Workflow Systems: Myths, Truths and Wishful Thinking

Workflow Systems

Brandon SatromChief Architect, Thought Ascentbrandon.satrom@thoughtascent.comwww.userinexperience.com

Myths, Truths and Wishful Thinking

Opinionated Architect. Often wrong.

Continually improving.

About Me - In Six Words

Long-time Microsoft developerFormer Enterprise Architect

Alt.Net guy, but still nicePresident, IASA Austin

Worth mentioning?

Experience with vendor WF toolsExperience with BizTalk (2002+)

Recently built a successful production implementation using WF 3.5See that “opinionated architect” comment.

What qualifies me to talk about Workflow…

So what is “Workflow” anyway?

A workflow is a depiction of a sequence of operations, declared as work of a person, a group of persons, an organization of staff, or one or more simple or complex mechanisms. Workflow may be seen as any abstraction of real work, segregated in workshare, work split or other types of ordering. For control purposes, workflow may be a view on real work under a chosen aspect, thus serving as a virtual representation of actual work. The flow being described often refers to a document that is being transferred from one step to another.

– from http://en.wikipedia.org/wiki/Workflow

How about something simpler?

The coordination of work in a “system”

Got it. So then what’s a “Workflow System?”

Perhaps…

An application that assists in the definition and/or execution and/or management of workflows

That sounds too similar to a “normal”

system. What’s the difference?

How a workflow system differs from a traditional program

In theory, at least…

Declarative

Activity A Activity B

Persistent

Activity A Activity B Activity C (Idle)

Activity D (Active)

Persistence Store

External Stimulus

Dynamic

Activity A

Activity B

Activity C

Activity D

Activity E

Activity F

Business Change

Divert to new activity

Configurable

Activity A Activity B Activity C

Rules Store

Activity D

Activity E

Centrally Defined…

… though not necessarily visual.

static SessionSaga(){ Define(() => { Initially( When(NewSession) .Then((saga, message) => saga.NewSessionStarted(message)) .TransitionTo(SessionActive) );

During(SessionActive, When(FeedbackCheckRequested) .Then((saga, message) => saga.CheckForFeedback(message)) When(new Timer() .StartOn(session.Start)

.RunAtInterval(session.CheckInterval) .Until(session.End))

.Then((saga, message) => saga.CheckForFeedback(message)) When(SessionComplete) .Then((saga, message) => saga.SessionEnded(message)) .Complete() ); });}

Ok, I get it. So why are we

still doing this presentation?

Workflow has a PR problem…

There seem to be two sides…

…who can’t (or won’t) get along.

The “Workflow will Save us all” side

The “Run like you’re on fire” side

I’d like a third option

please.

How about the best of both?

Consider both sides of the story…

And be a cautious optimist…

There are reasons to get excited about Workflow…

Visual, Visual, Visual

Clear expression of intent from domain experts…

The Next “Great Leap” in software

…and there are reasons to be wary…

Steep-learning cu

Poor Performance

Sleights of hand and shell-games

Both sides are right …

Both sides are wrong….

Right and wrong? How

Myths, Truths and Wishful Thinking

1) Visual Workflow Tools are the only way to “do” Workflow

Is this really easier to comprehend…

Than this?

require 'rubygems' require 'statemachine'

vending_machine = Statemachine.build do state :waiting do

event :dollar, :paid, :activate event :selection, :waiting on_entry :sales_mode on_exit :operation_mode

end trans :paid, :selection, :waiting, :release trans :paid, :dollar, :paid, :refund context VendingMachineContext.new

The Truth

Many open-source “code-first” solutions offer most of the benefits of a workflow system without the steep learning curve.

Demo –Workflow with Mass Transit

2) Workflow should be running all your application logic

Turn a simple flow…

…into “Spaghetti Flow”

The Truth

Workflow systems can be a good choice for managing long-running, complex processes, but don’t yet perform well-enough to handle all your logic.

3) Domain experts can (and should) easily change workflows at runtime

Wishful Thinking…

The Truth

We don’t change systems at runtime without some diligence. So why would our users?

That said. There are models that are more illustrative of reality…

4) Declarative/Visual App Dev is easier than traditional dev…

Half-Truth

The Truth

Where it’s easier:OOB programming constructs (IF, While, etc)Encourages/ Rewards SRP-development

Where it’s harder:Visual IDEs slower than code IDEsTesting is hard, if not impossibleRefactoring involves more rework than necessary

5) “I can build a WF system in 100 lines of code”

Wishful Thinking…

The TruthCode-only solutions can address simple scenarios quickly…

But tend to unravel when persistence, durability, scale, timed-events, long-running processes, human workflow and other complex issues are introduced.

The Faceplant Application“Social Speaking”

Congratulations! You’ve done an excellent

job of not telling me

what I should do…

Open Discussion – When should a Workflow Tool be considered?

When does WF make sense?

I think it’s time for the bottom

line…

There is no simple answer…

Only the right tool for the job

The Right Tool for The Job might be…

“Roll Your Own” WorkflowUse an open-source Bus

NServiceBusMass TransitSimple ServiceBus

Use an open-source State management toolSimple State Machine

Use Windows WFAfter you’ve exhausted all other possibilities

Consider a “Workflow System” when:

Need a visual, changeable representationTimed-events are keyLong-running:

TransactionsConversations Services

Many, complex processes Economies of scale principle

Don’t start with a workflow system as a solution.

Get there by eliminating other options

And pay attention…

Software development is changing.

Questions?

brandon.satrom@thoughtascent.comwww.userinexperience.com

Twitter: @thesatch

Code and slides available at: http://github.com/bsatrom/WorkflowSystems

Image Credits

WF System, InfoWorldhttp://www.infoworld.com/d/developer-world/product-review-ultimus-jump-starts-bpm-deployment-546?page=0,1

Pinnochio – House of Sims, Flickrhttp://www.flickr.com/photos/houseofsims/2662410465/

Myth – Mythbusters on Discoveryhttp://dsc.discovery.com/fansites/mythbusters/wallpaper/wallpaper.html

Steep Learning Curve – Casual Game Designhttp://www.casualgamedesign.com/?p=27

Skeptic Guy – Flickhttp://www.flickr.com/photos/mcleod/3909431214/in/set-72157607796029636

Workflow Systems: Myths, Truths and Wishful Thinking

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Transcript of Workflow Systems: Myths, Truths and Wishful Thinking

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