The document discusses several topics related to designing software, including: 1. Legacy code that was written for a specific purpose in the past and may not be well-suited for reuse due to outdated practices, but some assets could potentially be incorporated as services behind a facade. 2. The importance of a user-centered, experience-driven approach where workflows and the user interface are defined based on what users actually want rather than starting with technical considerations. 3. Key aspects of modern software architecture like separating concerns into distinct stacks, using domain-driven design principles, and event-driven architectures.

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Dino Esposito
Designing Software Driven by the Domain

2. Mirror the Business Domain
Domain
Model
Tasks User
Experience

3. User Experience
Architecture Briefs
Task-based design
DDD and Legacy
Code
Key Points

4. Legacy Code
Code that works
Code you don’t
like to have
around
Code you can
hardly get rid of
Not necessarily badly and poorly written code!

5. Has an established and implicit model
Doesn’t typically have a public programmable API
Written to have some work done, not to be reused
Written years ago according to practices now obsolete
Common Aspects of Legacy Code

6.  Rewrite from scratch with all the abstractions you need
 While rewriting consider, incorporating existing assets as services
 Put legacy assets behind a façade and connect it to the core application
Legacy Code as a Service
NEW
System
Legacy Asset #1
Legacy Asset #2
ACL
ACL

7. Not all assets
are equal
• Some can be reused
as services, some not
• Some are just old and
obsolete
Before
integrating
• Evaluate costs of not
rewriting from scratch
• Evaluate costs of
integration
If it can become
a service
• Just let it go
• Focus on other things
to do!
LEGACY CODE

8. All systems are CRUD systems.
CREATE
READ
UPDATE
DELETE
to some extent

9. Quick and easy to write
Unrealistic
C R U D
Database-centric
Not tracking actions
Limited features
• Amount of business logic
• Concurrency
• Dependencies

10. What’s CRUD today?

11. Database-centric
Not tracking actions
Persistence model is just one
model to think about
Context of change must be tracked. An update
can’t simply update overriding the current state
Limited features
Plenty of business logic, concurrency issues,
interconnected entities
C R U D
Graphs of entities
Fill out view models
Log changes
to the state
C U D
R

12. Way too many great ideas have been first sketched
out on the paper napkins of some cafeterias.

13. What users perceive of each application is
what they see and what they get while
interacting with it.
What You See Is What You Get
User Interface User Experience

14. User Experience
The experience that users go
through when they interact with the
application.

15. The Fine Art of Architecting Software
BUSINESS LOGIC BUSINESS LOGIC

16. Bottom up Top-down

17. Bottom-up
Design
Passive users
accepting any UI
enforcements

19. Build up UI forms
as users love
them
Define
workflows from
there
Connect
workflows to
existing biz logic
Sign-off
here
UX-driven Design in 3 Steps

20. Sign off on what users
really want
• Sketches/wireframes
• In some cases, mockups
Build prototypes from
requirements
• Do not start on billable hours
until signed off
In Summary

21. For each screen have a basic flowchart
Determine what comes in and out and create view model classes
Make application layer endpoints receive/return such DTO classes
Make application layer orchestrate tasks on layers down the stack

22. Responsibilities
Information
architecture
Interaction Visual design
Usability
reviews
Tools Balsamiq UXPin
Infragistics
Indigo
JustInMind
The UX Architect

23. Pillars of Modern Software
• Task-based
and starting
from UX
• Distinct
stacks
• Avoid tiers
• Ubiquitous
language
• Bounded
contexts
DDD
Analysis
Layers
Top-
down
design
CQRS +
Events