[jira] [Commented] (SQOOP-2266) Sqoop2: Solution of communication between client and server about ErrorCode

["Jarek Jarcec Cecho (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SQOOP-2266?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14379991#comment-14379991 ] 

Jarek Jarcec Cecho commented on SQOOP-2266:
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Thanks for creating this follow up JIRA [~richard_zhou]. Very nice summary! I've introduced the exception propagation from server to client couple of years back as a way to show user what went wrong on the server. It was merely a better debugging tool then a real part of the protocol where users of the API could depend on the error codes to perform certain actions. I do see the use case of good error propagation, so I agree that we should do something about that. 

I do not feel that the {{ErrorCodes}} are the best way to achieve this though. The way we've designed {{SqoopException}} and the {{ErrorCode}} is to easily add/change additional error codes to see what exactly and where went wrong in the code. By design Sqoop is highly pluggable (almost every part is a plugin) and we are expecting  that users will take advantage of this pluggability - if nothing else, I'm fully expecting that users will be dumping in new third party connectors that will certainly bring their own {{ErrorCode}} classes that won't be known to our client. 

As we can't guarantee that client will always have all {{ErrorCodes}} available, I'm thinking that the better solution is to make a parallel system to the current one. We can define some common errors in the protocol itself (whatever way we see fit), but in addition to that we should allow unknown {{ErrorCodes}} to be sent across the wire as well. I'm wondering what others think about it?



> Sqoop2: Solution of communication between client and server about ErrorCode
> ---------------------------------------------------------------------------
>
>                 Key: SQOOP-2266
>                 URL: https://issues.apache.org/jira/browse/SQOOP-2266
>             Project: Sqoop
>          Issue Type: Bug
>          Components: sqoop2-client
>    Affects Versions: 1.99.5
>            Reporter: Richard
>             Fix For: 2.0.0
>
>
> When the client receives the response with throwable bean from the server, it will try to reflect the exception class. However, if the {{ErrorCode}} class is in {{sqoop-core}} or other module instead of {{sqoop-common}}, {{NPE}} will be throw (SQOOP-2054). So [~abec] and me moved all {{ErrorCode}} to {{sqoop-core}} (SQOOP-2054, SQOOP-2172). Several time passed, on the other hand, [~jarcec] fixed {{NPE}} with avoid throwing exception (SQOOP-2225), and then moved several {{ErrorCode}} back to their own modules (SQOOP-2248, SQOOP-2249, SQOOP-2251 and SQOOP-2247). But this solution does not solve the problem that client could not reflect the exception class from server, which is needed in {{Authorization}} part. (The client need to identify the exception type to decide which message should be shown in the CLI).
> This JIRA is to address this issue.



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