Rise of the state machines
Mat Warger
@mwarger
state Management
and more
state Management
state Management
state Management
state Management
state Management
state Management
problems
- Software
- Time
- Users
software
software
is hard
"THIS SHOULD NEVER HAPPEN"
Title Text
Title Text
Title Text
Time
Time
is relative
situation
Reece went back in time too late, Sarah was killed, and John Connor was never born.
result
SKYNET results in JUDGEMENT DAY. DEATH to all humans.
Reece went back just in time, Sarah was saved, and John Connor was born.
SKYNET results in JUDGEMENT DAY. John Connor led the resistance and saved HUMANITY.
situation
result
A user types in their username and password, taps the sign-in button, and then clicks a link to a page.
User is signed in and is routed to the selected page.
A user types in their username and password, clicks a link to a page, and then taps the sign-in button.
User begins navigating and then executes a login action - may the fastest request win!
users
users
Are
U
N
p
R
e
d
i
c
t
a
b
l
e
users
Are
U
N
p
R
e
d
i
c
t
a
b
l
e
your users
your users
USER INPUT
STATE MACHINES
STATE MACHINES
Finite Automata
What are state machines?
- An INITIAL STATE
- A finite number of STATES
- A number of EVENTS
- A TRANSITION function between states
- A FINAL STATE (optional)
What are state machines?
example
example
example
goals of xstate
- Event-based architecture
- Platform and framework-agnostic
- Adherence to the SCXML Specification (including serialization)
- Functional, type-safe*, with zero dependencies
example
INITIAL STATE
Fetch Machine
STATES
EVENTS
example
INITIAL STATE
Fetch Machine
STATES
EVENTS
and TRANSITIONS
Final State
state
state
action
state
event
state
event
+
=
state
event
+
=
state
state
event
+
=
transition
state
event
+
=
something happens
sound familiar?
you're already using them
you're already using them
one
key
Difference
one
state
at a time
what can I do with this?
- State Visualization
-
Animations
- Transitions
- CSS
- Model-based Testing
visualize large workflows
animations
model-based testing
demo
trade-offs and gotchas
everything is a state
(async, "loading", etc)
NO EXCEPTIONS!
Resources
Thank you
@mwarger - Twitter, Github
mw.codes