Build HDFS-Connected Web Apps in Servoy

Servoy is a rapid application development and deployment platform. When paired with the CData JDBC Driver for HDFS, users can build HDFS-connected apps that work with live HDFS data. This article describes how to connect to HDFS from Servoy and build a simple web app to display and search HDFS data.

With built-in optimized data processing, the CData JDBC Driver offers unmatched performance for interacting with live HDFS data. When you issue complex SQL queries to HDFS, the driver pushes supported SQL operations, like filters and aggregations, directly to HDFS and utilizes the embedded SQL engine to process unsupported operations client-side (often SQL functions and JOIN operations). Its built-in dynamic metadata querying lets you work with HDFS data using native data types.

Connect to HDFS in Servoy Developer

To build HDFS-connected apps, you need to first create a data provider in Servoy Developer using the CData JDBC Driver for HDFS.

1. Install the JDBC Driver.
2. Copy the JDBC Driver JAR file. (cdata.jdbc.hdfs.jar) to the /application_server/drivers/ directory in the installation directory for Servoy.
3. Open Servoy Developer.
4. In the Solution Explorer, right-click Database Server (under Resources) and choose "Connect to existing database" -> "empty."
   1. Name the server.
   2. Click to show the advanced server settings.

      • Set the URL, for example: jdbc:hdfs:Host=sandbox-hdp.hortonworks.com;Port=50070;Path=/user/root;User=root;

        Built-In Connection String Designer

        For assistance in constructing the JDBC URL, use the connection string designer built into the HDFS JDBC Driver. Either double-click the JAR file or execute the jar file from the command-line.

        java -jar cdata.jdbc.hdfs.jar

        Fill in the connection properties and copy the connection string to the clipboard.

        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
      • Select the Driver class you just copied, for example, cdata.jdbc.hdfs.HDFSDriver

Build a HDFS-Connected Web App

Once you have configured the connection to HDFS in the Servoy Developer resources, you are ready to build apps with access to live HDFS data.

Create a New Solution

1. In the Server Explorer, right-click "All solutions" and select "Create new solution."
2. Name the solution.
3. Select the checkbox to include the "search" module.
4. Click "Finish."

Create a New Form

Right-click "Forms" and select "Create new form."

1. Name the form.
2. Select a Datasource.
3. Set the type (e.g., Simple) and click "Finish."

Add a Data Grid to the Form

1. Drag a Data Grid component (from Servoy NG-Grids) onto the form.

2. Drag a column component onto the Data Grid and set the "dataprovider" property for each column component to a column from the HDFS "table" (e.g., FileId from the Files table).

   Continue adding columns as desired.

Add Searching to the App

Note that the "svySearch" extension is required to add search functionality (included by default when you create a new solution). If you did not add the extension when you created the solution or you are modifying an existing solution, you can add the search module by right-clicking Modules (in the solution) and selecting "Add Module." Select "svySearch" and click "OK."

1. Drag a Text Field component onto the Form.
2. Right-click the Form and select "Open in Script Editor."
3. Create a new variable (JavaScript) to hold the search value:

   var searchText = '';
   

4. Back on the Form, in the Text Field properties:
   1. Set the "dataprovider" property to the Form variable you just created.
   2. Double-click to add a method for the onAction event.
   3. Click to create the method in "Form," name the method (e.g., onEnter), and click "Create private."
   4. Click "OK & Show."
5. Add the following JavaScript to the JavaScript file to use the Servoy framework to implement searching bound data based on the text in the Text Field:

   var search = scopes.svySearch.createSimpleSearch(foundset).setSearchText(searchText);
   search.setSearchAllColumns();
   search.loadRecords(foundset);
   

Save and Launch the App

Save the form and JavaScript file, then click Run -> Launch NGClient to start the web app.

Download a free, 30-day trial of the CData JDBC Driver for HDFS and start building HDFS-connected apps with Servoy. Reach out to our Support Team if you have any questions.