Advanced Perl Programming

Chapter 11. Implementing Object Persistence

God gave us our memories so that we might have roses in December.

—James Matthew Barrie

The Amazon is formed by the confluence of two rivers: the Solimões, a yellowish, silt-laden river, and the dramatic Rio Negro, a river with jet-black water.^[40] Twelve miles downstream of their meeting, the two rivers defiantly retain their separate identities while sharing the same bed. Somehow, this seems to bear a strange resemblance to the subject at hand: object persistence.

There are two important camps in the commercial computing world: purveyors of OO (language designers, object evangelists) and persistence vendors (database and TP^[41] monitor implementors). Like the Solimões and the Rio Negro, the two camps (and multiple camps within their ranks) have their own agendas, even as they strive to merge at some point in the future.

The OO folks would like nothing more than commercial-grade persistence (in terms of performance, stability, and scalability) and propose methods to retrofit various persistence stores onto an object model. Some of their prominent efforts include the CORBA Persistence Services specification from the Object Management Group, Sun’s PJava (Persistent Java), and the OLE Persistence framework from Microsoft. Meanwhile, the database folks are grafting OO features onto their offerings: RDBMS vendors such as Informix and Oracle have announced object-relational databases (supporting abstract data types, not just plain scalar data), ...