2 OPMN: Overview

This chapter provides an overview of OPMN for Oracle Fusion Middleware. It includes the following topics:

What is OPMN?

OPMN is installed and configured with the following installation types:

  • Web Tier Installation: OPMN manages Oracle HTTP Server and Oracle Web Cache

  • Oracle Portal, Forms, Reports, and Discoverer Installation: OPMN manages Oracle Portal, Oracle Forms Services, Oracle Reports, Oracle Business Intelligence Discoverer, and Oracle EM Agent and Service Manager

  • Oracle Identity Management Installation: OPMN manages Oracle Internet Directory and Oracle Virtual Directory

OPMN features the following functionality:

  • Provides a command-line interface for process control and monitoring for single or multiple system components.

  • Provides an integrated way to manage system components.

  • Enables management of system subcomponents and sub-subcomponents.

  • Channels all events from different system component instances to all system components that can utilize them.

  • Solves interdependency issues between system components by enabling you to start and stop components in order.

  • Enables customizing of enterprise functionality by using event scripts.

  • Enables gathering of host and system process statistics and tasks.

  • Provides automatic restart of system processes when they become unresponsive, terminate unexpectedly, or become unreachable as determined by ping and notification operations.

  • Provides automatic death detection of system processes.

  • Enables you to control an Oracle instance through modifications to the opmn.xml file.

An Oracle instance is a directory that contains a set of system components managed by a common OPMN.

The OPMN server should be started as soon as possible after turning on the computer. OPMN must be running whenever system components are turned on or off.

On Microsoft Windows, OPMN is created as a service for each Oracle instance.

Oracle Fusion Middleware components that are managed by OPMN should never be started or stopped manually. Do not use command line scripts or utilities from previous versions of Oracle Fusion Middleware for starting and stopping system components. OPMN must be the last service turned off whenever you restart or turn off your computer.

Use the Fusion Middleware Control Console and the opmnctl command line utility to start or stop system components.


Refer to Chapter 4 for more information about the opmnctl command.

How OPMN Works

OPMN consists of a core grouping of three components that interpret and convey notification information sent between system processes within the same or different OPMN servers.

The core of OPMN consists of the following three components:

Figure 2-1 shows the architecture of the core of OPMN.

Figure 2-1 OPMN Architecture

Description of Figure 2-1 follows
Description of "Figure 2-1 OPMN Architecture"

Oracle Notification Server

Oracle Notification Server (ONS) is the transport mechanism for failure, recovery, startup, and other related notifications between components in Oracle Fusion Middleware. It operates according to a publish-subscribe model: a system component receives a notification of a certain type for each subscription to ONS. When such a notification is published, ONS sends it to the appropriate subscribers.

Unlike previous versions of Oracle Fusion Middleware, ONS is not configured to discover other OPMN servers. OPMN does not need to connect to other OPMNs for normal operation because all administration is centralized in the WebLogic domain. The WebLogic domain establishes remote client connections to each OPMN server as needed.

Oracle Process Manager

Oracle Process Manager (PM) is the centralized process management mechanism used to manage system processes. The PM is responsible for starting, restarting, stopping, and monitoring every process it manages. The PM handles all requests sent to OPMN associated with controlling a process or obtaining status about a process. The PM is also responsible for performing death-detection and automatic restart of the processes it manages. The system processes that PM is configured to manage are specified in the opmn.xml file.

The PM waits for a user command to start a specific, or all system processes. When a process is stopped, the PM receives a request as specified by the request parameters.

The OPMN server consists of 2 processes. The first OPMN server process has only one purpose: to start the second OPMN server process when necessary. The second OPMN server process handles all request traffic and does all the work. If the second OPMN server process goes down as part of an opmnctl reload command or an unexpected crash it is restarted by the first OPMN server process.

On Microsoft Windows, the second OPMN server process is not restarted if it is deliberately terminated. Instead, the first OPMN server process exits as well. Recovering from this situation is accomplished by restarting the OPMN server from the command line or service manager.

The Fusion Middleware Control Console also uses PM to manage processes.

The PM uses the ONS to:

  • detect that a process has completed initialization and is ready to receive requests

  • determine what ports are in use

  • obtain component specific runtime information

PM Modules

The Oracle Process Manager Modules (PM Modules) implement system component-specific process management functionality. The PM Modules pass notification information returned by other system component PM Modules within the same or different OPMN servers.

The PM Modules:

  • handle any communications originating from the running component.

  • construct system component specific control information (how to start, stop, restart the component).

  • test responsiveness in an system component specific manner to determine if a component is responding to requests.

See Also:

Chapter 6 for the common configuration of the opmn.xml file.

What System Components Does OPMN Manage?

OPMN manages all system components including the Oracle EM Agent and Service Manager.

You can also configure OPMN to manage other processes (including Oracle and other third-party products) using the Custom PM Module. See Appendix A for more information about configuring a custom process.

OPMN manages the following Oracle Fusion Middleware components:

  • OHS

  • Oracle Web Cache

  • Oracle Internet Directory

  • Oracle Virtual Directory

  • Oracle Forms

  • Oracle Reports

  • Oracle Business Intelligence Discoverer

Oracle Enterprise Manager Fusion Middleware Control Console

In addition to OPMN, you can also manage your enterprise using the Fusion Middleware Control Console. The Fusion Middleware Control Console leverages the functionality of OPMN to manage your Oracle Fusion Middleware enterprise. Using a Web browser, Fusion Middleware Control Console provides a graphical interface that enables management of all system components in your network and enterprise.

See Also:

Oracle Fusion Middleware Administrator's Guide for more information about Oracle Fusion Middleware management.