Node.js からImpala Data をクエリ

API Server は、データを外部に公開します。CData API Server のOData エンドポイントを使って、Node.js からImpala data へのCRUD クエリを実行します。

CData API Server とADO.NET Provider for Impala(もしくは210+ の他のADO.NET Providers)を使って、Impala をOData エンドポイントして公開し、Node.js からシンプルなHTTP リクエストでクエリを実現します。本記事ではAPI Server を使ってJSON でフォーマットされたImpala データをNode.js でリクエストする方法を説明します。

Set Up the API Server

Follow the steps below to begin producing secure Impala 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 Impala

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

In order to connect to Apache Impala, set the Server, Port, and ProtocolVersion. You may optionally specify a default Database. To connect using alternative methods, such as NOSASL, LDAP, or Kerberos, refer to the online Help documentation.

You can then choose the Impala 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 Impala 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 Customers data. The example URL below applies a simple filter that searches for records with a value of US in the Country column.

var http = require('http'); http.get({ protocol: "http:", hostname: "MyServer.com", port: MyPort, path: "/api.rsc/Customers?$filter=" + encodeURIComponent("Country eq 'US'"), 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); });
 
 
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