Connect to HDFS Data from Blazor Apps

Blazor is a framework for developing modern, client-side web UIs using .NET technology. Instead of coding in JavaScript, developers can use the familiar C# language and .NET libraries to build app UIs.

The CData ADO.NET Provider for HDFS can be used with standard ADO.NET interfaces, such as LINQ and Entity Framework, to interact with live HDFS data. Since Blazor supports .NET Core, developers can use CData ADO.NET Providers in Blazor apps. In this article, we will guide you to build a simple Blazor app that talks to HDFS using standard SQL queries.

Install the CData ADO.NET Provider for HDFS

CData ADO.NET Providers allow users to access HDFS just like they would access SQL Server, using simple SQL queries.

Install the HDFS ADO.NET Data Provider from the CData website or from NuGet. Search NuGet for "HDFS ADO.NET Data Provider."

Create a HDFS-Connected Blazor App

Start by creating a Blazor project that references the CData ADO.NET Provider for HDFS

1. Create a Blazor project on Visual Studio.
2. From the Solution Explorer, right click Dependencies, then click Add Project Reference.
3. In the Reference Manager, click the Browse button, and choose the .dll file of the installed ADO.NET Provider (e.g. System.Data.CData.HDFS.dll, typically located at C:\Program Files\CData\CData ADO.NET Provider for HDFS\lib etstandard2.0).

SELECT HDFS Data from the Blazor App

1. Open the Index.razor file from the Project page.
2. In a HDFSConnection object, set the connection string:

   In order to authenticate, set the following connection properties:

   • Host: Set this value to the host of your HDFS installation.
   • Port: Set this value to the port of your HDFS installation. Default port: 50070

   For example: Host=sandbox-hdp.hortonworks.com;Port=50070;Path=/user/root;User=root;

3. The code below creates a simple Blazor app for displaying HDFS data, using standard SQL to query HDFS just like SQL Server.

         @page "/"
         @using System.Data;
         @using System.Data.CData.HDFS;
         
         <h1>Hello, world!</h1>
         
         Welcome to your Data app.
         
         <div class="row">
             <div class="col-12">
         
                 @using (HDFSConnection connection = new HDFSConnection(
                   "Host=sandbox-hdp.hortonworks.com;Port=50070;Path=/user/root;User=root;"))
                 {
                     var sql = "SELECT FileId, ChildrenNum FROM Files WHERE FileId = '119116'";
                     var results = new DataTable();
         
                     HDFSDataAdapter dataAdapter = new HDFSDataAdapter(sql, connection);
                     dataAdapter.Fill(results);
         
                     <table class="table table-bordered">
                         <thead class="thead-light">
                             <tr>
                                 @foreach (DataColumn item in results.Rows[0].Table.Columns)
                                 {
                                     <th scope="col">@item.ColumnName</th>
                                 }
                             </tr>
                         </thead>
                         <tbody>
                             @foreach (DataRow row in results.Rows)
                             {
                                 <tr>
                                     @foreach (var column in row.ItemArray)
                                     {
                                         <td>@column.ToString()</td>
                                     }
                                 </tr>
                             }
                         </tbody>
                     </table>
                 }
             </div>
         </div>
       

4. Rebuild and run the project. The ADO.NET Provider renders HDFS data as an HTML table in the Blazor app.

   At this point, you have a HDFS-connected Blazor app, capable of working with live HDFS data just like you would work with a SQL Server instance. Download a free, 30-day trial and start working with live HDFS data in your Blazor apps today.