The document discusses how to specify a default exception strategy in Mule applications. It provides an example of a flow that handles exceptions, showing how to configure a global catch-exception strategy that sets a 400 status code and error payload if any exceptions occur. It also shows sample output when the flow receives valid versus invalid input.

1. Specifying a default exception
strategy

2. Abstract
• The main motto of this PPT is How to use
Specifying a default exception strategy in our
applications.

3. Example

7. .mflow
• <?xml version="1.0" encoding="UTF-8"?>
• <mule xmlns:http="http://www.mulesoft.org/schema/mule/http"
xmlns="http://www.mulesoft.org/schema/mule/core"
xmlns:doc="http://www.mulesoft.org/schema/mule/documentation"
• xmlns:spring="http://www.springframework.org/schema/beans"
• xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
• xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-current.xsd
• http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
• http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd">
• <http:listener-config name="HTTP_Listener_Configuration" host="localhost" port="8088" doc:name="HTTP
Listener Configuration"/>
• <flow name="ExceptionHandlingFlow">
• <http:listener config-ref="HTTP_Listener_Configuration" path="/" doc:name="HTTP"/>
• <logger message="-Flow started" level="INFO" doc:name="Logger"/>
• <set-property propertyName="token"
value="#[message.inboundProperties.'http.query.params'.token.toString()]" doc:name="Property"/>
• <logger message="--Token value: ----#[message.outboundProperties.token]" level="INFO"
doc:name="Logger"/>
• <set-payload value="{
• &quot;token&quot;:&quot;#[message.outboundProperties.token]&quot;
• }" doc:name="Set Payload"/>
• </flow>
• </mule>

8. • Global flow:
• <?xml version="1.0" encoding="UTF-8"?>
• <mule xmlns:cluster="http://www.mulesoft.org/schema/mule/ee/cluster"
xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns="http://www.mulesoft.org/schema/mule/core"
xmlns:doc="http://www.mulesoft.org/schema/mule/documentation"
• xmlns:spring="http://www.springframework.org/schema/beans"
• xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
• xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-current.xsd
• http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
• http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd">
• <configuration defaultExceptionStrategy-ref="GlobalCatch_Exception_Strategy" doc:name="Configuration">
• <http:config useTransportForUris="false"/>
• </configuration>
• <catch-exception-strategy name="GlobalCatch_Exception_Strategy">
• <set-property propertyName="http.status" value="400" doc:name="Property"/>
• <set-payload value="{
• &quot;message&quot;:&quot;Bad Request&quot;
• }" doc:name="Set Payload"/>
• </catch-exception-strategy>
• </mule>

9. • Output:
• If the input is valid input:
• INFO 2016-12-23 10:03:37,163
[[ExceptionHandling].HTTP_Listener_Configuratio
n.worker.01]
org.mule.api.processor.LoggerMessageProcessor:
-Flow started
• INFO 2016-12-23 10:03:37,233
[[ExceptionHandling].HTTP_Listener_Configuratio
n.worker.01]
org.mule.api.processor.LoggerMessageProcessor:
--Token value: ----a1b2c3d4

11. • If the input is invalid input:
• INFO 2016-12-23 10:04:02,030 [[ExceptionHandling].HTTP_Listener_Configuration.worker.02]
org.mule.api.processor.LoggerMessageProcessor: -Flow started
• ERROR 2016-12-23 10:04:02,072 [[ExceptionHandling].HTTP_Listener_Configuration.worker.02]
org.mule.exception.CatchMessagingExceptionStrategy:
• ********************************************************************************
• Message : Execution of the expression
"message.inboundProperties.'http.query.params'.token.toString()" failed.
(org.mule.api.expression.ExpressionRuntimeException).
• Payload : {NullPayload}
• Element XML : <set-property propertyName="token"
value="#[message.inboundProperties.'http.query.params'.token.toString()]"
doc:name="Property"></set-property>
• Payload Type : org.mule.transport.NullPayload
• Element : /ExceptionHandlingFlow/processors/1 @
ExceptionHandling:ExceptionHandling.xml:13 (Property)
• --------------------------------------------------------------------------------
• Root Exception stack trace:
• java.lang.NullPointerException
• at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
• at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
• at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

13. References
• https://docs.mulesoft.com/mule-user-
guide/v/3.6/error-handling