[wsdm][UPlat] Collections

["Andrea Westerinen" <andreaw@cisco.com>]

Title: Message

Updates to the text based on the UPlat discussion this morning.

 

What?

A collection is an ordered or unordered set, which is itself a manageable resource and which groups zero or more other entities. The members of a collection may be manageable resources in their own right, and may have their own management interfaces.

 

A collection provides a grouping and scability mechanism for the management system.

 

Why?

At the most basic level, a concept of collections is needed to group manageable resources.  For example, a group of fans may be identified as the "spares" for the engineering department of a company.  Taking the example further, these fans may be protected by a warranty based on purchase date.  So, there may be criteria (a basic ordering of the set members) by which a fan is selected from the spare group.

 

Another use of collections is as a proxy for its members.  A manager may send a single request to a collection where the result is that its members are acted upon as specified in the request. The result of a manager sending a single request to a collection must be the same as a manager sending a separate message to each of the members of the collection. It is not necessary that the collection actually send separate messages to each of its members, only that the result to the members is the same. For instance, using a collection, a manager can query for the state of each resource using one request, rather than querying each resource individually. Also, it would be possible to reset the state of certain metrics for the resources in the collection using a single request. 

 

A collection provides the ability for a management system to scale much better than a system not supporting collections. Also, there are cases where the exact membership of a group is better known by an entity, such as a collection, that may be "closer" to the group than a manager. This allows the manager to defer to the collection to determine the exact entities upon which to act.

 

Andrea