Package org.basex.query

Class QueryModule

java.lang.Object

org.basex.query.QueryModule

public abstract class QueryModule
extends Object

The XQuery import module statement can be used to import XQuery modules as well as Java instances, which will be treated as modules. Any class with a public, empty constructor can be imported as module.

If a class extends the QueryModule class, it inherits the queryContext and staticContext variables, which provide access to all properties of the current query. E.g., they provide access to the current context value or the declared namespaces of a query.

The default properties of functions can be overwritten via annotations:

• Java functions can only be executed by users with ADMIN permissions. You may annotate a function with QueryModule.Requires(QueryModule.Permission) to also make it accessible to users with less privileges.
• Java code is treated as "non-deterministic", as its behavior cannot be predicted by the XQuery processor. You may annotate a function as QueryModule.Deterministic if you know that it will have no side effects and will always yield the same result.
• Java code is treated as "context-independent". If a function accesses the specified queryContext, it should be annotated as QueryModule.ContextDependent.
• Java code is treated as "focus-independent". If a function accesses the current context value, position or size, it should be annotated as QueryModule.FocusDependent.

If the QueryResource is implemented, its QueryResource.close() method will be called after the query has been evaluated. It should always be implemented if a module opens connections, resources, etc. that eventually need to be closed.

Please visit our documentation to find more details on Packaging, Java Bindings and User Management. The XQuery 3.0 specification gives more insight into function properties.

Author:

BaseX Team 2005-21, BSD License, Christian Gruen

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static @interface	QueryModule.ContextDependent	Java code is treated as "context-independent".
static @interface	QueryModule.Deterministic	Java code is treated as "non-deterministic", as its behavior cannot be predicted from the XQuery processor.
static @interface	QueryModule.FocusDependent	Java code is treated as "focus-independent".
static @interface	QueryModule.Lock	Set additional locks to be fetched.
static enum	QueryModule.Permission	Permission required to call a function.
static @interface	QueryModule.Requires	Java functions can only be executed by users with ADMIN permissions.
static @interface	QueryModule.Updating	If a function is annotated as QueryModule.Updating, its function body will be treated as updating.

Field Summary

Fields

Modifier and Type	Field	Description
QueryContext	queryContext	Global query context.
StaticContext	staticContext	Static context.

Constructor Summary

Constructors

Constructor	Description
QueryModule()

Method Summary

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

queryContext

public QueryContext queryContext

Global query context.

staticContext

public StaticContext staticContext

Static context.

Constructor Details

QueryModule

public QueryModule()