i think the coste of using ODMG is very big only looking how in ODMG we query an object. in ODMG it use OQL (like SQL synthaxis where ....) so is very diferent to PB wiche use Criteria to build a condition !!!!!
what do you think Mr Armine On 3/9/06, ABOU LINA <[EMAIL PROTECTED]> wrote: > > Hi, > > ok so, i made DAO implementation with OJB PB in a critical project and > we are in step of delivring some module of the application (the mainly > module now are developped and tested). my question is : > > 1. what will be the cost of migrating from PB to ODMG. ??? > 2. there are some tools making this migration easy and fast ??? > 3. in your opinion, the probleme about deleting collection elements > justify using ODMG instead of PB ??? > 4. Best practice of ODMG and good examples ?? > > > Thanks. > > > > On 3/9/06, Armin Waibel <[EMAIL PROTECTED]> wrote: > > > > Hi, > > > > ABOU LINA wrote: > > > thank first, > > > > > > PersistenceBroker *delete elements* from the database that have been > > removed > > > from the collection only if i do this : > > > for example : A 1:n B > > > 1. i get A from database using OJB Broker. > > > 2. i delete one element B from A : A.getBCollection().remove(o); > > > > > > in this case yes the PB delete the element from database . but in > > generale > > > we don't > > > invoke remove but we construct a new collection and we set it : > > > 1. get A from database. > > > 2. Collection bCol = new ArrayList(); > > > A.setBCollection(bCol); > > > > > > in this case the element that not figure in bCol are not deleted > > because i > > > use ArrayList. (in my Application i can't put RemovalAwareList > > directly > > > > There is no need to handle with RemovalAwareList instances in your > > POJO's. Using type 'List' is sufficient and on insert of new objects you > > > > can use ArrayList, so > > > > > 2. Collection bCol = new ArrayList(); > > > A.setBCollection(bCol); > > > > is valid when insert new objects. > > But you are right, when updating objects you have to use > > Collection.remove (...) method. > > > 2. i delete one element B from A : A.getBCollection().remove(o); > > > > it's not allowed to replace the old List with a sub-List instance. > > > > > > > inorder to keep the application independent of OJB classes ...) > > > > > > so what is the solution please ... without using ODMG ????? > > > > There is none. > > That's the main difference between the PB-api and ODMG. The ODMG > > implementation use a "Unit of work" pattern (object state detection, > > detection of new/deleted objects) the PB-api does immediately write > > objects to DB and does not keep the objects state "in mind". > > > > For the next major release of OJB we plan to extend the PB-api to > > support a "unit of work" pattern with locking. > > > > regards, > > Armin > > > > > > > > Thanks > > > > > > On 3/7/06, Armin Waibel <[EMAIL PROTECTED]> wrote: > > >> Hi, > > >> > > >> ABOU LINA wrote: > > >>> Hi, > > >>> in ojb document : > > >>> --------------------------------------- > > >>> Say you use the PB to query an object O that has a collection > > attribute > > >> col > > >>> with five > > >>> elements a,b,c,d,e. Next you delete Objects d and e from col and > > store O > > >>> again with > > >>> PersistenceBroker.store(O); > > >>> PB will store the remaining objects a,b,c. But it will not delete d > > and > > >> e ! > > >>> If you then > > >>> requery object O it will again contain a,b,c,d,e !!! > > >>> -------------------- > > >>> > > >>> i ask if the new version of PB (1.0.4) still behave like this ??? > > >> Oops! Seems you found some outdated documentation - I will fix this > > till > > >> next release. > > >> With corresponding settings OJB 1.0.4 is able to detect the deleted > > >> objects of the 1:n reference. More info see > > >> > > >> > > http://db.apache.org/ojb/docu/guides/basic-technique.html#1%3An+auto-xxx+setting > > >> > > >> > > http://db.apache.org/ojb/docu/guides/advanced-technique.html#which-collection-type > > >> > > >> regards, > > >> Armin > > >> > > >> > > >> > > >> --------------------------------------------------------------------- > > >> To unsubscribe, e-mail: [EMAIL PROTECTED] > > >> For additional commands, e-mail: [EMAIL PROTECTED] > > >> > > >> > > > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > For additional commands, e-mail: [EMAIL PROTECTED] > > > > >
