Users need access tokens to invoke APIs subscribed under an application. Access tokens are passed in the HTTP header when invoking APIs. The API Manager provides a Token API that you can use to generate and renew user and application access tokens. The response of the Token API is a JSON message. You extract the token from the JSON and pass it with an HTTP Authorization header to access the API.
The following topics explain how to generate access tokens and authorize them. WSO2 API Manager supports the four most common authorization grant types and you can also define additional types.
Renewing access tokens
After an access token is generated, sometimes you might have to renew the old token due to expiration or security concerns. You can renew an access token using a refresh token, by issuing a REST call to the Token API with the following parameters.
- The Token API URL is https://localhost:8243/token, assuming that both the client and the Gateway are run on the same server.
"grant_type=refresh_token&refresh_token=<retoken>". Replace the
<retoken>value with the refresh token generated in the
Authorization :Basic <base64 encoded string>, Content-Type: application/x-www-form-urlencoded. Replace
<base64 encoded string>as appropriate.
For example, the following cURL command can be used to access the Token API.
You receive a response similar to the following:
The above REST message grants you a renewed access token along with a refresh token, which you can use the next time you renew the access token. A refresh token can be used only once. You can configure an expiration time for the refresh token by setting it in the
<RefreshTokenValidityPeriod> element in the
Revoking access tokens
After issuing an access token, a user or an admin can revoke it in case of theft or a security violation. You can do this by calling the Revoke API using a utility like cURL. The Revoke API's endpoint URL is http://localhost:8280/revoke.
Parameters required to invoke this API are as follows:
- The token to be revoked
- Consumer key and consumer secret key. Must be encoded using Base64 algorithm
Revoking access tokens obtained with an Implicit grant
If you obtained an access token with the Implicit grant type, you do not have to provide the client secret to revoke it. The sample cURL command to revoke an access token with Implicit grant is given below.
You receive an empty response with the HTTP status as 200. The following HTTP headers are returned:
Note that if you use an invalid access token, you still receive an empty response with the HTTP status as 200 but only the following HTTP headers are returned:
Configuring the token expiration time
User access tokens have a fixed expiration time, which is set to 60 minutes by default. Before deploying the API Manager to users, extend the default expiration time by editing the
<AccessTokenDefaultValidityPeriod> element in the
Also take the time stamp skew into account when configuring the expiration time. The time stamp skew is used to manage small time gaps in the system clocks of different servers. For example, let's say you have two Key Managers and you generate a token from the first one and authenticate with the other. If the second server's clock runs 300 seconds ahead, you can configure a 300s time stamp skew in the first server. When the first Key Manager generates a token (e.g., with the default life span, which is 3600 seconds), the time stamp skew is deducted from the token's life span. The new life span is 3300 seconds and the first server calls the second server after 3200 seconds.
You configure the time stamp skew using the
<TimestampSkew> element in the
Tip: Ideally, the time stamp skew should not be larger than the token's life span. We recommend you to set it to zero if the nodes in your cluster are synchronized. Also, note that when the API Gateway cache is enabled (it is enabled by default), even after a token expires, it will still be available in the cache for consumers until the cache expires in approximately 15 minutes.
When a user access token expires, the user can try regenerating the token as explained in the Renew user tokens section.