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Adaptors Level


The adaptors level forms the third level of the JMX architecture.  A JMX agent should contain atleast one protocol adaptor or connector.  These protocol adaptors and connectors provides the possibilities of remote management, by defining the manager components which are capable of communicating with the agents.  There is no specific mention about the adaptors level and how they should be written or about the interaction between the adaptors level and other levels, according to JMX specification, version 1.0.

 Protocol Adaptors and Connectors  

Protocol adaptors and connectors make the agent accessible from remote management applications. They provide a view through a specific protocol of the MBeans instantiated and registered in the MBean server. They enable a management application outside the JVM to:
Protocol adaptors provide a management view of the JMX agent through a given protocol. They adopt the operations of MBeans and the MBean server into a representation in the given protocol, and possibly into a different information model, for example SNMP.

Connectors are used to connect an agent with a remote JMX-enabled management application, namely, a management application developed using the distributed services of the JMX specification. This kind of communication involves a connector server in the agent and a connector client in the manager. These components convey management operations transparently point-to-point over a specific protocol.

Both connector servers and protocol adaptors use the services of the MBean server to apply the management operation they receive to the MBeans, and to forward notifications to the management application. For an agent to be manageable, it must include at least one protocol adaptor or connector server.  The adaptors and connectors provided by an implementation of the JMX specification will be implemented as MBeans.

 Difference Between Adaptors and Connectors 

Protocol adaptors, adapt the operations of MBeans and the MBean server into a representation in the given protocol, and possibly into a different information model, as it is in SNMP, whereas Connectors are used to connect an agent with a remote JMX-enabled management application, i.e. a management application developed using the distributed services of the JMX specification.

Protocol adaptors usually have server part of the adaptor which converts the JMX communications into protocol specific communications, whereas in case of Connectors,  communication involves a connector server in the agent and a connector client in the manager. Management applications that connect to a protocol adaptor are usually specific to the given protocol, whereas management application which uses connectors are developed using the distributed services of the JMX specification.  

For example, legacy management applications that rely on a specific management protocol, will use protocol adaptors and they access through operations that are mapped to those of the MBean server.   Whereas management applications, that uses connectors will access the JMX agent through a remote representation of the MBean server.

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