Oracle Call Interface (OCI) is the comprehensive, high performance, native C language interface to Oracle Database. It exposes the full power of Oracle Database to custom or packaged C applications. Oracle In-Memory Database Cache also supports access from OCI programs.
A broad range of customers including Fortune 500 customers and ISVs develop high performance applications directly in OCI.
OCI is highly reliable. Oracle tools such as SQL*Plus, Real Application Testing (RAT), SQL*Loader, and Data-Pump all use OCI. OCI also provides the foundation on which other language-specific interfaces such as Oracle JDBC-OCI, Oracle Data Provider for Net (ODP.Net), Oracle Precompilers, Oracle ODBC, and Oracle C++ Call Interface (OCCI) drivers are built. OCI is also used by leading scripting language drivers such as PHP OCI8, ruby-oci8, Perl DBD::Oracle, Python cx_Oracle, and the statistical programming language R's ROracle driver.
OCI libraries are included by default in Oracle Database 12c. OCI is also in the lightweight Oracle Instant Client, allowing ISVs and customers to quickly install and deploy OCI applications and tools. See the Oracle Instant Client page for more information.
View this great Oracle Open World session from Nancy Ikeda, a senior developer at Oracle.
The session description was: Best practice coding samples and techniques show how to resolve connection management, statement execution, and data fetching inefficiencies in applications using APIs such as JDBC, OCI, ODBC, ODP.Net, or higher-level scripting languages. This session shows how the Automatic Workload Repository feature of Oracle Database and Automatic Database Diagnostic Monitor profiling tools help diagnose application design and coding issues. Specific solutions show how to resolve these and other issues to enhance applications for scalability and resilience. Among the solutions discussed are Oracle Database 12c’s new client configuration file. Developers or DBAs can use it to tune and configure applications without modifying code. Examples use JDBC and OCI but are applicable to all APIs.
The new OCI features in Oracle Database 12c include:
Oracle Instant Client
Oracle Database 11g
Oracle Database 10g