Standalone TP
monitors are also used less frequently today for workload management (see
Figure 13-2), as this capability is now built into middle-tier applications.
Figure 13-2. Application server with TP monitor
Clients
Application Server
with Transaction
Processing Monitor
Database
Servers
310 | Chapter 13: Oracle Distributed Databases and Distributed Data
If you are still considering the use of TP monitors, you likely have one of these scenarios:
??? Migration of legacy applications (usually originally written using CICS and
COBOL for a mainframe) to CICS on Unix or Windows NT
??? Need for two-phase commits between Oracle and other XA-compliant databases
Moving Data Between Distributed Systems
The previous section discussed the use of multiple database servers acting together as
part of a single logical database for users. The following situations call for the contents
of a database to be duplicated and moved between systems:
??? When data available locally eliminates network bandwidth issues or contention
for system resources
??? When mobile database users can take their databases with them and operate disconnected
from the network
??? When redundant databases can help to deliver higher levels of reliability, as each
database can be used as a backup for other databases
In many grid implementations, the ability to share resources across the grid can also
require data to be replicated to multiple servers within the grid.
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