isn't a Petri net instead ?

@mickaelandrieu a workflow is a subset of a petri net (and a state machine a subset of workflow). The component does not support all features necessary to implement a petri net

it's unclear to me right now, but it's not a problem in the docs: I just need to learn a little bit more about all of theses implementations ^^

Thank you@stof

The more I read this, the more I think we should rename - at least in docs -Workflow component toWorkflow Engine component. Am I crazy ? /c@Nyholm

please remove the empty lines (except from one)

You should also the initial place with something like:If a definition has no explicit initial place, it uses the first place defined.

I suggest to usedrafted andneeds_review instead ofdraft andreview. That allows more readability, one may needs more statuses likereviewed andneeds_correction. (I do :D). What about addingarchived too?

What aboutstatus?

It's not about domain logic, it's more about Workflow management logic, isn'it ?

I'd say instead "This will keep your Workflow logic in one place and not spread all over your applications.", what do you think ?

Interesting. I would always consider this the domain logic because the "workflow management logic" is a part of your domain.

The theory behind "Workflow management" is to put the Workflow managementoutside of your domain, if I've well understood. BlogPost entity shouldn't be modified every time the rules of publishing evolve, for instance.

I'm pretty noob of this field, so correct me if I'm wrong :)

BlogPost entity shouldn't be modified every time the rules of publishing evolve, for instance.

Correct, you just edit the workflow when the rules of publishing changes.

The theory behind "Workflow management" is to put the Workflow management outside of your domain, if I've well understood.

Outside the domain or outside yourmodel? The way I see it there is only three places you can put code/config:

• In the framework
• In your domain
• The glue between your domain and the framework.

Can@lyrixx give some input?

I'm not sure to understand the question / debate here.
Basically, the the data are stored in the model, and you can put the places / transitions everywhere you want. I don't have a rule of thumb for that. IMHO, Simple things are always better than perfect code.

If you write an issue with a summary of your thoughts with pros and cons, I'll be happy to submit a PR for that issue.

I can't do it, because the primary purpose of this Workflow component is not obvious for me:

It would be nice to describe the purpose of the component more.

The component is designed as very generic thing, so in theory it probably may have some interesting applications. However, providedexamples don't impress. Compare it with rich domain model:

finalclass Article{private$id;private$title;private$approvedByJournalist;private$approvedBySpellchecker;private$published;publicstaticfunctionpostDraft(int$articleId,ArticleTitle$title):Article    {$draft =newself();$draft->apply(newDraftArticleWasPosted($articleId,$title));$draft->apply(newArticleWasSentForApproval($this->id));return$draft;    }privatefunction__construct() {}publicfunctionapproveByJournalist()    {if ($this->approvedByJournalist) {return;        }$this->apply(newArticleWasApprovedByJournalist($this->id));$this->publishIfItIsReady();    }publicfunctionapproveBySpellchecker()     {if ($this->approvedBySpellchecker) {return;        }$this->apply(newArticleWasApprovedBySpellchecker($this->id));$this->publishIfItIsReady();    }publicfunctionchangeTitle(ArticleTitle$newTitle)    {if ($this->title->equals($newTitle)) {return;        }$this->apply(newArticleTitleWasChanged($this->id,$newTitle));$this->apply(newArticleWasSentForApproval($this->id));    }privatefunctionpublishIfItIsReady()    {if ($this->approvedByJournalist &&$this->approvedBySpellchecker) {$this->apply(newArticleWasPublished($this->id));        }    }// ...privatefunctiononArticleWasApprovedByJournalist(ArticleWasApprovedByJournalist$event)    {$this->approvedByJournalist =true;    }privatefunctiononArticleWasSentForApproval(ArticleWasSentForApproval$event)    {$this->approvedByJournalist =false;$this->approvedBySpellchecker =false;$this->published =false;    }privatefunctiononArticleTitleWasChanged(ArticleTitleWasChanged$event)    {$this->title =$event->getNewTitle();    }}

We see use-cases (postDraft,approveBySpellchecker,approveBySpellchecker,changeTitle), events (ArticleWasApprovedByJournalist, ...,ArticleTitleWasChanged) and it's not hard to understand lifecycle of theArticle from this code. We lose this expressiveness.

Further, that sample projectchecks permissions withGuardEvent hook:

publicfunctiononTransitionJournalist(GuardEvent$event)    {if (!$this->checker->isGranted('ROLE_JOURNALIST')) {$event->setBlocked(true);        }    }

... and how you can solve it with commands:

finalclass ApproveArticleByJournalistHandler{/**     * @acl_role ROLE_JOURNALIST     */publicfunctionhandle(ApproveArticleByJournalist$command)    {$blogPost =$this->blogPostRepository->find($command->getArticleId());$blogPost->approveByJournalist();$this->blogPostRepository->save($blogPost);    }}

And again we lose expressiveness by genericGuardEvent hook. It's harder to find it in the project, your have to search for string "workflow.article.guard.journalist_approval" instead of typing class name "ApproveArticleByJournalis...".

I would like to know if I'm wrong.

IMHO, all this debate is totally out of the scope of this PR.

How is it possible to write docs for the component without clear applications, examples?

I did not said that. But you you are telling us the Workflow component is useless and it's better to write code like your example. It's really a matter of taste (I have a strong opinion on that ; but I let people making their own choices). So I'm juste saying: The component is here, and it's useless to discuss if it's better to use CQRS / ES over Workflow Component.

For the record, the discussion is about the following sentence:

The workflow will keep your domain logic in one place and not spread all over your application

IMHO, it's more important to document how the component works.

I like the@Nyholm's work ; so let's focus on what matter.

@unkind: I hear you. Your arguments are valid.
@mickaelandrieu: Your arguments are also valid.

This is, as Grégoire says, out of scope for this PR.@unkind, I've asked you to create an issue on the symfony/symfony repository. I amhappy to make a PR to try to improve the Workflow component regarding your input. Let's work together on this, but not in this PR.

please prefix the example with// ... to indicate things are left out (but shown above).

// ...$post =newBlogPost();