Just a follow up, is there any problem with this design:
AbstractClass - contains the db open in the constructor:
--------------
constructor:
protected Implementation odmg = OJB.getInstance();
protected Database db = odmg.newDatabase();
//open database
try {
db.open("repository.xml", Database.OPEN_READ_WRITE);
} catch (ODMGException ex) {
ex.printStackTrace();
}
abstract public Iterator listAll();
abstract public Iterator listAll();
ConcreteClass - extends AbstractClass
----------------------------------------
- calls super() that performs the db connection.
- uses the odmg
Ethel Emmons wrote:
> In the ODMG tutorial 2 below, an application class
>
> performs db connect/open and passes
> the odmg instance to the delete, edit, insert etc
> classes.
> In a web app where I have several tables to
> update, insert, etc. where can I put the
> connection?
> Do I need to close the connection? Is the
> connection always on?
> Can I check if odmg and db are null before I
> obtain the instance or open the db?
>
> Thanks,
> Ethel
>
> public Application()
> {
> // get odmg facade instance
> Implementation odmg = OJB.getInstance();
> Database db = odmg.newDatabase();
> //open database
> try
> {
> db.open("repository.xml",
> Database.OPEN_READ_WRITE);
> }
> catch (ODMGException ex)
> {
> ex.printStackTrace();
> }
>
> useCases = new Vector();
> useCases.add(new UCListAllProducts(odmg));
> useCases.add(new UCEnterNewProduct(odmg));
> useCases.add(new UCDeleteProduct(odmg));
> useCases.add(new UCQuitApplication(odmg));
> }
>
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