org.exist.xmldb
Interface XPathQueryServiceImpl

All Known Implementing Classes:

LocalXPathQueryService, RemoteXPathQueryService

public interface XPathQueryServiceImpl

Extends org.xmldb.api.modules.XPathQueryService by additional methods specific to eXist.

Author:

Wolfgang

Method Summary

void	beginProtected() Execute all following queries in a protected environment.
void	declareVariable(java.lang.String qname, java.lang.Object initialValue) Declare an external XPath variable and assign a value to it.
void	endProtected() Close the protected environment.
ResourceSet	query(XMLResource res, java.lang.String query) Process an XPath query based on the result of a previous query.
ResourceSet	query(XMLResource res, java.lang.String query, java.lang.String sortExpr) Process an XPath query based on the result of a previous query and sort the results using the second XPath expression.

Method Detail

query

public ResourceSet query(XMLResource res,
                         java.lang.String query)
                  throws XMLDBException

Process an XPath query based on the result of a previous query. The XMLResource contains the result received from a previous query.

Parameters:

res - an XMLResource as obtained from a previous query.

query - the XPath query

Throws:

XMLDBException

query

public ResourceSet query(XMLResource res,
                         java.lang.String query,
                         java.lang.String sortExpr)
                  throws XMLDBException

Process an XPath query based on the result of a previous query and sort the results using the second XPath expression. The XMLResource contains the result received from a previous query.

Parameters:

res - an XMLResource as obtained from a previous query

query - the XPath query

sortExpr - another XPath expression, which is executed relative to the results of the primary expression. The result of applying sortExpr is converted to a string value, which is then used to sort the results.

Throws:

XMLDBException

declareVariable

public void declareVariable(java.lang.String qname,
                            java.lang.Object initialValue)
                     throws XMLDBException

Declare an external XPath variable and assign a value to it. A variable can be referenced inside an XPath expression as $variable. For example, if you declare a variable with

 	declareVariable("name", "HAMLET");
 

you may use the variable in an XPath expression as follows:

 	//SPEECH[SPEAKER=$name]
 

Any Java object may be passed as initial value. The query engine will try to map this into a corresponding XPath value. You may also pass an XMLResource as obtained from another XPath expression. This will be converted into a node.

Parameters:

qname - a valid QName by which the variable is identified. Any prefix should have been mapped to a namespace, i.e. if a variable is called x:name, there should be a prefix/namespace mapping for the prefix x

initialValue - the initial value, which is assigned to the variable

Throws:

XMLDBException

beginProtected

public void beginProtected()

Execute all following queries in a protected environment. Protected means: it is guaranteed that documents referenced by the query or the result set are not modified by other threads until endProtected() is called.

endProtected

public void endProtected()

Close the protected environment. All locks held by the current thread are released. The result set is no longer guaranteed to be stable.