I dette element udpeges den Action der skal udføres – værdien af Action bør være det samme som SOAPAction HTTP headeren – og de gyldige actions står defineret i WSDL filen for IDWS endpointet. Wsu:Id attributten er påkrævet.

XML-Eksempel;

<wsa:Action xmlns:wsa="http://www.w3.org/2005/08/addressing" xmlns:wsu="http://docs.oasisopen.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" wsu:Id="_7b5a33d3-887e-4be4-8d79-
f8bfcd3ffbe0">http://www.dkma.dk/medicinecard/xml.schema/2012/06/01#GetMedicineCardAsPDF</wsa:Action>

Der skal i hvert request medsendes et unikt message id – typisk et UUID – f.eks. 'urn:uuid:7a2e1f9a-91c9- 4886-a7c3-1e8554f0dd74', eller en lignende unik streng. Denne er påkrævet og benyttes til at logge kaldet og sørge for at response logges sammen med.

Ligeledes vil der i response være en reference til dette message-id i RelatesTo headeren.

Wsu:Id attributten er påkrævet.

XML-Eksempel (request og response):

<wsa:MessageID xmlns:wsa="http://www.w3.org/2005/08/addressing" xmlns:wsu="http://docs.oasisopen.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" wsu:Id="_90e86943-a8b9-4674-b1be-
400f1f5fdb80">urn:uuid:8b410a98-764c-4bf4-9e7f-cc67b46a235c</wsa:MessageID>

XML-Eksempel (kun response):

<wsa:RelatesTo xmlns:wsa="http://www.w3.org/2005/08/addressing" xmlns:wsu="http://docs.oasisopen.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"
RelationshipType="http://www.w3.org/2005/08/addressing/reply" wsu:Id="_cfee7063-6ba4-4b2f-9cfc-
2817afe525a9">urn:uuid:8b410a98-764c-4bf4-9e7f-cc67b46a235c</wsa:RelatesTo>

Wsu:Id attributten er påkrævet når elementerne findes.

XML-Eksempel

<wsa:To xmlns:wsa="http://www.w3.org/2005/08/addressing" xmlns:wsu="http://docs.oasisopen.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" wsu:Id="_f85a30d3-8d7e-4971-b1c0-
923b661a4c19">http://localhost:8080/fmk12/idws/MedicineCardIdwsEndpoint</wsa:To>
<wsa:ReplyTo xmlns:wsa="http://www.w3.org/2005/08/addressing" xmlns:wsu="http://docs.oasisopen.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" wsu:Id="_ad769333-4211-435e-8e79-
66a0f44e306f">
    <wsa:Address>http://www.w3.org/2005/08/addressing/anonymous</wsa:Address>
</wsa:ReplyTo>