Introduction

This directory contains a small technology domonstration for the following technical issues:
  1. Representing data objects using Ada 95
  2. Usage of an SQL based RDBMS to achieve persistency for Ada 95 instances.
  3. Relations between objects.

The data model used for the demonstration is quite simple. Each person identified by its name. Assigned to each person there are upto N accounts assgined. Each account includes a balance.  Each person may be included into multiple groups, e.g. family group. A group again may be associated with accounts.

Representing data objects using Ada 95

Each object of the data model is represented by data type which is derived from the type Persistent.Object which implements the basic functionality to serialize/deserialize the data instance into a blob which is stored in a database record. In order to retrieve such an instance a so called object id is used as a retieval key.  The key is defined when the objects is instanciated, e.g. in the example below

procedure Demo is
...
   Father  : Person.Object(1);

begin
----

end Demo;