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Ruby-Processing and java.lang.ExceptionInInitializerError

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1. rp5 run samples/jwishy.rb   
2. RubyGlobal.java:135:in `createGlobals': java.lang.ExceptionInInitializerError  
3.     from Ruby.java:939:in `init'  
4.     from Ruby.java:172:in `newInstance'  
5.     from Main.java:199:in `run'  
6.     from Main.java:110:in `run'  
7.     from Main.java:94:in `main'  

rp5 run samples/jwishy.rb 
RubyGlobal.java:135:in `createGlobals': java.lang.ExceptionInInitializerError
    from Ruby.java:939:in `init'
    from Ruby.java:172:in `newInstance'
    from Main.java:199:in `run'
    from Main.java:110:in `run'
    from Main.java:94:in `main'

... the culprit was the alternative version of the JRE I was using (OpenJDK). After swtiching to the standard Sun JDK everything worked fine.

Golem Statemachine

Following a frustrating week with the acts_as_state_machine/AASM plugin, I ended up writing my own finite state machine library for Ruby.

It's called Golem, and it's now on Github, here: http://github.com/zuk/golem_statemachine/tree/master

The code is cleaner than AASM's (or at least I think so), which should make debugging less frustrating. There's also a nice DSL for defining the state machine.

For example, to implement this statemachine:

You would define it like so:

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1. define_statemachine do  
2.   initial_state :HUNGRY  
3.   
4.   state :HUNGRY do  
5.     on :eat do  
6.       transition :to => :SATIATED, :if => :likes?  
7.       transition do  
8.         action do |monster|   
9.           puts "#{monster} says BLAH!!"  
10.         end  
11.       end  
12.     end  
13.   end  
14.   
15.   state :SATIATED do  
16.     enter do |monster|  
17.       puts "#{monster} says BURP!!!"  
18.     end  
19.   end  
20. end  

define_statemachine do
  initial_state :HUNGRY

  state :HUNGRY do
    on :eat do
      transition :to => :SATIATED, :if => :likes?
      transition do
        action do |monster| 
          puts "#{monster} says BLAH!!"
        end
      end
    end
  end

  state :SATIATED do
    enter do |monster|
      puts "#{monster} says BURP!!!"
    end
  end
end

The state machine definition goes inside your Ruby class (or ActiveRecord model), endowing the class with finite state machine behavior:

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1. require 'golem'  
2.   
3. class Monster  
4.   include Golem  
5.   
6.   attr_accessor :state  
7.   
8.   def initialize(name)  
9.     @name = name  
10.   end  
11.   
12.   def to_s  
13.     @name  
14.   end  
15.   
16.   def likes?(food)  
17.     food.kind_of?(String)  
18.   end  
19.   
20.   define_statemachine do  
21.     # ...  
22.   end  
23. end  
24.   
25. m = Monster.new("Stringosaurus")  
26. puts m.current_state # ==> :HUNGRY  
27. m.eat(12345)         # ==> "Stringosaurus says BLAH!!"  
28. puts m.current_state # ==> :HUNGRY  
29. m.eat("abcde")       # ==> "Stringosaurus says BURP!!"  
30. puts m.current_state # ==> :SATIATED  

require 'golem'

class Monster
  include Golem

  attr_accessor :state

  def initialize(name)
    @name = name
  end

  def to_s
    @name
  end

  def likes?(food)
    food.kind_of?(String)
  end

  define_statemachine do
    # ...
  end
end

m = Monster.new("Stringosaurus")
puts m.current_state # ==> :HUNGRY
m.eat(12345)         # ==> "Stringosaurus says BLAH!!"
puts m.current_state # ==> :HUNGRY
m.eat("abcde")       # ==> "Stringosaurus says BURP!!"
puts m.current_state # ==> :SATIATED

python-xml woes

Python ImportErrors like the following (stemming from the recent deprecation of the python-xml library in Ubuntu):

Failed to load application: No module named ext

... can be easily addressed by:

sudo apt-get install python-xml
export PYTHONPATH=$PYTHONPATH:/usr/lib/python2.5/site-packages/oldxml

This caused me a good few hours' grief earlier today.

A PHP Client for JasperServer (via SOAP)

I needed a PHP version of my Ruby SOAP client for JaserpServer.

Here it is: http://gist.github.com/26205

Usage (this runs the report unit '/my_report' and returns the result in PDF format):

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1. $jasper_url = "http://jasper.example.com/jasperserver/services/repository";  
2. $jasper_username = "jasperadmin";  
3. $jasper_password = "topsecret";  
4.   
5.   
6. $client = new JasperClient($jasper_url, $jasper_username, $jasper_password);  
7.   
8. $report_unit = "/my_report";  
9. $report_format = "PDF";  
10. $report_params = array('foo' => 'bar', 'fruit' => 'apple');  
11.   
12. $result = $client->requestReport($report_unit, $report_format,$report_params);  
13.   
14. header('Content-type: application/pdf');  
15. echo $result;  

 
  $jasper_url = "http://jasper.example.com/jasperserver/services/repository";
  $jasper_username = "jasperadmin";
  $jasper_password = "topsecret";


  $client = new JasperClient($jasper_url, $jasper_username, $jasper_password);

  $report_unit = "/my_report";
  $report_format = "PDF";
  $report_params = array('foo' => 'bar', 'fruit' => 'apple');
 
  $result = $client->requestReport($report_unit, $report_format,$report_params);

  header('Content-type: application/pdf');
  echo $result;

gittidy

I had my first run in with git today. After trying to sync an out-of-whack git-svn local repo with github things turned ugly:

git push
error: remote 'refs/heads/master' is not a strict subset of local ref 'refs/heads/master'. maybe you are not up-to-date and need to pull first?
error: failed to push to 'git@github.com:gunark/rubycas-server.git'

Turns out that remotely deleting the master branch on github (as described here) and then recreating it fixed the problem:

git push origin :heads/master
deleting 'refs/heads/master'
Everything up-to-date
git push origin master
updating 'refs/heads/master'
  from 0000000000000000000000000000000000000000
  to   6dd64b1b025c324d0b287805d6c18183b9f20b9e
Generating pack...
Done counting 1395 objects.
Deltifying 1395 objects...
 100% (1395/1395) done
Writing 1395 objects...
 100% (1395/1395) done
Total 1395 (delta 960), reused 0 (delta 0)

Yay

There was some weirdness in the github project page after this, but performing another commit and push seems to have taken things back to normal.

WS-Management + Openwsman + openSUSE + Ruby

Yet another failed attempt at using SNMP for monitoring application-level services led me to WS-Management, an HTTP/SOAP-based protocol meant to replace SNMP. DS-Management might not be the first protocol to attempt usurping SNMP, but this one looks promising. Widespread support and implementation is claimed by Microsoft, and a reasonably mature open-source implementation -- Openwsman -- is sponsored by SuSE.

Documentation for Openwsman unfortunately seems rather lacking. It took some poking around, but I was able to get a basic client-server session going under openSUSE 10.3. Here's how:

First, add the development channel for openwsman and install the openwsman packages:

1. sudo smart channel --add http://download.opensuse.org/repositories/home:/kwk:/Management/openSUSE_10.3/home:kwk:Management.repo  
2. sudo smart update home_kwk_Management  
3. sudo smart install openwsman openwsman-client openwsman-server wsmancli openwsman-yast  

sudo smart channel --add http://download.opensuse.org/repositories/home:/kwk:/Management/openSUSE_10.3/home:kwk:Management.repo
sudo smart update home_kwk_Management
sudo smart install openwsman openwsman-client openwsman-server wsmancli openwsman-yast

If you run into PGP key problems, try disabling PGP key checking first:

1. smart config --set rpm-check-signatures=false  

smart config --set rpm-check-signatures=false

The openwsman-server package installs openwsmand -- a stand-alone server providing WS-Management services. We'll need to configure the authentication system before running the server. I was unable to get things going with the default Basic authentication, but Digest worked for me:

1. htdigest2 -c /etc/openwsman/digest_auth.passwd OPENWSMAN admin  
2. Adding password for admin in realm OPENWSMAN.  
3. New password: test  
4. Re-type new password: test  

htdigest2 -c /etc/openwsman/digest_auth.passwd OPENWSMAN admin
Adding password for admin in realm OPENWSMAN.
New password: test
Re-type new password: test

Now edit the Openwsman config file to use Digest authentication. The config file is under /etc/openwsman/openwsman.conf and should be altered to look something like this (note that we've uncommented the 'digest_password_file' option):

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1. [server]  
2. port = 8889  
3. #ssl_port = 8888  
4. ssl_cert_file = /etc/openwsman/servercert.pem  
5. ssl_key_file = /etc/openwsman/serverkey.pem  
6. digest_password_file = /etc/openwsman/digest_auth.passwd  
7. #basic_password_file = /etc/openwsman/simple_auth.passwd  
8.   
9. min_threads = 4  
10. max_threads = 10  
11.   
12. #use_digest is OBSOLETED, see below.  
13.   
14. #  
15. # Authentication backend for BASIC authentication. Default is to read a configuration file defined with 'basic_password_file'  
16. #  
17.   
18. basic_authenticator = libwsman_pam_auth.so  
19. basic_authenticator_arg = openwsman  
20.   
21.   
22. [client]  
23. port = 8889  
24. agent = openwsman 0.6.0  
25.   
26. #  
27. # settings for the CIM plugin  
28. #  
29.   
30. [cim]  
31. default_cim_namespace = root/cimv2  
32.   
33. # The following are in part fake namespaces for some publicly available CIM implementations.  
34. vendor_namespaces = OpenWBEM=http://schema.openwbem.org/wbem/wscim/1/cim-schema/2,Linux=http://sblim.sf.net/wbem/wscim/1/cim-schema/2,OMC=http://schema.omc-project.org/wbem/wscim/1/cim-schema/2  
35.   
36. # CIMOM host, default is localhost  
37. # host = localhost  
38.   
39. # CIMOM port, default is 5988  
40. # port = 5988  

[server]
port = 8889
#ssl_port = 8888
ssl_cert_file = /etc/openwsman/servercert.pem
ssl_key_file = /etc/openwsman/serverkey.pem
digest_password_file = /etc/openwsman/digest_auth.passwd
#basic_password_file = /etc/openwsman/simple_auth.passwd

min_threads = 4
max_threads = 10

#use_digest is OBSOLETED, see below.

#
# Authentication backend for BASIC authentication. Default is to read a configuration file defined with 'basic_password_file'
#

basic_authenticator = libwsman_pam_auth.so
basic_authenticator_arg = openwsman


[client]
port = 8889
agent = openwsman 0.6.0

#
# settings for the CIM plugin
#

[cim]
default_cim_namespace = root/cimv2

# The following are in part fake namespaces for some publicly available CIM implementations.
vendor_namespaces = OpenWBEM=http://schema.openwbem.org/wbem/wscim/1/cim-schema/2,Linux=http://sblim.sf.net/wbem/wscim/1/cim-schema/2,OMC=http://schema.omc-project.org/wbem/wscim/1/cim-schema/2

# CIMOM host, default is localhost
# host = localhost

# CIMOM port, default is 5988
# port = 5988

Okay, now we can run the server:

1. sudo /usr/sbin/openwsmand -d  

sudo /usr/sbin/openwsmand -d

We can now connect to the server using a few simple Ruby commands. Open an interactive ruby session (using irb) and enter the following:

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1. require 'rwsman'  
2. client = WsMan::Client.new('http', 'localhost', 8889, '/wsman', 'admin', 'test')  
3. client_opt = WsMan::ClientOption.new  
4. identify = client.identify(client_opt)  
5. puts identify.rawxml  

require 'rwsman'
client = WsMan::Client.new('http', 'localhost', 8889, '/wsman', 'admin', 'test')
client_opt = WsMan::ClientOption.new
identify = client.identify(client_opt)
puts identify.rawxml

If everything worked, you should get a response that looks something like this:

1. <s:envelope s="http://www.w3.org/2003/05/soap-envelope" wsmid="http://schemas.dmtf.org/wbem/wsman/identity/1/wsmanidentity.xsd">  
2.  <s:header>  
3.  <s:body>  
4.    <wsmid:identifyresponse>  
5.      <wsmid:protocolversion>http://schemas.dmtf.org/wbem/wsman/1/wsman.xsd</wsmid:protocolversion>  
6.      <wsmid:productvendor>Openwsman Project</wsmid:productvendor>  
7.      <wsmid:productversion>1.5.9</wsmid:productversion>  
8.    </wsmid:identifyresponse>  
9.  </s:body>  
10. </s:header>  
11. </s:envelope>  

 
 
   
     http://schemas.dmtf.org/wbem/wsman/1/wsman.xsd
     Openwsman Project
     1.5.9
   
 

The identify object returned by the client also exposes product_version, protocol_version, and product_vendor methods that return their respective values from the parsed XML data.

With the YAST plugin installed, Openwsman can access diagnostic information about your SuSE system. For example try this:

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1. client_opt.property_add('ycp', '{ import "SuSERelease"; return SuSERelease::ReleaseInformation("/"); }' )  
2. result = client.invoke('http://schema.opensuse.org/YaST/wsman-schema/10-3/YCP', 'eval', client_opt)  
3. puts "SUSE Version: #{result.body}"  

client_opt.property_add('ycp', '{ import "SuSERelease"; return SuSERelease::ReleaseInformation("/"); }' )
result = client.invoke('http://schema.opensuse.org/YaST/wsman-schema/10-3/YCP', 'eval', client_opt)
puts "SUSE Version: #{result.body}"