#include <DbXml.hpp>
XmlQueryContext XmlManager::createQueryContext(
    XmlQueryContext::ReturnType rt =XmlQueryContext::LiveValues,
    XmlQueryContext::EvaluationType et = XmlQueryContext::Eager)
      Creates a new XmlQueryContext .
Specifies whether to return live or dead values:
                        XmlQueryContext::LiveValues
                    
Return references to the actual document stored in Berkeley DB XML.
                        XmlQueryContext::DeadValues
                    
Return a copy of the data stored in Berkeley DB XML.
The evaluation type must be specified as either:
                        XmlQueryContext::Eager
                    
The query is executed and its resultant values are derived and stored in-memory before query evaluation is completed.
                        XmlQueryContext::Lazy
                    
The query is executed and its resultant values are calculated as you ask for them.