Why Don't you Groovy?Engineering Communities

05 May 2016

Orest IvasivSoftware engineer, Softserve

Audience

Java developers

No experience in Groovy

Disclaimer

We will not talk about Groovy language in details

It's not a tutorial

We are not Groovy haters/lovers. We are pragmatic devs

Groovy is not a panacea, Groovy is a hammer

Hipsters are not Groovy (it's 2016)

Problems and Tasks

Java devs should not write scripts in Java

Bash, Python, Ruby, etc.

How to re-use existence Java knowledge in automation tasks

How to choose the right scripting language

How to automate on Windows, Linux and OSX

Why Java is bad for scripting and automation?

Tedious File and Network processing

Tedious collection processing

Tedious XML/JSON processing

Verbose type declaration

Limited DSL support

Painful object construction code

Just too verbose for small tasks

Slow Edit-Compile-Run loop

Scripts vs Tools

Scripts

Run on all major OSs

Easy to distribute

Easy to read and maintain

Reasonably small

Quick Edit-Run cycle

Performance is not important

E.g.

- Bash, Ruby, Python, Node.js, Groovy - Tcl, Lua

Tools

No sources

"Fat" binary

Popular or/and minimal runtime

No runtime - single binary

Very easy to distribute

Low maintenance cost

E.g.

- Java/JVM, Go - C/C++, Python, Node.js

Groovy

JVM language

Java, Scala, Clojure, Groovy, Kotlin

Superb interoperability with Java

Syntax is very similar to Java

All Java libraries can be used in Groovy

Almost all Java code is Groovy code

Groovy language is full of modern features

DSL

Groovy is compiled Language

Groovy is a dynamic language Dynamic != interpreted Interpreted == a runtime interprets an AST Groovy compiles down to JVM bytecode

Language features

Language features

List

Map

GString

GDK

MOP

Builders

Groovy Samples

Launching a Jetty server to serve Groovy templates

@Grapes([ @Grab(group='org.eclipse.jetty.aggregate', module='jetty-server', version='8.1.7.v20120910'), @Grab(group='org.eclipse.jetty.aggregate', module='jetty-servlet', version='8.1.7.v20120910'), @Grab(group='javax.servlet', module='javax.servlet-api', version='3.0.1')]) import org.eclipse.jetty.server.Server import org.eclipse.jetty.servlet.* import groovy.servlet.* def runServer(duration) { def server = new Server(8080) def context = new ServletContextHandler(server, "/", ServletContextHandler.SESSIONS); context.resourceBase = "." context.addServlet(TemplateServlet, "*.gsp") server.start() sleep duration server.stop() } runServer(10000)

What's ugly in Groovy

JVM and Groovy script start time is slow

Limited OS-level scripting (see Python, Ruby)

Groovy is another language. It’s not Java (thanks cap)

Groovy is not well accepted in other communities

Not convenient to use Groovy without IDE

References

Who is Groovy? by Cédric Champeau – history and people behind Groovy language(http://melix.github.io/blog/2015/02/who-is-groovy.html)

Blog about Groovy, Gradle and Grails (http://mrhaki.blogspot.com)

http://groovy-lang.org/ (http://groovy-lang.org/)

Groovy on the Shell (https://www.youtube.com/watch?v=1ogwSsl6EGQ)

Curated list of awesome groovy libraries, frameworks and resourcesy (https://github.com/kdabir/awesome-

groovy)

Thank you

05 May 2016Tags: groovy (#ZgotmplZ)

Orest IvasivSoftware engineer, Softserve@halyph (http://twitter.com/halyph)