If you really want to handle all exceptions being thrown in the same way
you can use a multi exception catch block[1](supported from Java 7) to do
this. That way the component developer doesn't have to worry about defining
exception hierarchies, which is really not the concern of the component
developer. Though I still think that this requirement is an excuse for
being lazy and will lead to problems for others who have to maintain the
code. Its always better to be explicit whenever possible for the sake of
clarity.
[1]
catch (IOException|FileNotFoundException ex) {
}
On 21 October 2016 at 12:37, Susinda Perera <[email protected]> wrote:
> +1 for having custom exceptions. However, as Malintha mentioned I believe
> it will help us having exception hierarchy. There may be cases where
> catching top level exceptions may be sufficient. If we have a hierarchy,
> programmer can decide which one to use depending on the context.
>
> Thanks
> Susinda
>
> On Fri, Oct 21, 2016 at 12:26 PM, Isuru Perera <[email protected]> wrote:
>
>> +1 for having separate exception classes. It's also good if you want to
>> define different hierarchies of exceptions, but we need to think carefully
>> and properly group those exceptions.
>>
>>
>>
>> On Fri, Oct 21, 2016 at 12:08 PM, Harsha Kumara <[email protected]> wrote:
>>
>>>
>>>
>>> On Fri, Oct 21, 2016 at 11:14 AM, Malith Jayasinghe <[email protected]>
>>> wrote:
>>>
>>>> Hi Harsha,
>>>>
>>>> It makes sense to define specific exceptions. However, I am wondering
>>>> (in most of these cases) whether the caller can do anything specially to
>>>> handle these exception (I guess this will depend on how you define the
>>>> exception (and when it will be thrown)?
>>>>
>>>> For example, if you throw APIMDAOException when you get a SQL exception
>>>> within a DAO method, how would the client code handle it? Can you give an
>>>> example?
>>>>
>>> Basically if we find a exception in DAO layer, let's say if we going to
>>> search users by name and it returns a SQL exception, we need catch it and
>>> throw defined exception with error message saying it's failed when
>>> searching users. In upper layers it will be useful. Also DAO layer may not
>>> only throw SQL exceptions, there might me different types of exceptions
>>> thrown from it. In service layer it might not need to aware all about it.
>>> We shouldn't expose DAO layer exceptions for end users as well. Because DAO
>>> layer exceptions might contains information regarding queries, schema and
>>> etc. Also with having defined exception we can send response back to the
>>> client accordingly. If we encounter server error we may return 404 while if
>>> we encounter security exception we may send response with other error
>>> accordingly.
>>>
>>> [1] http://tutorials.jenkov.com/java-exception-handling/exce
>>> ption-wrapping.html
>>>
>>>>
>>>> Thanks
>>>>
>>>> Malith
>>>>
>>>>
>>>>
>>>> On Thu, Oct 20, 2016 at 3:31 PM, Harsha Kumara <[email protected]>
>>>> wrote:
>>>>
>>>>> Definitely we need to have well defined set of exceptions instead
>>>>> using APIManagementException in all places. As Uvindra mentioned, for API
>>>>> Manager database access, we can have APIMDAOExcepton. For security related
>>>>> exceptions we can have APIMSecurityException and so on. In jaggary level
>>>>> also we check the instance type of a thrown exception and return responses
>>>>> accordingly.
>>>>>
>>>>> [1] http://howtodoinjava.com/best-practices/java-exception-h
>>>>> andling-best-practices/
>>>>>
>>>>> On Thu, Oct 20, 2016 at 2:27 PM, Uvindra Dias Jayasinha <
>>>>> [email protected]> wrote:
>>>>>
>>>>>> I would like to know your thoughts on $subject.
>>>>>>
>>>>>> Previously we have a single custom exception class in APIM called
>>>>>> 'APIManagementException' and this was used when throwing exceptions
>>>>>> specific to the APIM product. Pros and Cons of doing it this way are,
>>>>>>
>>>>>> *Pros* - Only one APIM specific exception needs to be handled in the
>>>>>> entire APIM code base
>>>>>>
>>>>>> *Cons* - When an exception is thrown its very difficult to pin point
>>>>>> the reason for the exception to be thrown. This results in,
>>>>>>
>>>>>> 1. Having to solely depend on the error message of the exception to
>>>>>> determine what has happened(Provided that the error message is clear)
>>>>>>
>>>>>> 2. Difficult to handle exception appropriately at code level because
>>>>>> we are not aware of the specifics of the exception
>>>>>>
>>>>>>
>>>>>> In light of this doesn't it make sense to define specific custom
>>>>>> exceptions? For example when interacting with the DAO component of APIM
>>>>>> if
>>>>>> any data access errors are encountered we could define an
>>>>>> 'APIMDAOException' and throw that. This allows users of the DAO component
>>>>>> to clearly identify and handle that specific exception appropriately.
>>>>>>
>>>>>>
>>>>>> This obviously needs to be applied in a way that makes sense at
>>>>>> component level(DAO, Gateway, etc.) so its clear which specific component
>>>>>> has run into an issue.
>>>>>>
>>>>>> WDYT?
>>>>>>
>>>>>> --
>>>>>> Regards,
>>>>>> Uvindra
>>>>>>
>>>>>> Mobile: 777733962
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Harsha Kumara
>>>>> Software Engineer, WSO2 Inc.
>>>>> Mobile: +94775505618
>>>>> Blog:harshcreationz.blogspot.com
>>>>>
>>>>> _______________________________________________
>>>>> Architecture mailing list
>>>>> [email protected]
>>>>> https://mail.wso2.org/cgi-bin/mailman/listinfo/architecture
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Malith Jayasinghe
>>>>
>>>> WSO2, Inc. (http://wso2.com)
>>>> Email : [email protected]
>>>> Mobile : 0770704040
>>>> Lean . Enterprise . Middleware
>>>>
>>>
>>>
>>>
>>> --
>>> Harsha Kumara
>>> Software Engineer, WSO2 Inc.
>>> Mobile: +94775505618
>>> Blog:harshcreationz.blogspot.com
>>>
>>> _______________________________________________
>>> Architecture mailing list
>>> [email protected]
>>> https://mail.wso2.org/cgi-bin/mailman/listinfo/architecture
>>>
>>>
>>
>>
>> --
>> Isuru Perera
>> Associate Technical Lead | WSO2, Inc. | http://wso2.com/
>> Lean . Enterprise . Middleware
>>
>> about.me/chrishantha
>> Contact: +IsuruPereraWSO2 <https://www.google.com/+IsuruPereraWSO2/about>
>>
>> _______________________________________________
>> Architecture mailing list
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>> https://mail.wso2.org/cgi-bin/mailman/listinfo/architecture
>>
>>
>
>
> --
> *Susinda Perera*
> Software Engineer
> B.Sc.(Eng), M.Sc(Computer Science), AMIE(SL)
> Mobile:(+94)716049075
> Blog: susinda.blogspot.com
> WSO2 Inc. http://wso2.com/
> Tel : 94 11 214 5345 Fax :94 11 2145300
>
>
> _______________________________________________
> Architecture mailing list
> [email protected]
> https://mail.wso2.org/cgi-bin/mailman/listinfo/architecture
>
>
--
Regards,
Uvindra
Mobile: 777733962
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