Deck Title

Golang as a Java Dev

My recent experience's with golang for creating small services
as a replacement for existing Java services at Semantico.

<-

George 'Malcolm' MacRorie

A little background info

"Java Web Developer" for Semantico
Mostly develop in XSLT and XQuery
Have recently been piloting a new role as a maintenance developer

Looking at Golang

"It's a fast, statically typed, compiled language that feels like a dynamically typed,

interpreted language."

Go Docs: http://golang.org/doc/

"Its concurrency mechanisms make it easy to write programs that

get the most out of multicore and networked machines,

while its novel type system enables flexible and modular program construction."

Similarities between Golang and Java

Main Method (+ curly brackets)

public static void main(string[] args) {}

func main() {}

Objects + Class (Struct) Definitions

public class Main {}

type Main struct {}

Interfaces

public interface Service {}

type Service interface {}

For (+ each) loops

for (int i=0; i < 10; i++) {}

for i := 0; i < 10; i++ {}

for (int i:collection) {}

for _, v := range collection {}

new Main();

new(Main)

Differences between Golang and Java

Accessors

public, private, protected

Exported(), notExported()

Hierarchical Inheritance

public Foo extends Bar {}

Ownership

Class Foo {
void Bar() {}
}

type Foo struct{}
func (f *Foo) Bar() {}

Where you place your types (+ argument sugar)

public String foo (int bar) {}

func foo(bar int) string {}

func foo(a, b int) string {}

func foo(bar int) (string, error) {}

func foo(bar int) (s string) {}

While Loops

while(true) {}

N/A

for {}

A glimpse at our architecture

/

Which backend service?

Service A

Service B

Webapp

What we wanted...

New Webapp

Request

We needed a service!

/

Which backend service?

Service A

Service B

Webapp

New Service

or

The solution ...

New Webapp

Request

We're Java Developers
We have a similar implementation packaged into all of our sites
We have the infrastructure in place to deploy java services

It compiles easily and quickly into a command line tool
It's standard libraries come with lots of webby goodness
It mixes interesting programming paradigms (Functional + OO)
Lot's of developers are talking about it! (and we want in)

Golang http libs

Check out: http://golang.org/pkg/net/http/

http.Handle("/foo", fooHandler)

http.HandleFunc("/bar", func(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "Hello, %q", html.EscapeString(r.URL.Path))
})

log.Fatal(http.ListenAndServe(":8080", nil))

s := &http.Server{
	Addr:           ":8080",
	Handler:        myHandler,
	ReadTimeout:    10 * time.Second,
	WriteTimeout:   10 * time.Second,
	MaxHeaderBytes: 1 << 20,
}
log.Fatal(s.ListenAndServe())

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.TimeUnit;

public class Main {

public static void main(String[] args) {

ExecutorService executor = Executors.newFixedThreadPool(2);

int[] vals = new int[]{7, 2, 8, -9, 4, 0};

int[] first = Arrays.copyOfRange(vals, 0, (int)Math.floor(vals.length/2));

int[] second = Arrays.copyOfRange(vals, (int)Math.floor(vals.length/2), vals.length);

ArrayList<Integer> results = new ArrayList<Integer>(2);

executor.execute(new Sum(first, results));

executor.execute(new Sum(second, results));

executor.shutdown();

try {

if (executor.awaitTermination(2l, TimeUnit.MINUTES)) {

System.out.println(String.format("%d, %d, %d", new Integer(results.get(0)), new Integer(results.get(1)), new Integer(results.get(0) + results.get(1))));