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From Stefan Groschupf ...@101tec.com>
Subject Re: Proposal for error handling in Pig
Date Fri, 29 Feb 2008 21:57:56 GMT
Hi Olga,
I the cookbook idea is really great!

Here my thoughts:

User Errors:
Agreed meaningful error messages for the user.
+ should we start using error codes and a message bundle for i18n in  
the very long run?
+ in debug mode we should also show the complete strack trace

Internal Errors:
+ java has assert statements and I like them very much since it helps  
to better understand the code - best documentation is always the code,  
isnt it? :) http://java.sun.com/j2se/1.4.2/docs/guide/lang/assert.html
It would be great to make the usage of assert to a coding standard in  
pig

"log the exception message to stderr": I suggest that we do always log  
using commons logging and have a Console appender and not logging into  
stderr directly.

Can we find a better name than Frontend Exception? Frontend is widely  
used for User Interface as well. Maybe Client - but I'm not very happy  
about client also. :-/

In general I'm in favor of the idea of having those exceptions. All  
pig exceptions should inheritance from RuntimeException. This would  
allow us to design API without Exception declaration (unchecked  
Exceptions). Since your proposal suggest to handle the error always on  
very top in the stack (what I like a lot) this will clean up all API  
and make them better understandable.
http://www.javapractices.com/topic/TopicAction.do?Id=129
http://www.onjava.com/pub/a/onjava/2003/11/19/exceptions.html

I'm always happy to assit in doing your suggest changes since we have  
a hight need in getting pig into a production ready state soon than  
later. :) Just let me know.

Cheers,
Stefan









On Feb 28, 2008, at 6:06 PM, Olga Natkovich wrote:

> Pig developers,
>
> We had many patches submitted that are trying to improve error  
> handling.
> This is really great as many users ask exactly for that. So it seems
> timely to establish some guidelines on how errors should be handled,
> propagated, delivered, etc.
>
> I put together a proposal to start the discussion. Please, review and
> comment. Once we have an agreement we would need to add the missing
> pieces to deploy it into Pig and then review the existing patches to
> make sure they follow the proposed practice.
>
> http://wiki.apache.org/pig/PigDeveloperCookbook
>
> I have also started a general document called Pig Developer Cookbook
> where we can keep track of development patterns we as a community want
> to follow.
>
> Thanks again for everybody's contributions!
>
> Olga

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
101tec Inc.
Menlo Park, California, USA
http://www.101tec.com



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