Metric Extensions and Management Plug-ins - Expert Oracle Enterprise Manager 12c

Database Reference

In-Depth Information

Listing 10-18. Boot Date Dynamic Property Example from sample_host1 Target

%scriptsDir%/sample_host1/data_collector.pl --collect BootDate --fake "%fake%"

</Property>

</QueryDescriptor>

</DynamicProperties>

</InstanceProperties>

A dynamic property can then be referenced in the fetchlet configuration for metrics in the Property element with

SCOPE="INSTANCE" —just like any other static property.

You can find more information on DynamicProperties in Section 3.3.6.2 of the Extensibility Programmer's

Reference . However, the official documentation is pretty sparse. You can find more details in the XML Schema

documentation under <EDK>/doc/partnersdk/mrs/emcore/targetType .

One of the best uses of dynamic properties is to define category properties that are, in turn, used for conditional

definitions in the target type metadata using a ValidIf element. This element can be defined as a child of several

elements such as Metric or QueryDescriptor so that certain metrics are activated only when the defined category

property is matching certain choices. Another use case is to configure different fetchlets to collect metric values

depending on the value of category property. Unfortunately, as of EM12c version 12.1.0.2.0, this functionality

is not officially documented, so you should be careful relying on it. However, it was available since

Grid Control 10g versions, and you can see how it's used in Oracle's out-of-the-box plug-ins (for example,

in its rac_database target type). You can find the rac_database target type metadata definition in

<AGENT_BASE>/plugins/oracle.sysman.db.agent.plugin_12.1.0.2.0/metadata/rac_database.xml .

Note that Oracle uses XML functionality by including other files' XML content to facilitate the reuse of identical

definitions. For example, the database version calculations are the same for the RAC database, the ASM instance,

and the database instance, so it's defined in the dyn_props.xmlp file that's referred from multiple target type

metadata definition files.

Note that Oracle's sample_host targets include other dynamic properties defining related links. I believe that this

part of the example has not been removed since 10g/11g Grid Control and isn't relevant anymore. Prior to EM12c, the

Extensibility framework had very few features to customize the home page of a target, and adding custom links to the

related links section on the home page was one of them. EM12c has rich target user interface definition options, and

related links via dynamic properties are not used anymore, so this dynamic property in all sample_host demo targets

is ignored and should have been removed.

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