Use Case: Reading a Meter
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Short Description
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A meter is read and the read values are stored in system.


Actor(s)
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Meter Reader


Trigger(s)
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A read-meter form is requested from portal.


Result(s)
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The new meter values are stored in database.


Incoming Data
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Meter ID, meter value, date and time of reading


Outgoing Data
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- Message about successful reading
- Log message


Precondition(s)
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Postcondition(s)
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Invariant(s)
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Essential Steps
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* Authenticate meter reader
* Get meter id, meter value, datetime
* Check input values:

  * Does the meter id exist?
  * If not, ask and add a new one.
  * value >= old value?

* Add new reading in database
* Output success message


Open Issues
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Meter data input can also be performed by some automatic system:

  - automatic meters send their data automatically (how does these
    data look like and where is it stored?)

  - a smartphone/tablet app might deliver the data by photograph/OCR

These input devices need an API to deliver data or they require some
API to be able to input data into the system.


Remarks
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