A mechanism to relate the portType(s) of an event source Web Service to the abstract description of the events it can produce is needed. 
This mechanism cannot be solely based on WS-MetadataExchange, as this information may be needed by clients at design time, before any service endpoints are available. 
The draft replaces the previous mechanism for advertising events produced by a source, based on a portType extension (using both the wse:EventSource attribute and notification and solicit/response operations), by two new mechanisms, one introducing a new language (Event Descriptions), the second one using a WSDL definition for the sink. 
Both mechanisms provide an abstract description of the events, but no mechanisms to relate them to the portType of the event source. Rather, it is suggested to use new WS-Eventing dialects in conjunction with WS-MetadataExchange to retrieve the descriptions at runtime.