Java Reference
In-Depth Information
requests to specific MBean operations and executes them. In addition, the proto-
col adapter can send an
SNMP
trap to an
NMS
in place of
JMX
notifications.
Using the
SNMP
protocol adapter, an
NMS
can access the MBeans in the
MBean server that represent various
MIB
s.
SNMP
does not support the richness
of
JMX
capabilities, but MBeans can be built that support all the capabilities of
SNMP
. This means your MBeans may have more capabilities than can be
accessed using
SNMP
, but existing
NMS
systems can take advantage of the
exposed capabilities that adhere to the
SNMP
standard. Java Community Pro-
cess (
JCP
) efforts are underway to standardize the mappings between
JMX
and
existing
SNMP
standards.
For more information about the
SNMP
protocol adapter and the
JDMK
, visit
9.5 Connecting by using a TCP adapter
Up to this point, you have seen how you can distribute access to your
JMX
agents
with a number of different technologies. For example, you can use the
RMI
con-
nector provided by Sun, or you can use Jini to allow your agents to be discov-
ered. In this section, you will write a
TCP
protocol adapter.
Note that you won't use any object serialization—we don't want you to re-
create an
RMI
-like connector. Instead, the
TCP
adapter is a socket-based adapter
that allows any capable client to connect and send simple commands in order to
interact with your agent. This command approach allows non-Java clients to
connect to your agent and work with MBeans. For instance, a C++ program
could open a socket to your remote agent and acquire attribute values from
existing MBeans.
The
TCP
adapter presented in this section can create MBeans, get and set
attributes, and invoke operations. It places a few restrictions on the order and
manner that arguments are sent by the client, as you will see when we walk
through the code. The adapter is modeled as an MBean that creates a
Server-
Socket
object to listen to a particular port. Figure 9.4 illustrates the use of the
TCP
adapter MBean.
When a client connects, the MBean creates a
TCPAdapter
object in a new
Thread
to handle the client request, and continues listening.
9.5.1
Writing the code
To complete this new protocol adapter, you need to create three classes and
one interface:
