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Posted to dev@commons.apache.org by Phil Steitz <ph...@gmail.com> on 2007/02/03 19:54:55 UTC
Re: [all] exceptions and localization
On 1/30/07, luc.maisonobe@free.fr <lu...@free.fr> wrote:
>
> Craig McClanahan wrote:
>
>
> > I'm late to the table on this thread, and only care about the Commons
> > libraries I care about :-)
>
> Thanks for your interest in this thread.
>
> > but you should be aware that this attitude will
> > disqualify the use of such libraries from use within code from
> organizations
> > that have strict rules about implementing localization. I work for such
> an
> > organization (Sun) ... the key rules are that any message that might be
> > visible to users *must* be localizable.
>
> I agree with you and thought localization should be provided by the layer
> which
> provides the message. Other people think this should be done at
> application
> level, if done at all.
>
> > For log messages, that tends to translate into a straightforward policy
> that
> > DEBUG and TRACE type messages do not need to be localized, but anything
> from
> > INFO level above must be. The issue for exception messages is a bit
> more
> > interesting. How does the library developer know whether or not the
> message
> > part of the exception will be displayed to end users? From a pragmatic
> > viewpoint, you can pretty much assume this will happen with exceptions
> in
> > webapps, while many Swing apps will hide that sort of stuff to some
> degree.
>
> I think that since low level components may be used almost anywhere, their
> messages *may* be displayed and this sole possibility is enough to justify
> a
> localized version should be made available. If the application gets an
> error it
> really doesn't know about, it can simply display it.
>
> > But, as a bottom line, if I'm interested in maximum adoption of a
> Commons
> > library I work on, I will diligently ensure that exception messages are
> > localizable :-).
>
> When I first started this long thread, I thought the need for localized
> error
> messages as provided by exceptions was acknowledged by everyone and asked
> for
> the way to implement it, starting from a simple one which already works. I
> was
> wrong. The disagreement started about the need itself and slipped to the
> level
> at which implementation should be done.
>
> I would really like to reach a compromise on this issue, something that
> could by
> accepted by everybody. I don't want to get banned with a -1 on a commit,
> but at
> least a few people would like localized error messages that can be simply
> forwarded upward from lower layers to upper layer for display without
> processing. Standard java already provides Throwable.getLocalizedMessage()
> since
> JDK 1.1. I could set up for [math] only an exception hierarchy that only
> add a
> few constructors and an implementation of this method without any change
> in the
> Throwable.getMessage() behaviour. Does this sound reasonable ?
Sorry I was out of pocket this week and could not reiterate my personal +1
for moving forward as you suggest, Luc. I will add a few of more comments
below. If anyone still has serious reservations - especially those who now
or in the future may contribute to [math] - pls speak up; otherwise we can
move on. Thanks to all who provided comments.
1) My initial +1 was based on the fact that the error management that you
need to support this approach is in fact there in Mantissa and if you
*don't* support localization when text is being generated, you either need
to get into nonsense like parsing and translating error messages,
complicating your exceptions hierarchy, or losing/hiding information at
higher levels. If you do the work to localize when the string is generated,
that gives a choice at higher levels, which to me is goodness (assuming you
are prepared to do the work and the implementation is robust against missing
bundles, etc.).
2) Commons math generates error messages now, and should generate better
messages (as Mantissa does) in the future that using applications may want
to display to end users or in application logs. I would like for those
messages to be localizable. If one of our solvers does not converge because
initial values do not bracket a root, for example, I would like the
developer of a localized client application that uses the solver to be able
to display that message directly in a log or to the user. Whether or not
logging is good or bad is completely irrelevant to this discussion.
3) Apache is a do-ocracy and we have a proposal before us to significantly
improve exception management and error reporting in [math] by extending and
leveraging the framework in Mantissa. Luc is volunteering to do this and
the only other active contributor to [math] who has chimed in (yours truly)
is also in favor. The arguments against are either it is too much work to
implement exception error message localization or it may not be robust. Luc
is stepping up to *do* the work (actually, leverage work already mostly done
in Mantissa) and I don't see robustness or performance risk in what he has
implemented. Pls speak up if I am missing something in the latter case.
Therefore, appreciating the feedback from others and reservations about
applying across commons, for [math] we should let Luc JFDI - i.e., move
forward with the proposal.
Thanks again, all, for this interesting discussion and thanks, Luc, for
helping make [math] more localization-friendly.
Phil
Luc
>
>
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: commons-dev-unsubscribe@jakarta.apache.org
> For additional commands, e-mail: commons-dev-help@jakarta.apache.org
>
>
Re: [all] exceptions and localization
Posted by Phil Steitz <ph...@gmail.com>.
On 2/3/07, James Carman <ja...@carmanconsulting.com> wrote:
>
> How would they subclass? The commons math code will be throwing these
> exceptions themselves, no? They wouldn't be able to tell commons math
> to throw a specific type of exception class that they wrote.
Yes, you're right.
I agree that the default case (the JDK's getMessage() method) should
> work so that nobody has to know about the special i18n facilities.
> But, if you're truly looking to provide a rich i18n framework for
> exceptions, you need to make it extensible/adaptable.
I think exposing the key and parts and adding getMessage(Locale) is probably
good enough.
Phil
Re: [all] exceptions and localization
Posted by James Carman <ja...@carmanconsulting.com>.
How would they subclass? The commons math code will be throwing these
exceptions themselves, no? They wouldn't be able to tell commons math
to throw a specific type of exception class that they wrote.
I agree that the default case (the JDK's getMessage() method) should
work so that nobody has to know about the special i18n facilities.
But, if you're truly looking to provide a rich i18n framework for
exceptions, you need to make it extensible/adaptable.
On 2/3/07, Phil Steitz <ph...@gmail.com> wrote:
> On 2/3/07, James Carman <ja...@carmanconsulting.com> wrote:
> >
> > How does a calling application override the message, if they wish?
>
>
> They could subclass and override translate() or, assuming we take your
> suggestion and carry the data along, they could access the data and do
> whatever they want with it. I agree that it is a good idea to persist and
> expose the key and parts. I just also think it is good for getMessage() and
> getMessage(Locale) to provide default localization out of the box.
>
> Phil
>
>
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Re: [all] exceptions and localization
Posted by Phil Steitz <ph...@gmail.com>.
On 2/3/07, James Carman <ja...@carmanconsulting.com> wrote:
>
> How does a calling application override the message, if they wish?
They could subclass and override translate() or, assuming we take your
suggestion and carry the data along, they could access the data and do
whatever they want with it. I agree that it is a good idea to persist and
expose the key and parts. I just also think it is good for getMessage() and
getMessage(Locale) to provide default localization out of the box.
Phil
Re: [all] exceptions and localization
Posted by James Carman <ja...@carmanconsulting.com>.
How does a calling application override the message, if they wish?
On 2/3/07, Phil Steitz <ph...@gmail.com> wrote:
> On 2/3/07, James Carman <ja...@carmanconsulting.com> wrote:
> >
> > Well, I wouldn't even provide a getMessage(Locale). I'd leave it up
> > to the running application to resolve the message. For instance, in
> > Tapestry, it doesn't use resource bundles to localize messages, at
> > least not directly in application code. It uses a special Messages
> > object. So, I would provide getKey()/getParameters() methods only and
> > leave it up to the containing application to localize the text. That
> > way, they can give some context to the error message instead of
> > relying upon us to be general enough.
>
>
> The problem with that is that generic handlers that display messages would
> not work. I like the idea of carrying the data along, though and exposing
> it, as well as providing translate (see
> http://svn.apache.org/viewvc/jakarta/commons/proper/math/trunk/src/mantissa/src/org/spaceroots/mantissa/MantissaException.java?view=markup
> )
> and getMessage(Locale) methods. That gives client apps the most
> flexibility. What do you think, Luc?
>
> Phil
>
> On 2/3/07, Niall Pemberton <ni...@gmail.com> wrote:
> > > On 2/3/07, Phil Steitz <ph...@gmail.com> wrote:
> > > > On 1/30/07, luc.maisonobe@free.fr <lu...@free.fr> wrote:
> > > > >
> > > > > Craig McClanahan wrote:
> > > > >
> > > > >
> > > > > > I'm late to the table on this thread, and only care about the
> > Commons
> > > > > > libraries I care about :-)
> > > > >
> > > > > Thanks for your interest in this thread.
> > > > >
> > > > > > but you should be aware that this attitude will
> > > > > > disqualify the use of such libraries from use within code from
> > > > > organizations
> > > > > > that have strict rules about implementing localization. I work
> > for such
> > > > > an
> > > > > > organization (Sun) ... the key rules are that any message that
> > might be
> > > > > > visible to users *must* be localizable.
> > > > >
> > > > > I agree with you and thought localization should be provided by the
> > layer
> > > > > which
> > > > > provides the message. Other people think this should be done at
> > > > > application
> > > > > level, if done at all.
> > > > >
> > > > > > For log messages, that tends to translate into a straightforward
> > policy
> > > > > that
> > > > > > DEBUG and TRACE type messages do not need to be localized, but
> > anything
> > > > > from
> > > > > > INFO level above must be. The issue for exception messages is a
> > bit
> > > > > more
> > > > > > interesting. How does the library developer know whether or not
> > the
> > > > > message
> > > > > > part of the exception will be displayed to end users? From a
> > pragmatic
> > > > > > viewpoint, you can pretty much assume this will happen with
> > exceptions
> > > > > in
> > > > > > webapps, while many Swing apps will hide that sort of stuff to
> > some
> > > > > degree.
> > > > >
> > > > > I think that since low level components may be used almost anywhere,
> > their
> > > > > messages *may* be displayed and this sole possibility is enough to
> > justify
> > > > > a
> > > > > localized version should be made available. If the application gets
> > an
> > > > > error it
> > > > > really doesn't know about, it can simply display it.
> > > > >
> > > > > > But, as a bottom line, if I'm interested in maximum adoption of a
> > > > > Commons
> > > > > > library I work on, I will diligently ensure that exception
> > messages are
> > > > > > localizable :-).
> > > > >
> > > > > When I first started this long thread, I thought the need for
> > localized
> > > > > error
> > > > > messages as provided by exceptions was acknowledged by everyone and
> > asked
> > > > > for
> > > > > the way to implement it, starting from a simple one which already
> > works. I
> > > > > was
> > > > > wrong. The disagreement started about the need itself and slipped to
> > the
> > > > > level
> > > > > at which implementation should be done.
> > > > >
> > > > > I would really like to reach a compromise on this issue, something
> > that
> > > > > could by
> > > > > accepted by everybody. I don't want to get banned with a -1 on a
> > commit,
> > > > > but at
> > > > > least a few people would like localized error messages that can be
> > simply
> > > > > forwarded upward from lower layers to upper layer for display
> > without
> > > > > processing. Standard java already provides
> > Throwable.getLocalizedMessage()
> > > > > since
> > > > > JDK 1.1. I could set up for [math] only an exception hierarchy that
> > only
> > > > > add a
> > > > > few constructors and an implementation of this method without any
> > change
> > > > > in the
> > > > > Throwable.getMessage() behaviour. Does this sound reasonable ?
> > > >
> > > >
> > > > Sorry I was out of pocket this week and could not reiterate my
> > personal +1
> > > > for moving forward as you suggest, Luc. I will add a few of more
> > comments
> > > > below. If anyone still has serious reservations - especially those
> > who now
> > > > or in the future may contribute to [math] - pls speak up; otherwise
> > we can
> > > > move on. Thanks to all who provided comments.
> > > >
> > > > 1) My initial +1 was based on the fact that the error management that
> > you
> > > > need to support this approach is in fact there in Mantissa and if you
> > > > *don't* support localization when text is being generated, you either
> > need
> > > > to get into nonsense like parsing and translating error messages,
> > > > complicating your exceptions hierarchy, or losing/hiding information
> > at
> > > > higher levels. If you do the work to localize when the string is
> > generated,
> > > > that gives a choice at higher levels, which to me is goodness
> > (assuming you
> > > > are prepared to do the work and the implementation is robust against
> > missing
> > > > bundles, etc.).
> > > >
> > > > 2) Commons math generates error messages now, and should generate
> > better
> > > > messages (as Mantissa does) in the future that using applications may
> > want
> > > > to display to end users or in application logs. I would like for
> > those
> > > > messages to be localizable. If one of our solvers does not converge
> > because
> > > > initial values do not bracket a root, for example, I would like the
> > > > developer of a localized client application that uses the solver to be
> > able
> > > > to display that message directly in a log or to the user. Whether or
> > not
> > > > logging is good or bad is completely irrelevant to this discussion.
> > > >
> > > > 3) Apache is a do-ocracy and we have a proposal before us to
> > significantly
> > > > improve exception management and error reporting in [math] by
> > extending and
> > > > leveraging the framework in Mantissa. Luc is volunteering to do this
> > and
> > > > the only other active contributor to [math] who has chimed in (yours
> > truly)
> > > > is also in favor. The arguments against are either it is too much
> > work to
> > > > implement exception error message localization or it may not be
> > robust. Luc
> > > > is stepping up to *do* the work (actually, leverage work already
> > mostly done
> > > > in Mantissa) and I don't see robustness or performance risk in what he
> > has
> > > > implemented. Pls speak up if I am missing something in the latter
> > case.
> > > > Therefore, appreciating the feedback from others and reservations
> > about
> > > > applying across commons, for [math] we should let Luc JFDI - i.e.,
> > move
> > > > forward with the proposal.
> > >
> > > +1 to those that do the work decide the direction.
> > >
> > > The only comment I would make is that there are two scenarios for
> > > application localization in terms of the user - single or multiple.
> > > Single being your application runs in one Locale only and multiple
> > > where you have users with different Locale. If you want to cater for
> > > the later then the exceptions should contain keys/replacement values
> > > and message be resolved when the user's Locale is known - which I
> > > think is James Carman's suggestion. Messages could be resolved outside
> > > of Math or you could provide a getMessage(Locale) method in your
> > > exceptions.
> > >
> > > Niall
> > >
> > > > Thanks again, all, for this interesting discussion and thanks, Luc,
> > for
> > > > helping make [math] more localization-friendly.
> > > >
> > > > Phil
> > > >
> > > > Luc
> > >
> > > ---------------------------------------------------------------------
> > > To unsubscribe, e-mail: commons-dev-unsubscribe@jakarta.apache.org
> > > For additional commands, e-mail: commons-dev-help@jakarta.apache.org
> > >
> > >
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: commons-dev-unsubscribe@jakarta.apache.org
> > For additional commands, e-mail: commons-dev-help@jakarta.apache.org
> >
> >
>
>
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Re: [all] exceptions and localization
Posted by James Carman <ja...@carmanconsulting.com>.
Why not getMessage(ResourceBundle) so that the client apps can use
their own resource bundle if they wish? Or, provide a common
interface and "adaptors" that adapt different i18n mechanisms to your
paradigm. So, you'd have:
String getMessage( MessageSource src );
And, you'd have different "flavors" of MessageSource, one for
ResourceBundles, one for HiveMind messages, one for commons i18n, etc.
On 2/3/07, Phil Steitz <ph...@gmail.com> wrote:
> On 2/3/07, James Carman <ja...@carmanconsulting.com> wrote:
> >
> > Well, I wouldn't even provide a getMessage(Locale). I'd leave it up
> > to the running application to resolve the message. For instance, in
> > Tapestry, it doesn't use resource bundles to localize messages, at
> > least not directly in application code. It uses a special Messages
> > object. So, I would provide getKey()/getParameters() methods only and
> > leave it up to the containing application to localize the text. That
> > way, they can give some context to the error message instead of
> > relying upon us to be general enough.
>
>
> The problem with that is that generic handlers that display messages would
> not work. I like the idea of carrying the data along, though and exposing
> it, as well as providing translate (see
> http://svn.apache.org/viewvc/jakarta/commons/proper/math/trunk/src/mantissa/src/org/spaceroots/mantissa/MantissaException.java?view=markup
> )
> and getMessage(Locale) methods. That gives client apps the most
> flexibility. What do you think, Luc?
>
> Phil
>
> On 2/3/07, Niall Pemberton <ni...@gmail.com> wrote:
> > > On 2/3/07, Phil Steitz <ph...@gmail.com> wrote:
> > > > On 1/30/07, luc.maisonobe@free.fr <lu...@free.fr> wrote:
> > > > >
> > > > > Craig McClanahan wrote:
> > > > >
> > > > >
> > > > > > I'm late to the table on this thread, and only care about the
> > Commons
> > > > > > libraries I care about :-)
> > > > >
> > > > > Thanks for your interest in this thread.
> > > > >
> > > > > > but you should be aware that this attitude will
> > > > > > disqualify the use of such libraries from use within code from
> > > > > organizations
> > > > > > that have strict rules about implementing localization. I work
> > for such
> > > > > an
> > > > > > organization (Sun) ... the key rules are that any message that
> > might be
> > > > > > visible to users *must* be localizable.
> > > > >
> > > > > I agree with you and thought localization should be provided by the
> > layer
> > > > > which
> > > > > provides the message. Other people think this should be done at
> > > > > application
> > > > > level, if done at all.
> > > > >
> > > > > > For log messages, that tends to translate into a straightforward
> > policy
> > > > > that
> > > > > > DEBUG and TRACE type messages do not need to be localized, but
> > anything
> > > > > from
> > > > > > INFO level above must be. The issue for exception messages is a
> > bit
> > > > > more
> > > > > > interesting. How does the library developer know whether or not
> > the
> > > > > message
> > > > > > part of the exception will be displayed to end users? From a
> > pragmatic
> > > > > > viewpoint, you can pretty much assume this will happen with
> > exceptions
> > > > > in
> > > > > > webapps, while many Swing apps will hide that sort of stuff to
> > some
> > > > > degree.
> > > > >
> > > > > I think that since low level components may be used almost anywhere,
> > their
> > > > > messages *may* be displayed and this sole possibility is enough to
> > justify
> > > > > a
> > > > > localized version should be made available. If the application gets
> > an
> > > > > error it
> > > > > really doesn't know about, it can simply display it.
> > > > >
> > > > > > But, as a bottom line, if I'm interested in maximum adoption of a
> > > > > Commons
> > > > > > library I work on, I will diligently ensure that exception
> > messages are
> > > > > > localizable :-).
> > > > >
> > > > > When I first started this long thread, I thought the need for
> > localized
> > > > > error
> > > > > messages as provided by exceptions was acknowledged by everyone and
> > asked
> > > > > for
> > > > > the way to implement it, starting from a simple one which already
> > works. I
> > > > > was
> > > > > wrong. The disagreement started about the need itself and slipped to
> > the
> > > > > level
> > > > > at which implementation should be done.
> > > > >
> > > > > I would really like to reach a compromise on this issue, something
> > that
> > > > > could by
> > > > > accepted by everybody. I don't want to get banned with a -1 on a
> > commit,
> > > > > but at
> > > > > least a few people would like localized error messages that can be
> > simply
> > > > > forwarded upward from lower layers to upper layer for display
> > without
> > > > > processing. Standard java already provides
> > Throwable.getLocalizedMessage()
> > > > > since
> > > > > JDK 1.1. I could set up for [math] only an exception hierarchy that
> > only
> > > > > add a
> > > > > few constructors and an implementation of this method without any
> > change
> > > > > in the
> > > > > Throwable.getMessage() behaviour. Does this sound reasonable ?
> > > >
> > > >
> > > > Sorry I was out of pocket this week and could not reiterate my
> > personal +1
> > > > for moving forward as you suggest, Luc. I will add a few of more
> > comments
> > > > below. If anyone still has serious reservations - especially those
> > who now
> > > > or in the future may contribute to [math] - pls speak up; otherwise
> > we can
> > > > move on. Thanks to all who provided comments.
> > > >
> > > > 1) My initial +1 was based on the fact that the error management that
> > you
> > > > need to support this approach is in fact there in Mantissa and if you
> > > > *don't* support localization when text is being generated, you either
> > need
> > > > to get into nonsense like parsing and translating error messages,
> > > > complicating your exceptions hierarchy, or losing/hiding information
> > at
> > > > higher levels. If you do the work to localize when the string is
> > generated,
> > > > that gives a choice at higher levels, which to me is goodness
> > (assuming you
> > > > are prepared to do the work and the implementation is robust against
> > missing
> > > > bundles, etc.).
> > > >
> > > > 2) Commons math generates error messages now, and should generate
> > better
> > > > messages (as Mantissa does) in the future that using applications may
> > want
> > > > to display to end users or in application logs. I would like for
> > those
> > > > messages to be localizable. If one of our solvers does not converge
> > because
> > > > initial values do not bracket a root, for example, I would like the
> > > > developer of a localized client application that uses the solver to be
> > able
> > > > to display that message directly in a log or to the user. Whether or
> > not
> > > > logging is good or bad is completely irrelevant to this discussion.
> > > >
> > > > 3) Apache is a do-ocracy and we have a proposal before us to
> > significantly
> > > > improve exception management and error reporting in [math] by
> > extending and
> > > > leveraging the framework in Mantissa. Luc is volunteering to do this
> > and
> > > > the only other active contributor to [math] who has chimed in (yours
> > truly)
> > > > is also in favor. The arguments against are either it is too much
> > work to
> > > > implement exception error message localization or it may not be
> > robust. Luc
> > > > is stepping up to *do* the work (actually, leverage work already
> > mostly done
> > > > in Mantissa) and I don't see robustness or performance risk in what he
> > has
> > > > implemented. Pls speak up if I am missing something in the latter
> > case.
> > > > Therefore, appreciating the feedback from others and reservations
> > about
> > > > applying across commons, for [math] we should let Luc JFDI - i.e.,
> > move
> > > > forward with the proposal.
> > >
> > > +1 to those that do the work decide the direction.
> > >
> > > The only comment I would make is that there are two scenarios for
> > > application localization in terms of the user - single or multiple.
> > > Single being your application runs in one Locale only and multiple
> > > where you have users with different Locale. If you want to cater for
> > > the later then the exceptions should contain keys/replacement values
> > > and message be resolved when the user's Locale is known - which I
> > > think is James Carman's suggestion. Messages could be resolved outside
> > > of Math or you could provide a getMessage(Locale) method in your
> > > exceptions.
> > >
> > > Niall
> > >
> > > > Thanks again, all, for this interesting discussion and thanks, Luc,
> > for
> > > > helping make [math] more localization-friendly.
> > > >
> > > > Phil
> > > >
> > > > Luc
> > >
> > > ---------------------------------------------------------------------
> > > To unsubscribe, e-mail: commons-dev-unsubscribe@jakarta.apache.org
> > > For additional commands, e-mail: commons-dev-help@jakarta.apache.org
> > >
> > >
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: commons-dev-unsubscribe@jakarta.apache.org
> > For additional commands, e-mail: commons-dev-help@jakarta.apache.org
> >
> >
>
>
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Re: [all] exceptions and localization
Posted by James Carman <ja...@carmanconsulting.com>.
I agree with Stephen that the commons libraries probably don't need
this type of support. They aren't doing anything that's "businessy"
enough (and they're not supposed to) to make it relevant to the user
(the user doesn't care that I'm using StringUtils to eat the white
space out of a String). My point was that if you *are* going to do
it, at least make it easy to extend/adapt.
I don't necessarily agree that the exceptions aren't used to convey
information to the user. As I've said, I use a BusinessLogicException
class in my code sometimes. I do this so that I don't have to come up
with many different exception types (UsernameAlreadyExistsException,
InsufficientFundsException, etc.) that really add no logic, but just
let me know something different is going on. I can use localized
messages for that case.
On 2/4/07, Stephen Colebourne <sc...@btopenworld.com> wrote:
> I'm sorry, but I find this extremely complicated and unreasonable. It
> really, really, really isn't a direction I want commons to take.
>
> Firstly, the use of a static will annoy the IoC (Spring) crowd, so that
> aspect of the proposal seems flawed.
>
> Secondly, this proposes adding a whole ream of new interfaces, classes,
> resources, factories and strategies to achieve this. All of this
> additional code will need to be documented in detail, with explanations
> of how to customise each part.
>
> Thirdly, we can be sure that you haven't met all the weird requirements
> that the users of the library will come up with. They will start asking
> for changes which will add even more bloat.
>
> Fourthly, since none of this is standard, each commons library will
> probably do it slightly differently, making using all of them together
> nigh on impossible.
>
>
> Let me be clear, this is a (mostly) well-designed solution to the
> perceived set of requirements. Its just that the requirements are in my
> view completely inappropriate.
>
> Exceptions are a programming tool. They are used by developers. They are
> not intended for user interaction. Ever.
>
> Adding ANY kind of localization behaviour to [math] or any other commons
> component is completely OUT OF SCOPE!!! [math] is a library of
> mathematics routines. Under no circumstances should I need to know or
> learn or have to worry about this or that localized configuration.
> Localization is completely orthogonal to the concept of well-tested
> robust mathematical routines.
>
> Finally, what is being proposed here is the creation of a FRAMEWORK. I
> am so opposed to this because I believe it is the antithesis of what the
> best commons components are, which is LIBRARIES.
>
> A library is simple. It does what it says it does. Without complication
> or need to buy into its specific religion.
>
> A framework is religious. You have to agree to its terms, and its way of
> doing things. Or choose not to use it.
>
> Commons has done pretty well in resisting the complications and
> religions of frameworks - we are a repository of libraries.
>
>
> So, what is appropriate?
>
> It is good to have multiple different exception classes, even as many as
> one for each different possible error.
>
> It is also good for those classes to store the data that caused the
> error as instance variables accessed by get methods.
> (http://joda-time.sourceforge.net/xref/org/joda/time/IllegalFieldValueException.html)
>
> But they should only have one error message, and no way to localize it
> (ie. there should be no error code for looking up resources). That is
> the role of the application/framework that embeds the library - and it
> can use the exception classname and get methods to access the data if
> required. Why? because every application/framework that does want to
> localize wants to do it differently. And in all probability, 90%+ of
> applications/frameworks don't want to localize at all.
>
> Stephen
>
>
> Luc Maisonobe wrote:
> > Two main classes would be used: the MathException base class and a
> > MessageFactory base class. MathException would delegate to
> > MessageFactory the task to build the message from its String key and
> > Object[] parameters (point 2). Both the key, parameters and message
> > would be available with appropriate getters (point 4 and 5). A static
> > method in MathException would allow upper layers to prepend a customized
> > MessageFactory instance (point 1) in front of already registered
> > factories following a chain of responsibility. The initial chain would
> > contain three different MessageFactory instances :
> > - a LocalizedMessageFactory using the key to retrieve a pattern from
> > a ResourceBundle for the default Locale (Locale.geDefault()) and
> > MessageFormat to build the message (point 3)
> > - a NonLocalizedMessageFactory using the key directly as a pattern
> > for MessageFormat
> > - a RawMessageFormat simply concatenating everything with toString
> >
> > The chain of responsibility is intended to provide robustness (point 6):
> > the first message factory providing a non null message is used. If a
> > factory fails, the next one is used. The last factory cannot fail.
> >
> > A user who simply wants to get messages localized for a Locale which is
> > not the default one would therefore only need to do :
> >
> > MathException.prependMessageFactory(new
> > LocalizedMessageFactory(myLocale));
> >
> > This would work even if its locale is not supported as its factory would
> > always fail but the following ones would be triggered as needed.
> >
> > I think an appropriate policy would be to always use US-english patterns
> > as keys as it would allow to get meaningful messages even if everything
> > else fails, and as it would help the translators tasks.
>
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>
>
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Re: [all] exceptions and localization
Posted by Stephen Colebourne <sc...@btopenworld.com>.
I'm sorry, but I find this extremely complicated and unreasonable. It
really, really, really isn't a direction I want commons to take.
Firstly, the use of a static will annoy the IoC (Spring) crowd, so that
aspect of the proposal seems flawed.
Secondly, this proposes adding a whole ream of new interfaces, classes,
resources, factories and strategies to achieve this. All of this
additional code will need to be documented in detail, with explanations
of how to customise each part.
Thirdly, we can be sure that you haven't met all the weird requirements
that the users of the library will come up with. They will start asking
for changes which will add even more bloat.
Fourthly, since none of this is standard, each commons library will
probably do it slightly differently, making using all of them together
nigh on impossible.
Let me be clear, this is a (mostly) well-designed solution to the
perceived set of requirements. Its just that the requirements are in my
view completely inappropriate.
Exceptions are a programming tool. They are used by developers. They are
not intended for user interaction. Ever.
Adding ANY kind of localization behaviour to [math] or any other commons
component is completely OUT OF SCOPE!!! [math] is a library of
mathematics routines. Under no circumstances should I need to know or
learn or have to worry about this or that localized configuration.
Localization is completely orthogonal to the concept of well-tested
robust mathematical routines.
Finally, what is being proposed here is the creation of a FRAMEWORK. I
am so opposed to this because I believe it is the antithesis of what the
best commons components are, which is LIBRARIES.
A library is simple. It does what it says it does. Without complication
or need to buy into its specific religion.
A framework is religious. You have to agree to its terms, and its way of
doing things. Or choose not to use it.
Commons has done pretty well in resisting the complications and
religions of frameworks - we are a repository of libraries.
So, what is appropriate?
It is good to have multiple different exception classes, even as many as
one for each different possible error.
It is also good for those classes to store the data that caused the
error as instance variables accessed by get methods.
(http://joda-time.sourceforge.net/xref/org/joda/time/IllegalFieldValueException.html)
But they should only have one error message, and no way to localize it
(ie. there should be no error code for looking up resources). That is
the role of the application/framework that embeds the library - and it
can use the exception classname and get methods to access the data if
required. Why? because every application/framework that does want to
localize wants to do it differently. And in all probability, 90%+ of
applications/frameworks don't want to localize at all.
Stephen
Luc Maisonobe wrote:
> Two main classes would be used: the MathException base class and a
> MessageFactory base class. MathException would delegate to
> MessageFactory the task to build the message from its String key and
> Object[] parameters (point 2). Both the key, parameters and message
> would be available with appropriate getters (point 4 and 5). A static
> method in MathException would allow upper layers to prepend a customized
> MessageFactory instance (point 1) in front of already registered
> factories following a chain of responsibility. The initial chain would
> contain three different MessageFactory instances :
> - a LocalizedMessageFactory using the key to retrieve a pattern from
> a ResourceBundle for the default Locale (Locale.geDefault()) and
> MessageFormat to build the message (point 3)
> - a NonLocalizedMessageFactory using the key directly as a pattern
> for MessageFormat
> - a RawMessageFormat simply concatenating everything with toString
>
> The chain of responsibility is intended to provide robustness (point 6):
> the first message factory providing a non null message is used. If a
> factory fails, the next one is used. The last factory cannot fail.
>
> A user who simply wants to get messages localized for a Locale which is
> not the default one would therefore only need to do :
>
> MathException.prependMessageFactory(new
> LocalizedMessageFactory(myLocale));
>
> This would work even if its locale is not supported as its factory would
> always fail but the following ones would be triggered as needed.
>
> I think an appropriate policy would be to always use US-english patterns
> as keys as it would allow to get meaningful messages even if everything
> else fails, and as it would help the translators tasks.
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Re: [all] exceptions and localization
Posted by Luc Maisonobe <Lu...@free.fr>.
Phil Steitz wrote :
> My recommendation is that we just modify the Mantissa class to
> expose the key and parts (so add members for them) and add
> getMessage(Locale). That is simple, not far from what we already have, and
> sufficient to meet localization needs and support other sorts of processing
> for clients who want to do that.
OK. I'll do that.
Luc
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Re: [all] exceptions and localization
Posted by Phil Steitz <ph...@gmail.com>.
On 2/4/07, Luc Maisonobe <Lu...@free.fr> wrote:
>
> Phil Steitz wrote :
> >
> > The problem with that is that generic handlers that display messages
> would
> > not work. I like the idea of carrying the data along, though and
> exposing
> > it, as well as providing translate (see
> >
> http://svn.apache.org/viewvc/jakarta/commons/proper/math/trunk/src/mantissa/src/org/spaceroots/mantissa/MantissaException.java?view=markup
> >
> >
> > )
> > and getMessage(Locale) methods. That gives client apps the most
> > flexibility. What do you think, Luc?
>
> Trying to synthetize all use cases, here is what I think is expected by
> everyone who has expressed views :
>
> 1) allow application level code to contribute to/configure message
> building
> 2) allow low layers to build messages with variable parts
> 3) allow localized messages
> 4) expose message parts (key and parameters)
> 5) allow handlers using only no arguments getMessage() to work as usual
> 6) use a mechanism robust enough to work even in case of code changes
> and missing localization data (of course in degraded, i.e. non
> localized
> mode)
>
> The following proposal is an attempt to address all these points.
>
> Two main classes would be used: the MathException base class and a
> MessageFactory base class. MathException would delegate to
> MessageFactory the task to build the message from its String key and
> Object[] parameters (point 2). Both the key, parameters and message
> would be available with appropriate getters (point 4 and 5). A static
> method in MathException would allow upper layers to prepend a customized
> MessageFactory instance (point 1) in front of already registered
> factories following a chain of responsibility. The initial chain would
> contain three different MessageFactory instances :
> - a LocalizedMessageFactory using the key to retrieve a pattern from
> a ResourceBundle for the default Locale (Locale.geDefault()) and
> MessageFormat to build the message (point 3)
> - a NonLocalizedMessageFactory using the key directly as a pattern
> for MessageFormat
> - a RawMessageFormat simply concatenating everything with toString
>
> The chain of responsibility is intended to provide robustness (point 6):
> the first message factory providing a non null message is used. If a
> factory fails, the next one is used. The last factory cannot fail.
>
> A user who simply wants to get messages localized for a Locale which is
> not the default one would therefore only need to do :
>
> MathException.prependMessageFactory(new
> LocalizedMessageFactory(myLocale));
>
> This would work even if its locale is not supported as its factory would
> always fail but the following ones would be triggered as needed.
>
> I think an appropriate policy would be to always use US-english patterns
> as keys as it would allow to get meaningful messages even if everything
> else fails, and as it would help the translators tasks.
>
> Does this seems sensible ?
I don't think we are going to please everyone here, Luc, and I agree with
Stephen that we don't want to over-complicate or get into the
framework-building business, but I disagree with the statement that we
should make localization impossible in generating strings (even exception
messages). My recommendation is that we just modify the Mantissa class to
expose the key and parts (so add members for them) and add
getMessage(Locale). That is simple, not far from what we already have, and
sufficient to meet localization needs and support other sorts of processing
for clients who want to do that.
Phil
Re: [all] exceptions and localization
Posted by Luc Maisonobe <Lu...@free.fr>.
Phil Steitz wrote :
>
> The problem with that is that generic handlers that display messages would
> not work. I like the idea of carrying the data along, though and exposing
> it, as well as providing translate (see
> http://svn.apache.org/viewvc/jakarta/commons/proper/math/trunk/src/mantissa/src/org/spaceroots/mantissa/MantissaException.java?view=markup
>
>
> )
> and getMessage(Locale) methods. That gives client apps the most
> flexibility. What do you think, Luc?
Trying to synthetize all use cases, here is what I think is expected by
everyone who has expressed views :
1) allow application level code to contribute to/configure message
building
2) allow low layers to build messages with variable parts
3) allow localized messages
4) expose message parts (key and parameters)
5) allow handlers using only no arguments getMessage() to work as usual
6) use a mechanism robust enough to work even in case of code changes
and missing localization data (of course in degraded, i.e. non
localized
mode)
The following proposal is an attempt to address all these points.
Two main classes would be used: the MathException base class and a
MessageFactory base class. MathException would delegate to
MessageFactory the task to build the message from its String key and
Object[] parameters (point 2). Both the key, parameters and message
would be available with appropriate getters (point 4 and 5). A static
method in MathException would allow upper layers to prepend a customized
MessageFactory instance (point 1) in front of already registered
factories following a chain of responsibility. The initial chain would
contain three different MessageFactory instances :
- a LocalizedMessageFactory using the key to retrieve a pattern from
a ResourceBundle for the default Locale (Locale.geDefault()) and
MessageFormat to build the message (point 3)
- a NonLocalizedMessageFactory using the key directly as a pattern
for MessageFormat
- a RawMessageFormat simply concatenating everything with toString
The chain of responsibility is intended to provide robustness (point 6):
the first message factory providing a non null message is used. If a
factory fails, the next one is used. The last factory cannot fail.
A user who simply wants to get messages localized for a Locale which is
not the default one would therefore only need to do :
MathException.prependMessageFactory(new
LocalizedMessageFactory(myLocale));
This would work even if its locale is not supported as its factory would
always fail but the following ones would be triggered as needed.
I think an appropriate policy would be to always use US-english patterns
as keys as it would allow to get meaningful messages even if everything
else fails, and as it would help the translators tasks.
Does this seems sensible ?
Luc
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Re: [all] exceptions and localization
Posted by Phil Steitz <ph...@gmail.com>.
On 2/3/07, James Carman <ja...@carmanconsulting.com> wrote:
>
> Well, I wouldn't even provide a getMessage(Locale). I'd leave it up
> to the running application to resolve the message. For instance, in
> Tapestry, it doesn't use resource bundles to localize messages, at
> least not directly in application code. It uses a special Messages
> object. So, I would provide getKey()/getParameters() methods only and
> leave it up to the containing application to localize the text. That
> way, they can give some context to the error message instead of
> relying upon us to be general enough.
The problem with that is that generic handlers that display messages would
not work. I like the idea of carrying the data along, though and exposing
it, as well as providing translate (see
http://svn.apache.org/viewvc/jakarta/commons/proper/math/trunk/src/mantissa/src/org/spaceroots/mantissa/MantissaException.java?view=markup
)
and getMessage(Locale) methods. That gives client apps the most
flexibility. What do you think, Luc?
Phil
On 2/3/07, Niall Pemberton <ni...@gmail.com> wrote:
> > On 2/3/07, Phil Steitz <ph...@gmail.com> wrote:
> > > On 1/30/07, luc.maisonobe@free.fr <lu...@free.fr> wrote:
> > > >
> > > > Craig McClanahan wrote:
> > > >
> > > >
> > > > > I'm late to the table on this thread, and only care about the
> Commons
> > > > > libraries I care about :-)
> > > >
> > > > Thanks for your interest in this thread.
> > > >
> > > > > but you should be aware that this attitude will
> > > > > disqualify the use of such libraries from use within code from
> > > > organizations
> > > > > that have strict rules about implementing localization. I work
> for such
> > > > an
> > > > > organization (Sun) ... the key rules are that any message that
> might be
> > > > > visible to users *must* be localizable.
> > > >
> > > > I agree with you and thought localization should be provided by the
> layer
> > > > which
> > > > provides the message. Other people think this should be done at
> > > > application
> > > > level, if done at all.
> > > >
> > > > > For log messages, that tends to translate into a straightforward
> policy
> > > > that
> > > > > DEBUG and TRACE type messages do not need to be localized, but
> anything
> > > > from
> > > > > INFO level above must be. The issue for exception messages is a
> bit
> > > > more
> > > > > interesting. How does the library developer know whether or not
> the
> > > > message
> > > > > part of the exception will be displayed to end users? From a
> pragmatic
> > > > > viewpoint, you can pretty much assume this will happen with
> exceptions
> > > > in
> > > > > webapps, while many Swing apps will hide that sort of stuff to
> some
> > > > degree.
> > > >
> > > > I think that since low level components may be used almost anywhere,
> their
> > > > messages *may* be displayed and this sole possibility is enough to
> justify
> > > > a
> > > > localized version should be made available. If the application gets
> an
> > > > error it
> > > > really doesn't know about, it can simply display it.
> > > >
> > > > > But, as a bottom line, if I'm interested in maximum adoption of a
> > > > Commons
> > > > > library I work on, I will diligently ensure that exception
> messages are
> > > > > localizable :-).
> > > >
> > > > When I first started this long thread, I thought the need for
> localized
> > > > error
> > > > messages as provided by exceptions was acknowledged by everyone and
> asked
> > > > for
> > > > the way to implement it, starting from a simple one which already
> works. I
> > > > was
> > > > wrong. The disagreement started about the need itself and slipped to
> the
> > > > level
> > > > at which implementation should be done.
> > > >
> > > > I would really like to reach a compromise on this issue, something
> that
> > > > could by
> > > > accepted by everybody. I don't want to get banned with a -1 on a
> commit,
> > > > but at
> > > > least a few people would like localized error messages that can be
> simply
> > > > forwarded upward from lower layers to upper layer for display
> without
> > > > processing. Standard java already provides
> Throwable.getLocalizedMessage()
> > > > since
> > > > JDK 1.1. I could set up for [math] only an exception hierarchy that
> only
> > > > add a
> > > > few constructors and an implementation of this method without any
> change
> > > > in the
> > > > Throwable.getMessage() behaviour. Does this sound reasonable ?
> > >
> > >
> > > Sorry I was out of pocket this week and could not reiterate my
> personal +1
> > > for moving forward as you suggest, Luc. I will add a few of more
> comments
> > > below. If anyone still has serious reservations - especially those
> who now
> > > or in the future may contribute to [math] - pls speak up; otherwise
> we can
> > > move on. Thanks to all who provided comments.
> > >
> > > 1) My initial +1 was based on the fact that the error management that
> you
> > > need to support this approach is in fact there in Mantissa and if you
> > > *don't* support localization when text is being generated, you either
> need
> > > to get into nonsense like parsing and translating error messages,
> > > complicating your exceptions hierarchy, or losing/hiding information
> at
> > > higher levels. If you do the work to localize when the string is
> generated,
> > > that gives a choice at higher levels, which to me is goodness
> (assuming you
> > > are prepared to do the work and the implementation is robust against
> missing
> > > bundles, etc.).
> > >
> > > 2) Commons math generates error messages now, and should generate
> better
> > > messages (as Mantissa does) in the future that using applications may
> want
> > > to display to end users or in application logs. I would like for
> those
> > > messages to be localizable. If one of our solvers does not converge
> because
> > > initial values do not bracket a root, for example, I would like the
> > > developer of a localized client application that uses the solver to be
> able
> > > to display that message directly in a log or to the user. Whether or
> not
> > > logging is good or bad is completely irrelevant to this discussion.
> > >
> > > 3) Apache is a do-ocracy and we have a proposal before us to
> significantly
> > > improve exception management and error reporting in [math] by
> extending and
> > > leveraging the framework in Mantissa. Luc is volunteering to do this
> and
> > > the only other active contributor to [math] who has chimed in (yours
> truly)
> > > is also in favor. The arguments against are either it is too much
> work to
> > > implement exception error message localization or it may not be
> robust. Luc
> > > is stepping up to *do* the work (actually, leverage work already
> mostly done
> > > in Mantissa) and I don't see robustness or performance risk in what he
> has
> > > implemented. Pls speak up if I am missing something in the latter
> case.
> > > Therefore, appreciating the feedback from others and reservations
> about
> > > applying across commons, for [math] we should let Luc JFDI - i.e.,
> move
> > > forward with the proposal.
> >
> > +1 to those that do the work decide the direction.
> >
> > The only comment I would make is that there are two scenarios for
> > application localization in terms of the user - single or multiple.
> > Single being your application runs in one Locale only and multiple
> > where you have users with different Locale. If you want to cater for
> > the later then the exceptions should contain keys/replacement values
> > and message be resolved when the user's Locale is known - which I
> > think is James Carman's suggestion. Messages could be resolved outside
> > of Math or you could provide a getMessage(Locale) method in your
> > exceptions.
> >
> > Niall
> >
> > > Thanks again, all, for this interesting discussion and thanks, Luc,
> for
> > > helping make [math] more localization-friendly.
> > >
> > > Phil
> > >
> > > Luc
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: commons-dev-unsubscribe@jakarta.apache.org
> > For additional commands, e-mail: commons-dev-help@jakarta.apache.org
> >
> >
>
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>
>
Re: [all] exceptions and localization
Posted by James Carman <ja...@carmanconsulting.com>.
Well, I wouldn't even provide a getMessage(Locale). I'd leave it up
to the running application to resolve the message. For instance, in
Tapestry, it doesn't use resource bundles to localize messages, at
least not directly in application code. It uses a special Messages
object. So, I would provide getKey()/getParameters() methods only and
leave it up to the containing application to localize the text. That
way, they can give some context to the error message instead of
relying upon us to be general enough.
On 2/3/07, Niall Pemberton <ni...@gmail.com> wrote:
> On 2/3/07, Phil Steitz <ph...@gmail.com> wrote:
> > On 1/30/07, luc.maisonobe@free.fr <lu...@free.fr> wrote:
> > >
> > > Craig McClanahan wrote:
> > >
> > >
> > > > I'm late to the table on this thread, and only care about the Commons
> > > > libraries I care about :-)
> > >
> > > Thanks for your interest in this thread.
> > >
> > > > but you should be aware that this attitude will
> > > > disqualify the use of such libraries from use within code from
> > > organizations
> > > > that have strict rules about implementing localization. I work for such
> > > an
> > > > organization (Sun) ... the key rules are that any message that might be
> > > > visible to users *must* be localizable.
> > >
> > > I agree with you and thought localization should be provided by the layer
> > > which
> > > provides the message. Other people think this should be done at
> > > application
> > > level, if done at all.
> > >
> > > > For log messages, that tends to translate into a straightforward policy
> > > that
> > > > DEBUG and TRACE type messages do not need to be localized, but anything
> > > from
> > > > INFO level above must be. The issue for exception messages is a bit
> > > more
> > > > interesting. How does the library developer know whether or not the
> > > message
> > > > part of the exception will be displayed to end users? From a pragmatic
> > > > viewpoint, you can pretty much assume this will happen with exceptions
> > > in
> > > > webapps, while many Swing apps will hide that sort of stuff to some
> > > degree.
> > >
> > > I think that since low level components may be used almost anywhere, their
> > > messages *may* be displayed and this sole possibility is enough to justify
> > > a
> > > localized version should be made available. If the application gets an
> > > error it
> > > really doesn't know about, it can simply display it.
> > >
> > > > But, as a bottom line, if I'm interested in maximum adoption of a
> > > Commons
> > > > library I work on, I will diligently ensure that exception messages are
> > > > localizable :-).
> > >
> > > When I first started this long thread, I thought the need for localized
> > > error
> > > messages as provided by exceptions was acknowledged by everyone and asked
> > > for
> > > the way to implement it, starting from a simple one which already works. I
> > > was
> > > wrong. The disagreement started about the need itself and slipped to the
> > > level
> > > at which implementation should be done.
> > >
> > > I would really like to reach a compromise on this issue, something that
> > > could by
> > > accepted by everybody. I don't want to get banned with a -1 on a commit,
> > > but at
> > > least a few people would like localized error messages that can be simply
> > > forwarded upward from lower layers to upper layer for display without
> > > processing. Standard java already provides Throwable.getLocalizedMessage()
> > > since
> > > JDK 1.1. I could set up for [math] only an exception hierarchy that only
> > > add a
> > > few constructors and an implementation of this method without any change
> > > in the
> > > Throwable.getMessage() behaviour. Does this sound reasonable ?
> >
> >
> > Sorry I was out of pocket this week and could not reiterate my personal +1
> > for moving forward as you suggest, Luc. I will add a few of more comments
> > below. If anyone still has serious reservations - especially those who now
> > or in the future may contribute to [math] - pls speak up; otherwise we can
> > move on. Thanks to all who provided comments.
> >
> > 1) My initial +1 was based on the fact that the error management that you
> > need to support this approach is in fact there in Mantissa and if you
> > *don't* support localization when text is being generated, you either need
> > to get into nonsense like parsing and translating error messages,
> > complicating your exceptions hierarchy, or losing/hiding information at
> > higher levels. If you do the work to localize when the string is generated,
> > that gives a choice at higher levels, which to me is goodness (assuming you
> > are prepared to do the work and the implementation is robust against missing
> > bundles, etc.).
> >
> > 2) Commons math generates error messages now, and should generate better
> > messages (as Mantissa does) in the future that using applications may want
> > to display to end users or in application logs. I would like for those
> > messages to be localizable. If one of our solvers does not converge because
> > initial values do not bracket a root, for example, I would like the
> > developer of a localized client application that uses the solver to be able
> > to display that message directly in a log or to the user. Whether or not
> > logging is good or bad is completely irrelevant to this discussion.
> >
> > 3) Apache is a do-ocracy and we have a proposal before us to significantly
> > improve exception management and error reporting in [math] by extending and
> > leveraging the framework in Mantissa. Luc is volunteering to do this and
> > the only other active contributor to [math] who has chimed in (yours truly)
> > is also in favor. The arguments against are either it is too much work to
> > implement exception error message localization or it may not be robust. Luc
> > is stepping up to *do* the work (actually, leverage work already mostly done
> > in Mantissa) and I don't see robustness or performance risk in what he has
> > implemented. Pls speak up if I am missing something in the latter case.
> > Therefore, appreciating the feedback from others and reservations about
> > applying across commons, for [math] we should let Luc JFDI - i.e., move
> > forward with the proposal.
>
> +1 to those that do the work decide the direction.
>
> The only comment I would make is that there are two scenarios for
> application localization in terms of the user - single or multiple.
> Single being your application runs in one Locale only and multiple
> where you have users with different Locale. If you want to cater for
> the later then the exceptions should contain keys/replacement values
> and message be resolved when the user's Locale is known - which I
> think is James Carman's suggestion. Messages could be resolved outside
> of Math or you could provide a getMessage(Locale) method in your
> exceptions.
>
> Niall
>
> > Thanks again, all, for this interesting discussion and thanks, Luc, for
> > helping make [math] more localization-friendly.
> >
> > Phil
> >
> > Luc
>
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Re: [all] exceptions and localization
Posted by Niall Pemberton <ni...@gmail.com>.
On 2/3/07, Phil Steitz <ph...@gmail.com> wrote:
> On 1/30/07, luc.maisonobe@free.fr <lu...@free.fr> wrote:
> >
> > Craig McClanahan wrote:
> >
> >
> > > I'm late to the table on this thread, and only care about the Commons
> > > libraries I care about :-)
> >
> > Thanks for your interest in this thread.
> >
> > > but you should be aware that this attitude will
> > > disqualify the use of such libraries from use within code from
> > organizations
> > > that have strict rules about implementing localization. I work for such
> > an
> > > organization (Sun) ... the key rules are that any message that might be
> > > visible to users *must* be localizable.
> >
> > I agree with you and thought localization should be provided by the layer
> > which
> > provides the message. Other people think this should be done at
> > application
> > level, if done at all.
> >
> > > For log messages, that tends to translate into a straightforward policy
> > that
> > > DEBUG and TRACE type messages do not need to be localized, but anything
> > from
> > > INFO level above must be. The issue for exception messages is a bit
> > more
> > > interesting. How does the library developer know whether or not the
> > message
> > > part of the exception will be displayed to end users? From a pragmatic
> > > viewpoint, you can pretty much assume this will happen with exceptions
> > in
> > > webapps, while many Swing apps will hide that sort of stuff to some
> > degree.
> >
> > I think that since low level components may be used almost anywhere, their
> > messages *may* be displayed and this sole possibility is enough to justify
> > a
> > localized version should be made available. If the application gets an
> > error it
> > really doesn't know about, it can simply display it.
> >
> > > But, as a bottom line, if I'm interested in maximum adoption of a
> > Commons
> > > library I work on, I will diligently ensure that exception messages are
> > > localizable :-).
> >
> > When I first started this long thread, I thought the need for localized
> > error
> > messages as provided by exceptions was acknowledged by everyone and asked
> > for
> > the way to implement it, starting from a simple one which already works. I
> > was
> > wrong. The disagreement started about the need itself and slipped to the
> > level
> > at which implementation should be done.
> >
> > I would really like to reach a compromise on this issue, something that
> > could by
> > accepted by everybody. I don't want to get banned with a -1 on a commit,
> > but at
> > least a few people would like localized error messages that can be simply
> > forwarded upward from lower layers to upper layer for display without
> > processing. Standard java already provides Throwable.getLocalizedMessage()
> > since
> > JDK 1.1. I could set up for [math] only an exception hierarchy that only
> > add a
> > few constructors and an implementation of this method without any change
> > in the
> > Throwable.getMessage() behaviour. Does this sound reasonable ?
>
>
> Sorry I was out of pocket this week and could not reiterate my personal +1
> for moving forward as you suggest, Luc. I will add a few of more comments
> below. If anyone still has serious reservations - especially those who now
> or in the future may contribute to [math] - pls speak up; otherwise we can
> move on. Thanks to all who provided comments.
>
> 1) My initial +1 was based on the fact that the error management that you
> need to support this approach is in fact there in Mantissa and if you
> *don't* support localization when text is being generated, you either need
> to get into nonsense like parsing and translating error messages,
> complicating your exceptions hierarchy, or losing/hiding information at
> higher levels. If you do the work to localize when the string is generated,
> that gives a choice at higher levels, which to me is goodness (assuming you
> are prepared to do the work and the implementation is robust against missing
> bundles, etc.).
>
> 2) Commons math generates error messages now, and should generate better
> messages (as Mantissa does) in the future that using applications may want
> to display to end users or in application logs. I would like for those
> messages to be localizable. If one of our solvers does not converge because
> initial values do not bracket a root, for example, I would like the
> developer of a localized client application that uses the solver to be able
> to display that message directly in a log or to the user. Whether or not
> logging is good or bad is completely irrelevant to this discussion.
>
> 3) Apache is a do-ocracy and we have a proposal before us to significantly
> improve exception management and error reporting in [math] by extending and
> leveraging the framework in Mantissa. Luc is volunteering to do this and
> the only other active contributor to [math] who has chimed in (yours truly)
> is also in favor. The arguments against are either it is too much work to
> implement exception error message localization or it may not be robust. Luc
> is stepping up to *do* the work (actually, leverage work already mostly done
> in Mantissa) and I don't see robustness or performance risk in what he has
> implemented. Pls speak up if I am missing something in the latter case.
> Therefore, appreciating the feedback from others and reservations about
> applying across commons, for [math] we should let Luc JFDI - i.e., move
> forward with the proposal.
+1 to those that do the work decide the direction.
The only comment I would make is that there are two scenarios for
application localization in terms of the user - single or multiple.
Single being your application runs in one Locale only and multiple
where you have users with different Locale. If you want to cater for
the later then the exceptions should contain keys/replacement values
and message be resolved when the user's Locale is known - which I
think is James Carman's suggestion. Messages could be resolved outside
of Math or you could provide a getMessage(Locale) method in your
exceptions.
Niall
> Thanks again, all, for this interesting discussion and thanks, Luc, for
> helping make [math] more localization-friendly.
>
> Phil
>
> Luc
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