Configuration Items are the name/value pairs (or “tuples”) of metadata that are currently associated with an Asset, as defined by the asset's actual asset configuration. For example, disk drive, memory module, device module, and CPU may all be metadata that you want to capture about your asset. When provided for your asset, the Axeda® Platform will create and store each as a configuration item. Configuration items can be provided by an asset (if it is configured to send its configuration) or from the Axeda SDK. Within the agent XML configuration, nodes and attributes become the Configuration Items of the related Path expression.
These tuples are composed of the following:
o Path – The Path expression corresponding to the location of this Configuration Item.
o Value – Any UTF-8 String value
For example, in the configuration <Config><Foo><Bar>bin</Bar></Foo></Config>, the nodes Config, Foo, and Bar are configuration items.
Note: There can be only ONE instance of any given Configuration Item associated with a single Asset.
Using Expression Rule functions (such as CfgHas, CfgNumItems and CfgBoolValue), you can perform operations on configuration items for a specified Path configuration. You can retrieve and compare values, determine what new value was set for a configuration item, get the previous value for that item, determine when a new value was set for the configuration item, and more. Each configuration item provides "attributes" or metadata that you can read or set and use in comparisons. As a result of the comparisons, you can configure actions to create Audit messages or notifications to users, for example.
Configuration item attributes that you can use in comparisons or read are as follows:
o modified date - UTC timestamp set when the configuration item was last modified; modified date is a String type and can be read using CfgItem() (as time)
o quality - indicates the quality of the Configuration item
o value - identifies the value of the Configuration Item; value is a String type and can be read using CfgItem()
o unit - identifies the unit of measurement for the configuration item, such as Kg, Mhz, Mb, Gig, Volts etc
When the configuration for an asset is created or updated, the Axeda® Platform creates configuration event messages. Using expression rules, you can compare the new configurations to the previous configurations, or read the new configuration to determine if certain conditions or settings are present in the asset. Then you can run actions based on the findings.