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[CDO] distinguish first-time construction from deserialization [message #672224]

Fri, 20 May 2011 11:46

Julien Jorge

Messages: 6
Registered: January 2011

Junior Member

Hi,

Is there a way to distinguish the first construction of a CDOObject instance from the construction resulting of the deserialization?

I am working on a code base in which some initialization is done in the constructor of the objects. This initialization must be done only once in the total lifespan of the instances. Unfortunately, when an instance in restored from the repository, the constructor of the class is called and this initialization is repeated.

I would like to avoid this situation. So is there a flag to distinguish those constructions? Or is there a way I can split the construction of CDOObjects in two parts to distinguish the first time construction and the deserialization construction?

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Re: [CDO] distinguish first-time construction from deserialization [message #686818 is a reply to message #672224]

Fri, 20 May 2011 13:25

Ed Merks

Messages: 33140
Registered: July 2009

Senior Member

Julien,

Maybe CDO provides something specific but there's no way in general to
know why an object is being constructed.

What kind of initialization are you doing? Why do you need to do it?

Julien Jorge wrote:
> Hi,
>
> Is there a way to distinguish the first construction of a CDOObject
> instance from the construction resulting of the deserialization?
>
> I am working on a code base in which some initialization is done in
> the constructor of the objects. This initialization must be done only
> once in the total lifespan of the instances. Unfortunately, when an
> instance in restored from the repository, the constructor of the class
> is called and this initialization is repeated.
>
> I would like to avoid this situation. So is there a flag to
> distinguish those constructions? Or is there a way I can split the
> construction of CDOObjects in two parts to distinguish the first time
> construction and the deserialization construction?
>

Ed Merks
Professional Support: https://www.macromodeling.com/

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Re: [CDO] distinguish first-time construction from deserialization (React to change) [message #686835 is a reply to message #672224]

Mon, 23 May 2011 07:03

Eike Stepper

Messages: 6682
Registered: July 2009

Senior Member

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html; charset=UTF-8" http-equiv="Content-Type">
<title></title>
</head>
<body bgcolor="#ffffff" text="#000000">
Hi Julien, 
 
It is like Ed already said, the lifecycles of the logical persistent
entity and the technical Java object that represents this entity
during some kind of session are kind of orthogonal or interleaved.
It does not make sense to mix them and there's no way to tell why
the constructor of the Java object has been called (other than
inspecting the call stack). 
 
The logical entity's lifecycle depends on the specific persistence
mechanism you've chosen, e.g. files, Hibernate (Teneo) or CDO. In
CDO this lifecycle is controlled by a finite state machine that
looks like: 
 
<img src="http://www.eclipse.org/forums/index.php?t=getfile&id=3099" alt="FSM"
height="358" width="600"> 
 
We're offering different hooks that you can register with: 
 
1)
org.eclipse.emf.cdo.view.CDOView.addObjectHandler(CDOObjectHandler) 
 
<title></title>
<style type="text/css">

</style>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">




<div class="java" align="left">
<table bgcolor="#ffffff" border="0" cellpadding="3"
cellspacing="0">
<tbody>
<tr>
 <td nowrap="nowrap" align="left"
valign="top"> <code>
public interface CDOObjectHandler 
{ 
 public void objectStateChanged(CDOView view, CDOObject object, CDOState oldState, CDOState newState); 
}</code> </td>
 </tr>
</tbody>
</table>
</div>


 
2)
org.eclipse.emf.cdo.transaction.CDOTransaction.addTransactionHandler(CDOTransactionHandlerBase) 
 
<title></title>
<style type="text/css">

</style>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">




<div class="java" align="left">
<table bgcolor="#ffffff" border="0" cellpadding="3"
cellspacing="0">
<tbody>
<tr>
 <td nowrap="nowrap" align="left"
valign="top"> <code>
public interface CDOTransactionHandler1 extends CDOTransactionHandlerBase 
{ 
 public void attachingObject(CDOTransaction transaction, CDOObject object); 
 public void detachingObject(CDOTransaction transaction, CDOObject object); 
 public void modifyingObject(CDOTransaction transaction, CDOObject object, CDOFeatureDelta featureDelta); 
}</code> </td>
 </tr>
</tbody>
</table>
</div>


 
<title></title>
<style type="text/css">

</style>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">




<div class="java" align="left">
<table bgcolor="#ffffff" border="0" cellpadding="3"
cellspacing="0">
<tbody>
<tr>
 <td nowrap="nowrap" align="left"
valign="top"> <code>
public interface CDOTransactionHandler2 extends CDOTransactionHandlerBase 
{ 
 public void committingTransaction(CDOTransaction transaction, CDOCommitContext commitContext); 
 public void committedTransaction(CDOTransaction transaction, CDOCommitContext commitContext); 
 public void rolledBackTransaction(CDOTransaction transaction); 
}</code> </td>
 </tr>
</tbody>
</table>
</div>


 
3) CDOView is an INotifier (offers an addListener method) that fires
this event for remote updates: 
 
<title></title>
<style type="text/css">

</style>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">




<div class="java" align="left">
<table bgcolor="#ffffff" border="0" cellpadding="3"
cellspacing="0">
<tbody>
<tr>
 <td nowrap="nowrap" align="left"
valign="top"> <code>
public interface CDOViewInvalidationEvent extends CDOViewEvent 
{ 
 public long getTimeStamp(); 
 public Set<CDOObject> getDirtyObjects(); 
 public Map<CDOObject, CDORevisionDelta> getRevisionDeltas(); 
 public Set<CDOObject> getDetachedObjects(); 
}</code> </td>
 </tr>
</tbody>
</table>
</div>


 
4) EMF adapters are notified for remote changes with a
CDODeltaNotification if you've registered a change subscription
policy via
org.eclipse.emf.cdo.view.CDOView.Options.addChangeSubscriptionPolicy(CDOAdapterPolicy) 
 
The real code contains more JavaDocs ;-) 
 
Cheers 
/Eike 
 
---- 
<a class="moz-txt-link-freetext" href="http://www.esc-net.de">http://www.esc-net.de</a> 
<a class="moz-txt-link-freetext" href="http://thegordian.blogspot.com">http://thegordian.blogspot.com</a> 
<a class="moz-txt-link-freetext" href="http://twitter.com/eikestepper">http://twitter.com/eikestepper</a> 
 
 
 
Am 20.05.2011 13:46, schrieb Julien Jorge:
<blockquote cite="mid:ir5jr7$2g4$1@news.eclipse.org" type="cite">Hi,
 
 
Is there a way to distinguish the first construction of a
CDOObject instance from the construction resulting of the
deserialization?
 
 
I am working on a code base in which some initialization is done
in the constructor of the objects. This initialization must be
done only once in the total lifespan of the instances.
Unfortunately, when an instance in restored from the repository,
the constructor of the class is called and this initialization is
repeated.
 
 
I would like to avoid this situation. So is there a flag to
distinguish those constructions? Or is there a way I can split the
construction of CDOObjects in two parts to distinguish the first
time construction and the deserialization construction?
 
 
</blockquote>
</body>
</html>

Attachment: moz-screenshot-26.png
(Size: 27.21KB, Downloaded 128 times)

Cheers
/Eike

----
http://www.esc-net.de
http://thegordian.blogspot.com
http://twitter.com/eikestepper

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