Build Azure Data Lake Storage-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 Cloud, Mendix provides instant, cloud-to-cloud access to Azure Data Lake Storage data for applications. This article demonstrates how to connect to a CData Connect Cloud data source from within Mendix.

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

Configure Azure Data Lake Storage Connectivity for Mendix

Connectivity to Azure Data Lake Storage from Mendix is made possible through CData Connect Cloud. To work with Azure Data Lake Storage data from Mendix, we start by creating and configuring a Azure Data Lake Storage connection.

1. Log into Connect Cloud, click Connections and click Add Connection
2. Select "Azure Data Lake Storage" from the Add Connection panel
3. Enter the necessary authentication properties to connect to Azure Data Lake Storage.

   Authenticating to a Gen 1 DataLakeStore Account

   Gen 1 uses OAuth 2.0 in Azure AD for authentication.

   For this, an Active Directory web application is required. You can create one as follows:

   1. Sign in to your Azure Account through the .
   2. Select "Azure Active Directory".
   3. Select "App registrations".
   4. Select "New application registration".
   5. Provide a name and URL for the application. Select Web app for the type of application you want to create.
   6. Select "Required permissions" and change the required permissions for this app. At a minimum, "Azure Data Lake" and "Windows Azure Service Management API" are required.
   7. Select "Key" and generate a new key. Add a description, a duration, and take note of the generated key. You won't be able to see it again.

   To authenticate against a Gen 1 DataLakeStore account, the following properties are required:

   • Schema: Set this to ADLSGen1.
   • Account: Set this to the name of the account.
   • OAuthClientId: Set this to the application Id of the app you created.
   • OAuthClientSecret: Set this to the key generated for the app you created.
   • TenantId: Set this to the tenant Id. See the property for more information on how to acquire this.
   • Directory: Set this to the path which will be used to store the replicated file. If not specified, the root directory will be used.

   Authenticating to a Gen 2 DataLakeStore Account

   To authenticate against a Gen 2 DataLakeStore account, the following properties are required:

   • Schema: Set this to ADLSGen2.
   • Account: Set this to the name of the account.
   • FileSystem: Set this to the file system which will be used for this account.
   • AccessKey: Set this to the access key which will be used to authenticate the calls to the API. See the property for more information on how to acquire this.
   • Directory: Set this to the path which will be used to store the replicated file. If not specified, the root directory will be used.
4. Click Create & Test
5. Navigate to the Permissions tab in the Add Azure Data Lake Storage Connection page and update the User-based permissions.

Add Azure Data Lake Storage OData Endpoints in Connect Cloud

After connecting to Azure Data Lake Storage, create OData Endpoints for the desired table(s).

1. Navigate to the OData page and click Add to create new OData endpoints
2. Select the Azure Data Lake Storage connection (e.g. ADLS1) and click Next
3. Select the table(s) you wish to work with and click Confirm

With the connection and OData endpoints configured, you are ready to connect to Azure Data Lake Storage data from Mendix.

Build a Azure Data Lake Storage-Connected App

With OData endpoints added to Connect Cloud, you can build an app in Mendix with live access to Azure Data Lake Storage data.

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 Cloud 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 Cloud username and PAT with the PAT you generated above: curl -u USER:PAT https://cloud.cdata.com/api/odata/service/$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 Cloud in Mendix

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

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/service 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 Cloud). 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 Azure Data Lake Storage data.

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