locking a record

[Pep Menval]

Can you share your knowledge about this issue with me. I failed my Developer Certification because of that.
Thanks a lot

[Philippe Maquet]

Hi Pep,
Welcome to this forum.

Can you share your knowledge about this issue with me. I failed my Developer Certification because of that.

I am sorry to hear you failed.
Locking is a broad subject, there are different possible requirements depending on the assignment you received, as there are multiple valid soutions.
So would it possible for you to post the locking requirements quoted from your instructions and explain briefly what you did to fulfil them ?
It will then be easier to enter in a - hopefully - useful discussion.
Best,
Phil.

[Adrian Muscalu]

Pep,
Don't worry, you'll be fine next time. You are not alone.
As Phil said, try to start this topic yourself on a particular aspect of locking.
Cheer up,
Adrian

[Pep Menval]

Originally posted by Adrian Muscalu:
Pep,
Don't worry, you'll be fine next time. You are not alone.
As Phil said, try to start this topic yourself on a particular aspect of locking.
Cheer up,
Adrian

[Pep Menval]

Thanks a lot, talking to you do cheer me up. Anyway, my assignment is Fly By Night Services, and people at SUN discounted 30 point out of 30 because my lock method should block instead o throwing an controlled Exception. I send some messages to them by the response was resubmission. Unfair I think, I just needed 12 point to pass.
Is there anyone who did this assignment before or someone who can help me about it.
Best
Pep

[Andrew Monkhouse]

Hi Pep,
We will be glad to help you with your locking code.
Perhaps you could start by telling us your design decision for why you chose to throw an exception rather than blocking as required in the instructions?
Regards, Andrew

[Pep Menval]

Originally posted by Andrew Monkhouse:
Hi Pep,
We will be glad to help you with your locking code.
Perhaps you could start by telling us your design decision for why you chose to throw an exception rather than blocking as required in the instructions?
Regards, Andrew

Just in case a thread would block too long or hang up. Obviously I made a great mistake. I'm looking in the forum for an answer.
Regards, Pep

[Philippe Maquet]

Hi Pep,
I initiated a thread which could interest you : Single table / Simple Locking - WeakHashMap vs WeakReferences.
That thread quickly slips into a discussion about map's semantics between Max and Jim, but I still think you should find the basics out there.
I guess you'll be resubmiting soon, and I am - as Andrew and most of people on this forum are - willing to help you pass.
So don't hesitate to post questions !
Best,
Phil.

[Andrew Monkhouse]

Hi Pep,
The basic answer comes from the instructions:

Extending suncertify.Data:
The lock method should block until the requested lock can be applied.

So Sun expect the lock method to call wait() if someone else has already locked the record you want, and the unlock() method should call notifyAll() to ensure that waiting clients get another chance to try and lock the record.
By the way, are you tracking ownership of the locks (to ensure that only the person who has locked the record may unlock it)?
Regards, Andrew
[ November 01, 2003: Message edited by: Andrew Monkhouse ]

[Adrian Muscalu]

Well said Andrew, in this case the specs are clear. The implementation requires to wait.
Pep, good luck with it.
Adrian