Learn how to provide a powerful command line interface to your JVM with CRaSH the shell for the Java Platform. CRaSH is an open source shell for extending and monitoring a Java Virtual Machine. The shell can be accessed by various means, either remotely using network protocols such as SSH or locally by attaching a shell to a running virtual machine. Commands are written in the Groovy language and can be developed live making the extensibility of the shell easy with quick development cycles. CRaSH comes with a bunch of commands such as thread management, log management, database access and JMX. The session will begin with an introduction to the shell, showing basic CRaSH features like auto completion and basic commands. The main part of the quickie will focus on showing how to develop CRaSH commands with several examples, showing how easy and powerful the development of a command can be. The target audience is pretty much anyone using a JVM. Attendees will learn how to install CRaSH, connect to an instance and develop a CRaSH command to interact with virtual machine resources or services.

1. CRaSH
TH E SH EL L FOR TH E J AVA PL ATFOR M
S E P T E M B E R 2 0 1 3
@julienviet
@defrancea

2. www.exoplatform.com - Copyright 2012 eXo Platform 2
JULIEN VIET
− Contact
− julien@julienviet.com
− @julienviet
− http://github.com/vietj
− Open source for 10 years
− Official mission: deliver enterprise grade portal
server
− Marseille JUG Leader
− Involved in Java Community Process

3. www.exoplatform.com - Copyright 2012 eXo Platform 3
WHAT IS EXO PLATFORM?
eXo Platform is an open
source social collaboration
software solution designed
for the Enterprise.
It is full featured, standard
based, extensible and has
an amazing design.
eXo Platform is featured in
Gartner's Magic Quadrant
for Horizontal Portal
Products 2012 as a User
eXperience Platform.

4. www.exoplatform.com - Copyright 2012 eXo Platform 4
ALAIN DEFRANCE
− Contact
− defrancea@gmail.com
− @alaindefrance
− http://github.com/defrancea
− Open source for 3 years
− Contributed to open source projects like
Crash
− Marseille JUG Leader

5. www.exoplatform.com - Copyright 2012 eXo Platform 5
BITTITAN
− SAAS Products
− MigrationWiz: Email migration
− SMTPLogic: SMTP gateway
− UserActivation: Easy onboarding to Office365
− Our blog
− http://blog.bittitan.com

6. www.exoplatform.com - Copyright 2012 eXo Platform 6
CRASH PROJECT
− Latest stable 1.2
− Work in progress 1.3
− Licensed under LGPL
− Compatibility
− Java 6+
− Groovy 1.7+

7. www.exoplatform.com - Copyright 2012 eXo Platform 7
KEY CONCEPTS
− Command Line Interface for JVM
− Create easily and quickly commands
− Compose commands into pipelines
− Connectors provide local or remote access

8. www.exoplatform.com - Copyright 2012 eXo Platform 8
MODULAR DESIGN
− Core, connectors, plugins
− Only use what you need
− Memory
− Dependencies

9. www.exoplatform.com - Copyright 2012 eXo Platform 9
CONNECTORS
− Defines shell interactions
− Asynchronous design
− Implemented by
− System.in / System.out
− Telnet
− SSH
− Web
− Attach

10. www.exoplatform.com - Copyright 2012 eXo Platform 10
PLUGIN ARCHITECTURE
− Keep core small and lightweight
− New features without impacting core
− Current plugins
− Authentication: simple, jaas, key, crowd, …
− Languages: java, groovy, ruby, …
− Services: mail, cron, …

11. www.exoplatform.com - Copyright 2012 eXo Platform 11
USER INTERFACE
− Interactive Real-Eval-Print-Loop
− SSH asynchronous execution
− Cron based execution (1.3)

12. www.exoplatform.com - Copyright 2012 eXo Platform 12
POLYGLOT
− Leverage polyglot JVM ecosystem
− Groovy
− Commands
− REPL (1.3)
− Java
− Commands (1.3)
− Ruby work in progress

13. www.exoplatform.com - Copyright 2012 eXo Platform 13
EXECUTION MODES
− Standalone
− Attach to a running JVM
− Embedded
− Servlet listener
− Spring
− Guice
− Grails
− VisualVM

14. www.exoplatform.com - Copyright 2012 eXo Platform 14
BASE COMMANDS
− Covers JVM packages
− system
− jdbc
− jndi
− jmx
− Utilities: filter, sort, egrep, sleep

15. www.exoplatform.com - Copyright 2012 eXo Platform 15
STANDALONE DEMO

16. www.exoplatform.com - Copyright 2012 eXo Platform 16
JNDI/JDBC/JPA
ATTACH
DEMO

17. www.exoplatform.com - Copyright 2012 eXo Platform 17
WRITING A COMMAND
public class mycommand {
@Command
@Usage(“the command”)
public void main(
@Usage(“foo option”)
@Option(names=[ “foo”]) String foo,
@Usage(“command arguments”)
@Argument List<String> args) {
…
}
}
% mycommand –foo the_option value1 value2

18. www.exoplatform.com - Copyright 2012 eXo Platform 18
EMBEDDED
− Trivial to embed
− Programmatic
− Spring
− Guice
− Servlet listener
− Levels
− Embed
− Virtual file system

19. www.exoplatform.com - Copyright 2012 eXo Platform 19
EMBEDDED BY

20. www.exoplatform.com - Copyright 2012 eXo Platform 20
SPRING EMDEDDED
TWITTER COMMAND
DEMO

21. www.exoplatform.com - Copyright 2012 eXo Platform 21
GIT LIKE COMMAND
public class git {
@Command
public void add(…) {…}
@Command
public void commit(…) {…}
…
}
% git add .
% git commit –m “feature implemented”

22. www.exoplatform.com - Copyright 2012 eXo Platform 22
TYPES
− String, primitive types, enums
− Converter
− properties, jmx object name …
− Completer
− java.io.File
− system property name
− enums
− …

23. www.exoplatform.com - Copyright 2012 eXo Platform 23
COMMAND PIPE
jmx find
ObjectName Map
jmx get sort

24. www.exoplatform.com - Copyright 2012 eXo Platform 24
COMMAND PIPE
public class wc {
@Command
public PipeCommand<String, Integer>) main() {
return new PipeCommand<String, Integer>() {
int count = 0;
public void provide(String s) {
count += s.split(“n”).length;
}
public void close() {
context.provide(count);
}
}
}
}

25. www.exoplatform.com - Copyright 2012 eXo Platform 25
JMX PIPE
DEMO

26. www.exoplatform.com - Copyright 2012 eXo Platform 26
MAIL/CRON
DEMO

27. www.exoplatform.com - Copyright 2012 eXo Platform 27
READ-EVAL-PRINT-LOOP
− Feature of 1.3
− Polyglot

28. www.exoplatform.com - Copyright 2012 eXo Platform 28
REPL
DEMO

29. www.exoplatform.com - Copyright 2012 eXo Platform 29
WRAP UP
− A multi facet, powerful and extensible tool
for all of us
− Try online : try.crashub.org
− Reach us at
− crashub.org
− @crashub
− crash-users@googlegroups.com