InterConnect: Server Side Swift for Java Developers

InterConnect
2017
6190:
Server-Side Swift:
An Introduction for Java EE Developers
Chris Bailey 
STSM, Technical Architect
Java, Node.js and Swift at IBM
Stephan Knitelius,
Senior Consultant 
Faktor Zhen AG

Swift Programming
Safe | Expressive | Fast

print("Hello, world!")
Swift: Hello World

> swift main.swift
Swift: Hello World

> swift main.swift
> main
Swift: Hello World

> swift main.swift
> main
"Hello, world!"
Swift: Hello World

let event = ”InterConnect"
print("Hello, (event)”)
Swift: Hello World

> swift main.swift
Swift: Hello World

> swift main.swift
> main
"Hello, InterConnect"
Swift: Hello World

let event = "InterConnect"
event = "Somewhere else"
Swift: Hello World

> swift main.swift
Swift: Hello World

> swift main.swift
error: cannot assign to value: 'event' is a 'let' constant
Swift: Hello World

var event = "InterConnect"
Swift: Hello World

> swift main.swift
Swift: Hello World

> swift main.swift
> main
"Hello, Somewhere else"
Swift: Hello World

func addInts(a: Int, b: Int) -> Int {
return a + b
}
Swift: Functions

func addInts(a: Int, b: Int) -> Int {
return a + b
}
addInts(a: 1, b: 3)
Swift: Functions

func addInts(_ a: Int, _ b: Int) -> Int {
return a + b
}
Swift: Functions

func addInts(_ a: Int, _ b: Int) -> Int {
return a + b
}
addInts(1, 3)
Swift: Functions

func move(from start: Point, to end: Point) -> Bool {
/* code */
}
Swift: Functions

func move(from start: Point, to end: Point) -> Bool {
/* code */
}
move(from: a, to: b)
Swift: Functions

func minAndMax(numbers: Int...) -> (min: Int, max: Int) {
}
Swift: Functions and Tuples

var min = numbers[0]
var max = numbers[0]
for number in numbers {
if number > max {
max = number
} else if number < min {
min = number
}
}
return (min, max)
}
Swift: Functions and Tuples

if number > max {
max = number
min = number
}
}
return (min, max)
}
let result = minAndMax(1, 2, 3, 4, 5)
Swift: Functions: Varargs and Tuples

if number > max {
max = number
min = number
}
}
return (min, max)
}
let result = minAndMax(1, 2, 3, 4, 5)
print(result.min)
print(result.max)
Swift: Functions: Varargs and Tuples

let expenseCosts = [34.4, 30.99, 250.0]
var sum: Double = 0
for expense in expenseCosts {
sum += expense
}
print("total cost is (sum)")
Swift: Loops and Iterators

let flavour = "Vanilla"
switch flavour {
case "Chocolate":
print("Quite nice")
case "Strawberry", "Rum'n'raisin":
print("Very nice")
case let str where str.hasPrefix("Mint"):
print("UGH!!!, I hate (str)")
default:
print("No opinion about this")
}
Swift: Switch Statements

switch flavour {
case "Chocolate":
print("Quite nice")
print("Very nice")
default:
}
> swiftc main.swift
> main

switch flavour {
case "Chocolate":
print("Quite nice")
print("Very nice")
default:
}
> swiftc main.swift
> main
"No opinion about this"

let flavour = "Mint Chocolate"
switch flavour {
case "Chocolate":
print("Quite nice")
print("Very nice")
default:
}

let flavour = "Mint Chocolate" 
switch flavour {
case "Chocolate":
print("Quite nice")
print("Very nice")
default:
}
> swiftc main.swift
> main

let flavour = "Mint Chocolate" 
switch flavour {
case "Chocolate":
print("Quite nice")
print("Very nice")
default:
}
> swiftc main.swift
> main
"UGH!!!, I hate Mint Chocolate"

let numbers = [1, 2, 3]
numbers.map({
(number: Int) -> Int in
return number * 5
})
// [5, 10, 15]
numbers.map({
number in number * 5
})
numbers.map { $0 * 5 }
Swift: Closures

class Square {
var area: Double = 0
init(sideLength: Double) {
self.sideLength = sideLength
}
var sideLength: Double {
get {
return sqrt(area)
}
set {
area = newValue * newValue
}
}
}
Swift: Classes

struct Point {
var x: Int
var y: Int
func description() -> String {
return "x=(x), y=(y)"
}
}
var coord = Point(x: 2, y: 4)
var newCoord = coord
coord.x = 4
print(coord.description()) // x=4, y=4
print(newCoord.description()) // x=2, y=4
Swift: Structs

enum ApprovalStatus {
case PendingOn(String)
case Denied 
case Approved(String)
}
var status = ApprovalStatus.PendingOn("Joe Bloggs")
status = .Approved("13213-4341321-2")
switch status {
case .PendingOn(let approver):
print("Request pending on approval from (approver)")
case .Denied:
print("Request DENIED")
case .Approved(let code):
print("Request approved - auth code (code)")
}
Swift: Enums

a queue - FIFO
put task into queue
to execute
dequeued tasks
are being executed
in wai8ng
Serial or Concurrent
FIFO Queue
Waiting Tasks
Tasks Added 
To Queue
Tasks Removed 
For Execution

a queue - FIFO
put task into queue
to execute
dequeued tasks
are being executed
in wai8ng
FIFO Queue
Waiting Tasks
Tasks Added 
To Queue
Tasks Removed 
For Execution
import Dispatch
let serialQueue = DispatchQueue(label: "serial queue")

a queue - FIFO
put task into queue
to execute
dequeued tasks
are being executed
in wai8ng
FIFO Queue
Waiting Tasks
Tasks Added 
To Queue
Tasks Removed 
For Execution
import Dispatch
let serialQueue = DispatchQueue(label: "serial queue")
serialQueue.async {
print("run on serial queue")
}
serialQueue.asyncAfter(deadline: .now() + DispatchTimeInterval.seconds(1)) {
print("run on serial queue")
}

a queue - FIFO
put task into queue
to execute
dequeued tasks
are being executed
in wai8ng
FIFO Queue
Waiting Tasks
Tasks Added 
To Queue
Tasks Removed 
For Execution
import Dispatch
let concurrentQueue = DispatchQueue(label: "concurrent queue", attributes: .concurrent)
concurrentQueue.async {
print("run on concurrent queue")
}

a queue - FIFO
put task into queue
to execute
dequeued tasks
are being executed
in wai8ng
FIFO Queue
Waiting Tasks
Tasks Added 
To Queue
Tasks Removed 
For Execution
import Dispatch
let queue = DispatchQueue(label: "group queue", attributes: .concurrent)
let group = DispatchGroup()

a queue - FIFO
put task into queue
to execute
dequeued tasks
are being executed
in wai8ng
FIFO Queue
Waiting Tasks
Tasks Added 
To Queue
Tasks Removed 
For Execution
import Dispatch
queue.async(group: group) {
print("work 1")
}
print("work 2")
}

a queue - FIFO
put task into queue
to execute
dequeued tasks
are being executed
in wai8ng
FIFO Queue
Waiting Tasks
Tasks Added 
To Queue
Tasks Removed 
For Execution
import Dispatch
print("work 1")
}
print("work 2")
}
group.notify(queue: queue) {
print("all work completed")
}

Swift @ IBM
public class Test {
private static void length (String string){
System.out.println(string.length());
}
public static void main(String[] args){
String string = null;
length(string);
}
}
SwiftJava

Swift @ IBM
func length(of string: String) -> Void {
print(string.characters.count)
}
var str: String? = nil
length(of: str)
public class Test {
}
length(string);
}
}
SwiftJava

Swift @ IBM
}
length(of: str)
> swiftc main.swift
public class Test {
}
length(string);
}
}
> javac Test.java
SwiftJava

Swift @ IBM
}
length(of: str)
> swiftc main.swift
public class Test {
}
length(string);
}
}
> javac Test.java
>
SwiftJava

Swift @ IBM
}
length(of: str)
> swiftc main.swift
> Error line 7: Value of optional type
‘String?’ not unwrapped;
> did you mean to use ‘!’ or ‘?’?
public class Test {
}
length(string);
}
}
> javac Test.java
>
SwiftJava

Swift @ IBM
}
length(of: str)
> swiftc main.swift
public class Test {
}
length(string);
}
}
> javac Test.java
> java Test
SwiftJava

Swift @ IBM
}
length(of: str)
> swiftc main.swift
public class Test {
}
length(string);
}
}
> javac Test.java
> java Test
Exception in thread "main"
java.lang.NullPointerException
at Test.length(Test.java:5)
at Test.main(Test.java:11)
SwiftJava

var optionalString: String? = nil
var string: String = optionalString
Swift: Structs

> swiftc main.swift
Swift: Structs

> swiftc main.swift
error: value of optional type 'String?' not unwrapped; did you mean to use '!'
or ‘?'?
^
Swift: Structs

var string: String = optionalString!
Swift: Structs

> swiftc main.swift
Swift: Structs

> swiftc main.swift
> main
Swift: Structs

> swiftc main.swift
> main
fatal error: unexpectedly found nil while unwrapping an Optional value
Swift: Structs

guard var string: String = optionalString else {
print(‘Error! Null string found’)
}
Swift: Structs

}
> swiftc main.swift
Swift: Structs

}
> swiftc main.swift
> main
“Error! Null string found”
Swift: Structs

Swift @ IBM
public class Test {
private static int length (String string){
return(string.length());
}
length(string);
}
}
SwiftJava

Swift @ IBM
func length(of string: String) -> Int {
return(string.characters.count)
}
var str: String = ”MyString”
length(of: str)
public class Test {
}
length(string);
}
}
SwiftJava

Swift @ IBM
}
length(of: str)
> swiftc main.swift
public class Test {
}
length(string);
}
}
> javac Test.java
SwiftJava

Swift @ IBM
}
length(of: str)
> swiftc main.swift
public class Test {
}
length(string);
}
}
> javac Test.java
>
SwiftJava

Swift @ IBM
}
length(of: str)
> swiftc main.swift
> Warning: result of call to ‘length(of:)’ is
unused
public class Test {
}
length(string);
}
}
> javac Test.java
>
SwiftJava

Swift @ IBM
@discardableResult
}
length(of: str)
> swiftc main.swift
public class Test {
}
length(string);
}
}
> javac Test.java
>
SwiftJava

Swift @ IBM
@discardableResult
}
length(of: str)
> swiftc main.swift
>
public class Test {
}
length(string);
}
}
> javac Test.java
>
SwiftJava

0
2
4
6
8
10
12
14
16
18

Duration(s)
(lowerisbetter)
http://benchmarksgame.alioth.debian.org/u64q/performance.php?test=spectralnorm
Typed vs Untyped Performance

4
0
2
4
6
8
10
12
14
16
18

Duration(s)
(lowerisbetter)

4 4.3
0
2
4
6
8
10
12
14
16
18

Duration(s)
(lowerisbetter)

4 4.3
15.8
0
2
4
6
8
10
12
14
16
18

Duration(s)
(lowerisbetter)

Kitura + Liberty 
Demo
https://github.com/sknitelius/RacketenMessages-Swift
https://github.com/sknitelius/RacketenMessages-Java

94 1/17/17
GATEWAY
PUBLIC NETWORK CLOUD NETWORK
Client Devices Hosted Services
ROUTING PROXY
Micro-ServicesBackend For Frontend 
(BFF)

Bluemix Mobile & Omni-Channel!
BMO-6321: Patterns in Omni-Channel
Cloud Application Development
Containers & Microservices!
BMC-2173: Introduction to Docker
Containers and Microservices
Visit the DevZone in the Concourse for open
Hello World labs and Ask Me Anything booths!
Wednesday, 11:15 AM - 12:00 PM | South Paciﬁc C | Session ID: 6321A
Tuesday, 4:45 PM - 5:30 PM | South Paciﬁc A | Session ID: 2173A
Tuesday, 11:00 AM - 12:45 PM | DevZone Ask Me Anything # 2 | Session ID: 7087A
Ask Me Anything: Bluemix Cloud-Native Development
Ask Me Anything: Server-Side Swift Development
Wednesday, 2:30 PM - 5:00 PM | DevZone Ask Me Anything # 6 | Session ID: 7088A
Node.js & LoopBack
BAP-1117: Introduction to LoopBack
Node.js Framework
Liberty & Microservices
BAP - 5081: Microservices with IBM WebSphere Liberty:
What, Why and When?
Wednesday, 11:15 AM - 12:00 PM | Islander F | Session ID: 1117A
Tuesday, 7:00 PM - 7:20 PM | Engagement Theater Booth #319 | Session ID: 5081A

1/17/17
Please note
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1/17/17
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1/17/17
Notices and disclaimers
continued
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InterConnect: Server Side Swift for Java Developers

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InterConnect: Server Side Swift for Java Developers