Information Flow Elements
Information flow diagram is UML behavior diagram which shows an exchange of information between system entities at some high levels of abstraction, at early design stages. Information flows may be useful to describe circulation of information through a system by representing aspects of models not yet fully specified or with less details.
Information flows do not specify the nature of the information, mechanisms by which it is conveyed, sequences of exchange, or any control conditions. Information items can be used to represent the information that flows through a system along the information flows before details of their realization have been designed.
Elements shown on the information flow diagrams are information flows and information items.
Information Flow
Information flow is a directed relationship that is used as a specification of some kind of “information channel” for unidirectional transmission of information from sources to targets.
Information moving along the information channel may be represented by abstract information items and/or by concrete classifiers.
Sources and targets of information flow must be of one of the following types: actor, use case, node, artifact, class, component, port, property, interface, package, activity node, activity partition, and instance specification.
An information flow is represented as a dashed line with an open arrow pointing from flow source(s) to target(s). Though this notation looks exactly as a dependency, it is not a dependency. To distinguish it, information flow should have the keyword «flow» above or below its dashed line.
When information item is “attached” to the dashed line of an information flow, the information item’s name is displayed close to the appropriate «flow» line. For unexplained reasons or by mistake, UML 2.x specifications show information item’s name in lowercase.
Information flow of order information item
from Customer to Billing Department.
Information Item
Information item is a classifier which represents some information transferred within a system from source(s) to target(s) of information flow.
Information items provide no details about the information they transfer as they do not have features.
Information items are abstract and cannot be instantiated.
When information item is “attached” to a dashed line of an information flow, the information item’s name is displayed close to the «flow» line. For unexplained reasons or by mistake, UML 2.x specifications show information item’s name in lowercase.
Information flow of order information item
from Customer to Billing Department.
Information item could be representation of some classifiers. The represented classifiers could clarify the structure or semantics of the information transferred by the information item. The classifier realizing an information item can only be another information item, class, interface, signal, component.
Information items can not participate in generalizations and associations.
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