Flow references, target variables and templates
How core features every Mule application has (flows and subflows, Flow Reference, target variables, On-Error components and Parse Template) shape the message a flow sees, including what a referenced flow's error handler returns to its caller.
Select and use fundamental features available to all Mule applications.
~7 min read · 2 practice questions
What the exam expects
- Choose between a flow and a subflow for reusable logic, given its need for a source or its own error handling.
- Predict the payload and variables after a Flow Reference, with and without a target variable, including when the referenced flow handles its own error.
- Distinguish On Error Continue from On Error Propagate by what they return to the owner and to a calling flow.
- Configure target variables (Target and Target Value) to keep the current message while storing an operation's result.
- Select Parse Template for text with embedded Mule expressions, and configure its template inline or from a file.
Core component: a component built into Mule runtime, such as Flow Reference, Set Variable, Logger, Choice or Try, available to every application. Flow Reference: routes the event to another flow or subflow in the same application and then back. Target variable: a variable named in an operation's Target field that stores its result instead of replacing the message. On-Error component: On Error Continue or On Error Propagate inside an Error Handler. Template: text with embedded Mule expressions that Parse Template evaluates and replaces with their results (Mule Components, Flow Reference, Parse Template).
Key facts
- Detail
- No event source, no error handling scope
- Detail
- Each Flow Reference is replaced by its contents
- Detail
- Use the literal name; dynamic names hurt performance and block MUnit analysis
- Detail
- Original payload and variables kept; result stored in the variable
- Detail
- Its own handler runs; with no handler, the caller's handler gets the error
- Detail
- Not set
- Detail
- Its result becomes the owner's successful result
- Detail
- Numbers, characters, underscores; no hyphens
- Detail
- The payload;
varskeyword not accepted
- Detail
location(file) orcontent(inline string)
- When must a quoted sub-expression in a template be wrapped in another
#[]? - Why would a template contain
\#[? - When would you configure a flow as initially stopped, and how is it started?
The questions are free to read. Answers with their sources and self-grading are included with the pack.
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