Enumerations will always be received as string, which is the most fail safe option. You can use in a microflow either an expressions such as:
if value='x' then x else if value='y' then y ....
or, if your enumeration has many values, you can use the following simple Java action:
return MyEnumerationname.valueOf(value).toString();
(Note that this will throw an exception upon an unknown value, so you might want to add an try catch, which returns null or some other sensible default)
update related to the comments
Mendix exposes strings, not enumerations in published webservices. As far as i know, primitive enumerations do not exist or are not very common in XSD.
It is possible to use a convert microflow, just define a 'convert using' in your XML to domain mapping. See for example the screenshots in this howto: https://world.mendix.com/display/howto25/Configure+an+XML-to-Domain+mapping
OK Michel,I will tell you the steps that I did and you can tell me what is the wrong:
If anyone has an answer please post it .