Token APIs

Token APIs can be used to generate and renew user access tokens. Users need access tokens to identify and invoke APIs subscribed under an application. User tokens are passed in the HTTP header when invoking APIs. Let's take a look at how to generate, authorize and renew access tokens.

Generating user tokens

You can use the Token API to invoke an API through a third-party application like a mobile app. The Token API comes bundled with the API Manager by default. It requires the base64 encoded string of the consumer-key:consumer-secret combination.

For instructions to generate an application-level access token from the API Store, see Working with Access Tokens.

Prerequisites

You need the following before using the Token API to generate a user token.

A valid user account in the API Store. See Signing up to API Store.
A valid consumer key and consumer secret. Initially, these keys must be generated through the management console by clicking the Generate link on My Subscriptions page. You can find more details in Working with Access Tokens.
A running API Gateway instance (typically an API Manager instance should be running). For instruction on API Gateway, refer to section Architecture Components.

Invoking Token API to generate user tokens

Combine the consumer key and consumer secret keys in the format consumer-key:consumer-secret and encode the combined string using base64. Encoding to base64 can be done using the URL: http://base64encode.org.
Here's an example consumer key and secret combination : wU62DjlyDBnq87GlBwplfqvmAbAa:ksdSdoefDDP7wpaElfqvmjDue.
Access the Token API by using a REST client such as the WSO2 REST Client or Curl, with the following parameters.
- Assuming that both the client and the API Gateway are run on the same server, the token API url is https://localhost:8243/token
- payload - "grant_type=password&username=<username>&password=<password>&scope=PRODUCTION". Replace the <username> and <password> values as appropriate.
- headers - Authorization :Basic <base64 encoded string>, Content-Type: application/x-www-form-urlencoded. Replace the <base64 encoded string> as appropriate.
For example, use the following cURL command to access the Token API. It generates two tokens as an access token and a refresh token. You can use the refresh token at the time a token is renewed .
```
curl -k -d "grant_type=password&username=<username>&password=<password>&scope=PRODUCTION" -H "Authorization :Basic SVpzSWk2SERiQjVlOFZLZFpBblVpX2ZaM2Y4YTpHbTBiSjZvV1Y4ZkM1T1FMTGxDNmpzbEFDVzhh" -H "Content-Type: application/x-www-form-urlencoded" https://localhost:8243/token
```
The Token API endpoint is specified in the <APIM_HOME>/repository/deployment/server/synapse-configs/default/api/_TokenAPI_.xml file [where _LoginAPI_.xml is the deprecated API]. When running the server with different port offsets from the default port (i.e., 9443), you need to update the endpoints defined inside the _TokenAPI_.xml and _LoginAPI_.xml files with that offset. See Changing the Default Ports with Offset.
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> tag in <PRODUCT_HOME>/repository/conf/identity.xml.
When a user access token expires, the user can try regenerating the token as explained in the Renew user tokens section.

Generating authorization code

Use the /authorize endpoint to utilize the Authorization Code grant type of OAuth2.0. Since this is a redirection-based flow, the client must be capable of interacting with the resource owner's user-agent (typically a Web browser) and receiving incoming requests (via redirection) from the authorization server. The client initiates the flow by directing the resource owner's user-agent to the authorization endpoint. It includes the client identifier, response_type, requested scope, and a redirection URI to which the authorization server sends the user-agent back after granting access. The authorization server authenticates the resource owner (via the user-agent) and establishes whether the resource owner granted or denied the client's access request. Assuming the resource owner grants access, the authorization server then redirects the user-agent back to the client using the redirection URI provided earlier. The redirection URI includes an authorization code.

The client then requests an access token from the authorization server's /token endpoint by including the authorization code received in the previous step. When making the request, the client authenticates with the authorization server. It then includes the redirection URI used to obtain the authorization code for verification. The authorization server authenticates the client, validates the authorization code, and ensures that the redirection URI matches the URI used to redirect the client from the /authorize endpoint in the previous response. If valid, the authorization server responds back with an access token and, optionally, a refresh token.

Assuming that both the client and the API Gateway are run on the same server, the Authorization API url is https://localhost:8243/authorize.

query component - response_type=code&client_id=<consumer_key>&scope=PRODUCTION&redirect_uri=<application_callback_url>
headers - Content-Type: application/x-www-form-urlencoded

For example, the client directs the user-agent to make the following HTTP request using TLS.

GET
/authorize?response_type=code&client_id=wU62DjlyDBnq87GlBwplfqvmAbAa&scope=PRODUCTION&redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb
HTTP/1.1 
Host: server.example.com 
Content-Type:
application/x-www-form-urlencoded

The authorization server redirects the user-agent by sending the following HTTP response:

HTTP/1.1 302 Found 
Location:
https://client.example.com/cb?code=SplxlOBeZQQYbYS6WxSbIA

Now the client makes the following HTTP request using TLS to the /token endpoint.

POST /token HTTP/1.1 
Host: server.example.com 
Authorization: Basic
SVpzSWk2SERiQjVlOFZLZFpBblVpX2ZaM2Y4YTpHbTBiSjZvV1Y4ZkM1T1FMTGxDNmpzbEFDVzhh
Content-Type:
application/x-www-form-urlencoded 
grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA&redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb

The /token endpoint responds in the same way like in password grant type.

Renewing user tokens

After an access token is generated, users sometimes may have to refresh or renew the old token due to expiration or security concerns. This can be done by issuing a REST call to the Token API through a REST client such as the WSO2 REST Client or Curl, with the following parameters.

Assuming that both the client and the API Gateway are run on the same server, the Token API URL is https://localhost:8243/token.
payload - "grant_type=refresh_token&refresh_token=<retoken>&scope=PRODUCTION". Replace the <retoken> value with the refresh token generated in the previous section .
headers - 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.

curl -k -d "grant_type=refresh_token&refresh_token=<retoken>&scope=PRODUCTION" -H "Authorization :Basic SVpzSWk2SERiQjVlOFZLZFpBblVpX2ZaM2Y4YTpHbTBiSjZvV1Y4ZkM1T1FMTGxDNmpzbEFDVzhh" -H "Content-Type: application/x-www-form-urlencoded" https://localhost:8243/token

The REST message will grant the user a renewed user token.