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From "Scott O'Bryan" <>
Subject Re: [Trinidad][API] New Exception tells whether JSF needs to report the exception for TRINIDAD-2038
Date Thu, 17 Feb 2011 01:25:24 GMT
Ahh cool.  Thanks Blake.  That clears things up consoderably.  I guess
I'm cool with it but I'm wondering if this might not be better served
by a RUNTIME annotation or even a new Trinidad exception class.

Having an interface on an exception seems a bit silly to me because it
requires some implementation.  Especially if that interface only
returns a Boolean.  An annotation marker might be a better thing to
use if you need to return exceptions with multiple origins or if these
wrapper exceptions can all come from the same base exception, a
special Trinidad exception type would be much more efficient because
we could simply return an instanceof and/or provide overloadable logic
to determine if logging is needed.

Just my .02, but I'm good with it.. ;)


On Feb 16, 2011, at 5:46 PM, Blake Sullivan <> wrote:

> The issue isn't that the problem has been handled by the model.  It hasn't.  Therefore
the model has to throw a RuntimeException in this case so that the component knows to preserve
its local value.  That's all good.
> The problem occurs if the model has its own mechanisms for reporting problems.  In that
case, we want to avoid reporting the same problem twice and that is where the interface comes
in.  The model wants to tell the view that there was a problem, but that the model will take
care of reporting it, so the view needn't bother.
> -- Blake Sullivan
> On 2/16/11 4:39 PM, Scott O'Bryan wrote:
>> If this exception is handled, why is it rethrown?  What would you
>> expect Trinidad to do in this case?
>> On Feb 16, 2011, at 5:37 PM, Hongbing<>  wrote:
>>> Hi Scott:
>>> One example is in the following UIXEditableValue.updateModel(FacesContext context)
>>>  public void updateModel(FacesContext context)
>>>  {
>>>    ....
>>>    try
>>>    {
>>>      Object localValue = getLocalValue();
>>>      expression.setValue(context.getELContext(), localValue);
>>>      setValue(null);
>>>      setLocalValueSet(false);
>>>      if (_LOG.isFiner())
>>>      {
>>>        _LOG.finer("Wrote value {0} to model {1} in component {2}",
>>>                   new Object[]{localValue,
>>>                                expression.getExpressionString(),
>>>                                this});
>>>      }
>>>    }
>>>    catch (RuntimeException e)
>>>    {
>>>    ...
>>>  expression.setValue(context.getELContext(), localValue) calls binding code and
then the model's code, where exception can be thrown.
>>>  In the catch part, we want to skip reporting the exception if it is handled
by model/controller code.
>>> Thanks,
>>> Hongbing
>>> On 2/16/2011 4:23 PM, Scott O'Bryan wrote:
>>>> Hogbing,
>>>> I'm taking a look at the bug now but just so I understand..  When you
>>>> refer to JSF, I assume you mean the Trinidad renderkit.  Is that
>>>> correct?
>>>> Scott
>>>> On Feb 16, 2011, at 4:23 PM, Hongbing<>   wrote:
>>>>> Hi Pavitra:
>>>>> It can happen in update model phase. For example, Model layer throws
exception when attribute value validation fails, binding layer detects it and re-throwd new
exception with the new interface to JSF. JSF then can handle it accordingly.
>>>>> thanks,
>>>>> Hongbing
>>>>> On 2/16/2011 2:09 PM, Pavitra Subramaniam wrote:
>>>>>> Hello Hongbing,
>>>>>> You mentioned that exceptions get thrown by model layer outside of
JSF. Can you give an e.g., of when this might occur?
>>>>>> How exactly will the interface get used?
>>>>>> Thanks
>>>>>> Pavitra
>>>>>> On 2/16/2011 1:01 PM, Hongbing wrote:
>>>>>>> Hi:
>>>>>>> This is for JIRA TRINIDAD-2038, please let me know your suggestion.
>>>>>>> There are cases that exception is thrown in update model phase,
like model layer validation failure, by model outside of JSF and the exception is also handled
and reported outside of JSF. To avoid the component's local value getting reset to null, JSF
needs to be notified when it happens. The proposed solution is to re-throw a special exception
to JSF to notify it and also let JSF know whether it needs to report the exception.
>>>>>>> Here is the interface of the exception:
>>>>>>> package org.apache.myfaces.trinidad.context;
>>>>>>> /**
>>>>>>> * Interface for exceptions that tells whether the exception needs
to be reported.
>>>>>>> * If an exception is thrown during JSF lifycycle and aleady reported,
then it should let
>>>>>>> * JSF know not to report it again.
>>>>>>> *
>>>>>>> */
>>>>>>> public interface Reportable
>>>>>>> {
>>>>>>>  /**
>>>>>>>   * Return false if JSF doesn't need to report this exception,
otherwise true.
>>>>>>>   */
>>>>>>>  public boolean isReportingMessage();
>>>>>>> }
>>>>>>> Thanks,
>>>>>>> Hongbing

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