Exception/Error Handling in WSO2 ESB Endpoint

When we create a service in ESB this needs to be send to a particular end point, in transport layer it might be possible that any error can come so it is necessary to handle this situation wherever an error occurred.

If the end point is not available or due to any firewall issue by which connection time out may occur then your message will be lost. Therefore to overcome from this situation error handling is required.

In endpoint configure for error handling can have below three states.

• Active: End point is up and ready to handle request.
• Timeout: An error has come but still message is received. It will keep on receiving message until maximum retries. If it keeps on failing then it will go to suspended state.
• Suspended: In this state message can’t be received or sent and endpoint result will go in fault. ESB waits until the initial duration to be passed by default it is 30 second. In between if any request gets succeeded then it will go to Active state else in timeout error. ESB waits before retrying messages using the following formula:

Min(current suspension duration * progressionFactor, maximumDuration)

Example:

<endpoint name="EmployyeDetails_EPR">

<address uri="http://XXXX:9773/services/getEmployeeDetails">

<timeout>

<duration>30000</duration>

</timeout>

<markForSuspension>

<errorCodes>101504, 101505</errorCodes>

<retriesBeforeSuspension>3</retriesBeforeSuspension>

<retryDelay>1</retryDelay>

</markForSuspension>

<suspendOnFailure>

<errorCodes>101500, 101501, 101506, 101507, 101508</errorCodes>

<initialDuration>3000</initialDuration>

<progressionFactor>1.0</progressionFactor>

</suspendOnFailure>

</address>

</endpoint>

Timeout Setting

Name	Values	Default	Description
duration	Miliseconds	60000	If within 60 second response does not come then it will go to timeout state
responseAction	discard, fault, none	none	On failure It checks whether message needs to be discarded or need to go in exception handling state

MarkForSuspension State

Name	Values	Default	Description
errorCodes	Comma separated list of error codes	101504, 101505	101504: shows the connection timeout error 101505: connection closed
retriesBeforeSuspension	Integer	0	It shows how many time it can retry to send message
retryDelay	milliseconds	0	wait time between the last retry  and the next retry.

SuspensionOnFailure State

Name	Values	Default	Description
errorCodes	Comma separated error codes	All the errors except the errors specified inmarkForSuspension	Errors that send the endpoint into the "Suspended" state.
initialDuration	milliseconds	30000	This is the default time after this time retry will occur
progressionFactor	Integer	1	The endpoint will try to send the messages after the initialDuration. If it still fails, the next duration is calculated as:
			Min(current suspension duration * progressionFactor, maximumDuration)
maximumDuration	milliseconds	Long.MAX_VALUE	Upper bound of retry duration.