Core services
Overview
You can find here some in-depth technical information about Keyple core services.
Observable reader states
An observable reader is active only when at least one reader observer is registered, and if the start of the detection has been requested. When active, an observable reader could switch between three internal states:
- Wait for card insertion
- Wait for card processing
- Wait for card removal
In the nominal case, a reader observer indicates to the observable reader that the processing of the card is finished by releasing the card channel. To manage a failure of the reader observer process, the observable reader interface provides also a method to finalize the card processing.
The states could be switched:
- due to an explicit API request (blue arrows):
- the release of the card channel,
- the call of an observable reader method:
- the addition or the remove of an observable reader,
- a request to start or stop the detection, to finalize the card processing.
- Or because of an external event (red arrows), the insertion or the remove of a card.
- the insertion of a card causing the observable reader to notify a
CARD_MATCHEDreader event (in case of successful scheduled selection) or aCARD_INSERTEDreader event (notification mode defined asALWAYS). - the removal of a card causing the observable reader to notify a
CARD_REMOVEDreader event.
- the insertion of a card causing the observable reader to notify a
If a card detection is started with the REPEATING detection mode, then later when the card is removed, the reader starts again the detection of a new card.
Notification of card removal during the card removal wait state is a feature of any observable reader. However, some observable readers may additionally have the ability to notify removal during the card processing state.
Card selection modes
Depending on the card transaction use case, or on the reader capability, there are two ways to manage the selection of a card:
- Either on a simple reader, a selection could be operated directly by transmitting the card selection scenario. In this case the same entity manages both the card selection and the card processing.
- Otherwise, on an observable reader, a scheduled card selection could be defined. In this case the card selection is operated automatically at the insertion of the card. In this case, the card selection is next managed by the observable reader, but the card processing is managed by a reader observer.
Internal adapters (release)
Service
Card resource service
Distributed
Internal adapters (snapshot)
Service
Card resource service
Distributed
