When you send an API request to the backend, you pass a token in the Authorization header of the request. The API Gateway uses this token to authorize access, and then drops it from the outgoing message. If you wish to use a different (or a custom generated) authorization token than the application generated access token, you can use it as a token exchange mechanism in mediation logic of the API. In this tutorial, we explain how to pass a custom authorization token that is different to the authorization token generated for the application.
Let's get started.
Download WSO2 Developer Studio (version 3.8.0 is used here) from http://wso2.com/products/developer-studio/ and open it by double clicking the
Eclipse.appfile inside the downloaded folder.
Click Window > Open Perspective > Other to open the Eclipse perspective selection window. Alternatively, click the Open Perspective icon shown below at the top right corner.
- On the dialog box that appears, click WSO2 APIManager and click OK.
- On the APIM perspective, click the Login icon as shown below.
- On the dialog box that appears, enter the URL, username and password of the Publisher server.
- On the tree view that appears, expand the folder structure of the existing API.
- Right-click on the
insequence folder and click Create to create a new
Name the sequence
Your sequence now appears on the Developer Studio console. From under the Mediators section, drag and drop a Property mediator to your sequence and give the following values to the mediator.
Tip: The Property Mediator has no direct impact on a message, but rather on the message context flowing through Synapse. For more information, see Property Mediator in the WSO2 ESB documentation.
Property Name New Property New Property Name Custom Value Type EXPRESSION Value Expression get-property('transport', 'Custom')
Similarly, add another Property mediator to your sequence and give the following values to the mediator.
Property Name New Property New Property Name Authorization Value Type EXPRESSION Value Expression get-property('Custom') Property Scope transport
Add a third Property mediator to your sequence and give the following values to the mediator.
Property Name New Property New Property Name Custom Property Action remove Property Scope transport
Save the sequence.
Right-click on the sequence and click Commit File to push the changes to the Publisher server.
Let's create a new API and engage the sequence you created to it.
Log in to the API Publisher, click the Add link and give the information in the table below.
Field Sample value Name TestAPI1 Context /test1 Version 1.0.0 Visibility Public
Leave the Resources section blank, and click Next: Implement >. Add a wildcard resource (/*) when prompted. Click Next: Implement > again to move to the Implement tab.
The Implement tab opens. Give the information in the table below.
Field Sample value Endpoint type HTTP endpoint Production endpoint Sandbox endpoint
Select the Enable Message Mediation check box, engage the
Insequence that you created earlier and click Manage.
In Flow, Out Flow and Fault Flow represent the custom In, Out and Fault sequences attached to the API by the user other than the default sequence definition of the API.
In the Manage tab, select the
Goldtier and click Save and Publish to publish the API to the API Store.
Let's subscribe to the API and invoke it.
Log in to the API Store and subscribe to the API using an available application and the Gold tier. If there are no applications available by default, create one.
Click the View Subscriptions button when prompted. The Subscriptions tab opens.
Click the Production Keys tab and click Generate Keys to create an application access token.
Install any REST client in your machine. We use cURL here.
Go to the command line, and invoke the API using the following cURL command. In this command, you pass the token that the backend expects, i.e., 1234, in the
Customheader with the authorization token that the system generates in the
Note the following:
- <access token> is the token that you got in step 20.
- <API URL> appears on the API's Overview page in the API Store. Copy the HTTP endpoint. If you select the HTTPs endpoint, be sure to run the cURL command with the -k option.
Here's an example:
Note the response that you get in the command line. According to the sample backend used in this tutorial, you get the response as "Request Received."
In this tutorial, you passed a custom token that the backend expects along with the system-generated Authorization token, and invoked an API successfully by swapping the system's token with your custom token.