The client tier consists of application clients that access a Java EE server and that are usually located on a different machine from the server.

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The client tier consists of application clients that access a Java EE server and that are usually located on a different machine from the server.

Since the source text refers to a 'machine' the UML Node has been used. (And BTW, yes I do realise that I might therefore have better used an implementation diagram here.)

So far only Classes have been used for analysis, however since a Component is a special kind of Class every part of the UML™ Parsing Analysis recipe that was shown so far also applies just as well for Component (roughly speaking), and we can "promote" any desired analysis Class to a Component in order to benefit from its extra capabilities, such as being able to contain a Node. This has been done for *Tier_Client above.

The source text is a bit inexact; previously 'client' was taken in the most general sense, and now it is used to refer to interaction with a specific kind of server, a Java EE one. This is handled by a Generalization "ladder", with the more concrete (less abstract) JavaEE elements stereotyped (and presumably in a separate namespace).

It is assumes that the when the machine dies, the client program dies, so the *Client Node composes strongly the *Client client program, whereas the *Tier_Client is now only considered to share it (loose aggregation).

Finally, the 'access' is assumed to be via the *Serve Interface, strictly modelled in port-based fashion.

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