Shared-memory architecture
Figure F–1 shows the shared-memory OpenEdge architecture.
The following sections explain the components of the architecture.
Broker
The initial database server process is identified as the broker (_mprosrv). The broker process manages shared resources and starts servers for remote users, as needed.
OpenEdge Database Monitor utility
The OpenEdge Database Monitor utility (_dbagent) displays performance and usage information about database status and activity.
For more information about the Database Monitor utility, see the description of the PROMON utility in OpenEdge Data Management: Database Administration
.
OpenEdge Watchdog utility
If a process terminates improperly, it can maintain a lock on a record or shared-memory structure. This can impact database concurrency. The OpenEdge Watchdog utility detects processes that have terminated improperly and cleans up after them.
At regular intervals, the Watchdog utility checks for processes that have terminated unexpectedly. If it finds one, it releases any locks or shared-memory structures that the process might hold.
The Watchdog utility checks for inactive processes approximately once every 10 seconds. It also checks for self-service clients that are no longer active, releases all the appropriate record locks, backs out of any live transactions, and releases any shared-memory locks. If a server process terminates unexpectedly, the Watchdog utility disconnects and cleans up the server’s remote clients.
For more information about the Watchdog utility, see the description and other details about the PROWDOG utility in OpenEdge Data Management: Database Administration
.
Background writers
The OpenEdge Enterprise RDBMS offers three background writer processes that improve performance. These processes continually perform certain housekeeping functions in the background. Because these functions are performed regularly by the dedicated background writer processes, client and server processes rarely have to wait for these functions to be performed.
The three types of background writers, asynchronous page writers, before-image writers, and after-image writers, are described in the "Processes in Windows platforms" section and in the "Processes on UNIX platforms" section. The AdminService starts the background writers if the AdminService has been configured to do this by Progress Explorer. For more information about background writers, see OpenEdge Data Management: Database Administration .