[openstack-dev] [Mistral] Actions design BP

Renat Akhmerov rakhmerov at mirantis.com
Mon Mar 17 14:35:02 UTC 2014

On 16 Mar 2014, at 19:05, Clint Byrum <clint at fewbar.com> wrote:

> From my perspective, as somebody who is considering Mistral for some
> important things, the fact that the taskflow people are not aligned with
> the Mistral people tells me that Mistral is not what I thought it was:
> taskflow for direct user consumption.

Yes, it was just an initial idea we were trying to pursue. As we moved forward we understood it was too limited and had a lot of pitfalls. The reason is the key difference between library and service. Making something a service flips everything upside down in terms of requirements to this new system. The logical questions/implications are:
If that’s a service why should its REST API be Python oriented? Bindings - yes (it gives a certain convenience) but that’s a different story..
A whole set of questions related to how we distribute Python-written tasks (especially in multi tenant environment, e.g. as a cloud hosted service):
Result serialisation
It becomes logical to be able to use it with non-python clients and external systems.
Orientation to long-lived processes(workflows). Synchronous execution model no longer works well, instead de facto asynchronous event-based architecture fits better. I know it may sound too generic, it’s a whole different topic..
It becomes logical to provide more high-level capabilities rather than a library does (e.g. Horizon Dashboard. It would not be much of use if the service was based on Python).

I believe it’s not the full list.

Despite of all this I’m not against of using TaskFlow in implementation, at least some pieces of it. My only call is: it should be really beneficial rather than bringing pain. So I’m ok if we keep aligning our capabilities, roadmaps, terminology and whatever else is needed. 

Btw, it would be really helpful if you could clarify what you meant “some important things”. Asking because I still feel like we could have much more input from potential users. Any information is appreciated.

> So, while it may be annoying to have your "day to day project
> activities" questioned, it is pretty core to the discussion considering
> that this suggests several things that diverge from taskflow's core
> model.

Np. I still keep finding things/rules in OpenStack that I’m not really aware of or didn’t get used to yet. If that’s not how it should be done in OS then it’s fine.
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