azure-cogn-auth.js

var azureCognitiveServicesAuthEndpoint = 'https://northeurope.api.cognitive.microsoft.com/sts/v1.0/issueToken';
var azureCognitiveServicesSubscriptionKey = "[...]";

[...]

// Azure Cognitive Services interface
var _cachedAzureToken = null;
var _cachedAzureTokenExpires = null;
function azureGetAuthToken(callback) {
    if (_cachedAzureToken && _cachedAzureTokenExpires) {
        if ((new Date).getTime() < _cachedAzureTokenExpires) {
            console.log("Using cached auth token: " + _cachedAzureToken);
            callback(null, _cachedAzureToken);
            return;
        }        
    }
    request({
        url: azureCognitiveServicesAuthEndpoint,
        method: "POST",
        headers: {
            'Content-Type' : 'application/x-www-form-urlencoded',
            'Content-Length': 0,
            'Ocp-Apim-Subscription-Key': azureCognitiveServicesSubscriptionKey
        }
    }, function (error, response, body){
        if (error) {
            callback(error, null);
        }
        else if (response.statusCode != 200) {
            callback(body, null);
        }
        else {
            _cachedAzureToken = body;
            _cachedAzureTokenExpires = (new Date).getTime() + (9 * 60 * 1000); // Expires in 10 minutes, refresh in 9
            console.log("Got auth token: " + _cachedAzureToken);
            callback(null, _cachedAzureToken);
        }
    });
}