Programs in Java use JDBC to access data from a database. Such programs using this base level abstraction have multiple issues:
* SQL is directly embedded in the java code,
* The data sources are hard coded into
the java code,
* Connections are explicitly opened and closed by each programmer,
* Cursors and Statements are explicitly managed in the code.
Although EJBs can provide solutions to some of these issues but not all.
Komatineni describes that most of these issues can be resolved by introducing externalized declarative
data access mechanisms based on a common set of interfaces for data access thus introducing a declaratively
composable hierarchical data abstraction mechanism.
“Another important innovation that I propose is the concept of a hierarchical
data abstraction. In a relational abstraction, the primary unit is a row set. In
a hierarchical abstraction, the primary unit is a collection of row sets that
are bound by parent child relationships. The goal is to declaratively define a
hierarchical data set by associating rowsets to each of the hierarchical nodes.
The eventual hierarchical dataset will be obtained by executing these individual
rowset adapters.” – Satya Komatineni
The Hierarchical data sets are XML based declarations (Universal Data
Definition – UDDs). I.e., the whole process involved generating XML directly and decclaratively from RDBMS.
The most interesting aspect of this presentation is the idea of elevating the
data abstraction layer from JDBC to a declarative hierarchical data layer.
For further information on this topic please refer to http://216.187.231.34/akc/index.html.
Charles Engelke's Blog 