So would this actually allow people upgrading from 1.2 to 1.2.1 not need to
wipe their data? If so, that's fantastic. If not, does this mean we won't
risk this problem in the future?
Serge Knystautas
Loki Technologies
http://www.lokitech.com/
----- Original Message -----
From: "Stuart Roebuck" <[EMAIL PROTECTED]>
To: "Java Apache Mail Server" <[EMAIL PROTECTED]>
Sent: Tuesday, November 28, 2000 1:34 PM
Subject: Re: Bug fix release vs release with new avalon
Following from this previous post (below). I tried making the change I
suggested and it didn't help at all (whoops - didn't spot the overriding
readObject() and writeObject() methods!). Having found no substantive
differences between the old and new MailImpl and MailAddress classes, in
terms of serialization, I eventually resorted to the more risky approach and
added in the following lines at the beginning of the respective classes:
MailImpl.java:
static final long serialVersionUID=-4289663364703986260L;
MailAddress.java:
static final long serialVersionUID=2779163542539434916L;
This may not be elegant, but it works!
Stuart.
P.S. Sorry if I've repeated someone else, my unreliable mail provider
(nothing to do with JAMES) is being unreliable at the moment and I'm not
getting any mail. If anyone particularly wants to mail me (not that you
would!) please use the .co.uk address.
On Tuesday, November 28, 2000, at 04:48 PM, Stuart Roebuck wrote:
> On Tuesday, November 28, 2000, at 12:16 PM, Serge Knystautas wrote:
>
> > I'd very much like to, but how can we do this? I believe the only
> > serialization problem revolve around the MailAddress class (both as the
> > sender and the collection of recipients). I'm not a wiz on
serialization,
> > so does anybody know how we could deserialize these objects across class
> > versioning?
> >
>
> I've just had a quick read of E.R.Harold's "Java IO" (O'Reilly) and a bit
of a net search on
> the subject.
>
> Basically, when a class is serialized, it is versioned with the value of
the static long
> final serialVersionUID. If this has not been explicitly set, then it is
automatically set
> (at run time?) by calculating a form of hash function based on things
about the class that
> affect serialization. So, in theory, if changes are made to a class that
don't affect
> serialization, they will have no effect on the automatic serialVersionUID.
>
> The serialver tool (part of the JDK) will output the serialVersionUID of a
given class, so
> you can compare two versions of a class and see if they have 'broken' the
serialization.
>
>
> Looking at the code, the problem is, I think, in
org/apache/james/core/MailImpl.java.
>
> Between versions 1.2 and 1.3 of that class, the serialized property
messageIn was
> removed. (Here's the declarations at the beginning of version 1.2 in the
CVS):
>
> > private String errorMessage;
> > private String state;
> > private MimeMessage message;
> > private InputStream messageIn; // <-- Removed in Version
1.3
> > private MailAddress sender;
> > private Collection recipients;
> > private String name;
> > private String remoteHost = "localhost";
> > private String remoteAddr = "127.0.0.1";
> > private Date lastUpdated = new Date();
>
> In theory, all that should be necessary to fix serialization is to add the
declaration back
> in.
>
> Next time we have to break serialization, we might want to mark as
"transient" any
> properties that don't need to be serialized so we are less likely to hit
this problem again.
>
> Stuart.
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> -------------------------------------------------------------------------
> Stuart Roebuck, BSc, MBA Tel.: 0131 228 4853 / Fax.: 0870 054 8322
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-------------------------------------------------------------------------
Stuart Roebuck [EMAIL PROTECTED]
Lead Developer Mac OS X, Java, XML, etc.
ADOLOS http://www.adolos.com/
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