SOAP中不允许出现PI，这是soap的一个语法规则
from:
http://www.experts-exchange.com/Programming/Languages/Java/Q_21666319.html
Also according to the SOAP 1.1 specification, “A SOAP message MUST NOT contain Processing Instructions.” Honestly this makes no sense to me whatsoever. I see little reason for forbidding these. This does mean that all information in a SOAP request must be passed through the defined SOAP structure, but it also means that it’s difficult to include other useful features beyond the SOAP structure. The most obvious is that you can’t easily apply a style sheet to a SOAP document, though that’s not a huge loss since SOAP documents aren’t meant for humans to read in the first place. However, it also means it’s difficult to serve SOAP documents out of the Cocoon application server. There are probably many other environment specific instances where this becomes inconvenient.
AXIOM's related class has override some method to perform this issue:
from:
createPI:
- Overrides:
createPIin classStAXOMBuilder