UML Sequence Diagram - Actors as Objects? Is it valid?

Question

I am currently building a sequence diagram and it would be much tidier if I could implement the actor as an object like this: http://www.tlg.uci.edu/~opoudjis/nicjpgs/umlefr/umlsum1.gif

However, I have never seen this anywhere else and I wanted to double check that this is valid and accepted in UML?

Alternatively, would it be better if I used an actor i.e. :Manager and link the actor to the :managerObject when the object is activated? So looks bit like this:

                                  [:manager]
                                       |
:manager------function()------------->[]

Thanks!

Answer 1

For me, instancied an actor and having a lifelin representing it is valid and accepted. This could be used in order to document the interactions of a use case for example.

Answer 2

Check here and here and here and especially the official:

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Icon presentation

When a stereotype includes the definition of an icon, this icon can be graphically attached to the model elements extended by the stereotype. Every model element that has a graphical presentation can have an attached icon. When model elements are graphically expressed as:

• Boxes (see Figure 12.14 on page 196): the box can be replaced by the icon, and the name of the model element appears below the icon. This presentation option can be used only when a model element is extended by one single stereotype and when properties of the model element (i.e., attributes, operations of a class) are not presented. As another option, the icon can be presented in a reduced shape, inside and on top of the box representing the model element. When several stereotypes are applied, several icons can be presented within the box.
• Links: the icon can be placed close to the link.
• Textual notation: the icon can be presented to the left of the textual notation.196 UML Infrastructure Specification, v2.4.1

Several icons can be attached to a stereotype. The interpretation of the different attached icons in that case is a semantic variation point. Some tools may use different images for the icon replacing the box, for the reduced icon inside the box, for icons within explorers, etc. Depending on the image format, other tools may choose to display one single icon into different sizes.

Some model elements are already using an icon for their default presentation. A typical example of this is the Actor model element, which uses the “stickman” icon. In that case, when a model element is extended by a stereotype with an icon, the stereotype’s icon replaces the default presentation icon within diagrams.

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