Build Harvest-Connected Apps in Mendix

Mendix is a high-productivity app platform that allows you to build and maintain both mobile and web applications at-scale. When paired with CData Connect AI, Mendix provides instant, cloud-to-cloud access to Harvest data for applications. This article demonstrates how to connect to a CData Connect AI data source from within Mendix.

CData Connect AI provides a pure cloud-to-cloud interface for Harvest, allowing you to import data from live Harvest data in Mendix — without replicating the data to a natively supported database. As you build web and mobile applications from within Mendix, CData Connect AI pushes all supported SQL operations (filters, JOINs, etc.) directly to Harvest, leveraging server-side processing to return the requested Harvest data quickly.

Configure Harvest Connectivity for Mendix

To work with Harvest data from Mendix, we need to connect to Harvest from Connect AI, provide user access to the connection, and create a Virtual Schema for the Harvest data.

Connect to Harvest 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

2. Select "Harvest" from the Add Connection panel

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

   Start by setting the Profile connection property to the location of the Harvest Profile on disk (e.g. C:\profiles\Harvest.apip). Next, set the ProfileSettings connection property to the connection string for Harvest (see below).

   Harvest API Profile Settings

   To authenticate to Harvest, you can use either Token authentication or the OAuth standard. Use Basic authentication to connect to your own data. Use OAuth to allow other users to connect to their data.

   Using Token Authentication

   To use Token Authentication, set the APIKey to your Harvest Personal Access Token in the ProfileSettings connection property. In addition to APIKey, set your AccountId in ProfileSettings to connect.

   Using OAuth Authentication

   First, register an OAuth2 application with Harvest. The application can be created from the "Developers" section of Harvest ID.

   After setting the following connection properties, you are ready to connect:

   • ProfileSettings: Set your AccountId in ProfileSettings.
   • AuthScheme: Set this to OAuth.
   • OAuthClientId: Set this to the client ID that you specified in your app settings.
   • OAuthClientSecret: Set this to the client secret that you specified in your app settings.
   • CallbackURL: Set this to the Redirect URI that you specified in your app settings.
   • InitiateOAuth: Set this to GETANDREFRESH. You can use InitiateOAuth to manage how the driver obtains and refreshes the OAuthAccessToken.
   
4. Click Save & Test
5. Navigate to the Permissions tab in the Add Harvest Connection page and update the User-based 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 Personal 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.

Configure Harvest Endpoints for Mendix

After connecting to Harvest, create a virtual schema for your desired table(s).

1. Navigate to the Virtual Schemas page and click Add to create a new Virtual Schema (enter a Virtual Schema Name and click Confirm), or select an existing one.
2. Click Add to open the Add Asset dialog and add new assets to the Virtual Schema.
3. Select the Harvest connection (e.g. API1) and click Next.
4. Select the table(s) you wish to work with and click Confirm.
5. Click View Endpoints and make note of the OData Service URL for your virtual schema, e.g. https://cloud.cdata.com/api/odata/{virtual_schema_name}

With the connection, PAT, and Virtual Schema configured, you are ready to connect to Harvest data from Mendix.

Build a Harvest-Connected App

Downloading the OData Metadata File

When creating a connection in Mendix, the connection flow requires a Data Source Contract File. Follow these steps to download the OData metadata file for CData Connect AI using curl, a command line tool:

1. Open a command-line window for your operating system. On Windows, open the start menu, type cmd, and press the Enter key to open a command prompt. On macOS and Linux, open a Terminal window.
2. To check if curl is installed on your system, type curl -help and press the enter key. If it is not installed, install it from the curl website.
3. Issue the following curl command, replacing USER with your CData Connect AI username and PAT with the PAT you generated above:

   curl -u USER:PAT https://cloud.cdata.com/api/odata/{virtual_schema_name}/$metadata -o metadata.xml

4. Locate the metadata.xml file that the curl command created and move it to an accessible location.

Connecting to CData Connect AI in Mendix

Follow these steps to establish a connection from Mendix to CData Connect AI:

1. Login to Mendix and open the Data Hub page.

2. In the Register a Data Source section, select OData.

3. Upload the metadata.xml file from the steps above and click Next.

4. Enter your desired values for Data Source Name and Data Source Version. In the Data Source Relative Path field, enter /api/odata/{virtual_schema_name} and click Next.

5. On the Application information page, click Register a new application.

6. Enter a name in Application Name and select a technical owner (by default, this is the user who is currently logged in).

7. Click Next. In the Environment Name field, enter a desired name (for example, CData Connect AI). In the Environment Location field, enter https://cloud.cdata.com and select the appropriate Environment Type (e.g. Production), depending on what is needed.

8. Click Done! to create your connection.

You can now use your connection in Mendix Studio Pro to easily create applications with access to live Harvest data.

Get CData Connect AI

To get live data access to hundreds of SaaS, Big Data, and NoSQL sources directly from your cloud applications, try CData Connect AI today!