Build Presto-Connected Web Apps with Axios and CData Connect AI

Axios is a JavaScript library that allows developers to make HTTP requests to servers from a web browser or Node.js. When paired with CData Connect AI, you get access to live Presto data for your web apps. This article shows how to connect to Presto and build web apps in Axios with access to live Presto data.

Getting Started

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Connect to Presto from Axios

To work with Presto in Axios, we need to connect to Presto from Connect AI, provide user access to the connection, and create a Workspace for the Presto data.

Connect to Presto from Connect AI

CData Connect AI uses a straightforward, point-and-click interface to connect to data sources.

1. Log into Connect AI, click Sources, and then click Add Connection
👁 Adding a Connection

2. Select "Presto" from the Add Connection panel
👁 Selecting a data source

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.
   👁 Configuring a connection (Salesforce is shown)
   
4. Click Save & Test
5. Navigate to the Permissions tab in the Add Presto Connection page and update the User-based permissions. 👁 Updating permissions
   

Add a Personal Access Token

When connecting to Connect AI 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 AI. 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 AI 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. 👁 Creating a new PAT
   
4. The personal access token is only visible at creation, so be sure to copy it and store it securely for future use.

Configure Presto Endpoints for Axios

After connecting to Presto, create a workspace for your desired table(s).

1. Navigate to the Workspaces page and click Add to create a new Workspace (or select an existing workspace). 👁 The Workspaces page.
   👁 Adding a new Workspace.
   
2. Click Add to add new assets to the Workspace.
3. Select the Presto connection (e.g. Presto1) and click Next. 👁 Selecting an Asset (Salesforce is shown).
   
4. Select the table(s) you wish to work with and click Confirm. 👁 Selecting Tables (Salesforce is shown).
   
5. Make note of the OData Service URL for your workspace, e.g. https://cloud.cdata.com/api/odata/{workspace_name}

With the connection, PAT, and Workspace configured, you are ready to connect to Presto data from Axios.

Connect to Presto Data in Axios Workflows

To establish a connection from Axios to CData Connect AI using the OData protocol, follow these steps.

1. Create a project directory for your web app. For example: ~/connect_cloud/
2. Open a terminal, navigate the the project directory and initialize a node project using the command:

   npm init -y

3. Install the Axios dependency in the project using the following command:

   npm install axios

4. In your project directory, create a file called server.js that contains the following code. Provide your CData Connect AI username (e.g. [email protected]) and PAT (the PAT you created in the prerequisites). You must also provide a query for your data, such as SELECT * FROM Presto1.SCHEMA.Customer.

   server.js code

    const axios = require('axios')
   
    const user = '[email protected]'
    const pat = '***********************************';
   
    //Your API endpoint
    const url = 'https://cloud.cdata.com/api/odata/{workspace_name}';
   
    //Your data to be sent in the POST request
    const data = {
    "query":"SELECT * FROM {workspace_name}.SCHEMA.Customer"
    };
   
    axios.post(url, data, {
    auth: {
    username: user,
    password: pat
    }
    })
    .then(response => {
    const rows = response.data.results[0].rows;
    const schema = response.data.results[0].schema;
   
    //Create an array of column names
    const columnNames = schema.map(col => col.columnName);
   
    //Loop through each row and log the column name with its value
    rows.forEach(row => {
    const rowObject = {};
    row.forEach((value, index) => {
    const columnName = columnNames[index];
    rowObject[columnName] = value;
    });
    console.log(rowObject);
    })
    })
    .catch(error => {
    console.error('Error:', error);
    });
    

5. In the terminal, execute the following command to run the server:

   node server.js

   The query results will appear:

    { ID: 1, VALUE: -2 }
    { ID: 2, VALUE: 1 }
    { ID: 11, VALUE: null }
    { ID: 3, VALUE: 2 }
    { ID: 4, VALUE: 5 }
    ...

Simplified Access to Presto Data from Cloud Applications

At this point, you have a direct connection to live Presto data from Axios. For more information on gaining simplified access to data from more than 100 SaaS, Big Data, and NoSQL sources in cloud applications like Axios, refer to our Connect AI page.