E3's Database Server uses OCI (Oracle Call Interface) to communicate with an Oracle server, that is, it uses Database's native form to improve communication performance with a Database.

A good example on how E3's Database Server communication with Oracle works is the Historic object. First, data acquisition is performed by a Historic that, with this data, immediately sends it as a request to a Database. These requests can be for creating a table, creating indexes and keys, adding data, etc. E3's Database Server contains a separated process specially designed to receive them. Depending on the type of operation to perform, data is formatted and saved in a temporary file or in memory.

At the same time, a Database has another process, responsible for retrieving requests and sending them to a database as SQL commands, by using OCI.

Communication between E3 and Oracle