This documentation is for WSO2 Enterprise Service Bus version 4.8.1 . View documentation for the latest release.

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The Validate Mediator is used for schema validation of messages.

The portion of the message that needs to be validated is chosen by evaluating the XPath expression. Then this message is validated against the schema specified. Users can specify a sequence to be executed in case of a validation failure. This mediator provides an extension point by providing properties to configure the underline validation engine.


<validate [source="xpath"]>
   <property name="validation-feature-id" value="true|false"/>*
   <schema key="string"/>+

The Validate Mediator validates the result of the evaluation of the source XPath expression, against the schema specified. If the source attribute is not specified, the validation is performed against the first child of the SOAP body of the current message. If the validation fails, the on-fail sequence of mediators is executed. Properties could be used to turn some of the features of the validator on/off.

UI Configuration

  • Key - Schema location. It can be chosen either from the Configuration Registry, Governance Registry (For Static Key) or from the Namespaces (For Dynamic Key). For more information on the registry, see Working with the Registry.


    To add a new Schema Key, use the "Add New Schema Key" link.

  • Source -XPath expression to extract the XML that needs to be validated. If not specified, the validation is performed against the first child of the SOAP body.


    You can click this link to add namespaces if you are providing an expression. You will be provided another panel named "Namespace Editor," where you can provide any number of namespace prefixes and URL that you have used in the XPath expression.

  • Features 


You can configure the Mediator using XML. Click on "switch to source view" in the "Mediator" window.


    <schema key="schema\sample.xsd"/>
                    <code value="tns:Receiver"
                    <reason value="Invalid Request!!!"/>
                <property name="RESPONSE" value="true"/>
                <header name="To" expression="get-property('ReplyTo')"/>

In the above Validate Mediator configuration, the required schema for validating messages going through the validate mediator is given as a registry key, schema\sample.xsd. In this sample configuration, there is no source attribute. Therefore, in this case, the Validate Mediator takes source as the first child of SOAP Body. Within on-fail, it is possible to specify mediation logic for the failed validation. In the above configuration, it creates a SOAP fault using makefault mediator and sends that back to the requested party.

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