The APEX_WEB_SERVICE API enables you to integrate other systems with APEX by enabling you to interact with Web Services anywhere you can use PL/SQL in your application.
The API contains procedures and functions to call both SOAP and RESTful style Web Services. Functions parse the responses from Web Services and encode/decode into SOAP-friendly base64 encoding.
This API also contains package globals for managing cookies and HTTP headers when calling Web Services whether from the API or by using standard processes of type Web Service. Cookies and HTTP headers can be set before invoking a call to a Web Service by populating the globals and the cookies and HTTP headers returned from the Web Service response can be read from other globals.