Belgian OutSystems community meetup presention of march 2019. Subject: How to handle execeptions like an OutSystems Pro

1. Enjoying challenges, providing solutions.

2. How to Handle Exceptions like a Pro

3. Topics
• What is an Exception?
• How does Outsystems categorize Exceptions?
• How does Outsystems handle Exceptions?
• Exception Encapsulation: Tips and Tricks
• Special Cases
• Timers
• BPT
• REST

4. What is an Exception?
An exception is an abnormal or unprecedented event that
occurs after the execution of a software program or
application. It is a runtime error of an undesired result or
event affecting normal program flow.
An exception is also known as a fault.
A person or thing that is excluded from a general statement
or does not follow a rule.

5. What is an Exception?

6. What is an Exception?

7. Outsystems Exceptions Tools
• Raise Exception
• Exception Message
• Exception (Type)

8. Outsystems Exceptions Tools
• Exception Handler
• Abort Transaction
• Log Error

9. Outsystems Exceptions Categorization
• Database Exception
• Security Exception
• Communication Exception
• Abort Activity Exception
• User Exceptions

10. Outsystems Exception Handling
Exception Handler for
MyUserException?
Exception Handler for
CategorizedExceptions?
Exception Handler for
AllExceptions?

11. Outsystems Exception Handling
Exception
Handler for UI
Flow?
Exception
Handler for the
Module/eSpace?
Application abort

12. Exception Encapsulation: Tips and Tricks
Integration Layer
• Catch the exception
• Log it
• Define an output with a success and a message
• Do not abort the transaction!
• Optional: Expose a ‘user friendly’ message in case of
unknown error

13. Exception Encapsulation: Tips and Tricks
Core Services Layer
• Which is the context?
• Sub-action of a bigger flow?
• Encapsulate
• Normal action to be used on the users layer?
• Do not encapsulate
• ‘User Friendly’ messages are a must (don’t forget the
translations)

14. Exception Encapsulation: Tips and Tricks
Users Layer
• Do not encapsulate

15. Special Cases
Timers
• The timeout issue
• Timeout Variable
• Timer scheduling properties
• Retry mechanism
• Service Center – Environment Configuration

16. Special Cases
BPT
• The timeout issue
• 5 min
• Theoretically, it can retry ‘forever’

17. Special Cases
REST
• All above a 400 is logged and thrown as an exception
• Sometimes it is an expected behaviour
• OnResponse Event allows to catch the response and
manipulated as needed

18. Useful Links
• https://success.outsystems.com/Documentation/11/Developing_an_Application/Implement_
Application_Logic/Handle_Exceptions
• https://success.outsystems.com/Documentation/11/Developing_an_Application/Implement_
Application_Logic/Handle_Exceptions/Exception_Handling_Mechanism
• https://success.outsystems.com/Documentation/11/Extensibility_and_Integration/REST/Con
sume_REST_APIs/Handling_REST_Errors
• https://success.outsystems.com/Documentation/11/Reference/OutSystems_Language/Proce
sses/Process_Tools/Automatic_Activity

19. Thank you!

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