En este evento hablaremos sobre una introducción a Dataweave 2.0, que te puede ayudar mucho si eres nuevo a Mule 4 y quieres aprender la sintaxis. También se verá sobre las excepciones "on propagate" y "on continue", ya que es un tema que viene incluido en el examen de certificación para Mule 4 (Level 1), y que hemos notado que no es muy claro para muchos Muleys.

1. May 14th, 2020: Meetup en español #1
ONLINE SPANISH

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Agenda
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• Introductions
• Presentations:
– Learning to use ”on propagate” and “on continue” exception handling
– Introduction to DW 2.0
• What’s next
• MuleSoft CONNECT

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Introductions
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• Organizers:
– David Morfin Diaz
– Josue Santiago
– Alexandra Martinez
– Luis Cantu
• Sponsor:
– Ad Victoriam Solutions

4. On-Error Propagate & On-Error Continue
Error Handling

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• Mule execution failures result in an error. When a Mule app is
running, both the Mule runtime engine and the module and
connector operations configured in the app can throw errors.
• Mule errors are grouped into error types that follow a hierarchical
order and use a naming convention that helps you identify the source
of the error and handle the error at the level you choose.
Error Handling

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Execution failures are represented with Mule errors that have the following components:
• A description of the problem.
• A type that is used to characterize the problem.
• A cause, the underlying Java Throwable that resulted in the failure.
• An optional error message, which is used to include a proper Mule Message regarding the
problem.
• Optional child errors, an optional collection of inner errors.
For example, when an HTTP request fails with a 401 status code, a Mule error provides the
following information:
• Description: HTTP GET on resource ‘http://localhost:36682/testPath’ failed: unauthorized (401)
• Type: HTTP:UNAUTHORIZED
• Cause: a ResponseValidatorTypedException instance
• Error Message: {"message" : "Could not authorize the user."}
Mule Errors

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Examples:
• EXPRESSION: indicates an error occurred while evaluating a DataWeave expression.
• REDELIVERY_EXHAUSTED: indicates that max attempts to reprocess a message from a source have been exhausted.
• ROUTING: indicates an error occurred while routing a message.
Mule Error Types

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Introduction
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Errors that occur in Mule belong to one of two major categories:
System Errors: Mule throws a system error when an exception occurs at the system
level and no Mule event is involved. A system error handler manages exceptions that
occur:
– During application startup.
– When a connection to an external system fails.
Messaging Errors: Mule throws a messaging error (a Mule error) whenever a problem
occurs within a flow of a Mule app, where Mule events and the messages they
contain are processed. You can handle Mule messaging errors in more than one way:
– You can rely on the default error handling mechanism.
– Within a flow, you can set up On-Error components (On Error Continue and On Error
Propagate) inside the flow’s built-in Error Handler component.

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• On-Error Propagate works exactly as the Mule 3 Catch exception
strategy.
• In case of any errors, On-Error Propagate processes the error
message and re-throws the error to its parent flow. No further
processing is done on that particular flow.
On-Error Propagate

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• On-Error Continue catches the error and does not report it as an
error, thus the processing of the flow continues even after the error
has occurred.
• This error handler can be used in flows where you don’t want to stop
the flow processing even if an error has occurred.
On-Error Continue

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• Default error handling: If there is no error handling written at any of the levels, the
Mule Default Error Handler is used, which stops the execution of the flow and logs
the exception.
• Global Error Handler: The Global Error Handler can, unlike the Mule Default Error
Handler, be configured to process errors and do what you want with them,
therefore you can put an On-Error Propagate or an On Error Continue scope (or
both, if you want to handle specific errors) in the global error handler.
• Try catch: The Try scope enables you to handle errors that may occur when
attempting to execute any of the components inside the Try scope.
• A try scope is used when you want to attempt to perform an action and catch the
error and attempt to handle the error before failing an entire flow.
Where can you manage errors?

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• Default Error Handler sample Default Error Handler sample
Default Error Handling / Global Error Handler

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• On Propagate/sample
On Propagate

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• On Continue sample
On Continue

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• Try Catch
Try Catch

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• When On-Error Propagate
– Error is propagated
– Original error is the final response
• When On-Error Continue
– No error is reported to father flow/final user
– Payload can be modified
Conclusion

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• https://docs.mulesoft.com/mule-runtime/4.3/intro-error-handlers
• https://docs.mulesoft.com/mule-runtime/4.3/error-handling
• https://dzone.com/articles/error-handling-in-mule-4
• https://docs.mulesoft.com/mule-runtime/4.3/mule-error-concept#error_types
• https://dzone.com/articles/error-handling-in-mule-1
• https://blogs.mulesoft.com/dev/training-dev/mule4-error-handling-deep-dive/
• https://blogs.mulesoft.com/dev/training-dev/mule4-error-handling/
• https://blogs.mulesoft.com/dev/training-dev/mule4-error-handling-use-cases/
Sources

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• The project used for the demo can be found here:
• https://github.com/dmorfindiaz/mule4-errorHandling
Demo’s project

19. Josue Santiago
Integration Architect
Introduction to DW 2.0

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• About me
• What is DW?
• Variables
• Functions
• Selectors
Agenda

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• MuleSoft certified Developer
• MuleSoft certified Architect
• Currently working at Appirio/Wipro as Integration Architect
• Long experience in:
– Banking
– Health care
– Retail
– https://www.linkedin.com/in/josue-santiago-70755546/
– josuer.santiagor@gmail.com
About me

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• DataWeave is a functional programming language.
• In DW everything is an expression:
• Immutable Data
What is DataWeave?
if(payload.size == 0){
x = 0
}else{
x=1
}
if(payload.size==0) 0 else 1
Statement
Expression

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• Header
• ---
• body
DW Structure

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• Global
• Local
Variables

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• In DW you can use functions:
Functions

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application/avro
application/csv
application/dw
application/flatfile
application/java
application/json
application/octet-stream
application/yaml
application/xml
application/x-ndjson
application/xlsx
application/x-www-form-urlencoded
multipart/*
text/plain
text/x-java-properties
MIME Types

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• In DW functions are categorized in different modules:
– Core (dw::Core)
– Arrays (dw::core::Arrays)
– Binaries (dw::core::Binaries)
– Encryption (dw::Crypto)
– Diff (dw::util::Diff)
– Objects (dw::core::Objects)
– Runtime (dw::Runtime)
– Strings (dw::core::Strings)
– System (dw::System)
– URL (dw::core::URL)
Functions

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• ++
• –
• Abs
• Avg
• Ceil
• Contains
• daysBetween
• distinctBy
• endsWith
• Filter
• IsBlank
• joinBy
• Min
• Max
• …
Core

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• CountBy
• divideBy
• Drop
• Dropwhile
• Every
• firstWith
• IndexOf
• indexWhere
• Join
• leftJoin
• Slice
• …
Arrays (dw::core::Arrays)

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• .keyName
• .*keyName
• ..keyName
• .&keyName
• Index
• Range
• XML attribute
• Namespace
• Key Present
• Assert Present
• Filter
• Metadata
DW Selectors

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• myKey[?(condition)]
Filter Selectors

32. Thanks! Questions?
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33. Quiz time!
3 lucky winners get a training or certification voucher!
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34. Quiz time!
1. Mention 3 types of errors
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35. Quiz time!
2. Why can’t we manage system errors?
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36. Quiz time!
3. Where does Global Error Handler have to be configured?
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37. Quiz time!
4. What kind of error handling is executed during default
error handling?
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38. Quiz time!
5. What information provides an error?
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39. Quiz time!
6. What type of programming language is DW?
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40. Quiz time!
7. Types of variables in DW 2.0?
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41. Quiz time!
8. What differentiates the core functions with the rest of the
functions?
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42. Quiz time!
9. With what can you use the selectors?
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43. Quiz time!
10. Mention some mime type
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What’s next
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• Share:
– Tweet your pictures with the hashtag #MuleMeetup
– Invite your network to join: meetups.mulesoft.com/online-group-spanish/
• Feedback:
– Contact any of your organizers to suggest topics
– Contact MuleSoft at meetup@mulesoft.com for ways to improve the program
• Slack
– Join our Slack workspace “MuleSoft Latino”
– Send your email to any of the organizers to receive the invite to join

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MuleSoft CONNECT Digital is a live virtual experience — bringing
you a full program of educational sessions and content, streamed
online for free.
AMERICAS: May 20, 2020
Register for free: https://connect.mulesoft.com