Re: How to deal with this kind of serialization compatibility issue?

[Paulex Yang]

As we discussed, I just attached a patch for JIRA 184 on TimeZone case
http://issues.apache.org/jira/browse/HARMONY-184

and suggested to mark this issue as "won't fix".

George Harley wrote:

Richard Liang wrote:

Stepan Mishura wrote:

Hi Paulex,

Currently, we have three options:
1. let it be, and speak it loudly in Harmony JavaDoc

I'd choose this option. It is open and honest - if we get unknown class for

deserialization (say sun.util.calendar.ZoneInfo or

com.someCompanyName.util.MyTimeZone) we should not do any tricks and create illusion for a user that we know how to deserialize it. Also I don't think

that "to be compatible" means to provide compatible implementation of
com.sun.* classes.

IMHO, the best we can do in Harmony implementation is not to do the same "serialization bug". I mean the following: factory methods of TimeZone class should return instances of SimpleTimeZone class. So Harmony implementation

will produce serial form that will be deserializable on any other
implementation. However I don't know whether it is possible or not to
implement in this way.

Agree. I'm just wondering what we shall say in Harmony JavaDoc. It's RI (SUN) who breaks its spec.

Hi Richard,

I sent a mail on this topic yesterday (maybe my mail client is playing up again ?) : the RI Javadoc for the java.util.TimeZone method getDefault() states that "The source of the default TimeZone may vary with implementation". Given that I personally do not think that they are breaking "the spec" in this instance : they are pretty much stating that this method is dependent on the Java implementation.

IMHO, their Javadoc needs to make it clearer that the return from their implementation of this method cannot be guaranteed to be interoperate with other Java implementations. Likewise, the Harmony Javadoc for the corresponding methods, and others like it that we have yet to discover, should seek to remove all such ambiguities. This is a great example of how our documentation can exceed that of the RI.

Best regards,
George

2. try to compatible with RI, by creating some adapter with RI's
serializable class name, i.e. com.sun.*, etc, and the behavior is even

not necessarily compatible with RI. we can even separate them all to a new component named as "compatibility", so that it is easily modify them

when RI changes its mind and improve. Not sure if it is legally fine.

IMHO, it is not the option. The word 'adapter' is used here only to soften

the fact that we have to implement a set of com.sun.* classes. And
definitely they won't be "compatible". So without them we are not

"compatible" and with them were are not still "compatible" :-) Why we should

do this?

3. also try to compatible with RI, by maintaining pairs in
ObjectInputStream, this approach maybe has less legal risk? (I have no
idea in fact.)

Not quite clear what you mean. Do you suggest changing serialization

framework? I mean that if it detects during deserialization, for example,

sun.util.calendar.ZoneInfo it will substitute it with
o.a.h.util.calendar.ZoneInfo. Right?

Thanks,
Stepan Mishura
Intel Middleware Products Division



On 3/8/06, Paulex Yang <[EMAIL PROTECTED]> wrote:

Mikhail

Mikhail Loenko wrote:

2006/3/7, Geir Magnusson Jr <[EMAIL PROTECTED]>:

This is somewhat terrifying, isn't it? Are there really references to

com.sun.* in serialized API objects?

Yes, there are.
For example, TimeZone.ser produced by the example from the JIRA issue
that started this thread, refers to "sun.util.calendar.ZoneInfo"

yes, and as I mentioned before, the TimeZone is composited by other
serializable class, so that all these classes cannot be serialization
compatible, feel like something as cancer :(

Can we list all the popular applications that exchange by serialized

objects

and identify which objects do they send/receive?

Rather than investigating almost infinite and uncertain(i.e. how to
define popular?) applications, I'd like to test all the serializable

class in JSE, at least it is a certain and limited set, we can just find

all these kind of incompatibilities one by one, and take some actions.

Currently, we have three options:
1. let it be, and speak it loudly in Harmony JavaDoc
2. try to compatible with RI, by creating some adapter with RI's
serializable class name, i.e. com.sun.*, etc, and the behavior is even

not necessarily compatible with RI. we can even separate them all to a new component named as "compatibility", so that it is easily modify them

when RI changes its mind and improve. Not sure if it is legally fine.
3. also try to compatible with RI, by maintaining pairs in
ObjectInputStream, this approach maybe has less legal risk? (I have no
idea in fact.)

Any other good ideas?

And before all of this, I cannot agree with Geir more - we should make
Sun be aware of this issue.

Thanks,
Mikhail

--
Paulex Yang
China Software Development Lab
IBM

--
Thanks,
Stepan Mishura
Intel Middleware Products Division

--
Paulex Yang
China Software Development Lab
IBM