# Backgroundrb and REXML issue

**URL:** <https://www.ruby-forum.com/t/backgroundrb-and-rexml-issue/92750>\
**Category:** Rails\
**Created:** [April 23, 2007, 7:41pm UTC](https://www.ruby-forum.com/t/backgroundrb-and-rexml-issue/92750 "2007-04-23T19:41:33Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![simon1](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/fbc32d/32.png) [@simon1](https://www.ruby-forum.com/u/simon1)\
**Post date:** [April 23, 2007, 7:41pm UTC](https://www.ruby-forum.com/t/backgroundrb-and-rexml-issue/92750/1 "2007-04-23T19:41:33Z")

</div>

Hi,

I have an application that receives XML files, and then hands each one  
off to a backgroundrb worker to parse and store the info. Everything  
was working, until I needed to support a larger character set. So I  
added the following to the top of my XML files: \<?xml version=“1.0”  
encoding=“ISO-8859-1”?\>

Adding this worked fine when I tested it without using backgroundrb.  
That is, when parsing within the main application, I get the expected  
behaviour. However, when I try to hand it off to a worker, I get the  
following error in backgroundrb.log:

20070423-13:36:41 (8456) Connection reset by peer -  
(DRb::DRbConnError)  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:563:in `read' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:563:in`load’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:629:in  
`recv_reply' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:918:in`recv\_reply’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1192:in  
`send_message' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1083:in`method\_missing’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1167:in `open' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1082:in`method\_missing’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1100:in  
`with_friend' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1081:in`method\_missing’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1069:in  
`respond_to?' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/rexml/xpath_parser.rb: 205:in`expr’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/rexml/xpath\_parser.rb:  
203:in `expr' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/rexml/xpath_parser.rb: 125:in`match’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/rexml/xpath\_parser.rb:56:in  
`parse' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/rexml/xpath.rb:53:in`each’  
20070423-13:36:41 (8456) /usr/local/src/rails/434Wireless/lib/workers/  
parser\_worker.rb:376:in `do_work' 20070423-13:36:41 (8456) /usr/local/src/rails/434Wireless/vendor/ plugins/backgroundrb/server/lib/backgroundrb/worker.rb:55:in`work\_thread’  
20070423-13:36:41 (8456) /usr/local/src/rails/434Wireless/vendor/  
plugins/backgroundrb/server/lib/backgroundrb/worker.rb:69:in  
`work_thread' 20070423-13:36:41 (8456) /usr/local/src/rails/434Wireless/vendor/ plugins/backgroundrb/server/lib/backgroundrb/worker.rb:67:in`work\_thread’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1552:in  
`perform_without_block' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1512:in`perform’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1586:in  
`main_loop' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1582:in`main\_loop’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1578:in  
`main_loop' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1427:in`run’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1424:in `run' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1344:in`initialize’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1624:in  
`start_service' 20070423-13:36:41 (8456) /usr/lib/ruby/gems/1.8/gems/slave-1.2.0/lib/ slave.rb:396:in`initialize’  
20070423-13:36:41 (8456) /usr/lib/ruby/gems/1.8/gems/slave-1.2.0/lib/  
slave.rb:391:in `initialize' 20070423-13:36:41 (8456) /usr/local/src/rails/434Wireless/vendor/ plugins/backgroundrb/server/lib/backgroundrb/middleman.rb:210:in`new\_worker’  
20070423-13:36:41 (8456) /usr/local/src/rails/434Wireless/vendor/  
plugins/backgroundrb/server/lib/backgroundrb/thread\_pool.rb:36:in  
`dispatch' 20070423-13:36:41 (8456) /usr/local/src/rails/434Wireless/vendor/ plugins/backgroundrb/server/lib/backgroundrb/thread_pool.rb:22:in`dispatch’  
20070423-13:36:41 (8456) /usr/local/src/rails/434Wireless/vendor/  
plugins/backgroundrb/server/lib/backgroundrb/middleman.rb:199:in  
`new_worker' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1552:in`perform\_without\_block’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1512:in  
`perform' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1586:in`main\_loop’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1582:in  
`main_loop' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1578:in`main\_loop’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1427:in `run' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1424:in`run’  
20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1344:in  
`initialize' 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1624:in`start\_service’  
20070423-13:36:41 (8456) /usr/local/src/rails/434Wireless/vendor/  
plugins/backgroundrb/server/lib/backgroundrb\_server.rb:315:in `run' 20070423-13:36:41 (8456) /usr/lib/ruby/gems/1.8/gems/daemons-1.0.5/lib/ daemons/application.rb:187:in`start\_proc’  
20070423-13:36:41 (8456) /usr/lib/ruby/gems/1.8/gems/daemons-1.0.5/lib/  
daemons/daemonize.rb:192:in `call_as_daemon' 20070423-13:36:41 (8456) /usr/lib/ruby/gems/1.8/gems/daemons-1.0.5/lib/ daemons/application.rb:191:in`start\_proc’  
20070423-13:36:41 (8456) /usr/lib/ruby/gems/1.8/gems/daemons-1.0.5/lib/  
daemons/application.rb:227:in `start' 20070423-13:36:41 (8456) /usr/lib/ruby/gems/1.8/gems/daemons-1.0.5/lib/ daemons/controller.rb:69:in`run’  
20070423-13:36:41 (8456) /usr/lib/ruby/gems/1.8/gems/daemons-1.0.5/lib/  
daemons.rb:182:in `run_proc' 20070423-13:36:41 (8456) /usr/lib/ruby/gems/1.8/gems/daemons-1.0.5/lib/ daemons/cmdline.rb:105:in`catch\_exceptions’  
20070423-13:36:41 (8456) /usr/lib/ruby/gems/1.8/gems/daemons-1.0.5/lib/  
daemons.rb:181:in `run_proc' 20070423-13:36:41 (8456) /usr/local/src/rails/434Wireless/vendor/ plugins/backgroundrb/server/lib/backgroundrb_server.rb:301:in`run’  
20070423-13:36:41 (8456) script/backgroundrb:29

I tried removing the line that gives the XML version from the top of  
the same test file, and then it crashes where I expect it to, when it  
encounters invalid characters. Any ideas as to what is happening?

Thanks,

Simon

---

<div class="post-metadata">

**Author:** ![simon1](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/fbc32d/32.png) [@simon1](https://www.ruby-forum.com/u/simon1)\
**Post date:** [April 24, 2007, 5:47am UTC](https://www.ruby-forum.com/t/backgroundrb-and-rexml-issue/92750/2 "2007-04-24T05:47:26Z")

</div>

> 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1083:in  
> 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/rexml/xpath\_parser.rb:  
> 20070423-13:36:41 (8456) /usr/local/src/rails/434Wireless/vendor/  
> 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1512:in  
> `initialize' plugins/backgroundrb/server/lib/backgroundrb/thread_pool.rb:36:in `perform’  
> 20070423-13:36:41 (8456) /usr/lib/ruby/1.8/drb/drb.rb:1624:in  
> daemons/application.rb:227:in `start’  
> 20070423-13:36:41 (8456) script/backgroundrb:29
> 
> I tried removing the line that gives the XML version from the top of  
> the same test file, and then it crashes where I expect it to, when it  
> encounters invalid characters. Any ideas as to what is happening?

Simon,

What I recommend doing is implementing the worker functionality in a  
helper class and then simply delegate from the backgroundrb worker to  
the helper. This way you can unit test the helper and don’t need to  
worry about backgroundrb.

# lib/app\_xml\_helper.rb

class AppXmlHelper

def self.do\_stuff(options={})  
…  
end

end

# lib/workers/app\_xml\_worker.rb

class AppXmlWorker \< BackgrounDRb::Worker::RailsBase

def do\_work(args)  
AppXmlHelper.do\_stuff(args) # delegate  
end

end  
AppXmlWorker.register

Now it’s easy to test and you can isolate your biz logic from  
backgroundrb.

Hope this helps,

–  
Zack C.  
[http://depixelate.com](http://depixelate.com)

---

<div class="post-metadata">

**Author:** ![simon1](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/fbc32d/32.png) [@simon1](https://www.ruby-forum.com/u/simon1)\
**Post date:** [April 25, 2007, 7:43am UTC](https://www.ruby-forum.com/t/backgroundrb-and-rexml-issue/92750/3 "2007-04-25T07:43:38Z")

</div>

Hi,

Yeah, I’ll try that to try and help figure out what the issue is.  
Just one quick question, can I just create that helper class file by  
itself, or does it need to be created through the use of any “script/  
something …”? And do I need to register it with any of my Models  
or anything like that, so that the helper class has access to them?

Thanks again,

Simon

---

<div class="post-metadata">

**Author:** ![simon1](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/fbc32d/32.png) [@simon1](https://www.ruby-forum.com/u/simon1)\
**Post date:** [April 25, 2007, 4:24pm UTC](https://www.ruby-forum.com/t/backgroundrb-and-rexml-issue/92750/4 "2007-04-25T16:24:18Z")

</div>

> Yeah, I’ll try that to try and help figure out what the issue is.  
> Just one quick question, can I just create that helper class file by  
> itself, or does it need to be created through the use of any “script/  
> something …”? And do I need to register it with any of my Models  
> or anything like that, so that the helper class has access to them?

Simon,

Yes, just drop the helper class file in lib/ and you should be good to  
go. You will have access to your models.

–  
Zack C.  
[http://depixelate.com](http://depixelate.com)

---

<div class="post-metadata">

**Author:** ![simon1](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/fbc32d/32.png) [@simon1](https://www.ruby-forum.com/u/simon1)\
**Post date:** [April 25, 2007, 4:54pm UTC](https://www.ruby-forum.com/t/backgroundrb-and-rexml-issue/92750/5 "2007-04-25T16:54:23Z")

</div>

Zack,

I tried that, and I get the following error:

20070425-10:51:11 (22978) undefined method `store_xml' for XmlHelper:Class - (NoMethodError) 20070425-10:51:11 (22978) /usr/local/src/rails/434Wireless/lib/workers/ parser_worker.rb:329:in`do\_work’

store\_xml is the function in my XmlHelper class, which is located at  
lib/xml\_helper.rb. I’ve restarted both servers after adding the file  
and making the changes. Any idea on what I’m still missing?

Thanks again,

Simon

---

<div class="post-metadata">

**Author:** ![simon1](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/fbc32d/32.png) [@simon1](https://www.ruby-forum.com/u/simon1)\
**Post date:** [April 25, 2007, 6:10pm UTC](https://www.ruby-forum.com/t/backgroundrb-and-rexml-issue/92750/6 "2007-04-25T18:10:36Z")

</div>

> 

Check that store\_xml is defined as a class method:

class XmlHelper  
def self.store\_xml(args)  
end  
end

–  
Zack C.  
[http://depixelate.com](http://depixelate.com)

---

<div class="post-metadata">

**Author:** ![simon1](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/fbc32d/32.png) [@simon1](https://www.ruby-forum.com/u/simon1)\
**Post date:** [April 25, 2007, 8:05pm UTC](https://www.ruby-forum.com/t/backgroundrb-and-rexml-issue/92750/7 "2007-04-25T20:05:47Z")

</div>

That was it. Thanks again.

Simon