Contact Us 1-800-596-4880
  1. Homepage
  2. Anypoint Code Builder

  3. Until Successful (<until-successful/>)

Until Successful (<until-successful/>)

Executes processors inside its scope, in order, until they all succeed or the scope exhausts the maximum number of retries.

Until Successful runs synchronously. If any processor within the scope fails to connect or to produce a successful result, Until Successful retries all the processors within it, including the one that failed, until all configured retries are exhausted. If a retry succeeds, the scope proceeds to the next component. If the final retry does not succeed, Until Successful produces an error.

Routing is successful if no exception is raised or if the response matches an expression.

Common processes that use Until Successful include:

  • Dispatching to outbound endpoints, for example, when calling a remote web service that might have availability issues

  • Executing a component method, for example, when executing on a Spring bean that might depend on unreliable resources

  • Using a Subflow component (<sub-flow/>) to re-execute several actions until they all succeed

Component XML

This component supports the following XML structure:

<until-successful
  doc:name="Until successful"
  doc:id="mbqhsp" >
  <!-- Components to execute inside the scope -->
</until-successful>

Until Successful (<until-successful/>) attributes are configurable through the UI and XML.

Attribute Name Attribute XML Description

Until successful (default)

doc:name

Editable name for the component to display in the canvas.

N/A

doc:id

Automatically generated identifier for the component.

Max retries

maxRetries

Maximum number of retries allowed. This attribute can be either a number or an expression that resolves to a number. Error messages look like this: Message: 'until-successful' retries exhausted. The Mule error type is MULE:RETRY_EXHAUSTED.

Millis between retries

millisBetweenRetries

Specifies, in milliseconds, the minimum interval between two retries. The length of the interval is affected by a previous execution but typically does not exceed twice the minimum. This attribute can be a number or an expression that resolves to a number. Defaults to 60000 milliseconds (one minute).

Variable Propagation

Every execution of the Until Successful scope starts with the same variables and values present before the execution of the block, even if an error occurs within the scope before the maximum number of retries is exhausted. New variables or modifications to already-existing variables while processing one element are not present when the scope executes. If the execution finishes successfully, the variables (and payload) are propagated to the rest of the flow.

Example Configuration of the Until Successful Scope

The following XML example configures a flow triggered by a Scheduler component and an Until Successful scope that executes an FTP Write operation:

<!-- FTP Connector config-->
<ftp:config name="FTP_Config" doc:name="FTP Config" >
  <ftp:connection workingDir="${ftp.dir}" host="${ftp.host}" />
</ftp:config>

<flow name="untilSuccessfulFlow" >
  <!-- Scheduler component to trigger the flow-->
  <scheduler doc:name="Scheduler" >
    <scheduling-strategy >
      <fixed-frequency frequency="15" timeUnit="SECONDS"/>
    </scheduling-strategy>
  </scheduler>
  <!-- Until Successful scope-->
  <until-successful maxRetries="5" doc:name="Until Successful" millisBetweenRetries="3000">
    <!-- FTP Write operation that executes as part of the Until Successful Scope -->
    <ftp:write doc:name="Write" config-ref="FTP_Config" path="/"/>
  </until-successful>
  <logger level="INFO" doc:name="File upload success" message="File upload success"/>
  <!-- Error Handler at flow level-->
  <error-handler>
    <on-error-continue enableNotifications="true" logException="true" doc:name="On Error Continue" type="RETRY_EXHAUSTED">
      <logger level="INFO" doc:name="File upload failed" message="File upload failed"/>
    </on-error-continue>
  </error-handler>
</flow>

Behavior of the example application:

  • If the FTP Write operation fails, Until Successful scope retries the operation every 3000 milliseconds until the operation succeeds, with a limit of 5 retries.

    If the last execution fails, the scope throws a MULE:RETRY_EXHAUSTED error. Then the <on-error-continue> handles the error and executes the Logger with the message File upload failed.

    Before throwing MULE:RETRY_EXHAUSTED, Mule also logs each unsuccessful attempt to retry execution of the processors on the Mule event, for example:

    ERROR 2022-12-09 17:41:44,910 ... event: cdad31c0-782b-11ed-af21-147ddaaf4f97]
...UntilSuccessfulRouter: Retrying execution of event, attempt 1 of 5.
...
ERROR 2022-12-09 17:41:55,079 ... event: cdad31c0-782b-11ed-af21-147ddaaf4f97]
...UntilSuccessfulRouter: Retrying execution of event, attempt 5 of 5.

  • If the FTP Write operation executes successfully in any of the attempts, the next processor after the Until Successful scope executes. In this example, the Logger executes with the message File upload success.

See Also