Hi hernan I will try to allocate more time to understand the execution because I think that this is important for our community to get a workflow engine. So I take it as a reverse engineering exercise. Now I'm super busy so I will get slow on it. Stef On Sun, Jan 21, 2018 at 9:31 AM, Hernán Morales Durand <hernan.morales@gmail.com> wrote:

Hi Stef,

2018-01-21 5:17 GMT-03:00 Stephane Ducasse <stepharo.self@gmail.com>:

...

Hi hernan

I started to clean the code in my fork. If you want to contribute let me know.

I don't know enough about workflow implementations yet. However I know how to run or what to expect from them. So I could give some feedback from there at first.

...

I started to clean all misclassified methods to force me to read the code. (I used them as a marker to know if I passed on the code).

That could result in a nice browser feature: To flag methods from menu item adding specific icon, maybe possible in Calypso? :)

...

For the moment I made sure that the code loads. - I created the variable as subclass of Object - I removed the dependencies to omnibase.

I added class comments about what I understood. I'm about to continue writing structural tests and I will start to try to understand how to run a workflow.

Maybe someone at Netstyle has some expressions to begin with?

Hernán

...

Stef

On Sun, Jan 21, 2018 at 9:02 AM, Hernán Morales Durand <hernan.morales@gmail.com> wrote:

...

Hi,

I decided to give a try to Aare or Workflow in Pharo 6, following instructions in https://github.com/Netstyle/Workflow . However, the installation script raised a Warning about missing WADynamicVariable class. Should I install Seaside?

I've been using a couple of bioinformatics workflows the last years, specially Taverna (https://en.wikipedia.org/wiki/Apache_Taverna) and Galaxy (https://www.galaxyproject.org/) both of them huge code bases maintained since some years now and with very active communities from biological sciences. I found a cool video showing Galaxy features: https://www.youtube.com/watch?v=rVYzMWWRMN8

As impressive as you may think, they are not a Panacea for workflow execution. An installation process could get really complicated, for example interfacing with nginx and PostgreSQL, and customization of toolshed could end in endless editing XML specifications.

I just skim through the white paper, but unfortunately didn't recognized any of the compared features or workflow systems. Is Aare intended to support only business workflows patterns? Considering the Galaxy video above, do you think scientific workflows could be supported in Aare or it is a completely different route?

Cheers,

Hernán

To complement, I found this reference useful (Generating Business Process Models from Object Behavior Models - joined). The model underlying Workflow-aare ressembles a Heuristic Networks that are explained in this paper. HTH, Cédrick I like this approach where there are incoming signals (announcements ?) compared to Aare.

On Sun, Jan 21, 2018 at 3:06 PM, Stephane Ducasse <stepharo.self@gmail.com> wrote:

Cedrick

My goal is one step at a time. I do not want grand plan. Just something working in one image.

​Yes be able to reproduce/run old cold is the first step. ​There was some discussions some months ago about resu​rrecting ​micro-workflow framework. Nobody try to do it ?​ -- Serge Stinckwich UMI UMMISCO 209 (IRD/UPMC/UY1) "Programs must be written for people to read, and only incidentally for machines to execute."http://www.doesnotunderstand.org/

Cédrick Béler <cdrick65@gmail.com> wrote:

Yes sure. But at this is an important requirement for me, I prefer to talk about it first :)

Distributed systems design is a different subject. Different constraints, different solutions. Stephan

HI cedrick

To solve this « pb », just create WADynamicVariable as a subclass of DynamicVariable already in Pharo.

Ok I will do it. What is important is to *share* knowledge and code. So I changed and publish the code in my branch to make CurrentWorkflowManager an dynamic variable. Before I just inherited from Object. Now we get a version that can be loaded. There are also missing part for the

export/import in XML (should be easy to fix and Max propose to give the code - DOMBuilder and co.) I tried to start a booklet with Stephane but it is too complicated right now. Stephane started a simpler version.

For now saving and loading is not important. :)

I put below a summary of the reflexion/discussion I had with Max.

Thanks. Now you should publish your code. I would have preferred to work from a working code. Because now it is like poking in the dark. Cedrick what did you get running? Stef Some comments below

========= INTRO

What's missing compared to the full (proprietary) solution are user interfaces that were web based (Seaside \+ Magritte). Also, persistence was achived through Omnibase. References were removed but they are stil some disfunctionning. Moreover, the completion of activities were mainly manual and achieved through web interface (web forms). They are, for now, no real way to introduce different kind of activities like those being message-based, event-based, service-based.

To evolve, one has to remove all dependancies to Omnibase and Magritte/Seaside.

There are also important design decisions to ensure WfWorkflow being a powerful and extensible workflow management system for Pharo. To me there are 2 main tasks: - rethink persistence (process definition and orchestration, realization) => persistance is essential and was central to Aare. Beside removing Omnibase references (and implication of WfManagedObject), some of the application features were very dependant on the persistence (like logging, tracing process evolution). All of these features are to be thing again considering as much as possible a loosely coupled solution. A general purpose storage solution like Voyage could be used. At first, in image storage will be used to focus on the running aspects of the library. - rethink interaction => Designing a general interaction sub-system is probably the more challenging tasks. Aare was web based. We want workflow to be UI agnostic. Moreover, we want to associate , remove Magritte (replace UI or build an independant system based on Annoucement for instance)

Yes I agree. Now I would like to be able to - define a super simple workflow: I picked sequence: start -> task1 -> task2 - execute it and script it resolution. I would like to understand the difference between frame and activation.

========= RANDOM QUESTIONS AND ANSWER (in black me - below max)

1)

The static definition of workflow is done through WfWorkflow, WfOutgoingEdge and WfSteps (+ WfConditions). The easy part :)

Yes the easy part. I started to add a test to cover his

The runtime aspect are achieved via WfActivation, WfWorkList, WfWorkflowHistory et WfWorkflowManager. More difficult to understand and make evolve.

WfWorkflowHistory represents the different versions of a workflow, so it belongs to the static part.

I saw and documented the interaction between a workflow history and its workflows. WfWorkflowManager managers workflow definitions

(static) and activations (dynamic). WfFrame is also a part of the dynamic side, connecting activations to a workflow. Workflows are hierarchical, i.e. a step can have a sub workflow (see WfWorkflowLibrary>>simpleSubflow)

Yes for now I do not want to understand this part.

3)

Going back to activations, here is my current understanding.

Once a step is activated (all condition on Edges leading to are true - to evaluate outgoing conditions of a step, the step execution has to be complete first) , we get an activation instance (I’m not 100% sure how completion of an activity and outgoing conditions are managed).

As far as I understand, a step can always be activated (e.g. manually). However, activating a step propagates the values of conditions on the edges to the next steps and their activations ("dead" or "alive"). Hence, an activation responds to #isAlive with true if at leat one incoming token was true ("alive") (see WfStep>>continueInFrame:fromStep:alive: and WfActivation>>isAlive). The conditions are evaluated once #complete is sent to the activation. Activation instances are created by two ways (slightly different for the start step), but generally they are created when a step receives tokens from the outgoing edges of an upstream activation (see WfStep>>continueInFrame:fromStep:alive:).

On the exemple of BLActivationHistoryItem that you gave, I’m not sure if it’s an activation of a history item stored in the history (subclasss of WfHistory?).

My idea was that it should represent a record for an activation (there might be multiple records for a single activation). So "HistoryItem" would be the general description of a record, of which "ActivationHistoryItem" is a special case for activations (I hope that makes sense).

4) Moreover I don’t see clearly the difference with a scheduler and a BP engine (they are at least really complementary). Do you see any ressemblance between Activation and ScheduledJob ?

I actually would like to have a (simple) scheduler with the BP engine :)

Well, it's certainly a matter of point of view. I would argue that an activation is something close to a "job". A "scheduled job" would be a more specific case of a "job", a job that is in a queue. An activation has no notion of scheduling but simply represents the idea of what happens when traversal between two nodes occurs. A scheduler would be one way of managing activations (WfWorklist seems pretty close to a scheduler, holding running and completed activations).

Too subtle for me.

To me the scheduler right now is not really existing besides having a list of simultaneous/parralelized steps to realize (activated or not). Activated means currently being done.

You're right, I think. The application that Workflow was designed for required manual interaction, hence there was no need for other methods of scheduling (e.g. by time or event).

This activation role is about logging and interacting with responsible users. But it is more than that. It’s the actual job being done.

Yes.

5)

Concerning run time modification of a process. Is it true that we can modify a currently executed workflow (steps that are not yet activated ?) ? I think that is possible (an cool). When activated, it shouldn’t. Would you think it would be interesting to allow activations to be suspended/resume (frozen), cancelled ?

The history of workflows consists of copies. The steps of a workflow reference the workflow they belong to. Therefore, while it is possible to modify a workflow, modifications do not impact running workflows, as the steps of that workflow continue to reference the previous version. The model suggests that it is ok to create a new version of a workflow but not to modify existing workflows.

For now I would like to get a workflow running without modifying it

The model does *allow* (in principle) to modify an existing workflow but I doubt that was the intention.

I think that it was because else why to bother. However, I don't see why modifying an existing

workflow has to be bad thing, as long as you can guarantee that only edges and steps are modified that have not yet been activated. That could open up some interesting possibilities. Cancellation of an activation could be very interesting. It would basically allow reversal of complex effects. Very nice idea! I'm not so sure though whether suspending makes much sense. Maybe when a step has the potential to take a long time for some operation. But then you may run into transaction problems. The nice thing about an activation at the moment is that it's atomic (in theory). But again, done right that could open up interesting possibilities.

If a running process is modified, do we track its evolutions in WfWorkflowManager ?

The modification of a workflow is indeed announced to WfWorkflowManager, yes. Workflow versions are stored in WfWorkflowHistory. For modifying a *running* workflow you will probably want to create a specific workflow manager for that, that does validation etc.

The goal of history(s) are to log the realization of the process. But is it one of its aim to « replay » the process execution ?

No. WfWorkflowHistory only stores the static definitions. However, the history of activations could be used to replay an execution (nice idea!).

i.o.w., Is it more than log/report ?

I think the activation history was designed as a log, the workflow history as a log and also as a way to undo changes. As you suggest, however, they could certainly be used for more things.

I agree with the separation (WfWFManager for the run time evolution of the process definition => adaptation and WfActivationHistory for the trace of interactive/automatic step realizations information).

#beginHistory implementation example was very helpful. I knew I missed something Just, as I see a MailManager (with role is obvious), is it something that has to be generalizable ? Like InteroperableManager ? MessageManager ? To get user interactions

That would be very nice, yes. You're completely free to do what you like. It would be cool though if we could evolve the project as opposed to you creating a fork to your own liking. If you're game we can set up a workflow on github where you open pull requests against our repository.

6) I’d like to remove fully the reference and need of Omnibase and Magritte/seaside forms.

Yes please!

I think Omnibase is ok, even storing in image for instance.

What’s more problematic to me is for user interactions (and even automatic interaction through program for instance). There are achieved in your example with seaside. It is ok but what if I’d like to do it more generally ? Would we use Annoucement for example ?

I think that is completely open to implementation. In my eyes, Workflow should remain a separate library that does not enforce any kind of specific presentation or persistence. What's critical for that is of course the right kind of interface. Announcements would certainly be an interesting way to decouple Workflow from other parts of the system.

I’d like to have an incomingMessageBox for each user and eventually transform these message in concrete action (user i/o) ? Or dispatch in JobQueues (each user being a distant worker thread). Again, the distinction between Scheduler and BPEngin is fuzzy to me.

Does it make sense to you ?

Yes, it does :) What I've asked myself (out of curiosity) is whether you want to have - a dedicated instance for executing workflows - a distributed workflow with autonomous synchronisation (parts of a workflow could run on every uses instance, others would need to be executed through agreement) - a partially distributed workflow with one or more managing nodes that control the core steps (e.g. you could designate parts of a workflow as independant)

PS: some random comments on your proposals

Parts of Workflow were never cleanly separated from the proprietary application, so there are indeed a couple of things that are missing (mostly #subclassResponsibility stuff etc.)

- initializeDefaults is not present for steps but thats ok.

- in #createIncoming: (doesn’t exist), I don’t get ….. => makePersistent asPersistentReference. You store persistentReference of steps. Is it like the step object itself ? I would store the step objects (as no persistance right now).

An activity step is a specific subclass of a step. Such a step includes additional information such as documents, duration and user roles. I'm not sure why "makePersistent asPersistentReference" is sent there, as WfStep already inherits from WfManagedObject and would, therefore, already be managed by OmniBase. But I don't know OmniBase, maybe some things need to be announced specifically.

- I don’t understand the offsetSeconds in your BLActivationHistoryItem

That's really just some business rule to modify the timestamp of the history item.

============= Others responses from Max

WfWorkflow - Load and Run All instances that inherit from WfManagedObject were managed by OmniBase, yes. DomBuilder is a small package for wrapping XML-Parser. I'll publish it so you can use it.

Cedric did you got this package? The XML-Parser package has been significantly modified and

is now named XMLParser (you can find it in the catalog). You should make the changes necessary to use the current incarnation of XMLParser (decide for yourself whether you still need DomBuilder or not).

But this is not really important.

Those IDXXX classes belong to another package a didn't publish (but will). This package also includes an OmniBase specific class. Magritte has changed significantly over the years but the core should be pretty much the same. Just load the newest Magritte and try working with that.

...

ok but avoidable ? try loading Magritte ? Long …

#beginInHistory should be implemented with #subclassResponsibility on WfActivation. Your explicit implementation could then look something like this: beginInHistory self history add: (MyActivationHistoryItem new message: 'started'; user: (WACurrentSession value ifNotNilDo: [ :session | session user ]); type: #started; yourself). MyMailManager noteNewActivation: self

Basically, what the history contains is up to the workflow implementation. I think it would makes sense though to have an abstract WfActivationHistoryItem. WfActivation>>history should be implemented like this: history ^self propertyAt: #history ifAbsentPut: [ OrderedCollection new ].

Although I think that it would be good to have a dedicated WfActivationHistory class. WfWorkflowHistory is associated with changes to the workflow, not activations. Both history classes should probably inherit from an abstract class WFAbstractHistory.

Seaside interaction

Here are a couple of action implementations in Seaside components that should give you an idea of how to interact with the workflow: MyActivationComponent>>complete self activation hasCompleted ifTrue: [ ^ self ]. self history add: (BLActivationHistoryItem new message: 'completed'; user: self session user; type: #completed; offsetSeconds: -1; yourself). self activation complete.

MyActivationForm>>accept: aString self activation authorized: true. self history add: (BLActivationHistoryItem new comment: aString; message: 'accepted'; user: self session user; type: #accepted; offsetSeconds: -2; yourself). self completeIfSatisfied.

MyActivityList>>addActivity self call: (MyActivityEditor new workflow: self workflow; yourself). self refresh.

MyActivityEditor>>buildActivity ^(self workflow newActivityStep initializeDefaults; yourself) asPersistentReference.

MyTransitionEditor>>createIncoming | step | step := (self workflow newActivityStep initializeDefaults; yourself) makePersistent asPersistentReference. self addIncoming: step. MyCurrentWorkflowComponent value showActivity: step.

MyTransitionEditor>>addIncoming: anActivity ^self add: anActivity to: self activity.

MyTransitionEditor>>add: aSourceActivity to: aDestinationActivity ^aSourceActivity addOutgoingEdgeFor: aDestinationActivity.

MyTransitionEditor>>editCondtions: anEdge | component | anEdge condition isTrueCondition ifTrue: [ anEdge condition: WfAllCondition new ]. component := (MyConditionEditor activity: self activity) container: anEdge; addDecoration: (MyToolbarDecoration new title: 'Edit Transition Conditions to: ' , anEdge to name; toolbar: [ :html | html icon: 'icon_close.gif' text: 'Close' action: [ component answer ]. html helpIconOn: component ]; yourself); yourself. self call: component.

MyConditionEditor>>addRule: aDescription | new | new := MyCondition newPersistent field: aDescription; asPersistentReference. new := self call: (self buildEditorFor: new titled: 'Add Rule for ' , aDescription asLabel). new isNil ifFalse: [ self condition add: new; markDirty. self changedForm ].

...

WfWorflowManager class is empty defining empty stubs/protocols. Its aim seems to be about “logging/noting” changes. Is is it’s only role ? Correct. You would use WfWorkflowManager to update the workflow in OmniBase (e.g. mark dirty, add new activation etc.). #generateID would generate an ID from OmniBase and #activationClass would answer your specific activation class, if you choose to override WfActivation.

Now I got all the TestGraphs green by commenting the graphiz dependencies. On Sun, Jan 21, 2018 at 3:33 PM, Stephane Ducasse <stepharo.self@gmail.com> wrote:

I got all the WfTestFlow green. So now we can study the execution a bit better.

On Sun, Jan 21, 2018 at 3:28 PM, Stephane Ducasse <stepharo.self@gmail.com> wrote:

...

HI cedrick

...

To solve this « pb », just create WADynamicVariable as a subclass of DynamicVariable already in Pharo.

Ok I will do it. What is important is to *share* knowledge and code. So I changed and publish the code in my branch to make CurrentWorkflowManager an dynamic variable. Before I just inherited from Object. Now we get a version that can be loaded.

There are also missing part for the

...

export/import in XML (should be easy to fix and Max propose to give the code - DOMBuilder and co.) I tried to start a booklet with Stephane but it is too complicated right now. Stephane started a simpler version.

For now saving and loading is not important. :)

...

I put below a summary of the reflexion/discussion I had with Max.

Thanks. Now you should publish your code. I would have preferred to work from a working code. Because now it is like poking in the dark.

Cedrick what did you get running?

Stef Some comments below

...

========= INTRO

What's missing compared to the full (proprietary) solution are user interfaces that were web based (Seaside \+ Magritte). Also, persistence was achived through Omnibase. References were removed but they are stil some disfunctionning. Moreover, the completion of activities were mainly manual and achieved through web interface (web forms). They are, for now, no real way to introduce different kind of activities like those being message-based, event-based, service-based.

To evolve, one has to remove all dependancies to Omnibase and Magritte/Seaside.

There are also important design decisions to ensure WfWorkflow being a powerful and extensible workflow management system for Pharo. To me there are 2 main tasks: - rethink persistence (process definition and orchestration, realization) => persistance is essential and was central to Aare. Beside removing Omnibase references (and implication of WfManagedObject), some of the application features were very dependant on the persistence (like logging, tracing process evolution). All of these features are to be thing again considering as much as possible a loosely coupled solution. A general purpose storage solution like Voyage could be used. At first, in image storage will be used to focus on the running aspects of the library. - rethink interaction => Designing a general interaction sub-system is probably the more challenging tasks. Aare was web based. We want workflow to be UI agnostic. Moreover, we want to associate , remove Magritte (replace UI or build an independant system based on Annoucement for instance)

Yes I agree. Now I would like to be able to - define a super simple workflow: I picked sequence: start -> task1 -> task2 - execute it and script it resolution.

I would like to understand the difference between frame and activation.

...

========= RANDOM QUESTIONS AND ANSWER (in black me - below max)

1)

The static definition of workflow is done through WfWorkflow, WfOutgoingEdge and WfSteps (+ WfConditions). The easy part :)

Yes the easy part. I started to add a test to cover his

...

The runtime aspect are achieved via WfActivation, WfWorkList, WfWorkflowHistory et WfWorkflowManager. More difficult to understand and make evolve.

WfWorkflowHistory represents the different versions of a workflow, so it belongs to the static part.

I saw and documented the interaction between a workflow history and its workflows.

WfWorkflowManager managers workflow definitions

...

(static) and activations (dynamic). WfFrame is also a part of the dynamic side, connecting activations to a workflow. Workflows are hierarchical, i.e. a step can have a sub workflow (see WfWorkflowLibrary>>simpleSubflow)

Yes for now I do not want to understand this part.

...

3)

Going back to activations, here is my current understanding.

Once a step is activated (all condition on Edges leading to are true - to evaluate outgoing conditions of a step, the step execution has to be complete first) , we get an activation instance (I’m not 100% sure how completion of an activity and outgoing conditions are managed).

As far as I understand, a step can always be activated (e.g. manually). However, activating a step propagates the values of conditions on the edges to the next steps and their activations ("dead" or "alive"). Hence, an activation responds to #isAlive with true if at leat one incoming token was true ("alive") (see WfStep>>continueInFrame:fromStep:alive: and WfActivation>>isAlive). The conditions are evaluated once #complete is sent to the activation. Activation instances are created by two ways (slightly different for the start step), but generally they are created when a step receives tokens from the outgoing edges of an upstream activation (see WfStep>>continueInFrame:fromStep:alive:).

On the exemple of BLActivationHistoryItem that you gave, I’m not sure if it’s an activation of a history item stored in the history (subclasss of WfHistory?).

My idea was that it should represent a record for an activation (there might be multiple records for a single activation). So "HistoryItem" would be the general description of a record, of which "ActivationHistoryItem" is a special case for activations (I hope that makes sense).

4) Moreover I don’t see clearly the difference with a scheduler and a BP engine (they are at least really complementary). Do you see any ressemblance between Activation and ScheduledJob ?

I actually would like to have a (simple) scheduler with the BP engine :)

Well, it's certainly a matter of point of view. I would argue that an activation is something close to a "job". A "scheduled job" would be a more specific case of a "job", a job that is in a queue. An activation has no notion of scheduling but simply represents the idea of what happens when traversal between two nodes occurs. A scheduler would be one way of managing activations (WfWorklist seems pretty close to a scheduler, holding running and completed activations).

Too subtle for me.

...

To me the scheduler right now is not really existing besides having a list of simultaneous/parralelized steps to realize (activated or not). Activated means currently being done.

You're right, I think. The application that Workflow was designed for required manual interaction, hence there was no need for other methods of scheduling (e.g. by time or event).

This activation role is about logging and interacting with responsible users. But it is more than that. It’s the actual job being done.

Yes.

5)

Concerning run time modification of a process. Is it true that we can modify a currently executed workflow (steps that are not yet activated ?) ? I think that is possible (an cool). When activated, it shouldn’t. Would you think it would be interesting to allow activations to be suspended/resume (frozen), cancelled ?

The history of workflows consists of copies. The steps of a workflow reference the workflow they belong to. Therefore, while it is possible to modify a workflow, modifications do not impact running workflows, as the steps of that workflow continue to reference the previous version. The model suggests that it is ok to create a new version of a workflow but not to modify existing workflows.

For now I would like to get a workflow running without modifying it

...

The model does *allow* (in principle) to modify an existing workflow but I doubt that was the intention.

I think that it was because else why to bother.

However, I don't see why modifying an existing

...

workflow has to be bad thing, as long as you can guarantee that only edges and steps are modified that have not yet been activated. That could open up some interesting possibilities. Cancellation of an activation could be very interesting. It would basically allow reversal of complex effects. Very nice idea! I'm not so sure though whether suspending makes much sense. Maybe when a step has the potential to take a long time for some operation. But then you may run into transaction problems. The nice thing about an activation at the moment is that it's atomic (in theory). But again, done right that could open up interesting possibilities.

If a running process is modified, do we track its evolutions in WfWorkflowManager ?

The modification of a workflow is indeed announced to WfWorkflowManager, yes. Workflow versions are stored in WfWorkflowHistory. For modifying a *running* workflow you will probably want to create a specific workflow manager for that, that does validation etc.

The goal of history(s) are to log the realization of the process. But is it one of its aim to « replay » the process execution ?

No. WfWorkflowHistory only stores the static definitions. However, the history of activations could be used to replay an execution (nice idea!).

i.o.w., Is it more than log/report ?

I think the activation history was designed as a log, the workflow history as a log and also as a way to undo changes. As you suggest, however, they could certainly be used for more things.

I agree with the separation (WfWFManager for the run time evolution of the process definition => adaptation and WfActivationHistory for the trace of interactive/automatic step realizations information).

#beginHistory implementation example was very helpful. I knew I missed something Just, as I see a MailManager (with role is obvious), is it something that has to be generalizable ? Like InteroperableManager ? MessageManager ? To get user interactions

That would be very nice, yes. You're completely free to do what you like. It would be cool though if we could evolve the project as opposed to you creating a fork to your own liking. If you're game we can set up a workflow on github where you open pull requests against our repository.

6) I’d like to remove fully the reference and need of Omnibase and Magritte/seaside forms.

Yes please!

I think Omnibase is ok, even storing in image for instance.

What’s more problematic to me is for user interactions (and even automatic interaction through program for instance). There are achieved in your example with seaside. It is ok but what if I’d like to do it more generally ? Would we use Annoucement for example ?

I think that is completely open to implementation. In my eyes, Workflow should remain a separate library that does not enforce any kind of specific presentation or persistence. What's critical for that is of course the right kind of interface. Announcements would certainly be an interesting way to decouple Workflow from other parts of the system.

I’d like to have an incomingMessageBox for each user and eventually transform these message in concrete action (user i/o) ? Or dispatch in JobQueues (each user being a distant worker thread). Again, the distinction between Scheduler and BPEngin is fuzzy to me.

Does it make sense to you ?

Yes, it does :) What I've asked myself (out of curiosity) is whether you want to have - a dedicated instance for executing workflows - a distributed workflow with autonomous synchronisation (parts of a workflow could run on every uses instance, others would need to be executed through agreement) - a partially distributed workflow with one or more managing nodes that control the core steps (e.g. you could designate parts of a workflow as independant)

PS: some random comments on your proposals

Parts of Workflow were never cleanly separated from the proprietary application, so there are indeed a couple of things that are missing (mostly #subclassResponsibility stuff etc.)

- initializeDefaults is not present for steps but thats ok.

- in #createIncoming: (doesn’t exist), I don’t get ….. => makePersistent asPersistentReference. You store persistentReference of steps. Is it like the step object itself ? I would store the step objects (as no persistance right now).

An activity step is a specific subclass of a step. Such a step includes additional information such as documents, duration and user roles. I'm not sure why "makePersistent asPersistentReference" is sent there, as WfStep already inherits from WfManagedObject and would, therefore, already be managed by OmniBase. But I don't know OmniBase, maybe some things need to be announced specifically.

- I don’t understand the offsetSeconds in your BLActivationHistoryItem

That's really just some business rule to modify the timestamp of the history item.

============= Others responses from Max

WfWorkflow - Load and Run All instances that inherit from WfManagedObject were managed by OmniBase, yes. DomBuilder is a small package for wrapping XML-Parser. I'll publish it so you can use it.

Cedric did you got this package?

The XML-Parser package has been significantly modified and

...

is now named XMLParser (you can find it in the catalog). You should make the changes necessary to use the current incarnation of XMLParser (decide for yourself whether you still need DomBuilder or not).

But this is not really important.

...

Those IDXXX classes belong to another package a didn't publish (but will). This package also includes an OmniBase specific class. Magritte has changed significantly over the years but the core should be pretty much the same. Just load the newest Magritte and try working with that.

...

ok but avoidable ? try loading Magritte ? Long …

#beginInHistory should be implemented with #subclassResponsibility on WfActivation. Your explicit implementation could then look something like this: beginInHistory self history add: (MyActivationHistoryItem new message: 'started'; user: (WACurrentSession value ifNotNilDo: [ :session | session user ]); type: #started; yourself). MyMailManager noteNewActivation: self

Basically, what the history contains is up to the workflow implementation. I think it would makes sense though to have an abstract WfActivationHistoryItem. WfActivation>>history should be implemented like this: history ^self propertyAt: #history ifAbsentPut: [ OrderedCollection new ].

Although I think that it would be good to have a dedicated WfActivationHistory class. WfWorkflowHistory is associated with changes to the workflow, not activations. Both history classes should probably inherit from an abstract class WFAbstractHistory.

Seaside interaction

Here are a couple of action implementations in Seaside components that should give you an idea of how to interact with the workflow: MyActivationComponent>>complete self activation hasCompleted ifTrue: [ ^ self ]. self history add: (BLActivationHistoryItem new message: 'completed'; user: self session user; type: #completed; offsetSeconds: -1; yourself). self activation complete.

MyActivationForm>>accept: aString self activation authorized: true. self history add: (BLActivationHistoryItem new comment: aString; message: 'accepted'; user: self session user; type: #accepted; offsetSeconds: -2; yourself). self completeIfSatisfied.

MyActivityList>>addActivity self call: (MyActivityEditor new workflow: self workflow; yourself). self refresh.

MyActivityEditor>>buildActivity ^(self workflow newActivityStep initializeDefaults; yourself) asPersistentReference.

MyTransitionEditor>>createIncoming | step | step := (self workflow newActivityStep initializeDefaults; yourself) makePersistent asPersistentReference. self addIncoming: step. MyCurrentWorkflowComponent value showActivity: step.

MyTransitionEditor>>addIncoming: anActivity ^self add: anActivity to: self activity.

MyTransitionEditor>>add: aSourceActivity to: aDestinationActivity ^aSourceActivity addOutgoingEdgeFor: aDestinationActivity.

MyTransitionEditor>>editCondtions: anEdge | component | anEdge condition isTrueCondition ifTrue: [ anEdge condition: WfAllCondition new ]. component := (MyConditionEditor activity: self activity) container: anEdge; addDecoration: (MyToolbarDecoration new title: 'Edit Transition Conditions to: ' , anEdge to name; toolbar: [ :html | html icon: 'icon_close.gif' text: 'Close' action: [ component answer ]. html helpIconOn: component ]; yourself); yourself. self call: component.

MyConditionEditor>>addRule: aDescription | new | new := MyCondition newPersistent field: aDescription; asPersistentReference. new := self call: (self buildEditorFor: new titled: 'Add Rule for ' , aDescription asLabel). new isNil ifFalse: [ self condition add: new; markDirty. self changedForm ].

...

WfWorflowManager class is empty defining empty stubs/protocols. Its aim seems to be about “logging/noting” changes. Is is it’s only role ? Correct. You would use WfWorkflowManager to update the workflow in OmniBase (e.g. mark dirty, add new activation etc.). #generateID would generate an ID from OmniBase and #activationClass would answer your specific activation class, if you choose to override WfActivation.

Ok so we redid everything in parallel. Too bad anyway I will continue and my changes are in my clone. I will update the booklet once I get it. Stef On Sun, Jan 21, 2018 at 6:05 PM, Cédrick Béler <cdrick65@gmail.com> wrote:

HI cedrick

I tried to start a booklet with Stephane but it is too complicated right now. Stephane started a simpler version.

For now saving and loading is not important. :)

Yes

I put below a summary of the reflexion/discussion I had with Max.

Thanks. Now you should publish your code. I would have preferred to work from a working code. Because now it is like poking in the dark.

Cedrick what did you get running?

Actually, I got the workflow working and the tests as you. And then I was able to run some examples (as I tried to wrote in the booklet).

I just din’t know yet how to publish on GitHub and friends… I discussed with Max about then… I’m learned a bit after how to use these tools especially for the booklet as we chatted…. Then end of the semester…. No time…. Should be better soon.

So sorry for that :)

I join the last pdf I had…. Fuzzy (especially since I tried to include automatically classes comments) but there are details of installation and what I could make work:

- rethink persistence (process definition and orchestration, realization)

=> persistance is essential and was central to Aare. Beside removing Omnibase references (and implication of WfManagedObject), some of the application features were very dependant on the persistence (like logging, tracing process evolution). All of these features are to be thing again considering as much as possible a loosely coupled solution. A general purpose storage solution like Voyage could be used. At first, in image storage will be used to focus on the running aspects of the library. - rethink interaction => Designing a general interaction sub-system is probably the more challenging tasks. Aare was web based. We want workflow to be UI agnostic. Moreover, we want to associate , remove Magritte (replace UI or build an independant system based on Annoucement for instance)

Yes I agree. Now I would like to be able to - define a super simple workflow: I picked sequence: start -> task1 -> task2

Done in WfWorkflowLibrary (with convenience method). An example in 2.4

- execute it and script it resolution.

See 2.5.

My way of running them and where I stopped and is a bit stuck.

To me we need now to design an interaction model (based on Annoucement ?)

Running a workflow.

Once a workflow is defined, to be executed, he calls the method #executeIn- newFrame. This method instanciate and populate the worklist (WfWorklist) that keep track of the state of the running workflow.

workflow := WfWorkflowLibrary simpleBranch. frame := workflow executeInNewFrame.

To see running activitions (activities that are started but not completed yet):

frame worklist running.

Once a activation is over, it has to be completed by sending the message #completed. For now, there are only manual completions but we could imag- ine in the future automatic or semi-atomatic completion based on extrenal interaction or if delegated to a program for instance.

anActivation := frame worklist any. anActivation complete. "complete mannully one activation" "or" frame complete: anActivation.

The workflow is running until there are no possible (accessible) activation left. This state is called implicit termination and can be checked with:

frame isCompleted.

Here is the code of the WfFrame»>completeAll

WfFrame>>>completeAll [self workList allRunning isEmpty] whileFalse:

[self completeActivation: self workList allRunning first].

I would like to understand the difference between frame and activation.

The frame is the container of the workflow resolution, the « manager » … A workflow runs in a frame (subworkflows in subframes)…

Activations are when a step (one activity defined in a workflow) is activated (we are starting for real to do the activity).

WfWorkflowManager managers workflow definitions

(static) and activations (dynamic). WfFrame is also a part of the dynamic side, connecting activations to a workflow. Workflows are hierarchical, i.e. a step can have a sub workflow (see WfWorkflowLibrary>>simpleSubflow)

Yes for now I do not want to understand this part.

You have too to get the workflow running I think.

3)

Going back to activations, here is my current understanding.

Once a step is activated (all condition on Edges leading to are true - to evaluate outgoing conditions of a step, the step execution has to be complete first) , we get an activation instance (I’m not 100% sure how completion of an activity and outgoing conditions are managed).

As far as I understand, a step can always be activated (e.g. manually). However, activating a step propagates the values of conditions on the edges to the next steps and their activations ("dead" or "alive"). Hence, an activation responds to #isAlive with true if at leat one incoming token was true ("alive") (see WfStep>>continueInFrame:fromStep:alive: and WfActivation>>isAlive). The conditions are evaluated once #complete is sent to the activation. Activation instances are created by two ways (slightly different for the start step), but generally they are created when a step receives tokens from the outgoing edges of an upstream activation (see WfStep>>continueInFrame:fromStep:alive:).

Activations are central.

On the exemple of BLActivationHistoryItem that you gave, I’m not sure if it’s an activation of a history item stored in the history (subclasss of WfHistory?).

My idea was that it should represent a record for an activation (there might be multiple records for a single activation). So "HistoryItem" would be the general description of a record, of which "ActivationHistoryItem" is a special case for activations (I hope that makes sense).

4) Moreover I don’t see clearly the difference with a scheduler and a BP engine (they are at least really complementary). Do you see any ressemblance between Activation and ScheduledJob ?

I actually would like to have a (simple) scheduler with the BP engine :)

Well, it's certainly a matter of point of view. I would argue that an activation is something close to a "job". A "scheduled job" would be a more specific case of a "job", a job that is in a queue. An activation has no notion of scheduling but simply represents the idea of what happens when traversal between two nodes occurs. A scheduler would be one way of managing activations (WfWorklist seems pretty close to a scheduler, holding running and completed activations).

Too subtle for me.

For now, the are no real workflow engine. More a state machine providing access to activable steps (and running one… hence remaining ones).

I/We will need a scheduler (even simple ones).

Max explains below:

To me the scheduler right now is not really existing besides having a list of simultaneous/parralelized steps to realize (activated or not). Activated means currently being done.

You're right, I think. The application that Workflow was designed for required manual interaction, hence there was no need for other methods of scheduling (e.g. by time or event).

This activation role is about logging and interacting with responsible users. But it is more than that. It’s the actual job being done.

Yes.

5)

Concerning run time modification of a process. Is it true that we can modify a currently executed workflow (steps that are not yet activated ?) ? I think that is possible (an cool). When activated, it shouldn’t. Would you think it would be interesting to allow activations to be suspended/resume (frozen), cancelled ?

The history of workflows consists of copies. The steps of a workflow reference the workflow they belong to. Therefore, while it is possible to modify a workflow, modifications do not impact running workflows, as the steps of that workflow continue to reference the previous version. The model suggests that it is ok to create a new version of a workflow but not to modify existing workflows.

For now I would like to get a workflow running without modifying it

Sure. But again an interesting decision to have first.

To me, what more interesting is to be able : - to cancel a task (an activation actually), - change dynamically the remaining workflow (to adapt)… - eventually suspend/resume (nice to time track but I also thin it’s not hard to have)

I know the second point seems too early but again this is important to consider now.

Designs decisions of Aare leaves some room to build more (and constrain its use).

[…]

DomBuilder is a small package for wrapping XML-Parser. I'll publish it so you can use it.

Cedric did you got this package?

No but I didn’t ask either. It’s possible to ask Max. But I think first, as you, we need to be able to run a process.

The XML-Parser package has been significantly modified and

is now named XMLParser (you can find it in the catalog). You should make the changes necessary to use the current incarnation of XMLParser (decide for yourself whether you still need DomBuilder or not).

But this is not really important.

Yep.

Cheers,

Cédrick

Hi Cédrick, 2018-01-21 8:04 GMT-03:00 Cédrick Béler <cdrick65@gmail.com>:

Hi Hernan,

I decided to give a try to Aare or Workflow in Pharo 6, following instructions in https://github.com/Netstyle/Workflow .

Cool :)

I started but had to stop until the semester is finish. Next month should be ok to continue on that.

However, the installation script raised a Warning about missing WADynamicVariable class. Should I install Seaside?

Happy to see people having interest in such tools :)

No.

I discussed with Max Leske.

To solve this « pb », just create WADynamicVariable as a subclass of DynamicVariable already in Pharo. There are also missing part for the export/import in XML (should be easy to fix and Max propose to give the code - DOMBuilder and co.)

Thanks. I cloned the Ducasse fork which already solved the issue.

I tried to start a booklet with Stephane but it is too complicated right now. Stephane started a simpler version.

I put below a summary of the reflexion/discussion I had with Max.

Cheers,

Cédrick

========= INTRO

What's missing compared to the full (proprietary) solution are user interfaces that were web based (Seaside \+ Magritte). Also, persistence was achived through Omnibase. References were removed but they are stil some disfunctionning. Moreover, the completion of activities were mainly manual and achieved through web interface (web forms). They are, for now, no real way to introduce different kind of activities like those being message-based, event-based, service-based.

To evolve, one has to remove all dependancies to Omnibase and Magritte/Seaside.

There are also important design decisions to ensure WfWorkflow being a powerful and extensible workflow management system for Pharo. To me there are 2 main tasks: - rethink persistence (process definition and orchestration, realization) => persistance is essential and was central to Aare. Beside removing Omnibase references (and implication of WfManagedObject), some of the application features were very dependant on the persistence (like logging, tracing process evolution). All of these features are to be thing again considering as much as possible a loosely coupled solution. A general purpose storage solution like Voyage could be used. At first, in image storage will be used to focus on the running aspects of the library. - rethink interaction => Designing a general interaction sub-system is probably the more challenging tasks. Aare was web based. We want workflow to be UI agnostic. Moreover, we want to associate , remove Magritte (replace UI or build an independant system based on Annoucement for instance)

It could be me that I am used to execute and wait processes jobs for hours or days in HPC: typical workflows of NGS trimming, QC, genome indexing, sequence alignment, etc. But integration of a monitoring system (like Ganglia) and interaction with a work load manager (like PBS, Condor, Slurm, etc.) would be also giant tasks.

========= RANDOM QUESTIONS AND ANSWER (in black me - below max)

1)

The static definition of workflow is done through WfWorkflow, WfOutgoingEdge and WfSteps (+ WfConditions). The easy part :)

The runtime aspect are achieved via WfActivation, WfWorkList, WfWorkflowHistory et WfWorkflowManager. More difficult to understand and make evolve.

WfWorkflowHistory represents the different versions of a workflow, so it belongs to the static part. WfWorkflowManager managers workflow definitions (static) and activations (dynamic). WfFrame is also a part of the dynamic side, connecting activations to a workflow. Workflows are hierarchical, i.e. a step can have a sub workflow (see WfWorkflowLibrary>>simpleSubflow)

2)

To me activations are really central entities (and I need to be sure of its correct role). They are said to the realization of an activity/step.

Can we consider the static definition of a workflow as « Plan » and the runtime as the concrete realization (like a job in a scheduler) ?

Yes, I would say so.

I see that:

FUTURE: Static BP définitions with steps (plans)

PRESENT: activation (realization)

PAST: History (experience feedback)

Yes, that's certainly one way to look at it. Although I'd say that the static definition is independent from time once it exists and that "future" would be the set of steps of the current definition that have not yet been activated (just a little nit picking :) ).

3)

Going back to activations, here is my current understanding.

Once a step is activated (all condition on Edges leading to are true - to evaluate outgoing conditions of a step, the step execution has to be complete first) , we get an activation instance (I’m not 100% sure how completion of an activity and outgoing conditions are managed).

As far as I understand, a step can always be activated (e.g. manually). However, activating a step propagates the values of conditions on the edges to the next steps and their activations ("dead" or "alive"). Hence, an activation responds to #isAlive with true if at leat one incoming token was true ("alive") (see WfStep>>continueInFrame:fromStep:alive: and WfActivation>>isAlive). The conditions are evaluated once #complete is sent to the activation. Activation instances are created by two ways (slightly different for the start step), but generally they are created when a step receives tokens from the outgoing edges of an upstream activation (see WfStep>>continueInFrame:fromStep:alive:).

On the exemple of BLActivationHistoryItem that you gave, I’m not sure if it’s an activation of a history item stored in the history (subclasss of WfHistory?).

My idea was that it should represent a record for an activation (there might be multiple records for a single activation). So "HistoryItem" would be the general description of a record, of which "ActivationHistoryItem" is a special case for activations (I hope that makes sense).

4)

Moreover I don’t see clearly the difference with a scheduler and a BP engine (they are at least really complementary). Do you see any ressemblance between Activation and ScheduledJob ?

I actually would like to have a (simple) scheduler with the BP engine :)

Well, it's certainly a matter of point of view. I would argue that an activation is something close to a "job". A "scheduled job" would be a more specific case of a "job", a job that is in a queue. An activation has no notion of scheduling but simply represents the idea of what happens when traversal between two nodes occurs. A scheduler would be one way of managing activations (WfWorklist seems pretty close to a scheduler, holding running and completed activations).

To me the scheduler right now is not really existing besides having a list of simultaneous/parralelized steps to realize (activated or not). Activated means currently being done.

You're right, I think. The application that Workflow was designed for required manual interaction, hence there was no need for other methods of scheduling (e.g. by time or event).

This activation role is about logging and interacting with responsible users. But it is more than that. It’s the actual job being done.

Yes.

5)

Concerning run time modification of a process. Is it true that we can modify a currently executed workflow (steps that are not yet activated ?) ? I think that is possible (an cool). When activated, it shouldn’t. Would you think it would be interesting to allow activations to be suspended/resume (frozen), cancelled ?

The history of workflows consists of copies. The steps of a workflow reference the workflow they belong to. Therefore, while it is possible to modify a workflow, modifications do not impact running workflows, as the steps of that workflow continue to reference the previous version. The model suggests that it is ok to create a new version of a workflow but not to modify existing workflows. The model does *allow* (in principle) to modify an existing workflow but I doubt that was the intention. However, I don't see why modifying an existing workflow has to be bad thing, as long as you can guarantee that only edges and steps are modified that have not yet been activated. That could open up some interesting possibilities. Cancellation of an activation could be very interesting. It would basically allow reversal of complex effects. Very nice idea! I'm not so sure though whether suspending makes much sense. Maybe when a step has the potential to take a long time for some operation. But then you may run into transaction problems. The nice thing about an activation at the moment is that it's atomic (in theory). But again, done right that could open up interesting possibilities.

If a running process is modified, do we track its evolutions in WfWorkflowManager ?

The modification of a workflow is indeed announced to WfWorkflowManager, yes. Workflow versions are stored in WfWorkflowHistory. For modifying a *running* workflow you will probably want to create a specific workflow manager for that, that does validation etc.

The goal of history(s) are to log the realization of the process. But is it one of its aim to « replay » the process execution ?

No. WfWorkflowHistory only stores the static definitions. However, the history of activations could be used to replay an execution (nice idea!).

i.o.w., Is it more than log/report ?

I think the activation history was designed as a log, the workflow history as a log and also as a way to undo changes. As you suggest, however, they could certainly be used for more things.

I agree with the separation (WfWFManager for the run time evolution of the process definition => adaptation and WfActivationHistory for the trace of interactive/automatic step realizations information).

#beginHistory implementation example was very helpful. I knew I missed something Just, as I see a MailManager (with role is obvious), is it something that has to be generalizable ? Like InteroperableManager ? MessageManager ? To get user interactions

That would be very nice, yes. You're completely free to do what you like. It would be cool though if we could evolve the project as opposed to you creating a fork to your own liking. If you're game we can set up a workflow on github where you open pull requests against our repository.

6) I’d like to remove fully the reference and need of Omnibase and Magritte/seaside forms.

Yes please!

I think Omnibase is ok, even storing in image for instance.

What’s more problematic to me is for user interactions (and even automatic interaction through program for instance). There are achieved in your example with seaside. It is ok but what if I’d like to do it more generally ? Would we use Annoucement for example ?

I think that is completely open to implementation. In my eyes, Workflow should remain a separate library that does not enforce any kind of specific presentation or persistence. What's critical for that is of course the right kind of interface. Announcements would certainly be an interesting way to decouple Workflow from other parts of the system.

I’d like to have an incomingMessageBox for each user and eventually transform these message in concrete action (user i/o) ? Or dispatch in JobQueues (each user being a distant worker thread). Again, the distinction between Scheduler and BPEngin is fuzzy to me.

Does it make sense to you ?

Yes, it does :) What I've asked myself (out of curiosity) is whether you want to have - a dedicated instance for executing workflows - a distributed workflow with autonomous synchronisation (parts of a workflow could run on every uses instance, others would need to be executed through agreement) - a partially distributed workflow with one or more managing nodes that control the core steps (e.g. you could designate parts of a workflow as independant)

PS: some random comments on your proposals

Parts of Workflow were never cleanly separated from the proprietary application, so there are indeed a couple of things that are missing (mostly #subclassResponsibility stuff etc.)

- initializeDefaults is not present for steps but thats ok.

- in #createIncoming: (doesn’t exist), I don’t get ….. => makePersistent asPersistentReference. You store persistentReference of steps. Is it like the step object itself ? I would store the step objects (as no persistance right now).

An activity step is a specific subclass of a step. Such a step includes additional information such as documents, duration and user roles. I'm not sure why "makePersistent asPersistentReference" is sent there, as WfStep already inherits from WfManagedObject and would, therefore, already be managed by OmniBase. But I don't know OmniBase, maybe some things need to be announced specifically.

- I don’t understand the offsetSeconds in your BLActivationHistoryItem

That's really just some business rule to modify the timestamp of the history item.

============= Others responses from Max

WfWorkflow - Load and Run All instances that inherit from WfManagedObject were managed by OmniBase, yes. DomBuilder is a small package for wrapping XML-Parser. I'll publish it so you can use it. The XML-Parser package has been significantly modified and is now named XMLParser (you can find it in the catalog). You should make the changes necessary to use the current incarnation of XMLParser (decide for yourself whether you still need DomBuilder or not).

Those IDXXX classes belong to another package a didn't publish (but will). This package also includes an OmniBase specific class. Magritte has changed significantly over the years but the core should be pretty much the same. Just load the newest Magritte and try working with that.

...

ok but avoidable ? try loading Magritte ? Long …

#beginInHistory should be implemented with #subclassResponsibility on WfActivation. Your explicit implementation could then look something like this: beginInHistory self history add: (MyActivationHistoryItem new message: 'started'; user: (WACurrentSession value ifNotNilDo: [ :session | session user ]); type: #started; yourself). MyMailManager noteNewActivation: self

Basically, what the history contains is up to the workflow implementation. I think it would makes sense though to have an abstract WfActivationHistoryItem. WfActivation>>history should be implemented like this: history ^self propertyAt: #history ifAbsentPut: [ OrderedCollection new ].

Although I think that it would be good to have a dedicated WfActivationHistory class. WfWorkflowHistory is associated with changes to the workflow, not activations. Both history classes should probably inherit from an abstract class WFAbstractHistory.

Seaside interaction

Here are a couple of action implementations in Seaside components that should give you an idea of how to interact with the workflow: MyActivationComponent>>complete self activation hasCompleted ifTrue: [ ^ self ]. self history add: (BLActivationHistoryItem new message: 'completed'; user: self session user; type: #completed; offsetSeconds: -1; yourself). self activation complete.

MyActivationForm>>accept: aString self activation authorized: true. self history add: (BLActivationHistoryItem new comment: aString; message: 'accepted'; user: self session user; type: #accepted; offsetSeconds: -2; yourself). self completeIfSatisfied.

MyActivityList>>addActivity self call: (MyActivityEditor new workflow: self workflow; yourself). self refresh.

MyActivityEditor>>buildActivity ^(self workflow newActivityStep initializeDefaults; yourself) asPersistentReference.

MyTransitionEditor>>createIncoming | step | step := (self workflow newActivityStep initializeDefaults; yourself) makePersistent asPersistentReference. self addIncoming: step. MyCurrentWorkflowComponent value showActivity: step.

MyTransitionEditor>>addIncoming: anActivity ^self add: anActivity to: self activity.

MyTransitionEditor>>add: aSourceActivity to: aDestinationActivity ^aSourceActivity addOutgoingEdgeFor: aDestinationActivity.

MyTransitionEditor>>editCondtions: anEdge | component | anEdge condition isTrueCondition ifTrue: [ anEdge condition: WfAllCondition new ]. component := (MyConditionEditor activity: self activity) container: anEdge; addDecoration: (MyToolbarDecoration new title: 'Edit Transition Conditions to: ' , anEdge to name; toolbar: [ :html | html icon: 'icon_close.gif' text: 'Close' action: [ component answer ]. html helpIconOn: component ]; yourself); yourself. self call: component.

MyConditionEditor>>addRule: aDescription | new | new := MyCondition newPersistent field: aDescription; asPersistentReference. new := self call: (self buildEditorFor: new titled: 'Add Rule for ' , aDescription asLabel). new isNil ifFalse: [ self condition add: new; markDirty. self changedForm ].

...

WfWorflowManager class is empty defining empty stubs/protocols. Its aim seems to be about “logging/noting” changes. Is is it’s only role ? Correct. You would use WfWorkflowManager to update the workflow in OmniBase (e.g. mark dirty, add new activation etc.). #generateID would generate an ID from OmniBase and #activationClass would answer your specific activation class, if you choose to override WfActivation.

Cool, thank you both for including your very valuable comments! I did my first experiment and have a script to start: | wf task1 task2 startStep frame | wf := WfWorkflowLibrary default workflowNamed: 'Test1'. task1 := wf newStepNamed: 'Step 1'. task2 := wf newStepNamed: 'Step 2'. startStep := wf start. startStep addOutgoingEdgeFor: task1. task1 addOutgoingEdgeFor: task2. frame := wf executeInNewFrame. frame workList running first complete. frame workList runningSteps. frame workList running first complete. frame workList runningSteps. wf To see how it matches with scientific workflows I will need more experiments. Cheers, Hernán