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1,078 bytes added ,  18:52, 18 November 2020
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* The namespace of the function name identifies the Java class.
* The local part of the name, which is rewritten to camel case, identifies a variable or function of that class.
* The middle dot character <code>[httphttps://www.fileformat.info/info/unicode/char/b7/index.htm ·]</code> (&amp;#xB7;, a valid character in XQuery names, but not in Java) can be used to append exact Java parameter types to the function name. Class types must be referenced by their full path.
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Please visit the XQuery 3.0 specification if you want to get more insight into
[httphttps://www.w3.org/TR/xpath-functions-3031/#properties-of-functions function properties]. ==Updates== The {{Code|@Updating}} annotation can be applied to mark Java functions that perform write or update operations: <syntaxhighlight lang="java"> @Updating public void backup() { // ... }</syntaxhighlight> An XQuery expression will be handled as an [[XQuery Update#Updating Expressions|updating expression]] if it calls an updating Java function. In contrast to XQuery update operations, the Java code will immediately be executed, but the result will be cached as if {{Function|Update|update:output}} was called. The annotation is particularly helpful if combined with a lock annotation.
==Locking==
{{Mark|Updated By default, a Java function will be executed in parallel with Version 9other code.4:}} Single annotation for read and write locksIf a Java function performs sensitive operations, it is advisable to explicitly lock the code.
By default, ===Java Locks=== Java provides a Java function will handful of mechanism to control the execution of code. The concurrent execution of functions can be executed in parallel avoided with other codethe {{Code|synchronized}} keyword. For more complex scenarios, Lock and Semaphor and Atomic classes exist.  ===XQuery Locks=== If a Java function performs sensitive operations, it is advisable you want to explicitly lock synchronize the execution of your code. This with BaseX locks, you can be realized via locking annotationstake advantage of the {{Code|@Lock}} annotation:
<syntaxhighlight lang="java">
@Lock("HEAVYIO")
public void read() {
// ...
}
 
@Updating
@Lock("HEAVYIO")
public void write() {
</syntaxhighlight>
If the function writes or updates dataan XQuery expression invokes {{Code|write()}}, a any other query that call {{Code|write lock should ()}} or {{Code|read()}} needs to wait for the query to be enforced via a finished. The {{FunctionCode|Update|update:outputread()}} function can be run in parallel; only those queries are queued that call: <syntaxhighlight lang="java">java-module:{{Code|write() => update:output()</syntaxhighlight>}}.
More details on parallel query execution concurrent querying can be found in the article on [[Transaction Management]].
==Data Types==
; Version 9.4
* Added: Annotation for [[#Updates|updating functions]].
* Updated: Single annotation for read and write locks.
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