This DataWeave module contains functions for interacting with Mule runtime.

Functions

causedBy

causedBy(Error, String): Boolean

This function matches an error by its type, like an error handler does.

causedBy is useful when you need to match by a super type, but the specific sub-type logic is also needed. It can also useful when handling a COMPOSITE_ROUTING error that contains child errors of different types.

Parameters
Name Description

error

Optional. An Error type.

errorType

A string that identifies the error, such as HTTP:UNAUTHORIZED.
Example

This XML example calls causedBy from a when expression in a Mule error handling component to handle a SECURITY error differently depending on whether it was caused by an HTTP:UNAUTHORIZED or HTTP:FORBIDDEN error. Notice that the first expression passes in the error (an Error type) explicitly, while the second one passes it implicitly, without specifying the value of the parameter. Note that error is the variable that DataWeave uses for errors associated with a Mule message object (see DataWeave Variables for Mule Runtime).

Source

  
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<error-handler name="securityHandler">
  <on-error-continue type="SECURITY">
    <!-- general error handling for all SECURITY errors -->
    <choice>
      <when expression="#[Mule::causedBy(error, 'HTTP:UNAUTHORIZED')]">
        <!-- specific error handling only for HTTP:UNAUTHORIZED errors -->
      </when>
      <when expression="#[Mule::causedBy('HTTP:FORBIDDEN')]">
        <!-- specific error handling only for HTTP:FORBIDDEN errors -->
      </when>
    </choice>
  </on-error-continue>
</error-handler>

lookup

lookup(String, Any, Number)

This function enables you to execute a flow within a Mule app and retrieve the resulting payload.

It works in Mule apps that are running on Mule Runtime version 4.1.4 and later.

Similar to the Flow Reference component (recommended), the lookup function enables you to execute another flow within your app and to retrieve the resulting payload. It takes the flow’s name and an input payload as parameters. For example, lookup("anotherFlow", payload) executes a flow named anotherFlow.

The function executes the specified flow using the current attributes, variables, and any error, but it only passes in the payload without any attributes or variables. Similarly, the called flow will only return its payload.

Note that lookup function does not support calling subflows.

Warning

Always keep in mind that a functional language like DataWeave expects the invocation of the lookup function to not have side effects. So, the internal workings of the DataWeave engine might cause a lookup function to be invoked in parallel with other lookup functions, or not to be invoked at all.

MuleSoft recommends that you invoke flows with the Flow Ref (flow-ref) component, using the target attribute to put the result of the flow in a var and then referencing that var from within the DataWeave script.
Parameters
Name Description

flowName

A string that identifies the target flow.

payload

The payload to send to the target flow, which can be any (Any) type.

timeoutMillis

Optional. Timeout (in milliseconds) for the execution of the target flow. Defaults to 2000 milliseconds (2 seconds) if the thread that is executing is CPU_LIGHT or CPU_INTENSIVE, or 1 minute when executing from other threads. If the lookup takes more time than the specified timeoutMillis value, an error is raised.
Example

This example shows XML for two flows. The lookup function in flow1 executes flow2 and passes the object {test:'hello '} as its payload to flow2. The Set Payload component (<set-payload/>) in flow2 then concatenates the value of {test:'hello '} with the string world to output and log hello world.

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<flow name="flow1">
  <http:listener doc:name="Listener" config-ref="HTTP_Listener_config"
    path="/source"/>
  <ee:transform doc:name="Transform Message" >
    <ee:message >
      <ee:set-payload ><![CDATA[%dw 2.0
output application/json
---
Mule::lookup('flow2', {test:'hello '})]]></ee:set-payload>
    </ee:message>
  </ee:transform>
</flow>
<flow name="flow2" >
  <set-payload value='#[payload.test ++ "world"]' doc:name="Set Payload" />
  <logger level="INFO" doc:name="Logger" message='#[payload]'/>
</flow>

p

p(String): String

This function returns a string that identifies the value of one of these input properties: Mule property placeholders, System properties, or Environment variables.

For more on this topic, see Configure Properties.

Parameters
Name Description

propertyName

A string that identifies property.
Example

This example logs the value of the property http.port in a Logger component.

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<flow name="simple">
 <logger level="INFO" doc:name="Logger"
   message="#[Mule::p('http.port')]"/>
</flow>

Types

Error

Type that represents an Error.

Definition

  
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{ /**
* Concise description of the error.
**/
description?: String, /**
* Detailed description of the error. This message can include information
* specific to a Java exception.
**/
detailedDescription?: String, /**
* Returns the type of the error.
**/
errorType?: ErrorType, /**
* Lists child Errors, if any.
*
* For example, the Scatter-Gather router might throw an error aggregating
* all of its routes errors as children.
*
* Not all failing components aggregate errors, so this type can return an
* empty collection.
**/
childErrors?: Array<Error> }

ErrorType

A type of error that a Mule component can throw.

The error type has a identifier string that end users can provide in the Mule configuration.

Every error belongs to a namespace to avoid collisions with errors that have the same identifier string but belong to different namespace.

Error types can be a specialization of a more general error type, in which case the parentErrorType should return the more general error type. This type is used during error type matching within error handlers. So when selecting the general error type for error handling, it also handles the more specialized error types.

Definition

  
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{ identifier?: String, namespace?: String, parentErrorType?: ErrorType | Null }

Message

Type that represents a Mule Message

Definition

  
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Object {class: "org.mule.runtime.api.message.Message"}