Can we describe exactly what references, direct transition, expression evaluation are doing in #2.
Expression evaluation especially seems to be an odd one, what's wrong with pythons expression evaluation? I can't quite see why that would/should exist in taskflow. I can see it being implemented in mistral, where mistral converts whatever DSL it wants into taskflow primitives and then taskflow runs the code; this decoupling ensures that taskflow does not force a DSL on people that want to use taskflow as a python library (this kind of restriction imho isn't acceptable for a library to do, and limits taskflows own usage and integration). Thanks, Josh From: Dmitri Zimine <d...@stackstorm.com<mailto:d...@stackstorm.com>> Reply-To: "OpenStack Development Mailing List (not for usage questions)" <openstack-dev@lists.openstack.org<mailto:openstack-dev@lists.openstack.org>> Date: Friday, April 11, 2014 at 9:55 AM To: "OpenStack Development Mailing List (not for usage questions)" <openstack-dev@lists.openstack.org<mailto:openstack-dev@lists.openstack.org>> Subject: [openstack-dev] [Mistral][TaskFlow] Mistral-TaskFlow Summary We prototyped Mistral / TaskFlow integration and have a follow-up discussions. SUMMARY: Mistral (Workflow Service) can embed TaskFlow as a workflow library, with some required modifications to function resliently as a service, and for smooth integration. However, the TaskFlow flow controls are insufficient for Mistral use cases. Details discussed on other thirds. The prototype scope - [0<https://etherpad.openstack.org/p/mistral-taskflow-prototype>]; code and discussion - [1<https://github.com/enykeev/mistral/pull/1>] and techical highlights - [2<http://lists.openstack.org/pipermail/openstack-dev/2014-April/032461.html>]. DETAILS: 1) Embedding TaskFlow inside Mistral: * Required: make the engine "lazy" [3<http://lists.openstack.org/pipermail/openstack-dev/2014-March/031134.html>], [4<http://paste.openstack.org/show/75389/>].This is required to support long-running delegates and not loose tasks when engine manager process restarts. * Persistence: need clarity how to replace or mix-in TaskFlow persistence with Mistral persistence. Renat is taking a look. * Declaring Flows in YAML DSL: done for simplest flow. Need to prototype for data flow. Rich flow controls are missing in TaskFlow for a representative prototype. * ActionRunners vs Taskflow Workers - not prototyped. Not a risk: both Mistral and TaskFlow implementations work. But we shall resolve the overlap. * Ignored for now - unlikely any risks: Keystone integration, Mistral event scheduler, Mistral declarative services and action definition. 2) TaskFlow library features * Must: flow control - conditional transitions, references, expression evaluation, to express real-life workflows [5<https://github.com/dzimine/mistral-workflows/tree/add-usecases>]. The required flow control primitives are 1) repeater 2) flow in flow 3) direct transition 4) conditional transition 5) multiple data. TaskFlow has 1) and 2), need to add 3/4/5. * Other details and smaller requests are in the discussion [1<https://github.com/enykeev/mistral/pull/1>] 3) Next Steps proposed: * Mistal team: summarize the requirements discussed and agreed on [2<http://lists.openstack.org/pipermail/openstack-dev/2014-April/032461.html>] and [3<http://lists.openstack.org/pipermail/openstack-dev/2014-March/031134.html>] * Mistral team: code sample (tests?) on how Mistral would like to consume TaskFlow lazy engine * Taskflow team: Provide a design for alternative TaskExecutor approach (prototypes, boxes, arrows, crayons :)) * Decide on lazy engine * Move the discussion on other elements on integration. References: [0] The scope of the prototype: https://etherpad.openstack.org/p/mistral-taskflow-prototype [1] Prototype code and discussion https://github.com/enykeev/mistral/pull/1 [2] Techical summary http://lists.openstack.org/pipermail/openstack-dev/2014-April/032461.html [3] Email discussion on TaskFlow lazy eninge http://lists.openstack.org/pipermail/openstack-dev/2014-March/031134.html [4] IRC discussion Mistral/Taskflow http://paste.openstack.org/show/75389/ [5] Use cases https://github.com/dzimine/mistral-workflows/tree/add-usecases
_______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
