Most of us have heard the mantra, "Slice your User Stories as thin as possible!" In my travels as a coach since the early 2000's, however, I've rarely seen stories that truly are thin. What are these rare creatures? Why don't I see more of them? Having good User Stories is crucial to the success of teams using them as the means for determining what needs to be built to fulfill a customer's need. Having thinly sliced stories is even more important!

1. How Thin is Thin? Effective Story Slicing
How Thin is Thin?
Effective Story Slicing
Agile DC
September 23, 2019

2. How Thin is Thin? Effective Story Slicing
Who is this guy anyway?
• Agile Practitioner & Coach
• Software Developer
• Recovering Manager
• Assumption Challenger
• Impatient Optimist
• The punchline to a joke or 10
• Member of the Agile community for this entire century
@daverooneyca on Twitter
www.linkedin.com/in/daverooneyagile/
medium.com/@daverooneyca and blog.daverooney.ca/
dave@daverooney.ca

3. How Thin is Thin? Effective Story Slicing
But enough about me! Who are you?
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• Product Managers?
• Product Owners?
• Business Analysts?
• ScrumMasters?
• Developers?
• QA?
• UX?
• Architects?
• Management?
• ???

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Why Use Small Stories?
• Better flow
• Better focus
• Reduced risk
• Improved visibility

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Why Small?

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So What Does Thin Mean?
User Interface
Web Server
Application Server
Business Logic
Database
Story
• A single “slice” through all layers of a
system
• Just enough functionality to provide
value to the Product Owner
• The Team can easily identify what
has to be done to deliver the story

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DatabaseRemote API
What About non-Web Systems? There’s no difference!
User Interface
Business Logic
Database
Story
User Interface
Business Logic
Story
API Gateway
Business Logic
Story

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A “Real World” Example - The Point of Sale (POS) System
• Client was building a web-based POS
system for salespeople taking orders in
the field
• The orders would be stored in the POS
database, but they would also be sent to
the Oracle back-end eBusiness Suite
• Customer and Product data would come
from the Oracle eBusiness Suite

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The First Story
• Used Personas and Story Mapping to identify how
the system would support the work of the
salespeople
• The Product Owner determined that the most
fundamental aspect of the system was to create
orders

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The First Story
TOO BIG!
• Used Personas and Story Mapping to identify how
the system would support the work of the
salespeople
• The Product Owner determined that the most
fundamental aspect of the system was to create
orders

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So what do we really need?
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For the first Story...

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For the first Story...
• Didn’t create tables for the Customer or Product
• Used hard-coded values for both
• No validation of those values
• Simple web page with “Create Order” button
• Second page to show that the order was created
(could have even been validated with an SQL
query!)

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Was This Story “Thin”?
User Interface
Web Server
Application Server
Business Logic
Database
Story
• A single “slice” through all layers of a
system
• Required work in all layers and
created the foundation for all later
stories
• Just enough functionality to provide value
to the Product Owner
• An Order was created
• The Team can easily identify what has to
be done to deliver the story
• Very small, easily verified

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The Next Story...

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The Next Story...
• Still using a hard-coded value for the Product
• Customer ID is entered manually
• Still no validation of those values
• Web page now has a text field for the Customer ID as
well as“Create Order” button
• Second page to show that the order was created
(could have even been validated with an SQL query!)

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Still “Thin”?
User Interface
Web Server
Application Server
Business Logic
Database
Story
• A single “slice” through all layers of a
system
• Just enough functionality to provide value
to the Product Owner
• An Order was created with the
specified Customer ID
• The Team can easily identify what has to
be done to deliver the story
• Very small, easily verified

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The Next Next Story...

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The Next Next Story...
• Still using a hard-coded value for the Product
• Customer is selected from a list of valid customers, but hard-
coded into the page
• No validation of the product, but the customer will be valid
• Web page now has a drop-down list for the Customer as well as
the “Create Order” button
• Second page to show that the order was created (could have
even been validated with an SQL query!)

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Are we still “Thin”?
User Interface
Web Server
Application Server
Business Logic
Database
Story
• A single “slice” through all layers of a
system
• Just enough functionality to provide value
to the Product Owner
• An Order was created with the
selected Customer ID
• The Team can easily identify what has to
be done to deliver the story
• Very small, easily verified

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The Stories Continue...

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The Stories Continue...
• The Product ID is entered in a text field
• Customer is selected from a list of valid customers, but
hard-coded into the page
• No validation of the product, but the customer will be valid
• Web page now has a drop-down list for the Customer, a
text field for the Product and a “Create Order” button
• Second page to show that the order was created

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Are we still “Thin”?
User Interface
Web Server
Application Server
Business Logic
Database
Story
• A single “slice” through all layers of a
system
• Required work in all layers and
created the foundation for all later
stories
• Just enough functionality to provide value
to the Product Owner
• An Order was created with the
selected Customer ID and a Line Item
was added for the Product ID entered
• The Team can easily identify what has to
be done to deliver the story
• Very small, easily verified

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Let’s Skip Ahead A Bit…

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Let’s Skip Ahead A Bit…
• We can now enter multiple Products selected from a list, hard-
coded into the page
• Customer is selected from a list of valid customers, but hard-
coded into the page
• Both the product and customer will be valid
• Web page now has a drop-down list for the Customer,
multiple drop-down lists for the Products and a “Create Order”
button
• Second page to show that the order was created

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Are we still “Thin”?
User Interface
Web Server
Application Server
Business Logic
Database
Story
• A single “slice” through all layers of a
system
• Required work in all layers and
created the foundation for all later
stories
• Just enough functionality to provide value
to the Product Owner
• An Order was created with the
selected Customer ID and Line Items
were created for each of the Products
• The Team can easily identify what has to
be done to deliver the story
• Very small, easily verified

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Ahead even further…

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Ahead even further…
• Both stories use the back-end Product and Customer
services to fill the drop-down lists
• The lists are valid as of the time the page is rendered
since they’re using the most up to date data
• The page is now a classic master/detail view with line
items for the products

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Are we still “Thin”?
User Interface
Web Server
Application Server
Business Logic
Database
Story
• A single “slice” through all layers of a
system
• Just enough functionality to provide value
to the Product Owner
• An Order was created using valid
Customers and Products from the
back-end services
• The Team can easily identify what has to
be done to deliver the story
• Very small, easily verified

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All of that from One Story!
• We built out Create Order using many small, valuable
slices
• Each one delivered value
• Each one further reduced risk
• Each one was tested:
• JUnit microtests at the code level
• Cucumber scenarios at the story level
• Each one allowed incremental delivery of the system
architecture

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So what did we just see?
• We used hard-coded values to simplify by excluding any processing
of user data entry
• A simple UI was used that was barely sufficient to support the
stories
• No validation of data entered before it was really required
• A story that had no “child” records was followed by a story with one
child then a story with many children
• Although the final system would have an interface with the Oracle
back-end services, we deferred using that interface until it was
necessary
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Story Splitting Patterns
• Hard coding values;
• Simple interface;
• Defer validation;
• Zero, then One, then Many (with the Products);
• Defer complexity (with the back-end Services).

33. How Thin is Thin? Effective Story Slicing
Exercise: The Digital Personal Video Recorder (PVR)
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• Process:
• Break out into groups of 6-10 (e.g. your table)
• Don’t worry about hardware details, focus on the stories about
someone will use the PVR
• Brainstorm the high-level functionality that should exist
• Brainstorm the stories that will deliver that functionality iteratively and
incrementally

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• The system downloads program information over Ethernet.
• The user can configure the following:
• Maximum number of episodes to record
• Finding the same show on other channels
• Time to keep the episodes before automatically deleting them
• Record only new or new and repeat episodes
• Shows can be rated when watched. This information is anonymously fed to an online
service that tracks ratings.
• The system makes recommendations based on what you like compared to what other
people like (all anonymously).
• The system integrates with social media like FaceBook, Twitter, etc.
Exercise: The Digital Personal Video Recorder (PVR)
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35. How Thin is Thin? Effective Story Slicing
Resources & Further Reading
• Story Splitting Patterns
• User Stories - An Agile Introduction
• How to Enable Estimate-Free Development
• It’s Just a Feature-for-Feature Port
Questions about the session? Contact me at dave@daverooney.ca
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