Hi Suho, All,
We were chatting at DEBS about possibility of supporting "templates" in
Siddhi, so we can build more descriptive functions into Siddhi without
having to extend the language. e.g. have a increasing( ..) function instead
of having to write complex query. (e.g. just like ESB templates)
I have been thinking about this and have some thoughts about how to do
this. Please comment.
e.g 1. consider "Increasing"
from e1=Speed->e2=speed[v > e1.v] insert into ...
template
=======
define template Increasing($S1, $val1){
e1=$S1->e2=$S2[v$val> e1.v];
return e1,e2;
}
then query will look like
from increasing("Speed", "v") insert into ..
e.g. 2
define template vShape($S1, $val1){
$S1 as e1, $S1[v$val> e1.v]+ as e2,$S1[v$val< e2[last].v]+ as e3;
return e1,e2, e3;
}
then final query looks like
from vShape("Speed", "v") insert into ..
Note this is just a template, not a function. We expand the query like a
macro.
Execution is that we expand queries using macros before execution. I think
macro can have chain of streams to make its functions readable.
We have to think about different scenarios, but in general I think this
should work.
Thanks
Srinath
--
============================
Srinath Perera, Ph.D.
Director, Research, WSO2 Inc.
Visiting Faculty, University of Moratuwa
Member, Apache Software Foundation
Research Scientist, Lanka Software Foundation
Blog: http://srinathsview.blogspot.com/
Photos: http://www.flickr.com/photos/hemapani/
Phone: 0772360902
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