Re: More questions on runtime schema generation

[Craig L Russell]

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.

Craig

On Apr 25, 2007, at 12:26 PM, Patrick Linskey wrote:

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.

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.


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?

Of course, this assumes that a) you have a class (not a ClassLoader), b)

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.

by email and then delete it.

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-----Original Message-----
From: David Jencks [mailto:[EMAIL PROTECTED]
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:[EMAIL PROTECTED]
P.S. A good JDO? O, Gasp!

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