Appengine ja-night-10

Mirah & Dubious Tuesday, August 31, 2010

Mirah & Dubious A bold and beautiful way to write Java, plus a new framework for App Engine Charles Nutter John Woodell Aug 30, 2010 2 Tuesday, August 31, 2010

Mirah A pragmatic blend of Ruby and Java Tuesday, August 31, 2010

Me • Charles Oliver Nutter • Engine Yard, Inc • headius@headius.com • @headius • JRuby core developer • Mirah creator Tuesday, August 31, 2010

Ruby • Beautiful language • Clean syntax • Easy-to-use closures • Nice core libraries • “Slow” language • Very dynamic == hard to optimize Tuesday, August 31, 2010

Java • High-performance language • Mostly static typing • Full system optimizations • Primitive math operations • Ugly language • (C++)-- of 1995 Tuesday, August 31, 2010

Mirah • “Apparent features” of Ruby • Syntax • Closures and iterators • Dynamic-feeling behaviors • Performance, typing like Java • As fast as Java for almost everything Tuesday, August 31, 2010

What If This... public class Foo { private int a; public Foo(int a) { this.a = a; } public void show() { System.out.println(a); } } Tuesday, August 31, 2010

...Could Be This class Foo def initialize(a) @a = a end def show puts @a end end Tuesday, August 31, 2010

Mirah class Foo def initialize(a:int) @a = a end def show puts @a end end Tuesday, August 31, 2010

“Java’s Ruby” • A nicer way to write Java • Ruby syntax with modiﬁcations • Feels like Ruby • Compiles to Java/JVM • No runtime library Tuesday, August 31, 2010

Features From Ruby • Optional arguments ✓ • Internal iteration ✓ • Closures ✓ • Literals ✓ • String interpolation ✓ • Mixins, “open” classes (soon) Tuesday, August 31, 2010

Features From X • (Coming Soon) • Extension methods (C#ish, but nicer) • Implicit type conversions (Scala) • Pattern matching? • Case classes? Tuesday, August 31, 2010

Ruby puts “Hello, world!” Tuesday, August 31, 2010

Mirah puts “Hello, world!” Tuesday, August 31, 2010

Mirah // Generated from DashE public class DashE extends java.lang.Object { public static void main(java.lang.String[] argv) { java.io.PrintStream temp$1 = java.lang.System.out; temp$1.println("Hello, world!"); } } Tuesday, August 31, 2010

Ruby def fib(a) if a < 2 a else fib(a - 1) + fib(a - 2) end end Tuesday, August 31, 2010

Mirah def fib(a:int) if a < 2 a else fib(a - 1) + fib(a - 2) end end Tuesday, August 31, 2010

Mirah // Generated from DashE public class DashE extends java.lang.Object { public static void main(java.lang.String[] argv) { } public static int fib(int a) { return (a < 2) ? (a) : ((DashE.fib((a - 1)) + DashE.fib((a - 2)))); } } Tuesday, August 31, 2010

Ruby def foo(a = 1, b = 2) puts a + b end Tuesday, August 31, 2010

Mirah def foo(a:int = 1, b:int = 2) puts a + b end Tuesday, August 31, 2010

Mirah public static java.io.PrintStream foo(int a, int b) { java.io.PrintStream temp$1 = java.lang.System.out; temp$1.println((a + b)); return temp$1; } public static java.io.PrintStream foo() { return foo(1); } public static java.io.PrintStream foo(int a) { return foo(a, 2); } Tuesday, August 31, 2010

Ruby a = [5,4,3,2,1] a.each do |x| puts x end Tuesday, August 31, 2010

Mirah a = [5,4,3,2,1] a.each do |x| puts x end Tuesday, August 31, 2010

Mirah // Generated from DashE public class DashE extends java.lang.Object { public static void main(java.lang.String[] argv) { java.util.List a = java.util.Collections.unmodifiableList( java.util.Arrays.asList(1, 2, 3, 4, 5)); java.util.Iterator __xform_tmp_1 = a.iterator(); label1: while (__xform_tmp_1.hasNext()) { java.lang.Object x = __xform_tmp_1.next(); label2: { java.io.PrintStream temp$3 = java.lang.System.out; temp$3.println(x); } } } } Tuesday, August 31, 2010

Ruby t = Thread.new do puts “in thread” end Tuesday, August 31, 2010

Mirah t = Thread.new do puts “in thread” end Tuesday, August 31, 2010

// Generated from DashE Mirah public class DashE extends java.lang.Object { public static void main(java.lang.String[] argv) { DashE.__xform_tmp_1 $binding = new DashE.__xform_tmp_1(); $binding.x = "in thread"; java.lang.Thread t = new java.lang.Thread(new DashE.__xform_tmp_2($binding)); } public static class __xform_tmp_1 extends java.lang.Object { java.lang.String x; } public static class __xform_tmp_2 extends java.lang.Object implements java.lang.Runnable { private DashE.__xform_tmp_1 binding; public __xform_tmp_2(DashE.__xform_tmp_1 binding) { this.binding = binding; } public void run() { DashE.__xform_tmp_1 $binding = this.binding; java.io.PrintStream temp$1 = java.lang.System.out; temp$1.println($binding.x); } } } Tuesday, August 31, 2010

Open Class (proposal) interface StringFunc def apply(str:String) end extend class String # java.lang.String def each(func:StringFunc) # String#split call from Java lines = split # like “for (String str: strArray)” lines.each do |str| func.apply(str) end end end Tuesday, August 31, 2010

Open Class (Java side) public interface StringFunc { public void apply(String str); } public class StringExtension { public void each(String str, StringFunc func) { for (String s: str.split()) { func.apply(str); } } } Tuesday, August 31, 2010

Open Class (usage) str = “hellongoodbyenworld” str.each {|s| ... } Tuesday, August 31, 2010

Open Class (Java usage) String str = “hellongoodbyenworld”; StringExtension.each(str, new StringFunc() { public void apply(String s) { ... } }); Tuesday, August 31, 2010

Open Class (Java usage) String str = “hellongoodbyenworld”; StringExtension.each(str, new StringFunc() { public void apply(String s) { ... YUCK! } }); Tuesday, August 31, 2010

Type Conversion str = “hellongoodbyenworld” # no “map” method on String... str.map {|s| # ERROR Tuesday, August 31, 2010

Type Conversion (by hand) str = “hellongoodbyenworld” # without type conversion Arrays.asList(str.split).map { ... Tuesday, August 31, 2010

Type Conversion (proposal) conversion(String => List) do |str| Arrays.asList(str.split) end conversion(List => String) do |list| list.join(‘n’) end Tuesday, August 31, 2010

Type Conversion (usage) str = “hellongoodbyenworld” # with type conversion! str.map { ... # OK!! Tuesday, August 31, 2010

It’s Not Ruby • Using Java’s libraries and type system • No “eval” • No runtime-mutable classes • Ruby libraries will not work Tuesday, August 31, 2010

But It Feels Like Ruby! • Clean, lightweight syntax • Iteration, closures • Far less “ceremony” than Java • Performance equivalent to Java Tuesday, August 31, 2010

mirah.org Tuesday, August 31, 2010

Tuesday, August 31, 2010

Dubious Dubious Mirah Web Tuesday, August 31, 2010

Me • John Woodell • Web developer at Google • Dubious creator • App Engine JRuby maintainer • @JohnWoodell Tuesday, August 31, 2010

Thank you for using "AppEngine/Java” "AppEngine/Java" 47 Tuesday, August 31, 2010

Spin-up time can make scaling “painful” • The most critical issue to be resolved is spin-up time, App Engine scales by adding new application instances. • Even if initialization could happen without affecting users some apps will need to scale instantly. 48 Tuesday, August 31, 2010

Spin-up? Yes, this is a problem... 49 Tuesday, August 31, 2010

...but now you can use Mirah and Dubious "Mirah/Dubious" 50 Tuesday, August 31, 2010

Dubious is Web framework for Mirah Dubious Mirah Web *du bi ous[ djbis | dj- ] [ ] [1] (( )) … ((of, about, as to ...)). [2] > 51 Tuesday, August 31, 2010

Write Rails-style code, it runs on Google App Engine GoogleAppEngine Rails 52 Tuesday, August 31, 2010

Benefits of Mirah on App Engine • Ruby syntax & apparent features + Java type system • Use Java or Ruby when Mirah lacks features you require • The generated Java source can be inspected at any time • Macros and plugins can be written in Ruby or Mirah • New instances always spin-up in about a second 53 Tuesday, August 31, 2010

Working with Dubious • Dubious framework uses familiar Rails conventions • Generate JSONs or work with ERb templates • MirahModel syntax is similar to DataMapper • Developers can create apps entirely in Rails, then refactor URLs that need to scale quickly • Some important features are currently missing, but “you” could have fun contributing them 54 Tuesday, August 31, 2010

Here’s code from Dubious (this is not Rails) Rails Dubious 55 Tuesday, August 31, 2010

Dubious controllers will be familiar Tuesday, August 31, 2010

Mirah can use ERb templates Tuesday, August 31, 2010

The generated Java source can be inspected Tuesday, August 31, 2010

The ERb is transformed into method calls Tuesday, August 31, 2010

Your model definition is very concise Tuesday, August 31, 2010

Code generation based on defined properties Tuesday, August 31, 2010

All the basic methods you need are generated Tuesday, August 31, 2010

It really works, and spins-up in ~1sec Spinup. 63 Tuesday, August 31, 2010

It isn’t "Dubious" http://dubious-demo.appspot.com 64 Tuesday, August 31, 2010

The Framework (coding in Mirah) Tuesday, August 31, 2010

Method signatures enforce types Tuesday, August 31, 2010

Return type can be enforced also Tuesday, August 31, 2010

Code is very concise Tuesday, August 31, 2010

Thank You Tuesday, August 31, 2010

Appengine ja-night-10

by John Woodell on Aug 30, 2010

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