Ernest,
Let me urge you to serialize into XML rather than using default Java
serialization. The virtue of XML serialization is that deserialization
will continue to work as long as the data elements the class represents
don't change. If the internal data representation changes, then you need
new code either way. The virtue of XML is that you don't get involved
with class level version number book-keeping that java serialization
forces on you.
-Alex-
___________________________________________________________________
S. Alexander Jacobson Shop.Com
1-212-697-0184 voice The Easiest Way To Shop
On Tue, 9 Nov 1999, Ernest Friedman-Hill wrote:
> Hi Alex,
>
> The exception is an automatic "feature" of Java serialization (which
> is used to implement bload/bsave.) Basically, it's telling you that
> the serialized data in the .bin file was generated from a set of
> classes that don't match the currently available .class files. This is
> usually what you want -- i.e., when a class changes, the number and
> type of data members often change, too, so old serialized data can't
> be used to reconstruct a new object.
>
> Now, sometimes classes change and the data members don't, and then
> you'd like to be able to use old data with new classes. Java lets you
> do this by including a version ID in each class. As long as the
> version ID doesn't change, the data is assumed to be compatible, even
> if the code changes.
>
> During the long Jess 5.x pre-release development cycle, when whole
> classes are being added and removed with each release, it would make
> no sense to try to use the versioning mechanism to make old data
> reusable -- far too much work for me. But when 5.x finally settles
> down (and that time is now iminent!) it will more become important for
> bsave images to be compatible with further releases. At this point I
> will indeed add the versioning info, and Jess 5.0 (final) bsaves
> should remain upwards compatible through any patch releases, hopefully
> until a version 6.0 arrives. If I ever have to break this contract, I
> will have to make an announcement to this effect. But for now, expect
> bsave images to break with each release until 5.0 final comes out.
>
>
> I think [EMAIL PROTECTED] wrote:
> >
> > I just "recompile" my .bin file (result of "bsave") using Jess50b2 and
> > everything works fine. The reported problem was a result of "bload"ing
> > what was "bsave"ed with previous version.
> >
> > Is it a problem of the version compatibility? It may create problems
> > for users with precompiled ruleset (result of "bsave") when they
> > upgrade. Any suggestion how to avoid this in the future?
> >
> > Alex
> >
> >
> > ______________________________ Reply Separator _________________________________
> > Subject: JESS: Migrating bload to jess50b2
> > Author: alex-bagerman-at-non ([EMAIL PROTECTED]) at HP-PaloAlto,mimegw9
> > Date: 11/9/99 12:14 PM
> >
> >
> > Hi,
> >
> > I'm trying to rebuild my app with just downloaded jess50b2. Before I
> > had my application built with JDK 1.1.8. At once I decided to try 50b2
> > and JDK 1.2.2.
> >
> > Here is an exception I got from application that used to run
> > bload/bsave without any trouble :
> >
> > java.io.InvalidClassException: jess.Rete; Local class not compatible:
> > stream classdesc serialVersionUID=479072369051011645 local class
> > serialVersionUID=-1625347106253991454
> > at
> > java.io.ObjectStreamClass.validateLocalClass(ObjectStreamClass.java:43
> > 8)
> > at
> > java.io.ObjectStreamClass.setClass(ObjectStreamClass.java:482)
> > at
> > java.io.ObjectInputStream.inputClassDescriptor(ObjectInputStream.java:
> > 785)
> > at
> > java.io.ObjectInputStream.readObject(ObjectInputStream.java:353)
> > at
> > java.io.ObjectInputStream.readObject(ObjectInputStream.java:232)
> > at
> > java.io.ObjectInputStream.inputObject(ObjectInputStream.java:978)
> > at
> > java.io.ObjectInputStream.readObject(ObjectInputStream.java:369)
> > at
> > java.io.ObjectInputStream.readObject(ObjectInputStream.java:232)
> > at jess.Dumper.call(DumpFunctions.java:85)
> > at jess.FunctionHolder.call(FunctionHolder.java:37)
> > at jess.Funcall.execute(Funcall.java:240)
> > at jess.Jesp.parseAndExecuteFuncall(Jesp.java:1604)
> > at jess.Jesp.parseSexp(Jesp.java:185)
> > at jess.Jesp.parse(Jesp.java, Compiled Code)
> > at jess.Rete.executeCommand(Rete.java:1522)
> > at MyClass.init(TestApp.java:99)
> > at TestApp.main(TestApp.java, Compiled Code)
> > MyClass.init() - Jess reported an error in routine bload while
> > executing (bload c:/temp/test.bin).
> > Message: IO Exception.
> > Program text: ( bload c:/temp/test.bin ) at line 0.
> >
> >
> > Any idea what is going on?
> >
> > Thanks,
> >
> > Alex
> >
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>
>
> ---------------------------------------------------------
> Ernest Friedman-Hill
> Distributed Systems Research Phone: (925) 294-2154
> Sandia National Labs FAX: (925) 294-2234
> Org. 8920, MS 9012 [EMAIL PROTECTED]
> PO Box 969 http://herzberg.ca.sandia.gov
> Livermore, CA 94550
>
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