So far, no Delphi version supports SOAP 1.2 clients or server.
I have tried for weeks to make it works, but every time a new problem, with VS/C# I could do the same, and make works in 3 days, but I need to do with Delphi 2009.
"I write a new version using Rem Objects SDK,", but the result was not better that I had with Delphi SOAP library.
But I'm wondering what choice else do I have, which library/component full support SOAP 1.2?
I found a message from Bruneau, suggesting Pocket SOAP
http://www.pocketsoap.com/pocketsoap/
I don't know how this works, Ill investigate and see what I can do.
Remember to vote for SOAP 1.2 support on codegear's QC:
http://qc.codegear.com/wc/qcmain.aspx?d=66864
Currently, it's voted the #2 report for Delphi (after 64bit support). I'm really sure that CodeGear is not going to ignore this.
Follow up. This has been implemented in Delphi 2010.
I suggest that you dig into the source. With Delphi 7, I was able to add all sorts of extras by copying the SOAP code into my app's folder and editing it carefully. In one case I did some string manipulation to adjust the incoming SOAP packet to make it work with the way Delphi worked. I've not had to do this with RemObjects yet, but you do get the source for that too. Plus they have active newsgroups you can ask questions on.
In some cases I found it much easier to write a proxy SOAP service in C# and VS, and consume it from Delphi with a simplified service description (WSDL). In the long term it was the most efficient solution, without any problems regarding stability or performance. The SOAP support in Delphi is not one of its highlights.