Workflow Systems: Myths, Truths and Wishful Thinking

Workflow Systems
Myths, Truths and Wishful Thinking
Brandon Satrom
Chief Architect, Thought Ascent
brandon.satrom@thoughtascent.com
www.userinexperience.com

Copyright 2009, Thought Ascent, Inc
About Me - In Six Words
Opinionated Architect.
Often wrong.
Continually improving.

Long-time Microsoft developer
Former Enterprise Architect
Alt.Net guy, but still nice
President, IASA Austin
Worth mentioning?

Experience with vendor WF tools
Experience with BizTalk (2002+)
Recently built a successful production implementation using WF 3.5
See 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

Persistent
External Stimulus
Persistence Store

Dynamic
Business Change
Activity F
Divert to new activity

Configurable
Activity D
Activity E
Rules Store

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 curves

Poor Performance

Sleights of hand and shell-games

Both sides are right …
Both sides are wrong….

Right and wrong? How so?

Myths, Truths and Wishful Thinking

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

Myth

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
end

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

Lie

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 IDEs
Testing is hard, if not impossible
Refactoring involves more rework than necessary

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

Wishful Thinking…

The Truth
Code-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”
Demo:

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” Workflow
Use an open-source Bus
NServiceBus
Mass Transit
Simple ServiceBus
Use an open-source State management tool
Simple State Machine
Use Windows WF
After you’ve exhausted all other possibilities

Consider a “Workflow System” when:
Need a visual, changeable representation
Timed-events are key
Long-running:
Transactions
Conversations
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.com
www.userinexperience.com
Twitter: @thesatch
Code and slides available at:
http://github.com/bsatrom/WorkflowSystems

Image Credits
WF System, InfoWorld
http://www.infoworld.com/d/developer-world/product-review-ultimus-jump-starts-bpm-deployment-546?page=0,1
Pinnochio – House of Sims, Flickr
http://www.flickr.com/photos/houseofsims/2662410465/
Myth – Mythbusters on Discovery
http://dsc.discovery.com/fansites/mythbusters/wallpaper/wallpaper.html
Steep Learning Curve – Casual Game Design
http://www.casualgamedesign.com/?p=27
Skeptic Guy – Flick
http://www.flickr.com/photos/mcleod/3909431214/in/set-72157607796029636

Workflow Systems: Myths, Truths and Wishful Thinking

by Brandon Satrom on Sep 21, 2009

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