| The challenge | Users, just like all other system components, are error generators. Even after doing everything to prevent user slips, they still slip. The only way to stop them from slips is by keeping them away from the system, but unfortunately, we need the users to control the system, to monitor, to find problems, to report about them and to fix them. The challenge is to find out which of the user actions is erroneous. |
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Error detection |
In a
service-oriented architecture, such as in the examples of cable TV or
production waste above, the user can access any service, any time. There is
nothing there that can hint about possible errors. However, if the user
interface is designed according to scenarios, then at each particular point of
each procedure, we expect only certain actions from the user. Any unexpected
action may be due to either a slip or an intentional deviation from the
procedure. |
| Validation | To conclude
that the user action is by mistake, we need to ask the users about their
intention. Typically, we use a dialog box to confirm that the suspected action
was intentional. If they confirm that the action was intentional, we need to
first make sure that we can obey to their command, and then to make sure that
the users wishes to cancel the last interaction. |
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