Migrating Core Components

The table below maps Mule 3.x components to their Mule 4 equivalents.

Mule 3.x Component Mule 4.0 Replacement

Mule 3.x Component	Mule 4.0 Replacement
All router	Use Scatter Gather instead or execute the operations one after the other with different target attributes and then use DW to merge results.
async[`processingStrategy`]	Async processing strategies are no longer needed with the non-blocking execution engine; remove all processing strategies from your scope when you migrate to Mule 4. Use an Async scope wrapping all the components that you want to execute asynchronously.
asynchronous-processing-strategy	Async processing strategies are no longer needed with the non-blocking execution engine; remove all processing strategies from your scope when you migrate to Mule 4. Use an Async scope wrapping all the components that you want to execute asynchronously.
bridge	Build an equivalent flow
catch-exception-strategy	Use error-handler with an `on-error-continue` strategy.
choice-exception-strategy	Use error-handler with different strategies inside using error type selection or when attribute.
combine-collections-transformer	No longer needed with the simplified message model. MuleMessageCollections are replaced with arrays of Mule Messages, which can be merged or iterated through using any Mule component, such as DataWeave or foreach.
component	Use the Java module.
composite-source	Create one flow per each source and invoke a private flow using flow-ref for the common functionality.
configuration[`defaultExceptionStrategy-ref`]	New name is `defaultErrorHandler-ref`
configuration[`flowEndingWithOneWayEndpointReturnsNull`]	No longer needed with new execution engine.
configuration[`useExtendedTransformations`]	Removed.
configuration[`enricherPropagatesSessionVariableChanges`]	Removed.
copy-attachments	Per the new Message Structure, attachments will now be part of the message Attributes. You can manipulate them at will using DataWeave
copy-properties	Per the new Message Structure, properties will now be part of the message Attributes. You can manipulate them at will using DataWeave
custom-agent	No longer supported.
custom-aggregator	Use the Mule SDK to build the custom aggregator.
custom-connector	Use the Mule SDK to build your own connector.
custom-exception-strategy	No longer needed. Use error-handler
custom-lifecycle-adapter-factory	No longer supported.
custom-object-store	Use Object Store connector to create custom stores.
custom-processor	Use the Mule SDK or the Scripting module instead
custom-queue-store	Use the new VM Connector.
custom-router-resolver	Use the Mule SDK to build a custom router.
custom-router	Use the Mule SDK to build a custom router.
custom-service	Use flows.
custom-source	Use the Mule SDK to write a new event source.
custom-splitter	Use DataWeave or the Mule SDK.
custom-transaction-manager	Use the `<bti:transaction-manager/>`.
custom-transaction	No longer supported.
default-exception-strategy	Use error-handler with an `on-error-propagate` strategy.
default-in-memory-queue-store	Use the new VM Connector.
default-persistent-queue-store	Use the new VM Connector.
default-service-exception-strategy	Use error-handler with an on-error-propagate strategy.
endpoint	Use connectors.
exception-strategy	Use error-handler.
expression-component	Depending on the nature of your expression, you can either use DataWeave (for data access expressions), Scripting module or the Mule SDK for algorithmic expressions, or the Java module for expressions which simply access Java.
file-queue-store	Use the new VM Connector.
flow[`processingStrategy`]	Removed. Non-blocking execution engine ensures that users do not need to tune this.
idempotent-message-filter	Replaced by idempotent-message-validator.
idempotent-redelivery-policy	New name is `redelivery-policy`.
idempotent-secure-hash-message-filter	Replaced by idempotent-message-validator.
in-memory-store	Use Object Store connector to create custom stores.
inbound-endpoint	Use the event sources or triggers defined on each connector or module.
include-entry-point	Use the Java module.
interceptor-stack	Removed. Use custom policies.
invoke	Use the Java module
jndi-transaction-manager	Use the `<bti:transaction-manager/>`.
jrun-transaction-manager	Use the `<bti:transaction-manager/>`.
legacy-abstract-exception-strategy	Use the new error-handler
managed-store	Use Object Store connector to create custom stores.
message-properties-transformer	Use Transform component and DataWeave.
model	Removed. Use flows instead.
mule[`version`]
outbound-endpoint	Element moved from the core namespace to the new transports namespace.
poll → watermark	This capability has been built inside event sources from many connectors, like Salesforce, Database, SFTP, File, etc. You can also use the object-store connector to manually set the watermark values.
poll	Replaced with scheduler component.
processor	Depending on the nature of your expression, you can either use DataWeave (for data access expressions), Scripting module or the Mule SDK for algorithmic expressions, or the Java module for expressions which simply access Java.
prototype-object	Use Java module or Spring module.
queue-profile	Use the VM Connector.
queue-store	VM Connector.
recipient-list	Removed.
reconnect-custom-notifier	Removed.
reconnect-custom-strategy	Removed.
reconnect-notifier	Removed.
remove-attachment	No longer needed per the new Message Structure, attachments
remove-property	PNo longer needed per the new Message Structure, attachments
response	No longer needed.
request-reply	Mule 4 will not longer support request-reply for all connectors. Connectors that had a “request-reply” behavior will provide a “request-reply” operation built in, such as the JMS `publish-consume` operation.
resin-transaction-manager	Removed.
rollback-exception-strategy	Use error-handler with an on-error-propagate strategy.
scatter-gather[`threading-profile`]	No longer needed now that Mule 4 is non blocking.
seda-model	No more SEDA queues in Mule 4. The execution engine in Mule 4 is non-blocking.
service	Use flows.
set-attachment	No longer needed. Attachments can be stored as variables.
set-property	Properties no longer exist in the new message model. You can store attributes from the Mule message in a variable.
set-session-variable	Session variables have been removed. Users must explicitly pass headers across transport boundaries.
simple-in-memory-queue-store	Use the new VM Connector.
simple-service	Use flows.
simple-text-file-store	Use object store module extension to create custom stores.
singleton-object	Use Java module or Spring module.
spring-object	Use Java module or Spring module.
synchronous-processing-strategy	The behavior related to flow components execution is the same as flows in 4.x but it doesn’t always execute in the same thread as in 3.x.
transactional scope	Replaced with “try” scope.
username-password-filter	Removed.
validator	Removed.
weblogic-transaction-manager	Use the `<bti:transaction-manager/>`.
websphere-transaction-manager	Use the `<bti:transaction-manager/>`.
all-strategy	Removed.
entry-point-resolver	Use the Java module.
filter	Filters are replaced by the Validation module.
interceptor	Interceptors are replaced with custom policies.
message-info-mapping	No longer needed
point-resolver-set	Use the Use the Java module.
router	Removed.
threading-profile	No longer needed. The Runtime now tunes itself.
transformer	Removed. Most explicit transformations are no longer needed. Use DataWeave for the corner cases.

All router

Use Scatter Gather instead or execute the operations one after the other with different target attributes and then use DW to merge results.

async[processingStrategy]

Async processing strategies are no longer needed with the non-blocking execution engine; remove all processing strategies from your scope when you migrate to Mule 4. Use an Async scope wrapping all the components that you want to execute asynchronously.

asynchronous-processing-strategy

bridge

Build an equivalent flow

catch-exception-strategy

Use error-handler with an on-error-continue strategy.

choice-exception-strategy

Use error-handler with different strategies inside using error type selection or when attribute.

combine-collections-transformer

No longer needed with the simplified message model. MuleMessageCollections are replaced with arrays of Mule Messages, which can be merged or iterated through using any Mule component, such as DataWeave or foreach.

component

Use the Java module.

composite-source

Create one flow per each source and invoke a private flow using flow-ref for the common functionality.

configuration[defaultExceptionStrategy-ref]

New name is defaultErrorHandler-ref

configuration[flowEndingWithOneWayEndpointReturnsNull]

No longer needed with new execution engine.

configuration[useExtendedTransformations]

Removed.

configuration[enricherPropagatesSessionVariableChanges]

Removed.

copy-attachments

Per the new Message Structure, attachments will now be part of the message Attributes. You can manipulate them at will using DataWeave

copy-properties

Per the new Message Structure, properties will now be part of the message Attributes. You can manipulate them at will using DataWeave

custom-agent

No longer supported.

custom-aggregator

Use the Mule SDK to build the custom aggregator.

custom-connector

Use the Mule SDK to build your own connector.

custom-exception-strategy

No longer needed. Use error-handler

custom-lifecycle-adapter-factory

No longer supported.

custom-object-store

Use Object Store connector to create custom stores.

custom-processor

Use the Mule SDK or the Scripting module instead

custom-queue-store

Use the new VM Connector.

custom-router-resolver

Use the Mule SDK to build a custom router.

custom-router

Use the Mule SDK to build a custom router.

custom-service

Use flows.

custom-source

Use the Mule SDK to write a new event source.

custom-splitter

Use DataWeave or the Mule SDK.

custom-transaction-manager

Use the <bti:transaction-manager/>.

custom-transaction

No longer supported.

default-exception-strategy

Use error-handler with an on-error-propagate strategy.

default-in-memory-queue-store

Use the new VM Connector.

default-persistent-queue-store

Use the new VM Connector.

default-service-exception-strategy

Use error-handler with an on-error-propagate strategy.

endpoint

Use connectors.

exception-strategy

Use error-handler.

expression-component

Depending on the nature of your expression, you can either use DataWeave (for data access expressions), Scripting module or the Mule SDK for algorithmic expressions, or the Java module for expressions which simply access Java.

file-queue-store

Use the new VM Connector.

flow[processingStrategy]

Removed. Non-blocking execution engine ensures that users do not need to tune this.

idempotent-message-filter

Replaced by idempotent-message-validator.

idempotent-redelivery-policy

New name is redelivery-policy.

idempotent-secure-hash-message-filter

Replaced by idempotent-message-validator.

in-memory-store

Use Object Store connector to create custom stores.

inbound-endpoint

Use the event sources or triggers defined on each connector or module.

include-entry-point

Use the Java module.

interceptor-stack

Removed. Use custom policies.

invoke

Use the Java module

jndi-transaction-manager

Use the <bti:transaction-manager/>.

jrun-transaction-manager

Use the <bti:transaction-manager/>.

legacy-abstract-exception-strategy

Use the new error-handler

managed-store

Use Object Store connector to create custom stores.

message-properties-transformer

Use Transform component and DataWeave.

model

Removed. Use flows instead.

mule[version]

outbound-endpoint

Element moved from the core namespace to the new transports namespace.

poll → watermark

This capability has been built inside event sources from many connectors, like Salesforce, Database, SFTP, File, etc. You can also use the object-store connector to manually set the watermark values.

poll

Replaced with scheduler component.

processor

prototype-object

Use Java module or Spring module.

queue-profile

Use the VM Connector.

queue-store

VM Connector.

recipient-list

Removed.

reconnect-custom-notifier

Removed.

reconnect-custom-strategy

Removed.

reconnect-notifier

Removed.

remove-attachment

No longer needed per the new Message Structure, attachments

remove-property

PNo longer needed per the new Message Structure, attachments

response

No longer needed.

request-reply

Mule 4 will not longer support request-reply for all connectors. Connectors that had a “request-reply” behavior will provide a “request-reply” operation built in, such as the JMS publish-consume operation.

resin-transaction-manager

Removed.

rollback-exception-strategy

Use error-handler with an on-error-propagate strategy.

scatter-gather[threading-profile]

No longer needed now that Mule 4 is non blocking.

seda-model

No more SEDA queues in Mule 4. The execution engine in Mule 4 is non-blocking.

service

Use flows.

set-attachment

No longer needed. Attachments can be stored as variables.

set-property

Properties no longer exist in the new message model. You can store attributes from the Mule message in a variable.

set-session-variable

Session variables have been removed. Users must explicitly pass headers across transport boundaries.

simple-in-memory-queue-store

Use the new VM Connector.

simple-service

Use flows.

simple-text-file-store

Use object store module extension to create custom stores.

singleton-object

Use Java module or Spring module.

spring-object

Use Java module or Spring module.

synchronous-processing-strategy

The behavior related to flow components execution is the same as flows in 4.x but it doesn’t always execute in the same thread as in 3.x.

transactional scope

Replaced with “try” scope.

username-password-filter

Removed.

validator

Removed.

weblogic-transaction-manager

Use the <bti:transaction-manager/>.

websphere-transaction-manager

Use the <bti:transaction-manager/>.

all-strategy

Removed.

entry-point-resolver

Use the Java module.

filter

Filters are replaced by the Validation module.

interceptor

Interceptors are replaced with custom policies.

message-info-mapping

No longer needed

point-resolver-set

Use the Use the Java module.

router

Removed.

threading-profile

No longer needed. The Runtime now tunes itself.

transformer

Removed. Most explicit transformations are no longer needed. Use DataWeave for the corner cases.