Clients connect to a middle-tier machine running the Oracle Net Connection
Oracle Features for OLTP | 213
Manager (CMAN). The Connection Manager multiplexes the traffic for multiple
clients into one network connection per Oracle Net dispatcher on the database
server. Unlike connection pooling, there is no notion of ???time-out??? for a client??™s
virtual network connection. The Oracle network topology can include multiple
machines running the Connection Manager to provide additional scalability and
fault-tolerance.
In terms of scalability, youcan think of connection pooling as the middleweight
solution and multiplexing via Connection Manager as the heavyweight solution.
Figure 9-5 illustrates these two network-scaling technologies.
Connection Manager has become more flexible in Oracle Database 10g, with the
added ability to dynamically alter configuration parameters without shutting down
Connection Manager and improved access rules to filter CMAN traffic.
Figure 9-5. Network scaling in Oracle Net
Shared Server
CONNECTION POOLING
Shared Server
Concentrators
Multiplexing
CONNECTION MULTIPLEXING
214 | Chapter 9: Oracle and Transaction Processing
Database Resource Manager
Oracle8i introduced the Database Resource Manager (DRM) to simplify and automate
the management of mixed workloads in which different users access the same
database for different purposes.
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