Use of SOAP in SAML2 Attribute Query protocol

[Daniele Pellone S231853]

Hi everyone,
I'm trying to use Shibboleth as an Attribute Provider using Attribute 
Query protocol and
I noticed that it only supports SOAP binding. I searched the Internet 
for an alternative,
considering that SAML Profile specifications only require a synchronous 
binding, but I found nothing.
Is there a reason why SOAP is the only supported binding for this 
profile?
Thanks in advance.

Daniele Pellone