
156 CHAPTER SEVEN
Table 7-3 lists some examples of grouping patterns.
The ALE specification requires that every filtered EPC that is part of an event cycle be part
of exactly one group. To ensure that each EPC will belong to only one group, the specifica-
tion requires that the patterns used for grouping must not all include the same results (i.e.,
must be disjoint).
Data Model
In this section, we’ll take a look at important data elements of the ALE specification. If you
are not going to be programming using ALE-compliant middleware, you can safely skip
this section.
Figure 7-16 shows a class diagram for the important data types in the ALE specification. As
shown, an ECSpec provides a means to specify the data that a client is interested in receiv-
ing; the client specifies the names of Readers from which it wants to receive data, and how
the event cycles map to the Readers’ read cycles. The ECBoundarySpec data type is used
for specifying the event boundaries. Instructions for filtering (ECFilterSpec) and grouping
(ECGroupSpec) the Reader observations are provided in the ECReportSpec. The ECRep-
ortSpec also provides specifications for what data should be reported back and how.
The ECReport defines what kind of reports the ALE servers will produce. An ECReport
provides a single report produced within an event cycle. Data within an ECReport is
grouped using ECReportGroup instances. Each instance ...