Build Kafka-Connected Web Apps in Servoy

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

With built-in optimized data processing, the CData JDBC Driver offers unmatched performance for interacting with live Kafka data. When you issue complex SQL queries to Kafka, the driver pushes supported SQL operations, like filters and aggregations, directly to Kafka 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 Kafka data using native data types.

Connect to Kafka in Servoy Developer

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

1. Install the JDBC Driver.
2. Copy the JDBC Driver JAR file. (cdata.jdbc.apachekafka.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:apachekafka:User=admin;Password=pass;BootStrapServers=https://localhost:9091;Topic=MyTopic;

        Built-In Connection String Designer

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

        java -jar cdata.jdbc.apachekafka.jar

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

        Set BootstrapServers and the Topic properties to specify the address of your Apache Kafka server, as well as the topic you would like to interact with.

        Authorization Mechanisms

        • SASL Plain: The User and Password properties should be specified. AuthScheme should be set to 'Plain'.
        • SASL SSL: The User and Password properties should be specified. AuthScheme should be set to 'Scram'. UseSSL should be set to true.
        • SSL: The SSLCert and SSLCertPassword properties should be specified. UseSSL should be set to true.
        • Kerberos: The User and Password properties should be specified. AuthScheme should be set to 'Kerberos'.

        You may be required to trust the server certificate. In such cases, specify the TrustStorePath and the TrustStorePassword if necessary.

      • Select the Driver class you just copied, for example, cdata.jdbc.apachekafka.ApacheKafkaDriver

Build a Kafka-Connected Web App

Once you have configured the connection to Kafka in the Servoy Developer resources, you are ready to build apps with access to live Kafka 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 Kafka "table" (e.g., Id from the SampleTable_1 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 Apache Kafka and start building Kafka-connected apps with Servoy. Reach out to our Support Team if you have any questions.