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Build a Simple VCL Application for HDFS Data

How to build a simple VCL Application to view HDFS data in RAD Studio using the CData FireDAC Components for HDFS.

Embarcadero RAD Studio provides a development environment for Delphi and C++Builder applications. With the CData FireDAC Components for HDFS, you gain access to live HDFS data within RAD Studio, abstracting the data into tables, views, and stored procedures that can be used to retrieve HDFS data. This article will walk through connecting to HDFS and creating a simple VCL application with the Form Designer.

Creating a VCL Application for HDFS Data

The following instructions show how to use the Form Designer to create a simple VCL Forms application that shows the basic FireDAC objects needed to connect to HDFS from any application.

The following example populates a TDBGrid control.

  1. Create a new VCL Forms Application.
  2. Drop a TFDPhysHDFSDriverLink and TFDConnection object onto the form.
  3. Double-click the TFDConnection object. The FireDAC Connection Editor is displayed. Select "CData.HDFS" in the DriverId menu and configure the connection properties.

    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

  4. Drop a TFDQuery object onto the form and set the properties below:

    • Connection - Set this property to the TFDConnection object, if this object is not already specified.
    • SQL - Click the button in the SQL property and enter a query.
    • Active - Set this property to true.
  5. Drop a TDataSource object onto the form and set the following property:

    • DataSet - In the menu for this property, select the name of the TFDQuery object.
  6. Drop a TDBGrid control onto the form and set the following property:

    • DataSource - Select the name of the TDataSource.
  7. Drop a TFDGUIxWaitCursor onto the form. This is required to avoid a run-time error.

You now have an executable application that displays the results of the SQL Query set in the TFDQuery object.