HP Intelligent Management Center Standard Software Platform - Manual (Page 741)

Five layers
The process by which Crystal Reports accesses data from a JDBC data
source consists of five layers.
• Crystal Reports layer
• JDBC translation layer
• JDBC layer
• DBMS translation (JDBC data source) layer
• Database layer
Crystal Reports layer
The Crystal Reports layer is database-driver independent, but it is used to
drive all of the remaining layers.
JDBC translation layer
Crystal Reports uses the Dynamic Link Library crdb_jdbc.dll to
communicate with JDBC. This file is unique to Crystal Reports environment
and provides your report with access to any JDBC data source. This is the
driver that actually passes data to and from JDBC.
JDBC layer
JDBC acts as a gateway through which database requests and data can
pass.
Note:
For more information on JDBC and the JDBC files, see the Sun Microsystems
web site.
JDBC uses the SQL language for all transactions between Crystal Reports
and JDBC. Even if the database does not normally use SQL to create and
work with tables, the JDBC driver provided by the database (the DBMS
translation layer) must communicate with JDBC using SQL. For most users,
Crystal Reports 2008 SP3 User's Guide 741
26 Accessing Data Sources
JDBC data sources