Database Reference
In-Depth Information
SNMP Adapter
While the idea of being able to collect metrics over SNMP (Simple Network Management Protocol) is nice, the
current implementation of the SNMP adapter makes it of very limited use for metric extensions. The SNMP adapter
is designed to collect metrics from a single SNMP server, normally running locally. However, up to the EM release
12.1.0.2.0, the SNMP adapter is basically broken, because it requires a specific dynamic property of the host target to
be evaluated correctly—
SNMPHostname
—and this property is resolved on only a very few hardware platforms. You can
apply a workaround by using the
emcli
command to manually set that property name, but you can't use the SNMP
adapter to collect metrics from multiple devices by using a single host target to deploy the metric extension to.
Note that you will also need to set SNMP credentials in order to use the SNMP adapter. The documentation on
this adapter is rather incomplete, so I suggest that you avoid using it at this point. Instead, use OS Command adapters
to collect SNMP metrics or use plug-ins (which have a full-featured SNMP metric-collection method, covered in the
second part of this chapter).
JMX Adapter
A JMX (Java Management Extensions) adapter is used to collect metrics from Java applications that have JMX-based
standard instrumentation embedded in JMX-enabled servers such as Oracle WebLogic, IBM WebSphere, Red Hat
JBoss, and even stand-alone JVM (Java Virtual Machine). For more information, refer to the standard documentation,
Oracle Enterprise Manager Cloud Control 12c Administrator's
Guide (Chapter 8, Section 8.4.1).
Although this documentation is admittedly skinny, as you learn about management plug-ins in the rest of
this chapter, you will also learn about underlying fetchlets, and the documentation on JMX fetchlets is a bit more
descriptive. For more information, see
Oracle Enterprise Manager Cloud Control Extensibility Programmer's Reference
(Chapter 20, “Using Fetchlets.” Section 20.11). A more complete example can be found in
Oracle Enterprise Manager
Cloud Control 12c Administrator's Guide
, (Chapter 20, “Monitoring Using Web Services and JMX”).
Adapters and Target Types
EM12c limits the choice of adapters for each target type. Although the documentation doesn't cover which adapters
are available for which target type, you can see the associations from the
EM_MEXT_TARGETTYPE_ADAPTERS
repository
view. From that view, you can also see that a couple of target types have Web Services Adapter support even though
it's not documented. You can also see in the
EM_MEXT_ADAPTERS
view that there are even more adapters available, such
as the RESTful Web Wervices Wdapter. However, they are not enabled for any of the target types. I expect that these
are provisions for the next releases, as we've seen features that were delivered internally and externalize only in a later
version.
Various OS Command adapters are available for some targets but not for others, which really makes little sense.
For example, the OS Command—Single Column adapter is available for Automatic Storage Management (but not for
Cluster ASM), Cluster Database, Database Instance, and a few other target types. Almost every target type has the OS
Command—Multiple Columns adapter available. The OS Command—Multiple Values adapter isn't associated with
any of the target types that are available on a system with default plug-ins in release 12.1.0.2.0.
You can find detailed official documentation on the metric extensions adapters in the
Oracle Enterprise
Manager Cloud Control 12c Administrator's Guide
(Section 8.4). If you are more interested in the under-the-hood
implementation, check out
EM_MEXT_%
views and tables in the
SYSMAN
schema. I will get back to some content in those
tables when I discuss plug-ins later in this chapter (see the “Under the Hood of Metric Extensions” section).
Chapter 8 of
Oracle Enterprise Manager Cloud Control 12c Administrator's Guide
has more details on other
capabilities of metric extensions, such as managing access to metric extensions, using alert options, and
exporting/importing metric extensions. There you can also find how to migrate your old user-defined metrics from
Grid Control 10g and 11g to the new metric extensions in 12c Cloud Control.
