The Data Capture Interface (DCI) supports a hierarchical name space that is used to uniquely identify specific instances of available metrics. All metrics are registered and their details and methods are kept in the name space. Metric consumers use the metrics name or identifier in the name space when reading or requesting metric data.
The metrics name space is grouped into two layers with as many levels per layer as necessary: one layer to identify a metric class and a lower layer to identify the available instances of that metric. The first layer is called a metric class identifier and the second an instance identifier. Together the two name space layers uniquely identify a metric instance. The data types for these three definitions are DCIClassId for the class identifier, DCIInstanceId for the instance identifier, and DCIMetricId for the combination of the two commonly called metric identifier.
The following figure shows the name space representation for an example
Class Id 254.1.3.2 with an Instance Id Level of 2.4.
The following figure shows an example of a filled in MetricId with a two-level
InstanceId.
Multiple instances can be represented within a single MetricId. Wildcarding
is done via a bit mask in the InstanceId structure. For example, InstanceId
level one uses the mask 1, InstanceId level two uses the mask 2, and InstanceId
level three uses the mask 4. Masks for multiple levels can be OR'd together.
The following figure shows an example of wildcarding.
Note: For Release 1, wildcarding is only supported for the last level of a class or an instance level.