Simple State Machine

Source code checked in, #80132

Project Collection Service Accounts — Mon, 01 Oct 2012 21:49:39 GMT

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Source code checked in, #80131

Project Collection Service Accounts — Mon, 01 Oct 2012 21:43:10 GMT

Checked in by server upgrade

New Post: yet another simple state machine...

justinc — Wed, 05 Oct 2011 06:24:30 GMT

Cool stuff by the way, I love boo and it's dsl capabilities. I just got done with a first go at implementing the same state machine dsl in a grammar I have been working on in case you were interested:

http://metasharp.codeplex.com/SourceControl/changeset/view/a2ccc29b7ad0#sdk%2fsamples%2fStateMachine%2fStateMachine%2fStateMachineParser.g

Not quite 2 files as the commenter on your Home page suggested but pretty slim. I think that Fowlers state machine dsl should end up becoming the standard first DSL for new DSL developers :)

New Post: Cannot seem to create transition actions

hardya — Wed, 06 Oct 2010 12:11:51 GMT

I am using this statemachine with code only and not using the boo dsl

I want to assosiate actions with transitions like you can in the uml and not just call backs for state entry/exit.

However, when I create a transition action thus:

            object[] o;
            o = new object[1];
            o[0] = "PosSetSensor";

m.AddNewTransitionAction("test", StateTransitionPhase.All, o); // where m is my state machine

when I create a sm context from m and start it, I find it attempts to execute an action, but finds that "test" is not present in _availableTasks in the tasks factory, the only task available appears to have a name more like a task type. it is something like "invoke method".

Is there any documentation that will help me map the creation many common uml elements such as a transition action, to the appropriate object constructions and method calls because I am not finding the method names intuitive.

I really appreciate any help or advice you are able to give.

Andrew

New Post: Memory Leak/Management Issue with SSM?

PlasticLIzard — Tue, 21 Sep 2010 03:30:50 GMT

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New Post: Memory Leak/Management Issue with SSM?

Zsolt2 — Tue, 21 Sep 2010 02:52:46 GMT

Hello,

First of all, thanks for making this library "free".

I need to create a number of SimpleStateMachine (1000+) instances in my application and then delete those.

Even though I de-reference the SimpleStateMachine instances, the StateMachineDSLEngine objects do not get garbage collected. There are exactly as many of them as StateMachines was created before. Among others, the size of a Dictionary <Type DslEngine> is also increasing...

Any hints what goes wrong?

Regards,
Zsolt

New Post: Conditional State Transitions

PlasticLizard — Thu, 19 Aug 2010 21:58:43 GMT

I've more or less moved my attention to Ruby development now. Aalthough we still use SSM in production in our .NET products, we aren't evolving it, and in fact we're in the process of porting our SSM state machines into Ruby. I would, however, be happy to apply a patch. Alternatively, with IronRuby being more or less ready for prime time, you might consider combining IronRuby with a Ruby state machine library such as AASM, state_machine or workflow (see github) to gain the flexible, DSL based syntax characteristic of Ruby and the deep .NET integration of IronRuby.

New Post: Conditional State Transitions

johano — Thu, 19 Aug 2010 19:36:55 GMT

Any solution to this case yet? It would make things a lot easier

Source code checked in, #55373

_TFSSERVICE — Mon, 02 Aug 2010 22:49:34 GMT

Checked in by server upgrade

New Post: This just works for me

Zsolt2 — Tue, 29 Jun 2010 17:17:43 GMT

Yes, it is rather easy to convert a SimpleStateMachine to Graphviz's DOT langauge. The result usually looks good enough. I use SVG output and then convert it to PNG with ImageMagick. Unfortunately the conversion takes awfull long, aprox. one second. This is a problem, because the state transitions are displayed as they occur on the fly and 1 sec latency is noticable. Does anyone know a fast .NET SVG to png rendering engine? For graphviz, instead of runing it as a new process, I'd recommend to load the neccessary functions with PInvoke to speed things up... ...you get the SVG output damn fast....

By the way, there was a question earlier regarding to "Parallel Proccess".

"Instead you may want to have a single state, AwaitingDocumentResults, and this state can either host an inner state machine for each document, or can handle waiting for the responses in application logic. In the end, I think the state machine library should probably be given the ability to manage multiple child states automatically, but it will take care not to drift into re-creating WF and building a sequential workflow library into the state machine library, where it doesn't belong. "

I don't quite understand how this would work in practice. To get around the very same issue, I use a custom task to transfer events from one state machine to an other. Typically the state machines run in separate processes and .NET remoting takes care of passing the events. The issue is, that defining how the 'independent' state machines interract eachother gets a bit complicated in the .boo file.

New Post: This just works for me

PlasticLizard — Tue, 29 Jun 2010 15:51:50 GMT

I'm pleased to hear that! Is graphviz easy to use for such tasks? That's something I would like to play with myself.

New Post: This just works for me

Zsolt2 — Sun, 27 Jun 2010 13:24:25 GMT

Hi,

I am using SimpleStateMachine for my project and it just works for me. I use "graphviz" to visualize the state machine and custom tasks to carry out actions.

Thanks for providing this stuff for us.

Regards,

New Post: Timed Events

PlasticLizard — Tue, 01 Sep 2009 15:59:02 GMT

For the timer, you would need some kind of a long running process to manage the timers, so you probably will need to implement that in whatever process is hosting your workflow and have the timer handler load your workflow and fire an event, TimeoutExpired or something. You could also do something sneaky using the .NET web cache (which is availble in all apps, not just ASP.NET apps)

http://www.codeproject.com/KB/aspnet/ASPNETService.aspx

I think I would also impelment the rule based logic srrounding the pin validation in a context or business object that provides context and events to the state machine. This particular state machine library is intended only to manage events and transitions, and leaves actually managing the state (how many times a user has failed with their pin) to the underlying business or context objects. I have considered having expression based conditional rules that can prevent or allow state transitions, but I haven't found the time to build that in. In the mean time, you can place such logic around event firing code in your business logic.

New Post: Timed Events

myersd — Thu, 27 Aug 2009 08:17:38 GMT

What would be the best way to have a timed based trigger. An example of what I mean is:

Imaging the scenario of a Call management workflow

After the call ages to being 24 hours old, its state should transition to an urgent state

A second question I have is whether or not you could have a transition being conditional upon a variable. An example of what I mean is:

Enter PIN, Validate.....if ok continue, else report invalid pin. If pin invalid 3 times, lock account.

Any ideas on both of these?

New Post: Parallel Process

PlasticLizard — Thu, 30 Apr 2009 18:30:12 GMT

That's a tough one. If you were using a sequential workflow, this would be a no brainer, you'd do a branch and join. We also have this need in our process flows, and I haven't settled on the right answer yet. Our workaround has been to handle it at a higher level, but I'm not terribly happy with our workaround, so I won't bother explaining it. Of your two options, I don't think I'd start creating states that represent combinations of other states, that sounds like a slipper slope. Instead you may want to have a single state, AwaitingDocumentResults, and this state can either host an inner state machine for each document, or can handle waiting for the responses in application logic. In the end, I think the state machine library should probably be given the ability to manage multiple child states automatically, but it will take care not to drift into re-creating WF and building a sequential workflow library into the state machine library, where it doesn't belong. Probably not a hugely helpful answer, but it's all I've got :)

New Post: Parallel Process

nirataro — Wed, 29 Apr 2009 13:13:57 GMT

I have a system that use a single column for case status. SimpleStateMachine state drives the value of this case status. So right now I have a design dillema.

I have a situation where I need to start two things at the same time. Say that the current state is DocumentsPending. Now I have to send two types of different documetns, which normal will move the state to DistrictLetterDocumentPrinted and ApprovalLetterDocumentPrinted. The next step of each of these statuses are DistrictDocumentWaitForResult and ApprovalLetterlDocumentWaitForResult.

Essentially I am sending two categories of documents to separate institution and I am waitng for both of their results to arrive before I move forward and I want the ability to check where the status of the case are at any given time.

Now should I add an additional case status column so that i can store both DistrictLetterDocumentPrinted and ApprovalLetterDocumentPrinted or should I create a third combination status which says "DOAndApprLetterPrinted" which adds 2/3 additional statuses for each combination but enable me to use just a single column.

New Post: Injecting dependencies into Tasks

k03123 — Tue, 24 Mar 2009 00:17:22 GMT

hi nirataro,

first you need to define your implementation of IObjectBuilder. I have defined mine as below:

public class WindsorObjectBuilder : IObjectBuilder
    {
        private readonly IWindsorContainer _container;

        public WindsorObjectBuilder(IWindsorContainer container)
        {
            _container = container;
        }

        public T Create<T>() where T : class
        {
            return _container.Resolve<T>();
        }

        public T Create<T>(Type type) where T : class
        {
            return _container.Resolve<T>();
        }
    }

then register it as suggested by plastic lizard:

ServiceLocator.RegisterService<IObjectBuilder>(new WindsorObjectBuilder(windsorContainer));

New Post: Injecting dependencies into Tasks

nirataro — Sun, 22 Mar 2009 08:53:57 GMT

Is there any example to do accomplish these tasks? Sorry, I'm lost with all the DI techniques being described here.

Created Issue: Replace existing IoC integration w/MS Service Locater

PlasticLIzard — Wed, 04 Mar 2009 16:42:10 GMT

Use service locater library for universal IoC support

New Post: Injecting dependencies into Tasks

katokay — Sun, 01 Mar 2009 23:33:07 GMT

We do use the CommonServiceLocator. The recent release of Prism 2.0 also uses it, as well as the Caliburn beta. But yes, still asking out of curiosity.