Protocol-Oriented Programming in Networking

PROTOCOL-ORIENTED
PROGRAMMING
IN NETWORKING
ISHKAWA

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ISHKAWA?

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OVERVIEW
PROTOCOL-ORIENTED PROGRAMMING IN NETWORKING
1. Wrapping NSURLSession using protocols
2. Generic programming on the protocols
3. Combination with RxSwift

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TOPIC 1
Wrapping NSURLSession using protocols
To make call-site code simpler
To get responses type-safely

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GOAL

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GOAL
l
e
t r
e
q
u
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s
t = R
e
q
u
e
s
t
(
)
S
e
s
s
i
o
n
.
s
e
n
d
R
e
q
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e
s
t
(
r
e
q
u
e
s
t
) { r
e
s
u
l
t i
n
/
/ r
e
s
u
l
t
: R
e
s
u
l
t
<
R
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q
u
e
s
t
.
R
e
s
p
o
n
s
e
, E
r
r
o
r
>
}

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GOAL
l
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t r
e
q
u
e
s
t = C
r
e
a
t
e
I
s
s
u
e
R
e
q
u
e
s
t
(
r
e
p
o
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i
t
o
r
y
I
D
: 1
2
3
, t
i
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e
: "
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"
)
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.
s
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d
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q
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t
(
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t
) { r
e
s
u
l
t i
n
/
/ r
e
s
u
l
t
: R
e
s
u
l
t

}
l
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t r
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q
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s
t = S
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a
r
c
h
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p
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i
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o
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R
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q
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t
(
q
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y
: "
s
w
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f
t
"
)
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e
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i
o
n
.
s
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n
d
R
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q
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t
(
r
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t
) { r
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s
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l
t i
n
/
/ r
e
s
u
l
t
: R
e
s
u
l
t

, E
r
r
o
r
>
}
The type of result changes depending on the request type

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WHY PROTOCOL?
1. To associate response type with request type
2. To provide flexible default implementation

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ASSOCIATING RESPONSE TYPE
WITH REQUEST TYPE
p
r
o
t
o
c
o
l R
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q
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t
T
y
p
e {
t
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v
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: N
S
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R
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e
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d
: H
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P
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d { g
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v
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: S
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g { g
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S
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: A
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,
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: N
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p
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n
s
e
) t
h
r
o
w
s -
> R
e
s
p
o
n
s
e
}

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WITH REQUEST TYPE
c
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s S
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n {
.
.
.
f
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>
(
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: R
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,
h
a
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: R
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<
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> -
> V
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) {
d
o {
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: N
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)
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)
) /
/ R
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} c
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(
.
F
a
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(
e
r
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)
)
}
}
}

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WITH REQUEST TYPE
l
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t r
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q
u
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s
t = C
r
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a
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I
s
s
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R
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q
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(
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p
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: 1
2
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, t
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: "
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)
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) { r
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/
/ r
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: R
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}
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t = S
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R
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)
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) { r
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/
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: R
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s
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t

, E
r
r
o
r
>
}
The type of result changes depending on the request type

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WHY PROTOCOL?

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PROVIDING DEFAULT IMPLEMENTATION
PART 1: COMMON CONFIGURATIONS
p
r
o
t
o
c
o
l G
i
t
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: R
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}
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v
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(
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:
/
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.
g
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b
.
c
o
m
"
)
!
}
}

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PART 2: PROTOCOL FOR JSON DECODING
s
t
r
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t S
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a
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c
h
R
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p
o
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i
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: G
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t
T
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f
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: A
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,
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: N
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p
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) t
h
r
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> R
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s
p
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n
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e {
g
u
a
r
d l
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i
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t
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a
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b
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? [
[
S
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: A
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l
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e {
t
h
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n
v
a
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O
b
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c
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(
o
b
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c
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)
}
l
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t r
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p
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i
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r
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i
c
t
i
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a
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.
m
a
p { t
r
y R
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p
o
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i
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(
$
0
) }
l
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P
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.
.
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(
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: r
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,
h
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N
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x
t
P
a
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: h
a
s
N
e
x
t
P
a
g
e
)
}

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p
r
o
t
o
c
o
l D
e
c
o
d
a
b
l
e {
s
t
a
t
i
c f
u
n
c d
e
c
o
d
e
(
o
b
j
e
c
t
: A
n
y
O
b
j
e
c
t
) t
h
r
o
w
s -
> S
e
l
f
}

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e
x
t
e
n
s
i
o
n R
e
q
u
e
s
t
T
y
p
e w
h
e
r
e R
e
s
p
o
n
s
e
: D
e
c
o
d
a
b
l
e {
f
u
n
c r
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s
p
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n
s
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F
r
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m
O
b
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c
t
(
o
b
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c
t
: A
n
y
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b
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c
t
,
U
R
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s
p
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: N
S
H
T
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P
U
R
L
R
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s
p
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n
s
e
) t
h
r
o
w
s -
> R
e
s
p
o
n
s
e {
r
e
t
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n R
e
s
p
o
n
s
e
.
d
e
c
o
d
e
(
o
b
j
e
c
t
)
}
}

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s
t
r
u
c
t S
e
a
r
c
h
R
e
p
o
s
i
t
o
r
i
e
s
R
e
q
u
e
s
t
: G
i
t
H
u
b
R
e
q
u
e
s
t
T
y
p
e {
l
e
t q
u
e
r
y
: S
t
r
i
n
g
/
/ M
A
R
K
: R
e
q
u
e
s
t
T
y
p
e
t
y
p
e
a
l
i
a
s R
e
s
p
o
n
s
e = P
a
g
i
n
a
t
i
o
n
R
e
s
p
o
n
s
e
<
R
e
p
o
s
i
t
o
r
y
>
v
a
r m
e
t
h
o
d
: H
T
T
P
M
e
t
h
o
d { r
e
t
u
r
n .
G
E
T }
v
a
r p
a
t
h
: S
t
r
i
n
g { r
e
t
u
r
n "
/
s
e
a
r
c
h
/
r
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p
o
s
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t
o
r
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" }
v
a
r p
a
r
a
m
e
t
e
r
s
: A
n
y
O
b
j
e
c
t { r
e
t
u
r
n [
"
q
"
: q
u
e
r
y
] }
}

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WHY PROTOCOL?
Simpler and safer call-site
Documentation-like request definition

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LINKS
APIKit:
RequestType, Session, etc.
Himotoki:
Decodable, etc.
https://github.com/ishkawa/APIKit
https://github.com/ikesyo/Himotoki

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TOPIC 2
Practical example of generic programming on protocols
Example: Pagination

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PAGINATION REQUEST
c
u
r
l -
v h
t
t
p
s
:
/
/
a
p
i
.
g
i
t
h
u
b
.
c
o
m
/
s
e
a
r
c
h
/
r
e
p
o
s
i
t
o
r
i
e
s
?
q
=
s
w
i
f
t
&
p
a
g
e
=
1

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PAGINATION REQUEST
p
r
o
t
o
c
o
l P
a
g
i
n
a
t
i
o
n
R
e
q
u
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s
t
T
y
p
e
: R
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q
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s
t
T
y
p
e {
t
y
p
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a
l
i
a
s R
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p
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s
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: P
a
g
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n
a
t
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n
R
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p
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T
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v
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: I
n
t { g
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f
u
n
c r
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q
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s
t
W
i
t
h
P
a
g
e
(
p
a
g
e
: I
n
t
) -
> S
e
l
f
}

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PAGINATION RESPONSE
H
T
T
P
/
1
.
1 2
0
0 O
K
S
e
r
v
e
r
: G
i
t
H
u
b
.
c
o
m
C
o
n
t
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n
t
-
T
y
p
e
: a
p
p
l
i
c
a
t
i
o
n
/
j
s
o
n
; c
h
a
r
s
e
t
=
u
t
f
-
8
L
i
n
k
: <
h
t
t
p
s
:
/
/
a
p
i
.
g
i
t
h
u
b
.
c
o
m
/
.
.
.
>
; r
e
l
=
"
n
e
x
t
"
{
"
t
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t
a
l
_
c
o
u
n
t
"
: 3
8
2
6
2
,
"
i
n
c
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m
p
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t
e
_
r
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s
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t
s
"
: f
a
l
s
e
,
"
i
t
e
m
s
"
: [
.
.
.
]
}

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PAGINATION RESPONSE
p
r
o
t
o
c
o
l P
a
g
i
n
a
t
i
o
n
R
e
s
p
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n
s
e
T
y
p
e {
t
y
p
e
a
l
i
a
s E
l
e
m
e
n
t
: D
e
c
o
d
a
b
l
e
v
a
r e
l
e
m
e
n
t
s
: [
E
l
e
m
e
n
t
] { g
e
t }
v
a
r h
a
s
N
e
x
t
P
a
g
e
: B
o
o
l { g
e
t }
}

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PAGINATION CLIENT
c
l
a
s
s P
a
g
i
n
a
t
i
o
n
C
l
i
e
n
t
<
R
e
q
u
e
s
t
: P
a
g
i
n
a
t
i
o
n
R
e
q
u
e
s
t
T
y
p
e
> {
l
e
t b
a
s
e
R
e
q
u
e
s
t
: R
e
q
u
e
s
t
l
e
t u
p
d
a
t
e
H
a
n
d
l
e
r
: V
o
i
d -
> V
o
i
d
i
n
i
t
(
b
a
s
e
R
e
q
u
e
s
t
: R
e
q
u
e
s
t
, u
p
d
a
t
e
H
a
n
d
l
e
r
: V
o
i
d -
> V
o
i
d
) { .
.
. }
v
a
r e
l
e
m
e
n
t
s
: [
R
e
q
u
e
s
t
.
R
e
s
p
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n
s
e
.
E
l
e
m
e
n
t
]
v
a
r h
a
s
N
e
x
t
P
a
g
e
: B
o
o
l
v
a
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PAGINATION CLIENT
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GENERIC PROGRAMMING ON PROTOCOLS
More type constraints,
more detailed implementation

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TOPIC 3
Advanced example with reactive streams

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RXPAGINATION

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PAGINATION VM WITH RXSWIFT
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}

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LIVE!

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STEPS TO IMPLEMENT PAGINATION
Give a base request to ViewModel
Bind input and output streams

View Slide

CONCLUSION
PROTOCOL-ORIENTED IN NETWORKING
1. Protocol is a good choice for abstraction of networking
2. More type constraints, more detailed implementation
3. Abstraction of event stream is also nice

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TRY! POP

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Protocol-Oriented Programming in Networking

Protocol-Oriented Programming in Networking

Yosuke Ishikawa

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