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# 通过 SPARQL 和 Node.js 使用 IAM 身份验证连接到 Amazon Neptune 数据库
<a name="iam-auth-connecting-sparql-node"></a>

## 使用签名 V4 签名和 Javascript V3 AWS 开发工具包进行查询
<a name="iam-auth-querying-sparql-js-sdk-v3"></a>

以下是如何使用带有签名版本 4 身份验证的 Node.js 和适用于 Javascript V3 的 S AWS DK 连接到 Neptune SPARQL 的示例：

```
const { HttpRequest }  = require('@smithy/protocol-http');
const { fromNodeProviderChain } = require('@aws-sdk/credential-providers');
const { SignatureV4 } = require('@smithy/signature-v4');
const { Sha256 } = require('@aws-crypto/sha256-universal');
const https = require('https');

var region = 'us-west-2'; // e.g. us-west-1
var neptune_endpoint = 'your-Neptune-cluster-endpoint';  // like: 'cluster-id.region.neptune.amazonaws.com'
var query = `query=PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX class: <http://aws.amazon.com/neptune/csv2rdf/class/>
PREFIX resource: <http://aws.amazon.com/neptune/csv2rdf/resource/>
PREFIX prop: <http://aws.amazon.com/neptune/csv2rdf/datatypeProperty/>
PREFIX objprop: <http://aws.amazon.com/neptune/csv2rdf/objectProperty/>

SELECT ?movies ?title WHERE {
  ?jel prop:name "James Earl Jones" .
  ?movies ?p2 ?jel .
  ?movies prop:title ?title
} LIMIT 10`;

runQuery(query);

function runQuery(q) {
  var request = new HttpRequest({
    hostname: neptune_endpoint,
    port: 8182,
    path: 'sparql',
    body: encodeURI(query),
    headers: {
      'Content-Type': 'application/x-www-form-urlencoded',
      'host': neptune_endpoint + ':8182',
    },
    method: 'POST',
  });

  const credentialProvider = fromNodeProviderChain();
  let credentials = credentialProvider();
  credentials.then(
    (cred)=>{
      var signer = new SignatureV4({credentials: cred, region: region, sha256: Sha256, service: 'neptune-db'});
      signer.sign(request).then(
        (req)=>{
          var responseBody = '';
          var sendreq = https.request(
            {
              host: req.hostname,
              port: req.port,
              path: req.path,
              method: req.method,
              headers: req.headers,
            },
          (res) => {
            res.on('data', (chunk) => { responseBody += chunk; });
            res.on('end', () => {
                console.log(JSON.parse(responseBody));
            });
          });
          sendreq.write(req.body);
          sendreq.end();
        }
      );
    },
    (err)=>{
      console.error(err);
    }
  );
}
```

## 使用签名 V4 签名和适用于 Javascript V2 的 AWS SDK 进行查询
<a name="iam-auth-querying-sparql-js-sdk-v2"></a>

以下是如何使用带签名版本 4 身份验证的 Node.js 和适用于 Javascript V2 的 S AWS DK 连接到 Neptune SPARQL 的示例：

```
var AWS = require('aws-sdk');

var region = 'us-west-2'; // e.g. us-west-1
var neptune_endpoint = 'your-Neptune-cluster-endpoint';  // like: 'cluster-id.region.neptune.amazonaws.com'
var query = `query=PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX class: <http://aws.amazon.com/neptune/csv2rdf/class/>
PREFIX resource: <http://aws.amazon.com/neptune/csv2rdf/resource/>
PREFIX prop: <http://aws.amazon.com/neptune/csv2rdf/datatypeProperty/>
PREFIX objprop: <http://aws.amazon.com/neptune/csv2rdf/objectProperty/>

SELECT ?movies ?title WHERE {
    ?jel prop:name "James Earl Jones" .
    ?movies ?p2 ?jel .
    ?movies prop:title ?title
} LIMIT 10`;

runQuery(query);

function runQuery(q) {

    var endpoint = new AWS.Endpoint(neptune_endpoint);
    endpoint.port = 8182;
    var request = new AWS.HttpRequest(endpoint, region);
    request.path += 'sparql';
    request.body = encodeURI(query);
    request.headers['Content-Type'] = 'application/x-www-form-urlencoded';
    request.headers['host'] = neptune_endpoint;
    request.method = 'POST';

    var credentials = new AWS.CredentialProviderChain();
    credentials.resolve((err, cred)=>{
        var signer = new AWS.Signers.V4(request, 'neptune-db');
        signer.addAuthorization(cred, new Date());
    });

    var client = new AWS.HttpClient();
    client.handleRequest(request, null, function(response) {
        console.log(response.statusCode + ' ' + response.statusMessage);
        var responseBody = '';
        response.on('data', function (chunk) {
            responseBody += chunk;
        });
        response.on('end', function (chunk) {
            console.log('Response body: ' + responseBody);
        });
    }, function(error) {
        console.log('Error: ' + error);
    });
}
```