This subsection describes the preconditions and notes on connecting to Oracle.
The preconditions for Oracle11g are as follows:
Table 3-27 Transaction support levels available for each RAR file (Oracle11g)
Used DB Connector (RAR file) | Transaction support level | Light transaction | |
---|---|---|---|
Enabled | Disabled | ||
DBConnector_Oracle_CP.rar | NoTransaction LocalTransaction | Y | Y |
DBConnector_Oracle_XA.rar | XATransaction | -- | Y |
DBConnector_CP_ClusterPool_Root.rar DBConnector_Oracle_CP_ClusterPool_Member.rar | NoTransaction LocalTransaction | Y | Y |
Note the following when you connect to Oracle:
The J2EE components available when you use Oracle JDBC Thin Driver to connect to Oracle are as follows:
When the data is stored in the database and when the data is extracted from the database, the JDBC driver converts the character code between Unicode and the database storage code appropriately. The following figure shows the locations where the character code conversion is implemented when you use Oracle JDBC Thin Driver.
Figure 3-18 Locations where the character code conversion is implemented when Oracle JDBC Thin Driver is used
The following table describes the character code conversion executed at each location in the figure.
Table 3-28 Locations where the character code conversion is implemented when Oracle JDBC Thin Driver is used
Location | Implemented content |
---|---|
1 | When the external data, such as a network or file, is read by the J2EE server, the external data code is converted to Unicode. |
2 | When the data read by the J2EE server is stored in the Oracle server, Unicode is converted to UTF-8. This code conversion is implemented by the JDBC driver part on the J2EE server. |
3 | The Oracle server converter converts UTF-8 to the database storage code. This code conversion is implemented on the Oracle server. |
4 | The Oracle server converter converts the database storage code to UTF-8. |
5 | When the data stored by the J2EE server is obtained from the Oracle server, UTF-8 is converted to Unicode. |
6 | When the data obtained with the J2EE server is written to a network or a file, Unicode is converted to the external data code. |
When you use Oracle JDBC Thin Driver, the characters might get garbled due to the differences in the mapping rules supported by the converters for JavaVM and the Oracle server. The garbled characters occur due to the combination of the external data character code and the database storage code, and the combination of converters that perform the character code conversion.
To avoid garbled characters, use the following combinations of the external data character code and the database storage code:
The following functionality is not available for dedicated server connections. To use the following functionality, use a shared server connection. For details, inquire with the Oracle Support Service.
When using Oracle with an XA transaction, if you issue the Oracle select statements for multiple databases that were updated in a transaction during the conclusion of a JTA transaction, the return value of each select statement might be different. This is due to the restrictions in the distributed read consistency for Oracle.
The method of connecting to Oracle using Oracle RAC varies according to the Oracle version or the functionality used for load balancing. The following table describes the mapping between the Oracle version, the functionality used for load balancing, and the RAR file used.
Table 3-29 Mapping between the Oracle version, functionality used, and the RAR file used
Oracle version | Functionality used for load balancing | DB Connector RAR file name |
---|---|---|
| Application Server functionality (Connection pool clustering functionality) | DBConnector_CP_ClusterPool_Root.rar DBConnector_Oracle_CP_ClusterPool_Member.rar |
Oracle functionality | DBConnector_Oracle_CP.rar DBConnector_Oracle_CP_Cosminexus_RM.rar |