How to cache the authentication token

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  • 2 min. za čitanje

This article demonstrates how to cache the authentication token in order to improve performance of your application.

Using ASP.NET

Import the Microsoft.IdentityModel.Clients.ActiveDirectory NuGet package, which is used to acquire a token. Next, use the following code to acquire an AuthenticationResult, using the authentication values you got when you created the Immersive Reader resource.

private async Task<AuthenticationResult> GetTokenAsync()
{
    AuthenticationContext authContext = new AuthenticationContext($"https://login.windows.net/{TENANT_ID}");
    ClientCredential clientCredential = new ClientCredential(CLIENT_ID, CLIENT_SECRET);
    AuthenticationResult authResult = await authContext.AcquireTokenAsync("https://cognitiveservices.azure.com/", clientCredential);
    return authResult;
}

The AuthenticationResult object has an AccessToken property which is the actual token you will use when launching the Immersive Reader using the SDK. It also has an ExpiresOn property which denotes when the token will expire. Before launching the Immersive Reader, you can check whether the token has expired, and acquire a new token only if it has expired.

Using Node.JS

Add the request npm package to your project. Use the following code to acquire a token, using the authentication values you got when you created the Immersive Reader resource.

router.get('/token', function(req, res) {
    request.post(
        {
            headers: { 'content-type': 'application/x-www-form-urlencoded' },
            url: `https://login.windows.net/${TENANT_ID}/oauth2/token`,
            form: {
                grant_type: 'client_credentials',
                client_id: CLIENT_ID,
                client_secret: CLIENT_SECRET,
                resource: 'https://cognitiveservices.azure.com/'
            }
        },
        function(err, resp, json) {
            const result = JSON.parse(json);
            return res.send({
                access_token: result.access_token,
                expires_on: result.expires_on
            });
        }
    );
});

The expires_on property is the date and time at which the token expires, expressed as the number of seconds since January 1, 1970 UTC. Use this value to determine whether your token has expired before attempting to acquire a new one.

async function getToken() {
    if (Date.now() / 1000 > CREDENTIALS.expires_on) {
        CREDENTIALS = await refreshCredentials();
    }
    return CREDENTIALS.access_token;
}

Next steps