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Jozef Marko updated DROOLS-1970:
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Fix Version/s: 7.7.0.Final
[DMN Editor] Hit policies
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Key: DROOLS-1970
URL:
https://issues.jboss.org/browse/DROOLS-1970
Project: Drools
Issue Type: Task
Components: DMN Editor
Affects Versions: 7.1.0.Beta2
Reporter: Jozef Marko
Assignee: Michael Anstis
Labels: reported-by-qe
Fix For: 7.7.0.Final
Implement hit policies of the DMN Specification:
- Unique (Single hit policy)
-- No overlap is possible and all rules are disjoint. Only a single rule can be matched.
This is the default.
- First (Single hit policy)
-- Multiple (overlapping) rules can match, with different output entries. The first hit
by rule order is returned (and
evaluation can halt). This is still a common usage, because it resolves inconsistencies
by forcing the first hit.
However, first hit tables are not considered good practice because they do not offer a
clear overview of the decision
logic. It is important to distinguish this type of table from others because the meaning
depends on the order of the
rules. The last rule is often the catch-remainder. Because of this order, the table is
hard to validate manually and
therefore has to be used with care.
- Priority (Single hit policy)
-- Multiple rules can match, with different output entries. This policy returns the
matching rule with the
highest output priority. Output priorities are specified in the ordered list of output
values, in decreasing order of
priority. Note that priorities are independent from rule sequence.
- Any (Single hit policy)
-- There may be overlap, but all of the matching rules show equal output entries for each
output, so any match can
be used. If the output entries are non-equal, the hit policy is incorrect and the result
is undefined.
- Output Order (Multiple hit policy)
-- returns all hits in decreasing output priority order. Output priorities are specified
in the ordered list of
output values in decreasing order of priority.
- Rule Order (Multiple hit policy)
-- Returns all hits in rule order. Note: the meaning may depend on the sequence of the
rules.
- Collect ( Multple hit policy with the aggregation operators +, >, < and #)
-- Returns all hits in arbitrary order. An operator (‘+’, ‘<’, ‘>’, ‘#’) can be
added to apply a simple function to the outputs. If no operator is present, the result is
the list of all the output entries. Collect operators are:
a) + (sum): the result of the decision table is the sum of all the distinct outputs.
b) < (min): the result of the decision table is the smallest value of all the
outputs.
c) > (max): the result of the decision table is the largest value of all the outputs.
d) # (count): the result of the decision table is the number of distinct outputs.
Other policies, such as more complex manipulations on the outputs, can be performed by
post-processing the
output list (outside the decision table).
Please ensure that the HIT policy can be changed whenever during modeling the decision
table.