NX: about lock cookie

[Bigwood Liu]

Hi,
My DBAccess interface have two lock concerning methods:

public long lockRecord(long recNo) throws RecordNotFoundException
 public long unlock(long recNo, long cookie) throws SecurityException 

Because the lock/unlock is consided only in network mode, I think the lock and unlock methods should be only implemented in RemoteData class, the Data class should only have empty lock/unlock methods like a WindowAdapter, am I right? thus there is a question: what should the lockRecord return, 0?
In network mode, I want to use the combination of the time when the record is locked and the record number as the cookie, thus the cookie is unique.
Waiting for your comment
Regards,
Tom

[Andrew Monkhouse]

Hi Damu,

Because the lock/unlock is consided only in network mode ...

Why is the lock/unlock only considered in network mode?
Or, why can't you use lock/unlock in standalone mode?
Regards, Andrew

[Bigwood Liu]

hey Andrew,
Thank you for your reply first, I think in standalone mode there is only one user use the computer at any time, so there is not multi thread problem, so the lock issue is unnecessary.
Regards,
Tom

[Philippe Maquet]

Hi damu,

In network mode, I want to use the combination of the time when the record is locked and the record number as the cookie, thus the cookie is unique.

System.currentTimeMillis() is not precise enough to make sure your cookie is unique. But, BTW your lock cookie does not need to be unique : just difficult to guess by a malicious coder. Think of Random.nextLong().

Because the lock/unlock is consided only in network mode, I think the lock and unlock methods should be only implemented in RemoteData class, the Data class should only have empty lock/unlock methods like a WindowAdapter, am I right? thus there is a question: what should the lockRecord return, 0?

I agree with Andrew. Your design will be simpler if you keep locking for local access.
Best,
Phil.

[Bigwood Liu]

Hi Philippe ,
Thank you for reply.
since you implement the lock/unlock in data class, will you use it in standalone mode? But I think it is unnecessary.
Regards,
Damu

[Philippe Maquet]

Hi damu,
You're right, it's "unnecessary", but IMO, if you do, the benefits are that it's simpler to implement and simpler to maintain, actually at no cost (if there are no other clients competing for locks, locks are granted immediately in any case).
Best,
Phil.

[Bigwood Liu]

hi Philippe ,
Yes, I see, you are right, thank you
Regards,
Damu