May 05, 2016 Engineering Communities - Why don't you Groovy? Ref: http://go-talks.appspot.com/github.com/halyph/talks/2016/why_dont_you_groovy.slide

1. Why Don't you Groovy?
Engineering Communities
05 May 2016
Orest Ivasiv
Software engineer, Softserve

2. Audience
Java developers
No experience in Groovy

3. 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)

4. 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

5. 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

6. Scripts vs Tools

7. 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

8. 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

9. 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

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

11. Language features

12. Language features
List
Map
GString
GDK
MOP
Builders

13. Groovy Samples

14. 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)

15. 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

16. 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)

17. Thank you
05 May 2016
Tags: groovy(#ZgotmplZ)
Orest Ivasiv
Software engineer, Softserve
@halyph(http://twitter.com/halyph)