Database Reference
In-Depth Information
an object-oriented application. This allows you to avoid writing extensive SQL code or stored
procedures to map from application objects to database tables and avoid having to use an object-
relational mapping (ORM) layer. ORM layers can be cumbersome, add complexity to your over-
all application, and slow down data operations.
Because you don't have to translate data from application objects into the relational model, ap-
plications with object databases can be very fast. You also don't need relational keys to help you
join data to fulfill queries, because data is findable in the database as it is in your application: by
following pointers.
Object databases have been with us since the mid-1970s and 1980s. They never really caught
on for widespread business application use, but have found some success in niche areas such
as computer-aided design (CAD) applications, spatial applications, telecommunications, and em-
bedded systems.
InterSystems' object database Caché is probably the best known commercial product, though
Persistent Objects and Extended database Technology (POET), which is now the Versant Object
Database, is also used for Java, .NET, and C++ applications.
There are some disadvantages to using object-oriented (OO) databases. Although there is often
a performance boost to be realized from using an OO database, typically it also tightly couples
your data store to your application, but the trade-off may be worth it, depending on your needs.
Also, object databases typically will only deserialize objects into the same programming lan-
guage used to serialize them, which can severely limit your architecture's flexibility by introdu-
cing even tighter coupling.
In recent years, there has been less interest and movement in object databases than the other
types of data stores discussed here, so I won't go into more detail.
XML Databases
XML databases are a special form of document databases, optimized specifically for working
with XML. The first working draft of XML was developed in 1996, and version 1.0 was pub-
lished as a W3C standard in February of 1998. XML quickly enjoyed widespread use, as web
applications found it expressive and easy to use as a transfer format across a wide variety of lan-
guages. So-called “XML native” databases soon sprang up, one of the first being Tamino from
Software AG. They are now employed in a variety of use cases, such as content management
and supply chain systems, document management, publishing, and support of SOA initiatives.
