FlexDB


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FlexDB

Last updated at 5:07 pm UTC on 22 June 2008

FlexDB comprises a plugin for accessing DBs with support for native threads and an API for adapting DB vendor drivers.

Modules and interfaces:
- o Smalltalk <-> plugin
- o plugin <-> mini driver
- A new DB (vendor) driver can be adapted to the mini-driver API.

See SqueakSource for a snapshot of the development in progress.

Module: Smalltalk API classes

The Smalltalk API offers the classic classes:

FlexDB, provides protocol for creation of a DB session
FlexDBSession, is associated with a mini-driver and its native thread
FlexDBResult, holds results of a command or a query
FlexDBRecordset, for mapping and accessing records
FlexDBRecord, for accessing the data of a record
FlexDBDataType, base class for non-trivial DB data type coercion

Module: FlexDBPlugin, written in Slang

The plugin handles native threads, loads/unloads mini-drivers and forwards primitive calls to the mini-driver by using the mini-driver API.

Module: mini-driver, dynamic loadable libraries

A mini-drivers adapts its vendor specific DB driver to the mini-driver API. Therefore the FlexDBPlugin does not know anything about the vendor specific DB driver's internals.

Interplay of mini-driver and Smalltalk API

Once a new mini-driver has been created and compiled into a dynamic loadable library, the Smalltalk side can be extended (by subclassing) for accessing the functionality of the associated vendor specific DB driver. There is no need for changing the FlexDBPlugin and the new mini-driver can be loaded on demand.

Module: Smalltalk API classes

Module: FlexDBPlugin, written in Slang

Module: mini-driver, dynamic loadable libraries

Interplay of mini-driver and Smalltalk API

Passing properties and parameters

Accessing DB data and types

DB data type coercion

Handling of BLOBs

FlexDB actions are performed asynchronously

Example DBs and tests

DB Minidriver API (draft)