...
Using both the API Manager and the ESB, you can implement an API facade architecture pattern. WSO2 recommends this architecture if you are performing heavy mediation in your setup. For implementation details of an API facade, see implementing an API facade with WSO2 API management platform. Since the API Manager does not have the ESB's GUI to perform mediation functions, you need to use the XML-based source view for configuration. Alternatively, you can create the necessary mediation sequences using the GUI of the ESB, and copy them from the ESB to the API Manager.
...