WBEM Sensors
WBEM stands for Web-Based Enterprise Management. It's a set of technologies that describe and share management information about various devices across different platforms. NetCrunch includes three WBEM sensors - Data, Object, and WQL Query: Object that allows access to all available WBEM classes.
WBEM Sensors are similar to their WMI Data, Query, and WQL Object counterparts.
General WBEM requirements
CIM Server (CIMOM) should be launched on a monitored machine along with CIM Providers to use these sensors.
Sensors support HTTP or HTTPS connections.
Credentials may be required, but it depends on the implementation of WBEM installed on a given machine.
wbem-data
WBEM Data
The sensor allows selecting WBEM class and instance key to retrieve object properties. The sensor enables the processing of multiple objects (and it's why it needs an instance key property).
The sensor allows setting alerts on performance counters only. Each numeric property of the selected class becomes a counter.
Some classes can return large datasets because the sensor does not filter any instance.
Requirements (standard for all WBEM sensors) To use this sensor, add it to the machine which has launched CIM Server (CIMOM) and some CIM Providers.
Example:
Processes monitoring:
- Namespace
- root/cimv2
- WBEM Class
- CIM_Process
- Instance Key
- Name
wbem-object
WBEM Object
The sensor monitors a specific WBEM object without writing a WQL query. So, in addition to the WBEM Data sensor, it requires an instance value to be set. The sensor checks it for equality, so you can't filter objects by several properties.
The sensor also allows setting alerts on performance counters and treats each object's numeric property as a counter. Additionally, it allows for tracking status properties.
Status alert tracks change from one value to the other. In such cases, you can always track status values and set them to appropriate values.
Finally, you can store the last object data in the program database. Widgets or UI can later access these data.
It is allowed to monitor only instances with unique instance property values.
wbem-wql-query$object
WBEM WQL Query: Object
WBEM WQL Query: Object Sensor The WBEM Object sensor has some limitations. For example, you can filter instances by a single field only. Unfortunately, simple things are limited, while flexible ones quickly become complicated.
It allows retrieving data of specific CIM Class instances by writing a WQL query. The query must point to only one instance.
Example
Monitoring of specific process
Namespace
root\cimv2
WQL Query
SELECTt * FROM CIM_Process WHERE name = '-bash'
Now you can access counters of the given process or set the status alert on property change.