I am not completely convinced from what I read about MBeans and JMX.
The idea is that (application) resources are managed by MBeans. This MBeans have the necessary means for sending and receiving notifications. This level is the
instrumentation level.
These MBeans are registered in the MBean server ( a kind of container object) as well as certain Agent services. This is the
agent level, and the server or the agents are called
JMX agents.
A third level, the
distributed service level, corresponds to the middleware that connect applications and the JMX agents. This level is composed of
protocol adapters which allow the management of the agents by translating protocols and
connectors which are kinds of proxies to the agents which can be manipulated by applications.
Metadata provided by resources
A number of pieces of informations are needed by the JMX architecture to manage resources.
- attributes about the state of the resource
- constructors to create instances of the resource
- operations which can be performed on the resources
- parameters necessary for constructors and operations
- notifications which are emitted by the resource
MBeans
There are different types of MBeans:
- Standard MBeans (they implement a very simple interface)
- Dynamic MBeans (the meta data is provided separately from the resource)
- Model MBeans (Model MBeans are dynamic MBeans with supplementary model information)
- Open MBeans (another type of MBean extending the OpenType class allowing extremely complex MBeans)
JMX notifications
Though most JMX agents work by collecting and querying the information they are supposed to manage, means of broadcasting changes are sometimes needed. For this, a broadcasting mechanism exists where agents are separated in two roles: notification broadcasters and notification listeners.
the MBean Server
The MBean server is a registry through which agents access the MBeans.
