1. DDL Compiler - Data Description Language compiler processes internal specifications in the DDL. It uses metadata information such as the name of the files, data items, storage details of each file, mapping information and constraints etc.
2. DML Compiler and Query optimizer - The DML commands such as insert, update, delete, and retrieve from the application program. Then, they are sent to the DML compiler to be set into object code for database access. The object code is optimized to perform a query by the query optimizer and then sent to the data manager.
3. Data Manager - The Data Manager is a vital software component of the DBMS also knows as Database Control System.
Example of DBMS software: Oracle, Microsoft SQL Server, MySQL
References:
http://74.125.93.104/search?q=cache:VIHaso1VOQkJ:www.cs.uiuc.edu/class/fa06/cs511/4-arch.ppt+dbms+architecture&cd=2&hl=en&ct=clnk&gl=ca
http://www.dbmsbasics.blogspot.com/2008/02/structure-of-dbms.html
http://www.jucs.org/ujs/jucs/Journal/Volume%208/Issue_8_6/efficient_content_based_and/images/fig4.gif
