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From "Mike Kienenberger" <mkien...@gmail.com>
Subject Re: Cayenne -- Apache automatic deploy problem
Date Tue, 03 Apr 2007 16:39:14 GMT
DataContext is serializable.   I serialize the read-only one in a session.
However, I don't want to serialize the entire modifiable context and
everything it contains as client-side state.   I only want to write
out specific objects for performance reasons.

When you serialize a DataObject without a DataContext, it's your
responsibility to reconnect your DataObject back to a DataContext.


On 4/3/07, Marc Gabriel-Willem
<marc.gabriel-willem@side-international.com> wrote:
> What your 'workaround' mean? Are you facing serialization /
> deserialization problem with application server and cayenne? Have you
> got some hasardous behavior?
> Normally, cayenne context should be 'serializable compliant', so if it
> is not, it should be addressed isn't it?
>
> -----Original Message-----
> From: Mike Kienenberger [mailto:mkienenb@gmail.com]
> Sent: Monday, April 02, 2007 4:32 PM
> To: user@cayenne.apache.org
> Subject: Re: Cayenne -- Apache automatic deploy problem
>
> I've used Cayenne in a couple of JSF applications.
>
> Up to this point, my best solution was to use a servlet filter to save
> and restore the primary DataContext in the session.   This is a
> read-only (or write-request-only) context, and I explicitly check at
> the end of every request to insure it's in a non-dirty state.   Thus,
> if necessary, I can create a completely-new DataContext on the next
> request -- storing this DataContext in the session is simply a
> performance enhancer.
>
> I then also have a set of modified DataObjects in a temporary
> DataContext that I saveState into the client-side save state.   I
> don't save the DataContext; I only save the objects.
>
> My DataObject superclass has these serialization methods.  There's a
> lot of extra logging in here from when I was debugging it -- not every
> path is taken.
>
>
>     ////// Serialization
>
>     private void writeObject(java.io.ObjectOutputStream out)
>         throws IOException
>     {
>         Logger logger = Logger.getLogger("serialization");
>         if (null == this.getDataContext())
>         {
>                 logger.info("writeObject: " + this.getClass().getName()
> + "
> [" + String.valueOf(this.hashCode()) + "] has no DC.");
>                 logger.info("writeObject: " + this);
>                 Thread.dumpStack();
>         }
>         out.writeBoolean(Boolean.TRUE ==
> this.getDataContext().getUserProperty("temporary"));
>         out.defaultWriteObject();
>
>         if (Boolean.TRUE ==
> this.getDataContext().getUserProperty("temporary"))
>         {
>                 logger.info("writeObject: " + this.getClass().getName()
> + "
> [" + String.valueOf(this.hashCode()) + "] has DC [" +
> String.valueOf(this.getDataContext().hashCode()) + "] and is marked
> temporary.");
>         }
>         else
>         {
>                 logger.info("writeObject: " + this.getClass().getName()
> + "
> [" + String.valueOf(this.hashCode()) + "] has DC [" +
> String.valueOf(this.getDataContext().hashCode()) + "] and is not
> marked temporary.");
>         }
>     }
>
>     private void readObject(java.io.ObjectInputStream in)
>         throws IOException, ClassNotFoundException
>     {
>         boolean isInTemporaryDataContext = in.readBoolean();
>         in.defaultReadObject();
>         this.isInTemporaryDataContext = isInTemporaryDataContext;
>
>         Logger logger = Logger.getLogger("serialization");
>         if (null != this.getDataContext())
>         {
>                 if (isInTemporaryDataContext)
>                 {
>                 logger.info("readObject: " + this.getClass().getName() +
> " [" + String.valueOf(this.hashCode()) + "] has DC [" +
> String.valueOf(this.getDataContext().hashCode()) + "] and is marked
> temporary.");
>                 }
>                 else
>                 {
>                 logger.info("readObject: " + this.getClass().getName() +
> " [" + String.valueOf(this.hashCode()) + "] has DC [" +
> String.valueOf(this.getDataContext().hashCode()) + "] and is not
> marked temporary.");
>                 }
>         }
>         else
>         {
>                 if (isInTemporaryDataContext)
>                 {
>                 logger.info("readObject: " + this.getClass().getName() +
> " [" + String.valueOf(this.hashCode()) + "] has no DC and is marked
> temporary.");
>                 }
>                 else
>                 {
>                 logger.info("readObject: " + this.getClass().getName() +
> " [" + String.valueOf(this.hashCode()) + "] has no DC and is not
> marked temporary.");
>                 }
>         }
>    }
>     /**
>      * Substitute self with an object registered in thread
>      * DataContext with the same ID.
>      */
>     protected Object readResolve() throws ObjectStreamException
>     {
>         if (null == getDataContext())
>         {
>             if (isInTemporaryDataContext)
>             {
>                 Logger logger = Logger.getLogger("serialization");
>                 logger.info("readResolve: " + this.getClass().getName()
> +
> " [" + String.valueOf(this.hashCode()) + "] has no DC and is marked
> temporary.");
>
>                 return this;
>             }
>             else
>             {
>                 Logger logger = Logger.getLogger("serialization");
>                 logger.info("readResolve: " + this.getClass().getName()
> +
> " [" + String.valueOf(this.hashCode()) + "] has no DC and is not
> marked temporary.");
>
>                 DataContext context;
>
>                 try {
>                     context = DataContext.getThreadDataContext();
>                 }
>                 catch (IllegalStateException e) {
>                     throw new NotActiveException("Can't deserialize
> object for id '"
>                             + getObjectId()
>                             + "' - no DataContext bound to thread.");
>                 }
>
>                 // return context.registeredObject(getObjectId());
>                 return context.localObject(getObjectId(), null);
>             }
>         }
>         else
>         {
>                 Logger logger = Logger.getLogger("serialization");
>                 logger.info("readResolve: " + this.getClass().getName()
> + "
> [" + String.valueOf(this.hashCode()) + "] has DC [" +
> String.valueOf(this.getDataContext().hashCode()) + "].");
>             return this;
>         }
>     }
>
>
>
>
>
> On 4/2/07, Marc Gabriel-Willem
> <marc.gabriel-willem@side-international.com> wrote:
> > Yes, it seems to have a problem with the 'awakeFromDeserialization'
> > function. Not sure to understand what you mean by 'code called before
> > cayenne is loaded' but for your information the code that crash is
> > called by a jsf action method.
> >
> > Moreover, the problem seems to come from 'relationship objects' (in my
> > case: m_editableGroup.getGroupContentArray()).
> >
> > To summarize:
> >
> > 1) In a backing bean, I create a child data context and store it as a
> > member variable.
> > 2) I link entity objects to that child data context.
> > 3) I modify those entity objects
> > 4) I shut down the tomcat server
> > 5) I restart the the tomcat server
> > 6) I call a jsf action method (in my business, a save) and then the
> > crash appear :|
> >
> > Thank you for your help.
> >
> > Marc
> >
> > -----Original Message-----
> > From: Andrus Adamchik [mailto:andrus@objectstyle.org]
> > Sent: Sunday, April 01, 2007 3:25 PM
> > To: user@cayenne.apache.org
> > Subject: Re: Cayenne -- Apache automatic deploy problem
> >
> > This likely means that 'awakeFromDeserialization' [1] failed to
> > attach DataContext to Cayenne stack. Is it possible that the code in
> > question called before Cayenne stack is loaded? Where is it called
> > anyways?
> >
> > Andrus
> >
> >
> > [1] http://svn.apache.org/repos/asf/cayenne/main/branches/STABLE-2.0/
> > cayenne/cayenne-java/src/cayenne/java/org/apache/cayenne/access/
> > DataContext.java
> >
> > On Mar 30, 2007, at 10:55 AM, Marc Gabriel-Willem wrote:
> >
> > > Hello,
> > >
> > > I checked the entity resolver value.
> > > Indeed, in this situation the value is 'null'.
> > >
> > > Marc
> > >
> > > -----Original Message-----
> > > From: Andrus Adamchik [mailto:andrus@objectstyle.org]
> > > Sent: Friday, March 30, 2007 4:16 PM
> > > To: user@cayenne.apache.org
> > > Subject: Re: Cayenne -- Apache automatic deploy problem
> > >
> > > I can't reproduce this error in a test case. I am out of ideas what
> > > might have caused it. Can you possibly debug this condition to
> figure
> > > out why the 'metadata' field in DataContextQueryAction is null?
> First
> > > thing to check:
> > >
> > > m_editableGroup.getObjectContext().getEntityResolver() != null
> > >
> > >
> > > Andrus
> > >
> > >
> > > On Mar 30, 2007, at 5:24 PM, Marc Gabriel-Willem wrote:
> > >
> > >> Hello,
> > >>
> > >> Sorry, it is the first time I'm using a list like this one. So, I'm
> > >> doing some crazy error with it :) For example, I hope my "reply
> > >> all" is
> > >> a correct action to do in this case.
> > >>
> > >> I saw your first reply.
> > >>
> > >> I have exactly the same error when I stop and restart properly the
> > >> Tomcat server. In fact, stoping and restarting the server simulate
> > >> the
> > >> serialization / deserialization operation that an application
> > >> server can
> > >> do at any time it wants (isn't it ?)
> > >>
> > >> Marc
> > >>
> > >> -----Original Message-----
> > >> From: Andrus Adamchik [mailto:andrus@objectstyle.org]
> > >> Sent: Friday, March 30, 2007 3:09 PM
> > >> To: user@cayenne.apache.org
> > >> Cc: Marc Gabriel-Willem
> > >> Subject: Re: Cayenne -- Apache automatic deploy problem
> > >>
> > >> Hi, See my original reply asking for more information here:
> > >>
> > >> http://objectstyle.org/cayenne/lists/cayenne-user/2007/03/0101.html
> > >>
> > >> BTW, it would be much easier to communicate if you subscribe to the
> > >> list :-)
> > >>
> > >> Andrus
> > >>
> > >>
> > >> On Mar 30, 2007, at 4:46 PM, Marc Gabriel-Willem wrote:
> > >>
> > >>> Hi,
> > >>>
> > >>>
> > >>>
> > >>> Sorry to repost that question, but I was not properly register to
> > >>> the
> > >>> mailing list, so I was unable to reply properly.
> > >>>
> > >>>
> > >>>
> > >>> I'm using Cayenne (2.0.2) with the apache web server (5.5.20) and
> > >>> I'm
> > >>> facing to the following problem.
> > >>>
> > >>>
> > >>>
> > >>> When apache does an automatic deploy, all objects are serialized /
> > >>> deserialized without any error.
> > >>>
> > >>> But after that, when the code accesses a cayenne persistent object
> > >>> (member variable of a jsf backing bean), the following problem
> > >>> occurs:
> > >>>
> > >>>
> > >>>
> > >>> Caused by: java.lang.NullPointerException
> > >>>
> > >>>         at
> > >>>
> org.apache.cayenne.access.DataContextQueryAction.interceptPaginatedQ
> >
> > >>> u
> > >
> > >>> e
> > >>
> > >>> ry
> > >>> (DataContextQueryAction.java:91)
> > >>>
> > >>>         at
> > >>> org.apache.cayenne.access.DataContextQueryAction.execute
> > >>> (DataContextQuer
> > >>> yAction.java:50)
> > >>>
> > >>>         at
> > >>>
> org.apache.cayenne.access.DataContext.onQuery(DataContext.java:1387)
> > >>>
> > >>>         at
> > >>>
> org.apache.cayenne.access.DataContext.performQuery(DataContext.java:
> > >>> 1376
> > >>> )
> > >>>
> > >>>         at
> > >>> org.apache.cayenne.access.ToManyList.resolvedObjectList
> > >>> (ToManyList.java:
> > >>> 307)
> > >>>
> > >>>         at
> > >>> org.apache.cayenne.access.ToManyList.size(ToManyList.java:260)
> > >>>
> > >>>         at
> > >>> com.sideinternational.web.profiling.group.GroupEditor.save
> > >>> (GroupEditor.j
> > >>> ava:246)
> > >>>
> > >>>         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native
> > >>> Method)
> > >>>
> > >>>         at
> > >>> sun.reflect.NativeMethodAccessorImpl.invoke
> > >>> (NativeMethodAccessorImpl.jav
> > >>> a:39)
> > >>>
> > >>>         at
> > >>> sun.reflect.DelegatingMethodAccessorImpl.invoke
> > >>> (DelegatingMethodAccessor
> > >>> Impl.java:25)
> > >>>
> > >>>         at java.lang.reflect.Method.invoke(Method.java:585)
> > >>>
> > >>>         at
> > >>> org.apache.myfaces.el.MethodBindingImpl.invoke
> > >>> (MethodBindingImpl.java:13
> > >>> 2)
> > >>>
> > >>>
> > >>>
> > >>> For information, the following code throws that exception (the
> > >>> call to
> > >>> the size() method) :
> > >>>
> > >>> List itemsToRemove = m_editableGroup.getGroupContentArray();
> > >>>
> > >>>       for (int i=0; i < itemsToRemove.size(); i)
> > >>>
> > >>>             ...
> > >>>
> > >>> Note: Child data context and ObjectEntities are stored in a
> > >>> serializable
> > >>> jsf backing bean.
> > >>>
> > >>>
> > >>>
> > >>> Thank you for your help.
> > >>>
> > >>>
> > >>>
> > >>> Marc Gabriel
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>
> > >>
> > >>
> > >
> > >
> > >
> >
> >
> >
>
>

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