Build Presto-Connected Apps in Choreo

The Choreo platform from WS02 is a versatile platform designed for low-code and cloud-native engineering. Developers, even those without advanced coding skills, can leverage Choreo's user-friendly low-code environment to simplify application development. When combined with CData Connect Cloud, users gain immediate cloud-to-cloud access to Presto data for applications. This article details the process of connecting to Presto using Connect Cloud and building an application with real-time access to Presto data within Choreo.

CData Connect Cloud delivers a pure cloud-to-cloud interface for Presto, enabling you to construct applications within Choreo that utilize live Presto data data, all without the need for data replication to a natively supported database. With its built-in optimized data processing capabilities, CData Connect Cloud efficiently directs all supported SQL operations, including filters and JOINs, directly to Presto, capitalizing on server-side processing to swiftly provide the requested Presto data.

Getting Started

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Configure Presto Connectivity for Choreo

Connectivity to Presto from Choreo is made possible through CData Connect Cloud. To work with Presto data from Choreo, we start by creating and configuring a Presto connection.

1. Log into Connect Cloud, click Sources, and then click Add Connection

2. Select "Presto" from the Add Connection panel

3. Enter the necessary authentication properties to connect to Presto.

   Set the Server and Port connection properties to connect, in addition to any authentication properties that may be required.

   To enable TLS/SSL, set UseSSL to true.

   Authenticating with LDAP

   In order to authenticate with LDAP, set the following connection properties:

   • AuthScheme: Set this to LDAP.
   • User: The username being authenticated with in LDAP.
   • Password: The password associated with the User you are authenticating against LDAP with.

   Authenticating with Kerberos

   In order to authenticate with KERBEROS, set the following connection properties:

   • AuthScheme: Set this to KERBEROS.
   • KerberosKDC: The Kerberos Key Distribution Center (KDC) service used to authenticate the user.
   • KerberosRealm: The Kerberos Realm used to authenticate the user with.
   • KerberosSPN: The Service Principal Name for the Kerberos Domain Controller.
   • KerberosKeytabFile: The Keytab file containing your pairs of Kerberos principals and encrypted keys.
   • User: The user who is authenticating to Kerberos.
   • Password: The password used to authenticate to Kerberos.
   
4. Click Create & Test
5. Navigate to the Permissions tab in the Add Presto Connection page and update the User-based permissions.

Add a Personal Access Token

When connecting to Connect Cloud through the REST API, the OData API, or the Virtual SQL Server, a Personal Access Token (PAT) is used to authenticate the connection to Connect Cloud. It is best practice to create a separate PAT for each service to maintain granularity of access.

1. Click on the Gear icon () at the top right of the Connect Cloud app to open the settings page.
2. On the Settings page, go to the Access Tokens section and click Create PAT.
3. Give the PAT a name and click Create.
4. The personal access token is only visible at creation, so be sure to copy it and store it securely for future use.

With the connection configured and a PAT generated, you are ready to connect to Presto data from Choreo.

Connect to Presto from Choreo

The steps below outline connecting to CData Connect Cloud from Choreo to create a new application with access to live Presto data.

Creating a Construct

1. Sign in to the Choreo platform. Note: This article is from the perspective of an Anonymous user.
2. Select Components from the left sidebar and then click +Create. Next, choose Manual Trigger and then Start from scratch.
3. Give the manual trigger a Name and Description and click Create.
4. After the trigger is created, click on Edit Code.
5. The Ballerina Low-Code IDE is displayed. Choreo automatically generates a construct in the low-code diagram view. Delete this construct by highlighting it and clicking on the trashcan icon.
6. Click the + icon towards the top of the screen and select Main from the Add Constructs toolbar on the right. In the following Function Configuration form, click Save.

Adding the CData Connect Cloud Connector

1. Click the + icon between the Start and End ellipses and click Connector.

2. In the Connectors sidebar on the right, search for "CData". Click CData Connect to open the Connector settings pane.

3. In the Connector settings pane, enter the configuration settings:
   • Enter an Endpoint Name for your use. In this example, we use "connectEndpoint".
   • In the User field, enter the email address of the CData Connect Cloud user, wrapped in quotation marks (for example, "[email protected]").
   • In the Password field, enter the PAT you generated earlier, wrapped in quotation marks (for example, "SampleToken").

4. After clicking Save, the low-code editor appears with the CData Connect Cloud logo.

Adding a Query Action

1. Click the + icon between the new and end shapes, select Action, and then select our existing connector endpoint.

2. Select query for the connector Operation. There is now an Action pane on the right.

3. Enter a SQL query to retrieve Presto data as the sqlQuery parameter for the query. For example:

   			SELECT * FROM Presto1.Presto.Customer LIMIT 10
   		

   • When writing the query, be sure to specify the Connection Name as the catalog and Data Source Name as the schema. For example, Presto1.Presto.
   • These parameters appear on the Connections page of your CData Connect Cloud dashboard.

Iterating over Presto Data

1. Click the Show Source icon in the top right of the code editor.
2. Add an import statment to import the ballerina/io library:

   		
   		import ballerina/io;
   	

3. Next, add a from statement after the query action to iterate through the results of the SQL query:

		
		check from record{} result in resultStream
		do {
			io:println("Full Customer details: ", result);
		};
	

4. The code for the construct will now look similar to this:

			
			import ballerinax/cdata.connect;
			import ballerinax/cdata.connect.driver as _;
			import ballerina/io;

			public function main() returns error? {
				connect:Client connectEp = check new (user = "connect_cloud_username", password="connect_cloud_pat");

				stream<record {}, error=""?> resultStream =
				connectEp->query(sqlQuery = `SELECT * FROM Presto1.Presto.Customer LIMIT 10`);

				check from record{} result in resultStream
				do {
					io:println("Full Customer details: ", result);
				};
			}
		

5. Click Save to save the action. The diagram should now look similar to this:

Deploying the Program

Once you have added all of your desired actions to your program, follow these steps:

1. Commit and push your final source code in the web editor and sync those changes with the Choreo platform.
2. Click Deploy in the left navigation bar of the Choreo Console.
3. Under Build Area, click Configure & Deploy to deploy your program.
4. When prompted, enter the same CData Connect Cloud username and password that you used earlier and click Deploy.

You have now created an application with access to live Presto data in Choreo.

Get CData Connect Cloud

For more information about using Choreo with CData Connect Cloud, see the CData Connect Ballerina Guide. To get live data access to 100+ SaaS, Big Data, and NoSQL sources directly from your cloud applications, try CData Connect Cloud today!