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From Rainer Döbele <doeb...@esteam.de>
Subject EMPIREDB-95
Date Thu, 27 Jan 2011 08:59:40 GMT
Oops, I have just realized that I have already committed some changes on EMPIREDB-95, that
have nothing to do with error handling. I missed that because it was assigned to 2.1.1 where
the commits actually affected 2.1. and even should have gone to EMPIREDB-91 which I have just
closed.

Francis what do you think. Should I revert my changes to the description of EMPIREDB-95, close
it and create a new issue, or leave it as it is now?

Regards
Rainer


Rainer Döbele wrote:
> from: Rainer Döbele [mailto:doebele@esteam.de]
> to: empire-db-dev@incubator.apache.org
> re: re: [jira] Updated: (EMPIREDB-97) Serialization of Empire-DB
> objects
> 
> Hi Francis,
> 
> yes I myself have asked this question a while ago, whether we should
> keep this old style error handling as an option.
> Currently we can switch between Exception-mode and an exception-less
> mode with Boolean return values for most functions to indicate an error.
> 
> I agree that this exception-less mode is not really needed and I have no
> problem getting rid of it and only do Exceptions in the future. However
> it only makes sense if we also change the return values of most
> functions and thus there is a lot to rethink an test - which means quite
> a bit of work.
> 
> I would suggest to leave it for now until we have finished our 2.1.
> release.
> This should then be a major task for a 2.2. release.
> 
> I thought we have an issue for this already but could not find any.
> I have now changed EMPIREDB-95 which was "Code cleanup and review" (did
> quite mean anything) to "Remove optional support for old style error
> handing".
> 
> Regards
> Rainer
> 
> 
> Francis De Brabandere wrote:
> > from: Francis De Brabandere [mailto:francisdb@gmail.com]
> > to: empire-db-dev@incubator.apache.org
> > re: Re: [jira] Updated: (EMPIREDB-97) Serialization of Empire-DB
> > objects
> >
> > Rainer,
> >
> > We probably already had a discussion about this ErrorObject idea. I
> > still see this as some kind of anti-pattern from old times where
> > inheritance was the key to everything.
> >
> > Could you (again) explain me what the added value of this ErrorObject
> > is (ignoring backwards compatibility)? I'll add that info to the wiki
> > in case I forget once again or somebody else asks the same question.
> >
> > Cheers,
> > Francis
> >
> > On Wed, Jan 26, 2011 at 11:36 PM, Rainer Döbele <doebele@esteam.de>
> > wrote:
> > > Hi Eike,
> > >
> > > I can follow your conclusion and agree that making ErrorObject
> > serializeable makes no sense (why would anyone want to serialize an
> > error anyway?), whereas serializing EmpireException is fine.
> > >
> > > I have not applied your patch yet (but I will do), but there is one
> > more thing that came to my mind:
> > > DBReader is not serializeable as it requires a reference to an open
> > java.sql.ResultSet.
> > > We have to make sure, that that a NotSerializeable exception is
> > thrown, when attempting to serialize this class.
> > >
> > > Thanks and regards,
> > > Rainer
> > >
> > >
> > > Eike Kettner (JIRA) wrote:
> > >> from: Eike Kettner (JIRA) [mailto:empire-db-
> dev@incubator.apache.org]
> > >> to: empire-db-commits@incubator.apache.org
> > >> re: [jira] Updated: (EMPIREDB-97) Serialization of Empire-DB
> > >> objects
> > >>
> > >>
> > >>      [ https://issues.apache.org/jira/browse/EMPIREDB-
> > >> 97?page=com.atlassian.jira.plugin.system.issuetabpanels:all-
> tabpanel
> > ]
> > >>
> > >> Eike Kettner updated EMPIREDB-97:
> > >> ---------------------------------
> > >>
> > >>     Attachment: 1_dbobject.patch
> > >>                 0_exception.patch
> > >>
> > >> Hi there,
> > >>
> > >> As I started working on the serialization thing, I figured that
> it's
> > >> not a good idea to let ErrorObject implement Serializable. Nearly
> > every
> > >> object extends ErrorObject and for some (and especially for objects
> > to
> > >> come) it is not desireable to be serializable. I think its not that
> > >> good
> > >> to open so many object for serialization. Then there are already
> > >> classes
> > >> that hold non-serializable references (I found XMLConfiguration to
> be
> > >> such a class). So, I think it could be a source of bugs to open
> every
> > >> object this way...
> > >>
> > >> The other side is, that ErrorObject uses a static ThreadLocal to
> hold
> > >> error info. This wouldn't be serialized anyways. This means
> > >> EmpireException wouldn't be serializable even if ErrorObject
> > implements
> > >> Serializable.
> > >>
> > >> Instead I chose to serialize EmpireException by using a
> serializable
> > >> implementation of ErrorInfo. The major difference here:
> > EmpireException
> > >> does not hold a reference to the concrete object anymore, but only
> a
> > >> copy of the error infos. IMHO, this is good for an exception, but I
> > >> have
> > >> no glue to what extend users rely on EmpireException#getErrorObject
> > to
> > >> return a DBTable, XMLConfiguration etc. This is applied with the
> > first
> > >> patch.
> > >>
> > >> Then I chose to let DBObject implement Serializable. I think that
> > it's
> > >> nice if data model objects are serializable. Plain SQL strings are
> > >> serializable and so I think objects like DBCommand or DBOrderByExpr
> > >> (that represent parts of SQL) should be serializable, too :). This
> is
> > >> applied in the second patch.
> > >>
> > >> Regards,
> > >> Eike
> > >>
> > >>
> > >> > Serialization of Empire-DB objects
> > >> > ----------------------------------
> > >> >
> > >> >                 Key: EMPIREDB-97
> > >> >                 URL:
> > https://issues.apache.org/jira/browse/EMPIREDB-
> > >> 97
> > >> >             Project: Empire-DB
> > >> >          Issue Type: Wish
> > >> >          Components: Core
> > >> >            Reporter: Eike Kettner
> > >> >         Attachments: 0_exception.patch, 1_dbobject.patch
> > >> >
> > >> >
> > >> > Looking at class EmpireException, it holds references to two non-
> > >> serializable objects: ErrorObject and ErrorType which breaks the
> > >> contract with the Exception API.
> > >> > Now, it would be great for several use-cases to have Empire-DB
> > >> objects serializable. If ErrorObject would be serializable, it
> would
> > >> first make EmpireException serializable (assuming ErrorType to be
> > >> serializable) and next it would make every other DBXyz object in
> this
> > >> hierarchy serializable.
> > >> > Here is for reference the mail thread from users@ mailing list:
> > >> > ------------------------------
> > >> > On Sat, Jan 22, 2011 at 7:26 PM, Eike Kettner <news@eknet.org>
> > wrote:
> > >> > > Hi Rainer and Francis,
> > >> > >
> > >> > > thanks for your quick replies and for giving this a chance.
> > >> Serializing
> > >> > > an exception is sure not something massive used, however
> > sometimes
> > >> it is
> > >> > > quite a nice feature. For example, a JMSLogger sends log events
> > to
> > >> a
> > >> > > broker, and there exceptions are serialized. Well, I see that
> > this
> > >> is
> > >> > > not used often, and more or less a "special case" :). Still,
I
> > >> would
> > >> > > consider a non-serializable exception a small "bug" - just
> > because
> > >> it's
> > >> > > dictated by the java api.
> > >> > >
> > >> > > I had a quick look at the sources and as far as I can see, it
> > >> should be
> > >> > > ok to make "everything" serializable. There is always the
> > >> > > "serializable-drawback" to consider: users can save objects on
> > disk
> > >> and
> > >> > > later try to load them with a new version of empire-db, where
> > class
> > >> > > definitions have changed. Well, I think one can live with this,
> > and
> > >> it
> > >> > > does not apply to many other use-cases of serialization (rmi,
> > >> > > serialization used in wicket or messaging), because objects are
> > >> > > serialized only for a short amount of time.
> > >> > >
> > >> > > Regards,
> > >> > > Eike
> > >> > >
> > >> > > On [Sat, 22.01.2011 13:49], Rainer D=F6bele wrote:
> > >> > >> Hi Eike,
> > >> > >>
> > >> > >> I agree with Francis that I don't quite see the point for
> > >> serializing an Exception, although I must admit that
> > >> java.lang.Throwable is Serializable.
> > >> > >>
> > >> > >> But then I agree that we should consider making DBObject
or
> > >> ErrorObject serializeable which then would apply to the entire
> object
> > >> hierarchy.
> > >> > >> Regards
> > >> > >>
> > >> > >> Rainer
> > >> > >>
> > >> > >>
> > >> > >> Francis De Brabandere wrote:
> > >> > >> > from: Francis De Brabandere [mailto:francisdb@gmail.com]
> > >> > >> > to: empire-db-user@incubator.apache.org
> > >> > >> > re: Re: Serialization of EmpireException
> > >> > >> >
> > >> > >> > Hi Eike,
> > >> > >> >
> > >> > >> > I see no reason for not making them Serializable.
> > >> > >> >
> > >> > >> > Rainer?
> > >> > >> >
> > >> > >> > Cheers,
> > >> > >> > Francis
> > >> > >> >
> > >> > >> > On Fri, Jan 21, 2011 at 4:31 PM, Eike Kettner
> <news@eknet.org>
> > >> wrote:
> > >> > >> > >
> > >> > >> > > Hello,
> > >> > >> > >
> > >> > >> > > I was trying to serialize EmpireException but ran
into an
> > >> error.
> > >> > >> > > EmpireException is marked as Serializable
> (RuntimeException)
> > >> > >> > > but it holds references to ErrorObject and ErrorType
which
> > are
> > >> not
> > >> > >> > > serializable. Hence a NotSerializableException
is thrown.
> > >> > >> > >
> > >> > >> > > When asking this, I like to ask whether there is
a thought
> > >> about making
> > >> > >> > > some model objects like DBRowset DBTable etc serializable.
> > >> Since most or all
> > >> > >> > > DBXyz objects hold model information only it should
be
> okay
> > >> for them to
> > >> > >> > > be serializable, imho? I use messaging and often
Apache
> > Wicket
> > >> which
> > >> > >> > > both use serialization, that's why I'm asking this.
(For
> > >> example, I'd
> > >> > >> > > like to pass around where and order-by expressions).
> > >> > >> > >
> > >> > >> > > Kind Regards,
> > >> > >> > > Eike
> > >> > >> > >
> > >> > >> > >
> > >> > >> > >
> > >> > >> >
> > >> > >> >
> > >> > >> >
> > >> > >> > --
> > >> > >> > http://www.somatik.be
> > >> > >> > Microsoft gives you windows, Linux gives you the whole
> house.
> > >> > >>
> > >> > >
> > >>
> > >> --
> > >> This message is automatically generated by JIRA.
> > >> -
> > >> You can reply to this email to add a comment to the issue online.
> > >
> > >
> >
> >
> >
> > --
> > http://www.somatik.be
> > Microsoft gives you windows, Linux gives you the whole house.

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