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From "Patrick Linskey" <plins...@bea.com>
Subject RE: More questions on runtime schema generation
Date Wed, 25 Apr 2007 22:56:50 GMT
Inside an appserver, there are parts of the PersistenceUnitInfo
interface that are designed for the appserver to communicate jars to
scan to the persistence provider.

-Patrick

-- 
Patrick Linskey
BEA Systems, Inc.
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> -----Original Message-----
> From: Craig.Russell@Sun.COM [mailto:Craig.Russell@Sun.COM] 
> Sent: Wednesday, April 25, 2007 3:55 PM
> To: open-jpa-dev@incubator.apache.org
> Subject: Re: More questions on runtime schema generation
> 
> The general solution to this problem lies in a crisper 
> definition of classloader domains in the app server. IIUC, 
> each app server has its own policies in terms of where 
> various components get loaded and when.
> 
> I think we need to engage the server spec team on this, 
> otherwise we will end up chasing multiple incompatible class 
> loader strategies, all of which turn out to be spec compliant.
> 
> And for a first cut at "reasonable" we might ask the Spring 
> folks how they handle this.
> 
> Craig
> 
> On Apr 25, 2007, at 12:26 PM, Patrick Linskey wrote:
> 
> >> However IIUC this dissects the system property java.class.path and 
> >> only parses stuff on that.  This might be reasonable for a command 
> >> line tool (although I have some
> >> doubts) but it seems to me that for any other situation a 
> scan of the 
> >> provided classloader would be more appropriate.
> >> Is this reasonable?
> >
> > It is. Of course, there is no standard way to scan 
> classloaders. The 
> > best I know of is to do:
> >
> >     cls.getProtectionDomain().getCodeSource().getLocation()
> >
> > and then scan from that URL.
> >
> > Of course, this assumes that a) you have a class (not a 
> ClassLoader), 
> > b) you have security privileges to get the protection 
> domain, and b) 
> > the location is parsable and accessible.
> >
> > Is there some other way that you know of to scan a ClassLoader?
> >
> >> Also, I would like to suggest a flag in the
> >> openjpa.jdbc.SynchronizeMappings=buildSchema(...) stuff to turn on 
> >> this eager scanning I'm trying to implement.  Does this seem 
> >> reasonable?
> >
> > It does.
> >
> > --
> > Patrick Linskey
> > BEA Systems, Inc.
> > 
> ______________________________________________________________________
> > _
> > Notice:  This email message, together with any attachments, may 
> > contain
> > information  of  BEA Systems,  Inc.,  its subsidiaries  and   
> > affiliated
> > entities,  that may be confidential,  proprietary,  copyrighted   
> > and/or
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> > individual or entity named in this message. If you are not the 
> > intended recipient, and have received this message in error, please 
> > immediately return this by email and then delete it.
> >
> >> -----Original Message-----
> >> From: David Jencks [mailto:david_jencks@yahoo.com]
> >> Sent: Wednesday, April 25, 2007 12:18 PM
> >> To: open-jpa-dev@incubator.apache.org
> >> Subject: More questions on runtime schema generation
> >>
> >> I'm working on modifications so that ddl can operate in a separate 
> >> transaction on a connection from the jta ds and I would 
> like to have 
> >> a complete scan and enhancement as soon as possible when 
> the EMF is 
> >> first accessed.  I have this working when the classes are listed 
> >> explicitly in the persistence.xml but not when they aren't.
> >>
> >> It looks like the relevant code is AbstractCFMetaDataFactory 
> >> getPersistentTypeNames
> >>
> >>              if (names.isEmpty() && devpath)
> >>                  scan(new ClasspathMetaDataIterator(null, 
> >> newMetaDataFilter()),
> >>                      newClassArgParser(), names, false, null);
> >>
> >>
> >> However IIUC this dissects the system property java.class.path and 
> >> only parses stuff on that.  This might be reasonable for a command 
> >> line tool (although I have some
> >> doubts) but it seems to me that for any other situation a 
> scan of the 
> >> provided classloader would be more appropriate.
> >> Is this reasonable?
> >>
> >> Also, I would like to suggest a flag in the
> >> openjpa.jdbc.SynchronizeMappings=buildSchema(...) stuff to turn on 
> >> this eager scanning I'm trying to implement.  Does this seem 
> >> reasonable?
> >>
> >> thanks
> >> david jencks
> >>
> >>
> >>
> >
> > Notice:  This email message, together with any attachments, may  
> > contain information  of  BEA Systems,  Inc.,  its subsidiaries   
> > and  affiliated entities,  that may be confidential,  
> proprietary,   
> > copyrighted  and/or legally privileged, and is intended 
> solely for the 
> > use of the individual or entity named in this message. If 
> you are not 
> > the intended recipient, and have received this message in error, 
> > please immediately return this by email and then delete it.
> 
> Craig Russell
> Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
> 408 276-5638 mailto:Craig.Russell@sun.com P.S. A good JDO? O, Gasp!
> 
> 

Notice:  This email message, together with any attachments, may contain information  of  BEA
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or entity named in this message. If you are not the intended recipient, and have received
this message in error, please immediately return this by email and then delete it.

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