Chapter 13: Using Systems Management
Systems Management includes the following functionality:
The master agent returns information contained in a management information base (MIB). To view an SNMP MIB, you must have an SNMP management console.
To use Systems Management, define the JAVA_HOME environment
variable to point to a JRE 1.4 installation, and start
EAServer using the
-jdk14 option. “Starting the server” explains
how to use this option.
Once started, the JMX agent consists of a JVM running as a separate process from any other managed application. It acts as a server, having a number of listener threads that are implemented via JMX adapters. These threads include one that responds to SNMP requests and another that responds to RMI requests. The JMX agent contains a number of MBeans, which are accessible via the listeners. The MBeans provide a variety of services, some of which are JMX related. Other services are related to the applications that the JMX agent is being used to manage.
When you start the JMX agent, the Bootstrap MBean is loaded, which loads all the remaining MBeans. The Bootstrap MBean checks the agent.props file to determine which MBeans to load and where they are located. See “Creating services” for details about setting this up correctly.The JMX agent in this release is based on the MX4J Release 1.1.1.
The remainder of this section describes the capabilities of the JMX agent in more detail.
Some of the MBeans deployed into the JMX agent are designated as service MBeans, which all expose a similar lifecycle API, and are all registered with the ServicesManager MBean.
The ServicesManager MBean provides a consistent view of all services and an API for manipulating service MBeans. In addition, the ServicesManager MBean can generate JMX notifications when operations are performed on underlying service MBeans. The ServicesManager MBean monitors the state of each of the underlying MBeans, and if any of their states have changed since the last poll, raises a JMX notification. This means that if one of the service MBeans is a proxy for an external process (for example, EAServer), then the ServicesManager MBean can generate a JMX notification when the remote process fails or stops.
Some of the underlying MBeans that are registered as services are proxy MBeans for remote services—including one for EAServer and one for SNMP. These MBeans provide a view of remote processes—such as EAServer or the SNMP master agent—and can monitor the state of these remote processes. If a remote process dies, you can obtain the state of the process from the proxy MBean.
You can also use a proxy MBean to start or stop a remote process directly, or to view the process’s log file.
The JMX agent includes an MBean that specifically listens for JMX notifications from the ServicesManager and other designated MBeans, and logs them to a file. Users can access this file remotely, via the Systems Management Console, which enables them to view significant events; for example, when a remotely managed server process goes down, or when someone starts a service. Logging events that are generated by other MBeans can also be recorded this way, as well as in the JMX agent log file.
MIB manager MBeans manage the underlying MIBs. This means that there is one for the NETWORK-SERVICES MIB, and one for the J2EE MIB. The MIB manager MBeans:
Register the object identifier (OID) sub-tree that is associated with the MIB
Create the tables defined in the MIB, and populate them with the appropriate rows
Provide support for rebuilding the tables when required
Listen for JMX events and map them to SNMP traps
Systems Management includes two adapter MBeans, SNMP and RMI. The SNMP adapter allows you to use an SNMP management console to view SNMP information that is exposed via the deployed MIBs; NETWORK-SERVICES and J2EE. The RMI adapter supports remote access to the JMX agent via RMI. The RMI adapter is used with a connector that replicates the local MBeanServer API to remote clients. See “Connecting to the JMX agent” for details about how to write clients that connect to the agent.
Systems Management includes a service MBean that can forward JMX notifications as JMS messages.
An EAServer proxy MBean is registered as a service MBean, with the ServicesManager MBean, when the JMX agent is started. This allows users to manage services, such as remote EAServer processes, using the ServicesManager MBean. The ServicesManager MBean can use the EAServer proxy MBean to monitor a remote EAServer process for changes in state, and for requests to start or stop the process. The state of registered services, such as the EAServer service (EAS), is available through the ServicesManager MBean, the Systems Management Console, SNMP clients, and JMX clients.
The EAServer proxy MBean provides methods that enable clients to start, stop, restart, and refresh EAServer. In addition, the proxy MBean provides methods that enable clients to retrieve information about EAServer, such as:
State information (running, stopped, or failed)
Log file details
Repository information, including component and package details
Message service information
Various other EAServer attributes
An SNMP proxy MBean is registered as a service MBean with the ServicesManager MBean when the JMX agent starts, and is subsequently monitored by the same ServicesManager MBean.
Clients of the SNMP proxy MBean can retrieve the SNMP log file, retrieve the state of the SNMP service, and start or stop the service.
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