Creating a Custom Metric Family › Understanding the Metric Family XML Structure › Expressions

Expressions

The Expressions section is composed of ExpressionGroup tags that are used for component discovery. During the component discovery, the values for the component item properties (such as the IndexList, Name, and Description) are calculated. The vendor certification expressions supporting the metric family expressions are used for this calculation.

Note: Do not confuse the metric family and vendor certification ExpressionGroup tags.

The ExpressionGroup tags for the following DestCert URIs must exist:

ExpressionGroup/name

(Optional) Specifies the expression group name.

Can be updated: Yes

Possible values: Plain text

Effect of updating: None

ExpressionGroup/destCert

Specifies the component facet that contains the destAttrs to populate. The facet name typically comes from the ComponentFacets section, except the Item and DeviceComponent facets.

Can be updated: Yes

Possible values: Facets that are defined in ComponentFacets, or the Item, DeviceComponent facet.

Effect of updating: Changes permissible expression destAttr

When does the update take effect: Component Rediscovery

Required actions for updates to take effect: None

ExpressionGroup/Expression

Specifies the expression for the component facet attribute.

Can be updated: Yes

Possible values: Any valid metric

Effect of updating: Changes permissible expression destAttr

When does the update take effect: Component Rediscovery

Required actions for updates to take effect: None

ExpressionGroup/Expression/destAttr

Specifies the component facet attribute name.

Can be updated: Yes

Possible values: Any valid attribute from that component facet.

Effect of updating: Changes the attribute name

When does the update take effect: Component Rediscovery

Required actions for updates to take effect: None