Re: object databases

In article <eiscn2$bd4$1@xxxxxxxxxxxxxx>, Sasa <sasa555@xxxxxxxxx> wrote:

"Frans Bouma" <perseus.usenet.NOSPAM.@xxxxxxxxx> wrote in message
news:xn0eth1al6dlbp002@xxxxxxxxxxxxxxxxx
frebe73@xxxxxxxxx wrote:
Also, the code is db agnostic: it works on any db supported by the
O/R mapper.

Since you brought this up - are there mappers which support non relational
storages (XML, proprietary formats, etc.)?

I'd suggest that peple look at Apple's WebObejcts, which includes Apple's
'Enterprise Objects Foundation', 'EOF', which is, among other things an
O/R mapper.

However, where Hibernate directly maps database constructs to Java
contstructs (essentially, tables to classes, etc), EOF uses an
Entity-Relationship model, which is then mapped to tables & columns on one
side, and to classes and fields on the other - though EOF can in fact use
a 'generic object' class (essentially a dictionary / hashtable) to
represent any entities for which you don't need to implement any bespoke
logic. WebObjects (and EOF) underly the iTunes Music Store, for instance.

EOF allows you to write your own 'database adaptor' classes; there have
been those that use flat files. It is generally used with relational
databases, though.


More recently, Apple have (as part of their Cocoa frameworks) introduced
'Core Data', which is not a general Object-relational modeler, but instead
is billed as an 'object graph management system', and which can use either
a relational database (SQLite) or an XML file as its underlying datastore
for persistence. However, with Core Data, you just design your object
model, and don't have any specific control over the database schema.

Sasa

Best wishes,

// Christian Brunschen
.

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