org.exist.xmldb
Interface XQueryService

All Known Implementing Classes:

LocalXPathQueryService, RemoteXPathQueryService

public interface XQueryService

Execute XQuery expressions on the database. This interface is similar to org.xmldb.api.modules.XPathQueryService, but provides additional methods to compile an XQuery into an internal representation, which can be executed repeatedly. Since XQuery scripts can be very large, compiling an expression in advance can save a lot of time.

Author:

Wolfgang Meier (wolfgang@exist-db.org)

Method Summary

CompiledExpression	compile(java.lang.String query) Compiles the specified XQuery and returns a handle to the compiled code, which can then be passed to #execute(CompiledExpression).
CompiledExpression	compileAndCheck(java.lang.String query) Tries to compile the specified XQuery and returns a handle to the compiled code, which can then be passed to #execute(CompiledExpression).
void	declareVariable(java.lang.String qname, java.lang.Object initialValue) Declare a global, external XQuery variable and assign a value to it.
void	dump(CompiledExpression expression, java.io.Writer writer) Return a diagnostic dump of the query.
ResourceSet	execute(Source source)
ResourceSet	execute(XMLResource res, CompiledExpression expression)
java.lang.String	getNamespace(java.lang.String prefix) Returns the URI string associated with prefix from the internal namespace map.
ResourceSet	query(java.lang.String query) Execute the specified query and return the results as a ResourceSet.
ResourceSet	query(XMLResource res, java.lang.String query) Process a query based on the result of a previous query.
void	removeNamespace(java.lang.String ns) Removes the namespace mapping associated with prefix from the internal namespace map.
void	setModuleLoadPath(java.lang.String path)
void	setNamespace(java.lang.String prefix, java.lang.String namespace) Sets a namespace mapping in the internal namespace map used to evaluate queries.
void	setXPathCompatibility(boolean backwardsCompatible) Enable or disable XPath 1.0 compatibility mode.

Method Detail

query

public ResourceSet query(java.lang.String query)
                  throws XMLDBException

Execute the specified query and return the results as a ResourceSet.

Parameters:

query -

Returns:

Throws:

XMLDBException

query

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

Process a 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

compile

public CompiledExpression compile(java.lang.String query)
                           throws XMLDBException

Compiles the specified XQuery and returns a handle to the compiled code, which can then be passed to #execute(CompiledExpression).

Parameters:

query -

Returns:

Throws:

XMLDBException

compileAndCheck

public CompiledExpression compileAndCheck(java.lang.String query)
                                   throws XMLDBException,
                                          XPathException

Tries to compile the specified XQuery and returns a handle to the compiled code, which can then be passed to #execute(CompiledExpression). If a static error is detected, an XPathException will be thrown.

Parameters:

query -

Returns:

Throws:

XMLDBException

XPathException

execute

public ResourceSet execute(Source source)
                    throws XMLDBException

Throws:

XMLDBException

execute

public ResourceSet execute(XMLResource res,
                           CompiledExpression expression)
                    throws XMLDBException

Throws:

XMLDBException

getNamespace

public java.lang.String getNamespace(java.lang.String prefix)
                              throws XMLDBException

Returns the URI string associated with prefix from the internal namespace map. If prefix is null or empty the URI for the default namespace will be returned. If a mapping for the prefix can not be found null is returned.

Parameters:

prefix - The prefix to retrieve from the namespace map.

Returns:

The URI associated with prefix

Throws:

XMLDBException - with expected error codes.
ErrorCodes.VENDOR_ERROR for any vendor specific errors that occur.

setNamespace

public void setNamespace(java.lang.String prefix,
                         java.lang.String namespace)
                  throws XMLDBException

Sets a namespace mapping in the internal namespace map used to evaluate queries. If prefix is null or empty the default namespace is associated with the provided URI. A null or empty uri results in an exception being thrown.

Parameters:

prefix - The prefix to set in the map. If prefix is empty or null the default namespace will be associated with the provided URI.

Throws:

XMLDBException - with expected error codes.
ErrorCodes.VENDOR_ERROR for any vendor specific errors that occur.
TODO: probably need some special error here.

removeNamespace

public void removeNamespace(java.lang.String ns)
                     throws XMLDBException

Removes the namespace mapping associated with prefix from the internal namespace map. If prefix is null or empty the mapping for the default namespace will be removed.

Throws:

XMLDBException - with expected error codes.
ErrorCodes.VENDOR_ERROR for any vendor specific errors that occur.

declareVariable

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

Declare a global, external XQuery variable and assign a value to it. The variable has the same status as a variable declare through the declare variable statement in the XQuery prolog. The variable can be referenced inside the XQuery expression as $variable. For example, if you declare a variable with

 	declareVariable("name", "HAMLET");
 

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

 	//SPEECH[SPEAKER=$name]
 

Any Java object may be passed as initial value. The implementation will try to map the Java object into a corresponding XQuery value. In particular, all basic Java types (Integer, Long, Double, String) should be mapped into the corresponding XML Schema atomic types. A Java array is mapped to an XQuery sequence. The implemenation should also recognize all DOM node types. As a special case, an XMLResource as obtained from a ResourceSet 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, using setNamespace(String, String). For example, if a variable is called x:name, a prefix/namespace mapping should have been defined for prefix x before calling this method.

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

Throws:

XMLDBException

setXPathCompatibility

public void setXPathCompatibility(boolean backwardsCompatible)

Enable or disable XPath 1.0 compatibility mode. In XPath 1.0 compatibility mode, some XQuery expressions will behave different. In particular, additional automatic type conversions will be applied to the operands of numeric operators.

Parameters:

backwardsCompatible -

setModuleLoadPath

public void setModuleLoadPath(java.lang.String path)

dump

public void dump(CompiledExpression expression,
                 java.io.Writer writer)
          throws XMLDBException

Return a diagnostic dump of the query. The query should have been executed before calling this function.

Parameters:

expression -

writer -

Throws:

XMLDBException