To access the SOAP header and its elements from your ABL application, you define callback procedures using specific signatures that act as header handlers. When you need to access the headers, you need separate header handlers for each Web service procedure object. A header handler can handle either the SOAP request headers or the SOAP response headers for all operations maintained by that procedure object. A single header handler cannot handle both types of headers. You can specify the handlers for a Web service procedure object by invoking the SET-CALLBACK-PROCEDURE( ) method on the corresponding procedure handle.

If you want to add additional handlers for the same port type managed by a Web service procedure object, you must map the port type using additional procedure objects.

Every time you invoke an operation for a port type where you have specified header handlers, the handlers execute as part of the operation invocation. For SOAP request messages, the handler intercepts and manages the SOAP headers before the message is sent to the Web service. For SOAP response messages, the handler intercepts and manages the SOAP headers before any message parameters are passed to complete invocation of the operation.