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Siddhi supports custom codes within queries. You can implement Windows, Transformers, OutputAttributeProcessors, Functions (Conditions and Expressions) in a pluggable manner using the current implementation.

Use of Namespaces and Functions in Siddhi Extensions

Siddhi allows extensions to have namespaces and function names, enabling users to easily identify the behaviour of the extensions when writing queries.

To add namespace and function names to the extension, use the following Java annotation in the extension class.

@SiddhiExtension(namespace = "testExt", function = "unique")
public class UniqueWindowProcessor extends WindowProcessor {
   ...
}

You can refer to the above class in the query as follows:

...

Custom extensions can be written in Siddhi in order to cater usecase specific logics that are not out of the box available in Siddhi. 

Refer SiddhiQL Guide 3.0#WritingCustomExtensions to get a general idea of how to write an extension. 

The following sections explains how we can create different types of Siddhi Extensions in details,

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