DBBaseContext - Base class for database contexts

The base class for database contexts provides some basic functionality for database context classes. The base context class for database context types provides two kinds of handler functions in order to handle different event types simply by overloading the handler function.

• do-handler handling client events
• notify handler handling server events

The basic handler implementations do not do anything and need not to be called from overloaded handlers. Handler functions are returning an execution error code ( >0 ), 0 in case of successful processing and -1 in order to indicate, that the handler did not work and the event has to be passed to the next available handler.

Handlers for database events are usually called within internal transactions. Thus, all modifications made by the event handler are reset when the transaction fails.

For a number of database operations error events are generated that are called in case of an error. An error could be a database (consistency) error but the process event (before event) could have denied the operation as well.