I personally do not use SOAP so I cannot help much with the question. The question might get more visibility on the InDesign Server forum. I'm moving this there.
Woah! The ID Server forum went AWAL... When did that happen?
Actually, that's why I posted here... Unfortunately, seems like the ID Server forum is gone
The InDesign Server forum is gone since beginning of September 2016 (my guess, because I did not visit it very often).
There was no warning sign before, that it would be removed. I wonder if at least all the posts could be made available again or if the whole forum could be made available again. It's a shame, that this happened without an announcement to the community.