Query Azure Data Lake Storage Data from Node.js

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CData API Server



The API Server exposes Web services that allow connectivity to your data. Use the OData endpoint of the CData API Server to execute CRUD queries to Azure Data Lake Storage data from Node.js.

The CData API Server, when paired with the ADO.NET Provider for Azure Data Lake Storage, exposes Azure Data Lake Storage data (or data from any of 200+ other ADO.NET Providers) as an OData endpoint, which can be queried from Node.js using simple HTTP requests. This article shows how to use the API Server to request JSON-formatted Azure Data Lake Storage data in Node.js.

Set Up the API Server

Follow the steps below to begin producing secure Azure Data Lake Storage OData services:

Deploy

The API Server runs on your own server. On Windows, you can deploy using the stand-alone server or IIS. On a Java servlet container, drop in the API Server WAR file. See the help documentation for more information and how-tos.

The API Server is also easy to deploy on Microsoft Azure, Amazon EC2, and Heroku.

Connect to Azure Data Lake Storage

After you deploy the API Server and the ADO.NET Provider for Azure Data Lake Storage, provide authentication values and other connection properties needed to connect to Azure Data Lake Storage by clicking Settings -> Connections and adding a new connection in the API Server administration console.

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.

You can then choose the Azure Data Lake Storage entities you want to allow the API Server access to by clicking Settings -> Resources.

Authorize API Server Users

After determining the OData services you want to produce, authorize users by clicking Settings -> Users. The API Server uses authtoken-based authentication and supports the major authentication schemes. Access can also be restricted based on IP address; all IP addresses except the local machine are restricted by default. You can authenticate as well as encrypt connections with SSL.

Consume Azure Data Lake Storage OData Feeds from Node.js

OData feeds are easy to work with in Node.js. You can use the HTTP client in Node.js to request JSON-formatted data from the API Server's OData endpoint. After making the request, you can construct the body of the response and call the JSON.parse() function to parse it into records.

The code below will make an authenticated request for Resources data. The example URL below applies a simple filter that searches for records with a value of FILE in the Type column.

var http = require('http'); http.get({ protocol: "http:", hostname: "MyServer.com", port: MyPort, path: "/api.rsc/Resources?$filter=" + encodeURIComponent("Type eq 'FILE'"), auth: 'MyUser:MyAuthtoken' }, function(res) { var body = ''; res.on('data', function(chunk) { body += chunk; }); res.on('end', function() { console.log(body); var jsonData = JSON.parse(body); }); }).on('error', function(e) { console.log("Error: ", e); });