| Purpose |
Encapsulate a request as an object. Enables polymorphic
client processing
of different requests. Fits naturally into [priority] queue processing,
typical
of transaction servers (e.g., file servers, web servers). Results in a
simple,
general interface that is unaffected by new commands/transactions.
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| Structure |
 |
| Consequences |
- May be able to extend functionality of Receiver w/o changing its formal interface.
|
| Implementation |
- A powerful, dangerous variation is to pass in a reference
of the Receiver to the Command object's execute method. This allows the
Command to manipulate the Receiver in new ways, not provided for at the
time the Receiver was deployed. Clearly, there are security concerns
associated with such power.
- If concrete commands are declared final, one possible security hole is plugged.
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| Sample Code |
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| Related Patterns |
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