CRaSH is the shell for the Java Virtual Machine

2. An extensible command line for
the JVM
Julien Viet Alain Defrance
Senior software engineer Software engineer
eXo Platform eXo Platform
@julienviet @alaindefrance

3. @julienviet @alaindefrance
10 years of Open Source 2 years of Open Source
■ eXo Platform 2008 ■ eXo Platform 2010
■ Red Hat 2006 Various
■ JBoss 2002 ■ Develop social product
Various
■ Portal stuff (JBoss / GateIn)
■ JCP a while ago
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4. Project
 Open source LGPL: http://www.crashub.org
 CRaSH 1.0 – April 2012
 CRaSH 1.1 – August 2012
 CRaSH 1.2 – Soon (in release candidate)

5. What/Why?
CLI are still relevant
Ubiquitous
Expressive: find . -name “*.java” -exec grep julien {} ; -
print
Made for us 
Trends: NoSQL, MS Powershell, Drupal, Jenkins, Cloud,
etc…
Fun!

6. Comparison with UN*X shell
Same client interface But hosted by JVM
■ History ■ Java threads
■ Completion ■ JVM access
■ Command Line Editing
■ Options & Arguments
■ Pipes
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7. Usage
Runtime modes Get it from
■ Standalone ■ crashub download
■ Embedded (web app, Spring, ■ Maven Central dependency
…)
■ Attach
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8. Simple stack
Native Client
SSH Telnet Web Console Attach VisualVM
Connectors
CRaSH
Groovy Commands

9. What you can do with CRaSH
 Swiss army knife
 Embed in your runtime
 Create your commands
 Monitoring tool
 Scripting
 And more…

10. Out of the box

11. Out of the box
 Install CRaSH
 Run CRaSH standalone
 CLI basics
 JVM base commands
 Test it online

12. The Swiss Knife

13. The Swiss Knife
 Attach CRaSH to JBoss Application Server
 Execute commands in the Application Server

14. Extend your runtime

15. Extend your runtime
 Embed CRaSH in a Spring web application
 Connect using remote protocol
 Develop a command to access Spring beans
 Add options and arguments to the command

16. Monitoring

17. Monitoring
 Attach to Tomcat with VisualVM
 Use JMX command pipes
 Create pipes
 Assemble in custom dashboard

18. Pipelined object stream
jmx
jmx get sort
find
<Void, ObjectName> <ObjectName, Map> <Map, Map>

19. Wrap up
Multi facet, powerful and extensible
Reach us
crash-users@googlegroups.com
@crashub
http://www.crashub.org
Hackergarten hands on coding Tuesday

20. Q&A