From my session at the Gatineau-Ottawa Agile Tour 2016

1. How Thin is Thin?
Effective Story Slicing
Gatineau-Ottawa Agile Tour
November 21, 2016
1

2. How Thin is Thin? Effective Story Slicing
Who is this guy?
2
•Software Development Manager
at You.i TV
•Recovering Developer & Agilist,
but frequently falls off the wagon
•Coding since C wasn’t even a
teenager yet and Java was
something you drank
•Part of the Agile community for
this entire century

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

4. How Thin is Thin? Effective Story Slicing
4
Why Use Small Stories?
• Better flow
• Better focus
• Reduced risk
• Improved visibility

5. How Thin is Thin? Effective Story Slicing
5
Why Small?

6. How Thin is Thin? Effective Story Slicing
6
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

7. How Thin is Thin? Effective Story Slicing
7
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

8. How Thin is Thin? Effective Story Slicing
8
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

9. How Thin is Thin? Effective Story Slicing
9
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

10. How Thin is Thin? Effective Story Slicing
10
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

11. So what do we really need?

12. How Thin is Thin? Effective Story Slicing
12
For the first Story...

13. How Thin is Thin? Effective Story Slicing
13
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!)

14. How Thin is Thin? Effective Story Slicing
14
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

15. How Thin is Thin? Effective Story Slicing
15
The Next Story...

16. How Thin is Thin? Effective Story Slicing
16
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!)

17. How Thin is Thin? Effective Story Slicing
17
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

18. How Thin is Thin? Effective Story Slicing
18
The Next Next Story...

19. How Thin is Thin? Effective Story Slicing
19
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!)

20. How Thin is Thin? Effective Story Slicing
20
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

21. How Thin is Thin? Effective Story Slicing
21
The Stories Continue...

22. How Thin is Thin? Effective Story Slicing
22
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

23. How Thin is Thin? Effective Story Slicing
23
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

24. How Thin is Thin? Effective Story Slicing
24
Let’s Skip Ahead A Bit…

25. How Thin is Thin? Effective Story Slicing
25
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

26. How Thin is Thin? Effective Story Slicing
26
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

27. How Thin is Thin? Effective Story Slicing
27
Ahead even further…

28. How Thin is Thin? Effective Story Slicing
28
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

29. How Thin is Thin? Effective Story Slicing
29
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

30. How Thin is Thin? Effective Story Slicing
30
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

31. How Thin is Thin? Effective Story Slicing
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
31

32. How Thin is Thin? Effective Story Slicing
32
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)
33
•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

34. How Thin is Thin? Effective Story Slicing
• 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)
34

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
35
• Questions about the session? Contact me at dave@daverooney.ca
• Interested in changing the world of video? We’re hiring at You.i TV!