Node.js からSpark 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Spark data へのCRUD クエリを実行します。

CData API Server とADO.NET Provider for Spark(もしくは170+ の他のADO.NET Providers)を使って、Spark 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Spark 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 Spark 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 Spark

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

Set the Server, Database, User, and Password connection properties to connect to SparkSQL.

You can then choose the Spark 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 Spark 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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