OTL 4.0, Introduction

Introduction

This document describes the Oracle, ODBC and DB2-CLI Template Library, Version 4.0 (OTL 4.0). OTL 4.0 is a C++ library based on C++ templates.

OTL 4.0 was designed as a combination of a C++ template framework and OTL-adapters. The framework is a generic implementation of the concept of OTL streams. The OTL-adapters are thin wrappers around the database APIs and are used as class type parameters to be passed into the template framework.

OTL 4.0 covers the functionality of a full featured C++ database access library with just a handful of classes: otl_stream, otl_connect, otl_exception, otl_long_string, and several template PL/SQL (Oracle) table container classes, generated from the template framework and the OTL-adapters.

The OTL code gets expanded into direct database API function calls, so it provides very decent performance (only 10-15% overhead compared with the database APIs themselves) and reliability in multiprocessor environments as well as traditional batch programs. OTL 4.0, being a template library, is highly portable since it is self-sufficient and compact enough.

OTL 4.0 is ANSI C++ compliant (ANSI C++ typecasts, clean templatized code, etc.), tightly integrated with the Standard Template Library (STL) via STL-compliant stream iterators, and natively supports the STL std::string by the otl_stream class. OTL integrates with ACE, and supports ACE_TStrings. A new C++ standard (C++11) was adopted in 2011. OTL uses C++-11 features like move constructors, move assignment operators, nullptr, etc. in order to keep its code clean and modern for compilers that support C++11 features.

OTL 4.0 supports all major and a few minor relational database types (Oracle, MS SQL Server, DB2, Informix, TimesTen, MAX/DB, etc.) natively via the corresponding database API. For the rest of database types (PostgreSQL, MySQL, Sybase, SQLite, MS ACCESS, Firebird, etc.), OTL has support via ODBC 3.x, or ODBC 2.5 (legacy applications).

In the last several years, transition from 32-bit platforms to 64-bit platforms has occurred: OTL's source code is portable, and it supports both 32-bit and 64-bit C++ compilers.

Also, OTL supports UTF-8 and UTF-16 string data for Oracle, and for the rest of the database types, when the underlying database API / ODBC driver has the corresponding support.

In 2011, C++11 standard was adopted. OTL started using C++11 features as soon as they became available in major C++ compilers (Visual C++, GNU C++, CLANG, etc.) in order to keep OTL as a general-purpose library relevant and modern over time.


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