Hi Tammy,
My apologies for my part of the communication breakdown; as you say,
we've been trying to include you, but given that you've really been
out on maternity leave the entire time, that hasn't really worked...
That said, we have tried to take chica's needs into account, and I do
think that we've organized things in a way that makes chica /better/
off, and I look forward to discussing and/or clarifying on
Wednesday's design call. Are you available for that? (I haven't
gotten a chance to look at the changes to logic yet, but will try to
do so before Wednesday.)
The genesis of it was that we started discussing "logic 2.0", and
realized that it would not be possible to switch to a new
lighter-weight design without hosing current logic users, so we
shifted to introducing the new design as the "calculation", and
leaving the current logic's design unchanged.
The plan we had laid out is:
* Chica will own logic, and have full ownership (and veto power)
over any changes. This largely means the 0.5 version you already
have running.
o Peeking at svn, the only changes since October have been: (1)
mavenizing logic, (2) switching it to use liquibase instead
of direct sql for its data model (hopefully you're okay with
maven+liquibase, but I guess it's up to you), and (3) the
changes that Wyclif committed.
* The intention of Wyclif's changes (which I haven't looked at yet)
is to add some /adapter/ classes to logic such that logic's
functionality can /also/ be accessed through the Calculation
interfaces, but this should have /zero/ impact on Chica's usage
of logic. I.e. the intention is that doing
logicService.eval("WEIGHT (KG)") will behave exactly as it does
now, and return a logic Result; and that an admin could also
configure things so that doing calculationService.eval("WEIGHT
(KG)") ends up calling that same underlying logic rule, and
getting back a calculation result.
o If the implementation of the adapters that Wyclif did impose
some new design or maintenance constraints on logic (they
shouldn't need to), we should fix that
So, to summarize, I completely agree that we want chica to own
/current/ logic (basically 0.5 + maven + liquibase), and I'd hope
that in the future you all add more functionality, and undo any bad
refactorings that we did there, but the main point is that there
should be no further changes to logic that breaks things for you,
because you'll be the gatekeeper.
AFAIK the only lines of code that Chica should need to change in the
short run are to go from Context.getLogicService() to
Context.getService(LogicService.class).
Further discussion on Wednesday.
-Darius
On Mon, Apr 2, 2012 at 11:02 AM, Tammy Dugan <[email protected]
<mailto:[email protected]>> wrote:
I finally had a chance to look at all the new logic code. First I
need to vent about a couple of things and then I will try to be
constructive:
* It took us MONTHS to get the last rewrite of logic to work
correctly with openmrs 1.7.x and the chica code
* We just got it working at the end of October 2011 and Openmrs
started rewriting it again in November 2011.
* The first round of design calls for the logic rewrite happened
in mid-November. I had a two week old baby and did not have time
to deal with it.
* Looking back through dev emails, the logic discussion ended at
the end of November and picked up in mid February
* In mid-February was the first time I saw anything about
Calculation.
* On March 5th there was a dev list email from Darius that he and
Mike would be here for one day and wanted to meet with me and
some other people
* I was still on part-time maternity leave but rearranged my
schedule with one days notice to meet with them
* When I met with them, I struggled to understand the logic
design that I had not looked at since I had only been back at
work for 2 weeks after maternity leave
* In that meeting, Darius asked us if we could own logic.
Basically we were supposed to own something that got completely
redesigned that we had little or no input into the design that
didn't make any sense to us and stuff that had been fixed
repeatedly was broken yet again.
Based on all this, you can see why I might be a little irritated.
Yes, I know you tried to include me in the design but you knew I
was pretty much unavailable. Yes, I could have said no when
Darius said we should own logic but I felt backed into a corner.
There was a breakdown in communication on several fronts. If I
would have know we were expected to own logic, I would have said
no to the rewrite to begin with.
Venting done. Now to be constructive:
* The name Calculation is a horrible name for that object. It
doesn't calculate anything! Why not call it "RuleDefinition"
since it defines the properties of the rule and then call
CalculationEvaluator "Rule"? Why was Rule split into two objects
anyway? Why not just add a getParameterDefinitionSet method to
the rule interface? Why would you ever want some object that
doesn't evaluate anything being called by logic? What is the
point in that?
* I think the strongly typed results and ParameterDefinitionSets
are nice changes
* Logic cannot hit the database for every token lookup. This is
an unacceptable performance hit for a system like chica. The
tokens need to be cached.
* CalculationEvaluators and Calculations should not be
singletons. Making them singletons is non-thread safe and
requires special programming that is not intuitive to the naive
programmer. A new instance should be created each time.
For a naive programmer, I think the new design complicates things
even more than before and makes it even less accessible for
developers to contribute.
In summary, if the chica group is going to own logic, we would be
willing to own the 0.5 logic that we worked so hard to getting
working. We are not willing to put the time and effort in to get
the new calculation version of logic working.
Thanks,
Tammy
On 3/29/2012 11:29 AM, Michael Seaton wrote:
Hi Tammy,
Is this an issue in the Calculation module? Or is this an issue
with how logic is exposing itself to Calculation? Weren't you
involved in the coding changes that took place during the
Sprint? That was meant to be for you and the Chica team to
contribute and own, not for anyone to impose on you.
It does seem we should cache calculation registrations in
memory, we are not doing this currently. But this shouldn't
necessarily be an issue for Chica, if it is going to the
logic_token_registration table for it's own purposes, should
it? I don't really see how exposing Logic to Calculation is a
risk for you, as long as you continue to access Logic natively
as you always have and just provide a couple of adapter classes
to expose it for other via the Calculation module.
Mike
On 03/29/2012 11:05 AM, Tammy Dugan wrote:
There were two major issues that came up when reviewing the
changes with Wyclif,
1. Logic cannot hit the database for every token lookup. This
is an unacceptable performance hit for a system like chica. The
tokens need to be cached.
2. Rules should not be singletons. Making them singletons is
non-thread safe and requires special programming that is not
intuitive to the naive programmer. A new instance should be
created each time.
I also want to point out that we have fixed #2 twice already in
previous versions and now it needs to be fixed for a third
time. Also, #1 was fixed in the previous version and now has to
be fixed again. It gets frustrating that these same problems
keeps getting reintroduced each time logic is refactored and
each time I have to make the case about why it should be that
way and we have to fix the problem. It is important when
refactoring to preserve the old behavior!
Because of these issues, we have no immediate plans to update
chica to use the new version of logic with Calculations. It
took us months to get things working before and we just don't
have the programming resources to do it now or in the near future.
Thanks,
Tammy Dugan
On 3/29/2012 10:08 AM, Friedman, Roger (CDC/CGH/DGHA) (CTR) wrote:
It appears that trunk produces 0.5.3 which includes
Calculation, last branch is 0.5.1 which is not mavenized,
0.5.2 is mavenized, can it be a branch even if not released?
*From:*[email protected] <mailto:[email protected]>
[mailto:[email protected]] *On Behalf Of *Wyclif Luyima
*Sent:* Friday, March 23, 2012 3:53 PM
*To:* [email protected]
<mailto:[email protected]>
*Subject:* [OPENMRS-DEV] Calculation sprint wrap up
Hi everyone,
For the past 2 weeks, we have been having a sprint on the
calculation module plus making logic and reporting to expose
themselves as calculations. We managed to get all the 27
tickets specific to the module done by Wednesday. Some work
has been done to retrofit logic and reporting to be exposed as
calculations, i went through the changes in logic with Tammy
and Win this afternoon, Tammy had some interesting points of
discussion which i believe she will send on the dev list.
In general, the code looks pretty good and i think we are
ready for its 1.0 release which could be in the next 1 -2
weeks, apparently we have to wait for final high level reviews
from Darius and Burke as contributors to its design to confirm
if it is actually what they envisioned.
The sprinter turn up was good which included the core
developers, Mike and Mykola, thank you all for your relentless
work.
Have a great weekend.
Wyclif
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Children's Health Services Research
IU School of Medicine
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IU School of Medicine
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