Read Action - modelint/shlaer-mellor-metamodel GitHub Wiki

The values of one or more Attributes of a single instance of a Class are accessed by a read action.

As shown below, the Read Action takes a Single Instance Flow as input along with a set of Attributes to be read.

images/attribute-access-subsystem/read-action-10.png

All attribute values are returned as a Tuple Flow. The Scalar Extract action (not shown) can be used to extract individual scalar values from any Tuple Flow.

Here is the Scrall corresponding to the above example (in combination with an implicit Scalar Extract action) and assuming that atc id has the value 51.

atc name, atc rating = Air Traffic Controller(ID: atc id).(Name, Rating)

The Scrall above combines an Identifier Select action which reduces to a Single Instance Flow input to the Read Action.

Identifiers

1. Action + Activity + Domain

Attributes

No non-referential attributes