Provide OData Services of JSON Services from a WCF Application

The CData ADO.NET Provider for JSON enables you to rapidly develop service-oriented applications using the Windows Communication Foundation (WCF) framework, providing JSON services data to OData consumers. This article guides you through creating an entity data model for connectivity and a WCF Data Service to expose OData services. You can then consume the feed with various OData clients, such as Power Pivot or applications using the CData ADO.NET Provider for OData.

Create the OData Service

Follow the steps below to create a WCF service application that will provide connectivity to JSON services via OData.

1. Open Visual Studio and create a new project. Select the WCF Service Application template.
2. Delete the autogenerated IService.cs and Service1.svc.
3. Install Entity Framework 6:

   Use the Package Manager Console in Visual Studio to install the latest version of Entity Framework. Run the following command to download and install Entity Framework automatically:

   Install-Package EntityFramework

4. Register the Entity Framework provider:
   1. Add the following provider entry in the "providers" section of your App.config or Web.config file. This section should already exist if the Entity Framework installation was successful.

      <configuration>
      ...
      <entityFramework>
       <providers>
       ...
       <provider invariantName="System.Data.CData.JSON" type="System.Data.CData.JSON.JSONProviderServices, System.Data.CData.JSON.Entities.EF6" />
       </providers>
      </entityFramework>
      </configuration>

   2. Add a reference to System.Data.CData.JSON.Entities.dll, located in lib/4.0 in the installation directory.
   3. Build the project to complete the setup for using EF6.
5. Click Project -> Add New Item -> ADO.NET Entity Data Model.
6. In the Entity Data Model wizard that is displayed, select the 'EF Designer from Database' option.
7. In the resulting Choose Your Connection dialog, click New Connection.

8. In the Connection properties dialog, select the CData JSON Data Source and enter the necessary credentials.

   A typical connection string is below:

   URI=C:/people.json;DataModel=Relational;

   See the Getting Started chapter in the data provider documentation to authenticate to your data source: The data provider models JSON APIs as bidirectional database tables and JSON files as read-only views (local files, files stored on popular cloud services, and FTP servers). The major authentication schemes are supported, including HTTP Basic, Digest, NTLM, OAuth, and FTP. See the Getting Started chapter in the data provider documentation for authentication guides.

   After setting the and providing any authentication values, set to more closely match the data representation to the structure of your data.

   The property is the controlling property over how your data is represented into tables and toggles the following basic configurations.

   • Document (default): Model a top-level, document view of your JSON data. The data provider returns nested elements as aggregates of data.
   • FlattenedDocuments: Implicitly join nested documents and their parents into a single table.
   • Relational: Return individual, related tables from hierarchical data. The tables contain a primary key and a foreign key that links to the parent document.

   See the Modeling JSON Data chapter for more information on configuring the relational representation. You will also find the sample data used in the following examples. The data includes entries for people, the cars they own, and various maintenance services performed on those cars.

   👁 Required connection properties, specified in the Add Connection dialog. (Salesforce is shown.)
   
9. Select JSON tables and views that you want OData clients to access. 👁 Available tables in the Entity Data Model Wizard. (Salesforce is shown.)
   
10. Click Project -> Add New Item -> WCF Data Service.

11. Specify the data source class and configure access to the new WCF Data Service. In the example below, the Access Rule for the entities is set to All. This means that any user will be able to read and modify data.

     
    using System;
    using System.Collections.Generic;
    using System.Data.Services;
    using System.Data.Services.Common;
    using System.Linq;
    using System.ServiceModel.Web;
    using System.Web;
    
    namespace JSONService{
     public class JSONDataService : DataService<JSONEntities> {
     public static void InitializeService(DataServiceConfiguration config) {
     config.SetEntitySetAccessRule("*", EntitySetRights.All);
     config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V3;
     }
     }
    }
    	

12. Run the project. Applications that support OData can now access the Salesforce data and reflect any changes. You can access the feed in your browser. The feed will resemble the following: 👁 The raw OData feed. (Salesforce is shown.)
    

Consume the OData Service from Power Pivot

You can now use the service from any OData client; for example, Excel Power Pivot.

1. Open Excel and click on the Power Pivot Window button.
2. A new pop-up will appear. Select the option From Data Feeds.
3. In the resulting Table Import Wizard, enter the OData URL. For example, http://localhost:12449/JSONDataService.svc/. 👁 The OData URL for JSON.
   
4. After connecting to the OData service, click the Next button at the bottom of the window.
5. A table listing of the available tables will appear in the next window of the wizard. Select which tables you want to import and click Finish. 👁 Available tables in the Table Import Wizard. (Salesforce is shown.)
   
6. Click Close to import the data in Power Pivot. 👁 The table loaded in Power Pivot. (Salesforce is shown.)