Java-Based Oracle Fusion Middleware Components Deployed to Oracle WebLogic Server

4-2 Oracle Fusion Middleware High Availability Guide Oracle Fusion Middleware components that access the database can be categorized in three ways: ■ Java-based Oracle Fusion Middleware components deployed to Oracle WebLogic Server ■ Java-based Oracle Fusion Middleware components that are standalone Java Clients ■ Non-Java Oracle Fusion Middleware components This chapter contains the following sections: ■ Section 4.1.1, Java-Based Oracle Fusion Middleware Components Deployed to Oracle WebLogic Server ■ Section 4.1.2, Using Multi Data Sources with Oracle RAC ■ Section 4.1.3, Configuring Multi Data Sources with Oracle RAC ■ Section 4.1.4, Oracle RAC Failover with WebLogic Server ■ Section 4.1.5, JDBC Clients ■ Section 4.1.6, System Clients

4.1.1 Java-Based Oracle Fusion Middleware Components Deployed to Oracle WebLogic Server

All Oracle Fusion Middleware components deployed to Oracle WebLogic Server support Oracle Real Application Clusters Oracle RAC. For establishing connection pools, Oracle Fusion Middleware supports only multi data sources for the Oracle RAC back end for both XA and non-XA JDBC drivers. For connection pooling, Oracle Fusion Middleware deployments do not support other connection failover features supported by Oracle JDBC drivers for Oracle RAC. Oracle RAC multi data sources are configured by Oracle Fusion Middleware Configuration Wizard. You can also configure multi data sources using the Oracle Fusion Middleware Administration console, or WLST commands. Please refer to component specific guides for multi data source configuration details When an Oracle RAC node or instance fails, session requests are redirected to another node in the cluster, either by Oracle WebLogic Server or by the Oracle Thin driver. There is no failover of existing connections, however, new connection requests from the application are managed using existing connections in the Oracle WebLogic pool or by new connections to the working Oracle RAC instance. In-flight transactions are typically rolled back when the database is the transaction manager. When the WebLogic Server is the Transaction Manager, in-flight transactions are failed over, meaning they are driven to completion or rolled back, based on the state of the transaction at the time of the failure. If the application requires load balancing across Oracle RAC nodes, WebLogic Server supports this capability through use of JDBC multi data sources configured for load balancing. The data sources that form a multi data source are accessed using a round-robin scheme the Oracle recommended configuration for deployments against Oracle RAC databases. When switching connections, WebLogic Server selects a connection from the next data source in the order listed. The next section briefly describes configuration of multi data sources with Oracle RAC. Considerations for High Availability Oracle Database Access 4-3

4.1.2 Using Multi Data Sources with Oracle RAC