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Definition: |
Pedefined Queries for EPCIS 1.0
In EPCIS 1.0, no query language is provided by which a client may express an arbitrary query for data. Instead, an EPCIS 1.0 implementation shall provide predefined queries, which a client may invoke using the poll and subscribe methods of the EPCIS Query Control Interface. Each poll or subscribe call may include parameters via the params argument. The predefined queries each have a large number of optional parameters; by appropriate choice of parameters a client can achieve a variety of effects.
An implementation of EPCIS is free to use any internal representation for data it wishes, and implement these predefined queries using any database or query technology it chooses, so long as the results seen by a client are consistent with this specification.
Simple Event Query
This query is invoked by specifying the string SimpleEventQuery as the queryName argument to poll or subscribe. The result is a QueryResults instance whose body contains a (possibly empty) list of EPCISEvent instances. Unless constrained by the eventType parameter, each element of the result list could be of any event type; i.e., ObjectEvent, AggregationEvent, QuantityEvent, TransactionEvent, or any extension event type that is a subclass of EPCISEvent.
The SimpleEventQuery shall be available via both poll and subscribe; that is, an implementation shall not raise SubscribeNotPermittedException when SimpleEventQuery is specified as the queryName argument to subscribe.
The SimpleEventQuery is defined to return a set of events that matches the criteria specified in the query parameters. When returning events that were captured via the EPCIS Capture Interface, each event that is selected to be returned shall be identical to the originally captured event, subject to the provisions of authorization, the inclusion of the recordTime field, and any necessary conversions to and from an abstract internal representation. For any event field defined to hold an unordered list, however, an EPCIS implementation need not preserve the order. |
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