• Name: Rate
• Alternate Name: Assign rating

This Service Genre has been developed from multiple projects and outlines the functionalities and behaviours required of ratings services. Services of this Genre allow users to assign a subjective assessment to a data item within a collection, without altering the underlying data.

• e-Framework Service Genre Version: v1.1
  

This Service Genre describes the assignment of a subjective evaluation as a property of an object. For example, an object is reviewed, and a value from a range of ratings is applied. Ratings are typically numbers, with higher numbers indicating a more generous subjective evaluation. (E.g. A website which rates cinema films may give a particular film a rating of "4 stars").

The original object MAY be modified by the Rating service. The Rating MAY be applied to a proxy of the object. The Rating MAY be applied as metadata. Ratings can be applied from any subjective scale; common examples include confidence or popularity.

The data used to make up the set from which ratings are drawn (the Rating Set) MUST be finite, and MUST be ordered. If neither of these conditions are met, a rating has not been applied (perhaps an annotation or classification has been instead). Ratings SHOULD be attached as a distinct property of an object. (E.g. The property could be "satisfaction" and the allowed Ratings could be "1", "2", "3").

Ratings MAY be made anonymously. Ratings MAY be accompanied by a comment.

As defined the Rate Service Genre is not access controlled. Any client may attempt to contact a Rate service end point. There are no authentication controls. The service end point is responsible for determining which individual objects can be rated and which clients can assign ratings to existing objects.

The Rate Service Genre supports functions that enable the assignment and alteration of ratings, and calculation of average rating for an object.

• Assign Rating - allows a requester to assign rating data to an existing object. The data assigned MAY include a "comment", but SHOULD include a metric representing the 'value' of the property being rated. Rating Services SHOULD store the rating permanently within the context of the object that has been rated.
• Alter Rating - allows a requester to edit an existing rating on an object.
• Delete Rating - allows a requester to remove an existing rating from an object.
• Calculate Average - calculates an average rating from all applied ratings to an object. Rating services may offer different types of averages (modal, median, mean).

No other functionality is defined. The functionality that is defined MAY be extended.

Ratings SHOULD be used when an ordered bounded value is to be assigned to an object.

Ratings MAY be applied to collections of objects as well individual objects.

Ratings SHOULD NOT be used if an unbounded value is to be assigned to an object. Annotation SHOULD be used instead.

Ratings SHOULD NOT be used if an unordered value is to be assigned to an object. Classify SHOULD be used instead.

Requests SHOULD be implemented to enable all functionality.

Assign Rating SHALL meet the following conditions:

• The Request SHOULD specify:
  • The target object to be rated
  • The Property against which the rating is to be applied
  • A value from the Rating Set to be applied
• The Request MAY Specify:
  • A comment to be applied to the rating
  • The author of the Rating

Alter Rating SHALL meet the following conditions:

• The Request SHOULD specify:
  • The target Property to be altered
  • A new value from the Rating Set which is to be the new rating
• The Request MAY specify:
  • A comment to be applied to the new Rating
  • The author of the new rating

Delete Rating SHALL meet the following conditions:

• The Request SHOULD specify the target Property to be deleted

Calculate Average SHALL meet the following conditions:

• The Request SHOULD specify:
  • The target object for which an average rating is to be calculated
  • The Property for which the average rating is to be calculated
• The Request MAY specify the type of average to be calculated
• The Response SHOULD specify the calculated average rating for the target object

Responses SHOULD:

• Indicate any error conditions (such as the Rating not being accepted)

Individual Service Expressions SHOULD provide models showing how clients interact with service interfaces.

None

Authorisation SHOULD be considered when specialising this Service Genre. Specifically, whether owners of the original object are authorised to delete and edit Ratings. Additionally, Service Expressions should consider whether Ratings can be modified by other Raters.

Management of the Ratings set SHOULD be specified by the Service Expression or SUM which incorporates Rating.

The management of which objects can be rated SHOULD be considered by the Service Expression or SUM which incorporates Rating.