The TechInsite Object Persistence Framework (tiOPF) is a free and Open Source framework of Delphi code that simplifies the mapping of an object oriented business model into a relational database. The project was commenced in 1999 and now features persistence layers for Interbase (IBX), Paradox (BDE), Access and SQLServer (ADO), XML (MSDOM) and Oracle (DOA). The choice of persistence layer can be made at compile time with the appropriate code being included in the main EXE. Persistence layers can also be loaded at runtime, which an application can access data via any of the supported persistence layers just by loading the appropriate package.Other features of the tiOPF include:A hierarchy of classes to build a business object model based on GoF's Composite pattern.Persistence mechanism based on GoF's Visitor and Template Method patterns.Swappable persistence layers based on GoF's Adaptor and Factory patterns.Select your own OID generation strategy from Amblers High/Low integer, GUIDs, custom HEX or roll your own OID generator.Map objects to a database using Ambler's OO-DB mapping strategy, or hand code the mappings your self.Automatically generate SQL (or XML query strings), compile SQL into the application or store the SQL outside the application using the tiOPF's tiSQLManager which lets you store the SQL in the database it self.Six persistence layers to choose from, or roll your own.There are 471 DUnit tests ensure stability.16 contributing authors.