Mule ESB provides options to handle errors through exception strategies. The default exception strategy handles all messaging exceptions by rolling back transactions and logging exceptions. Users can configure alternative exception strategies like catch, rollback, reference, and choice strategies to customize error handling for different situations. Catch strategies always commit transactions after exceptions while rollback strategies attempt to redeliver messages before committing failed transactions. Reference strategies refer to global exception handling and choice strategies route messages based on content during exceptions. Exception strategies provide flexibility in how Mule applications manage errors and exceptions.

1. Presented By
Sindhu VL

2.  Mule ESB provides numerous options for
handling errors. Faults that occur within Mule
are referred to as exceptions; when an activity
in your Mule instance fails, Mule throws an
exception. To manage these exceptions, Mule
allows you to configureexception strategies.

3.  It implicitly applies to all Mule applications —
manages errors (i.e. thrown exceptions) in Mule flows.
When your flows require more sophisticated error
management, you can implement one or more
exception strategies to construct precise, efficient
protocols for handling errors.
 Mule ESB’s default exception strategy implicitly and
globally handles all messaging exceptions that are
thrown in Mule applications. You can override Mule’s
default exception strategy by adding a catch, rollback,
or choice exception strategy to a flow. Otherwise, when
an exception is thrown in a flow, Mule automatically
rolls back any pending transaction and logs the
exception; if no transaction is involved, the default
exception strategy simply logs the exception.

4. 1. System Exceptions
 Mule invokes a System Exception
Strategy when an exception is thrown at
the system-level (i.e., when no message is
involved, exceptions are handled by system
exception strategies). For example, system
exception strategies handle exceptions that
occur:
 During application start-up
 When a connection to an external system fails

5.  Messaging Exceptions : Mule invokes a Messaging
Exception Strategy whenever an exception is thrown
within a flow (i.e., whenever a message is involved,
exceptions are handled by messagingexception
strategies).
 When a message being processed through a Mule flow
throws an exception, normal flow execution stops and
processes transfers to the message processor sequence
within the exception strategy. You can incorporate any
number of message processors – and in one case, other
exception strategies – into an exception strategy to
handle the exception precisely as you wish. The
diagram below illustrates what happens when a
message throws an exception.

7.  Default Exception Strategy
 Catch exception strategy
 Rollback exception strategy
 Reference exception strategy
 Choice exception strategy

8. USE :
TRANSACTION ERROR
HANDLING :
 Defined and implicitly
applied by default to
handle all messaging
exceptions that are
thrown in Mule
applications
 When a message throws
an exception, the
default exception
strategy rolls back the
message and logs the
exception.

9. USE :
TRANSACTION ERROR
HANDLING :
 When a message throws
an exception, the
default exception
strategy rolls back the
message and logs the
exception.
 When a message throws
an exception, the catch
exception
strategyalways commits
the transaction and
consumes the message.

10. USE :
TRANSACTION ERROR
HANDLING :
 Define a rollback
exception strategy to
ensure that a message that
throws an exception in a
flow is rolled back for
reprocessing (if the
message source supports
redelivery). Rollback
exception strategies do not
consume inbound
messages.
 When a message throws an
exception, the rollback
exception strategy makes
one or more attempts to
rollback the message and
redeliver it for processing (if
the message source supports
redelivery). If the message
exceeds its redelivery
attempts, then the rollback
exception strategy commits
the failed transaction and
consumes the message.

11. USE :
TRANSACTION ERROR
HANDLING :
 Define a reference
exception strategy to
refer and adhere to the
error handling
parameters defined in a
global catch, rollback or
choice exception
strategy.
 When a message throws
an exception, the reference
exception strategy refers
and adheres to the error
handling parameters
defined in a global catch,
rollback or choice
exception strategy. (The
reference exception
strategy itself never
actually performs any
rollback, commit, or
consume activities.)

12. USE :
TRANSACTION ERROR
HANDLING :
 Define a choice
exception strategy to
customize the way
Mule handles a message
that throws an
exception based on the
message’s content at the
moment it throws the
exception.
 When a message throws
an exception, the choice
exception strategy
makes a decision about
where to route the
message for further
processing. (The choice
exception strategy itself
never actually performs
any rollback, commit, or
consume activities.)

13.  Each flow can contain only one exception
strategy.
 Each exception strategy can contain any
number of message processors.
 Choice exception strategies can contain one or
more catch and/or rollback exception
strategies. (Rollback and catch exception
strategies cannot, however, contain other
exception strategies.)

14. Thank You!!!!!!!!!!!!