Completed proposal for Req004

["Durand, Jacques R." <JDurand@us.fujitsu.com>]

"Catch" operator:

 

http://wiki.oasis-open.org/tamie/RequirementItems

 

updated proposal based on previous feedback:

 

- the "temporal" order (based on posting date)  is not necessarily same as order of selection of events in a combination.

- the use (setting/reading) of variables that help message correlation, must be compatible with the order of selection of events of a same combination, (no "forward" reference)

- propose that the order of selection is the order in which the <match> elements appear in the <catcher>.

- added some @min, @max attributes to <match> for dealing with optional events, or multiple evts of a kind.

 

NOTE: We must remember that sucha "Catch" operator will be used as an iterator over the Evt Board.

I.e. it will not just be expected to wait and catch the first evt / combination that matches its selector.

When used inside a Trigger, and if the trigger has a <repeat> element, the Catch must iterate over all matching events.

This iterative behavior can be controlled in 2 ways:

(a) by controlling where each Catch starts selecting in the Evt Board (e.g. starting from a particular evt sequence number)

(b) by relying on XSLT2 features such as <xsl:next-match>

In case what we select is a combination of events, things are a little more complicated.(a) is tricky. With (b) I have good hope that an XSLT implementation can still iterate over all combinations.

 

Jacques