> -----Original Message----- > From: Alex Paransky [mailto:[EMAIL PROTECTED]] > Sent: Monday, February 11, 2002 4:38 PM > To: [EMAIL PROTECTED] > Subject: Re: versioning on top of entity beans > > > You forgot the ONE most IMPORTANT issue: d) Relationships. Your bean > (data) does not live in isolation. What to do when thereis a > relationships > between A and B, and B moves to a new version? Do you create > a new version > of A called A' and map it to a new version of B, called B'? > What if there > are other relationships to A, what to do with those?
Well, it would probably necessitate your relationships being bi-directional, so you could get the objects referencing the current object easily. It really depends what your requirements are as to whether you need to version the entire object graph or just create a new version of the one that's changed and tell all of the relationship objects to point to the head revision (to steal from Perforce's CM vocabulary). This is probably sufficient in this case. > > As someone else suggested, using version in a PK is > interesting, but what a > mess for relationships. > Not really. You need to update relationships anyway. You can't have two different entities with the same PK, so something has to change. If you use the version ID as part of the PK and use FK relationships, then you can see the relationships in an old version and old versions maintain relationships with the versions that were there when they were the head revision. Again, this would be true no matter what, but you can see it more clearly with the version as part of the PK. > -AP_ > Jason Carreira ==========================================================================To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff EJB-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".
