why the project must be configured as a farm solution.

Figure 9-9. Creating a BDC Model Visual Studio project.

The project opens and displays a graphical representation of an entity (ECT) with one identity (property) and two methods (operations), the ReadItem—a specific finder method, and ReadList—a finder method. This is the minimum needed to create an External list. The External list displays one or more entity items that are returned by the ReadList method, and if you select one of those items and choose to view properties, the ReadItem method is called.

The other task panes open and might include the Solution Explorer, which displays the project structure that includes the BDC model, BdcModel1.bdcm, the Properties, BDC Method Details, and the BDC Explorer, which abstracts the underlying XML and displays it in a tree view (see Figure 9-10). To display the BDC Explorer, you can click the link in the BDC Method Details task pane or on the View menu. Next, click Other Windows, and then click BDC Explorer. It will then appear in the upper-right corner, in front of the Solution Explorer task pane. If the Properties task pane is not open, press F4.

Figure 9-10. The Visual Studio workspace includes BDC-related task panes.

The task panes are related to one another. When you click the BdcModel1.bdcm file in Solution Explorer, the Properties task pane displays file properties. When you click the ReadItem method in the BDC Explorer, the Properties and BDC Method Details task panes are populated with related information. For example, you can see that the ReadItem method has two parameters: id with an in direction and returnParameter with a direction of Return. The ReadItem method passes the id parameter, the primary key, to the external system, and the item that is identified by the ID will be returned by the ReadItem method in the Return parameter.

When you make changes in any of these task panes—the graphical representation of the entity (known as the ECT designer), the BDC Method Details, the BDC Explorer of the Properties task pane—you are writing XML to BdcModel1.bdcm; you do not need to manually edit the XML in the file. Sometimes it is easier to see what is incorrect in your BDC model and correct the XML yourself. To quickly open the .bdcm file and write XML, in the Solution Explorer, right-click the file to open the shortcut menu, and then click Open With. In the Open With dialog box, select XML (text) Editor.

The project created from the “Business Data Connectivity Model” project template is a fully working example of a BDC model. After you add the Feature Event receiver to enable the deployment of BDC models from within Visual Studio, press F5 to compile, package, and deploy it. This will also check that you have coded the Feature Event receiver correctly.

There are two types of BCS connectors that you will use when creating BDC models with Visual Studio:

A BCS solution is a combination of declarative and programmatic elements. This fact is hidden when you create a no-code solution with SharePoint Designer. When you display the External Content Types galley in SharePoint Designer, you can see that the BDC model is a .NET Assembly connector. The BDC model is therefore telling SharePoint that you are using a custom .NET Assembly implementation of the BDC model, thereby tying together the declarative XML with the custom code. Therefore, the “Business Data Connectivity Model” project template should really be named the “BDC .NET Assembly” project template.

When you create an External list from the BDC model that you create with Visual Studio, it contains two columns named Identifier1 and Message, which is defined in Entity1.cs and are called Type Descriptors. Use this file to define the entity and its fields. This file maps to the ECT:

Public partial class Entity1
{
   //TODO: Implement additional properties here.
   public string Identifier1 { get; set; }
   public string Message { get; set; }
}

The External list would display one external content item: 0,Hello World. This is the result of the ReadList method that is defined in the Entity1Service.cs file. Use this file to define how to implement the operations, such as the CRUD operations. When you create methods in the task panes, stubs are created in this file, for which you will need to provide the code. You can therefore develop operations that SharePoint Designer cannot provide:

public static IEnumerable<Entity1> ReadList()
{
  // TODO: This is just a sample. Replace this simple sample with valid code.
  Entity1[] entityList = newEntity1[1];
  Entity1 entity1 = newEntity1();
  entity1.Identifier1 = "0";
  entity1.Message = "Hello World";
  entityList[0] = entity1;
  return entityList;
}

To create an ECT by using Visual Studio, perform the following steps:

If you want to extend a BDC model created in SharePoint Designer, or you wish to deploy the BDC model as part of you BCS solution, you will first need to import the BDC model into Visual Studio. To import the BDC model, perform the following steps: