# Should Perl talk to Rails via LWP

**URL:** <https://www.ruby-forum.com/t/should-perl-talk-to-rails-via-lwp/57991>\
**Category:** Rails\
**Created:** [April 17, 2006, 4:46pm UTC](https://www.ruby-forum.com/t/should-perl-talk-to-rails-via-lwp/57991 "2006-04-17T16:46:32Z")\
**Posts on this page:** 8\
**Page:** 1

<div class="post-metadata">

**Author:** ![Bealach\_Na\_Bo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e19b73/32.png) [@Bealach\_Na\_Bo](https://www.ruby-forum.com/u/Bealach_Na_Bo)\
**Post date:** [April 17, 2006, 4:46pm UTC](https://www.ruby-forum.com/t/should-perl-talk-to-rails-via-lwp/57991/1 "2006-04-17T16:46:32Z")

</div>

Hi folks,

I need your opinions on a basic design issue.

I’ve seen the light of RoR and have replaced my Perl (DBI/CGI) based web  
server \<-\> RDBMS communication with RoR, but I still have a whole host  
of users (other servers/OS’s etc) out there wanting to talk to my  
RDBMS and they only talk Perl. Also they don’t want to talk Perl/DBI  
directly (they are not allowed to connect to the RDBMS directly). What  
I did in the “old” days was to provide, through Perl modules on the  
servers out there, a very simple hash based interface for my users.

Using their own Perl and my modules they could populated hashes with  
data bound for the RDBMS and send them to my “proxy server” (the web  
server with all the Perl/DBI/CGI). Similarly the data they got back  
from the RDBMS (via the “proxy”) was a hash.

The whole thing is very simplistic and not very robust on error  
handling.

Now that I’ve got a Rails to make my life a lot more fun I’m wondering  
how to allow the same simple communication.

I could hack another LWP (what I used with the “old” solution)  
solution and let them “fill in forms” created by RoR, but this can not  
possibly be the best solution! I know very little about XMLProxy and  
am not sure that this the best way to go. Forcing everyone to  
abandon Perl and use Ruby is also out of the question.

Any ideas on what might be the best way to provide my users with what  
they are used to and keep my newfound love, RoR?

Bealach

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<div class="post-metadata">

**Author:** ![Bealach\_Na\_Bo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e19b73/32.png) [@Bealach\_Na\_Bo](https://www.ruby-forum.com/u/Bealach_Na_Bo)\
**Post date:** [April 17, 2006, 5:14pm UTC](https://www.ruby-forum.com/t/should-perl-talk-to-rails-via-lwp/57991/2 "2006-04-17T17:14:27Z")

</div>

What your users need is a Web Service. Lucky for you, rails has  
ActionWebService to make your life easier! Once you get a web  
service up and running, your users can use a variety of perl modules  
to access your data, including SOAP::Lite. You get to focus on your  
application - let someone else mess with the perl modules.

And the best part is … with a web service up and running, your  
users don’t HAVE to use perl. They could use anything! Ruby!  
Java! Perl! even PHP! It doesn’t matter to you cuz you’re using a  
standards compliant web service!

I know you’re smiling right now. And you should be. LIfe just got  
good.

Unfortunately I haven’t the time to explain everything. If you have  
the Agile Web Programming book, you’re good to go - check out chapter  
20. Otherwise, try googling rails ActionWebService. Or perhaps this  
link will be enlightening: [Peak Obsession](http://manuals.rubyonrails.com/read/book/10)

-Derrick S.

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<div class="post-metadata">

**Author:** ![Bealach\_Na\_Bo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e19b73/32.png) [@Bealach\_Na\_Bo](https://www.ruby-forum.com/u/Bealach_Na_Bo)\
**Post date:** [April 17, 2006, 5:42pm UTC](https://www.ruby-forum.com/t/should-perl-talk-to-rails-via-lwp/57991/3 "2006-04-17T17:42:23Z")

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Ditto on the web services thing. That’s really what web services are  
for, you expose your API via XML, and then your users can decide for  
themselves what language they want to handle the XML in. Perl has tons  
of strong XML tools so your users will be totally happy, and although  
XML for web services tends to be rather verbose, it’s actually very  
simple and very powerful. I haven’t played with AWS but from first  
glance it looks very capable.

–  
Giles B.  
[http://www.gilesgoatboy.org](http://www.gilesgoatboy.org)

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<div class="post-metadata">

**Author:** ![Bealach\_Na\_Bo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e19b73/32.png) [@Bealach\_Na\_Bo](https://www.ruby-forum.com/u/Bealach_Na_Bo)\
**Post date:** [April 17, 2006, 7:25pm UTC](https://www.ruby-forum.com/t/should-perl-talk-to-rails-via-lwp/57991/4 "2006-04-17T19:25:08Z")

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On Mon, 17 Apr 2006, Giles B. wrote:

> Ditto on the web services thing. That’s really what web services are  
> for, you expose your API via XML, and then your users can decide for  
> themselves what language they want to handle the XML in. Perl has tons  
> of strong XML tools so your users will be totally happy, and although  
> XML for web services tends to be rather verbose, it’s actually very  
> simple and very powerful. I haven’t played with AWS but from first  
> glance it looks very capable.

I just moved an application from Perl Client/Perl Server (XMLRPC::Lite)  
to  
Perl Client, AWS Server. The only real issue I ran across was stricter  
data typing and how I was delivering the results (Hash references vs.  
Arrays). But it was a pretty smooth transition, and my Perl client  
isn’t  
having any problems at all talking to AWS.

–Wade

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<div class="post-metadata">

**Author:** ![Bealach\_Na\_Bo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e19b73/32.png) [@Bealach\_Na\_Bo](https://www.ruby-forum.com/u/Bealach_Na_Bo)\
**Post date:** [April 17, 2006, 6:03pm UTC](https://www.ruby-forum.com/t/should-perl-talk-to-rails-via-lwp/57991/5 "2006-04-17T18:03:53Z")

</div>

Thanks for your comments guys. Looks like I’ve some homework to do  
before I can bug you again 🙂

Bealach

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<div class="post-metadata">

**Author:** ![Bealach\_Na\_Bo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e19b73/32.png) [@Bealach\_Na\_Bo](https://www.ruby-forum.com/u/Bealach_Na_Bo)\
**Post date:** [April 18, 2006, 9:23am UTC](https://www.ruby-forum.com/t/should-perl-talk-to-rails-via-lwp/57991/6 "2006-04-18T09:23:39Z")

</div>

I’m feeling particularly stupid now! I’ve followed the discussion in  
section 20.2 of the Agile Web Dev book, but can not get it to run.

Somebody please tell me that I’m having an attack of dyslexia and that  
this is easy to fix!

Here are my app/apis/product\_api.rb and  
app/controllers/backend\_controller.rb

class ProductApi \< ActionWebService::API::Base  
api\_method :find\_all\_products,  
:returns =\> [[:int]]  
api\_method :find\_product\_by\_id,  
:expects =\> [:int],  
:returns =\> [Product]  
end

class BackendController \< ApplicationController  
wsdl\_service\_name ‘Backend’  
web\_service\_api ProductApi  
web\_service\_scaffold :invoke  
def find\_all\_products  
Product.find(:all).map{ |product| product.id }  
end

def find\_product\_by\_id(id)  
Product.find(id)  
end  
end

And I end up with the following error:

------------------ERROR-----------------  
NameError in #

neither BackendApi or BackendAPI found

RAILS\_ROOT: script/…/config/…  
Application Trace | Framework Trace | Full Trace

/usr/lib/ruby/gems/1.8/gems/actionwebservice-1.1.0/lib/action\_web\_service/container/action\_controller\_container.rb:76:in  
`require_web_service_api' /usr/lib/ruby/gems/1.8/gems/actionwebservice-1.1.0/lib/action_web_service/container/action_controller_container.rb:50:in`web\_service\_api’  
/usr/lib/ruby/gems/1.8/gems/actionwebservice-1.1.0/lib/action\_web\_service/container/action\_controller\_container.rb:87:in  
`inherited_without_action_controller' /usr/lib/ruby/gems/1.8/gems/actionwebservice-1.1.0/lib/action_web_service/dispatcher/action_controller_dispatcher.rb:34:in`inherited’  
#{RAILS\_ROOT}/app/controllers/backend\_controller.rb:1  
generated/routing/recognition.rb:3:in `eval' generated/routing/recognition.rb:3:in`recognize\_path’

/usr/lib/ruby/gems/1.8/gems/actionwebservice-1.1.0/lib/action\_web\_service/container/action\_controller\_container.rb:76:in  
`require_web_service_api' /usr/lib/ruby/gems/1.8/gems/actionwebservice-1.1.0/lib/action_web_service/container/action_controller_container.rb:50:in`web\_service\_api’  
/usr/lib/ruby/gems/1.8/gems/actionwebservice-1.1.0/lib/action\_web\_service/container/action\_controller\_container.rb:87:in  
`inherited_without_action_controller' /usr/lib/ruby/gems/1.8/gems/actionwebservice-1.1.0/lib/action_web_service/dispatcher/action_controller_dispatcher.rb:34:in`inherited’  
/usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active\_support/dependencies.rb:129:in  
`load' /usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active_support/dependencies.rb:56:in`require\_or\_load’  
/usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active\_support/dependencies.rb:30:in  
`depend_on' /usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active_support/dependencies.rb:74:in`require\_dependency’  
/usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active\_support/dependencies.rb:87:in  
`const_missing' /usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active_support/dependencies.rb:120:in`const\_missing’  
/usr/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action\_controller/routing.rb:237:in  
`traverse_to_controller' /usr/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action_controller/routing.rb:237:in`traverse\_to\_controller’  
/usr/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action\_controller/routing.rb:477:in  
`recognize!' /usr/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/dispatcher.rb:38:in`dispatch’  
/usr/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/webrick\_server.rb:115:in  
`handle_dispatch' /usr/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/webrick_server.rb:81:in`service’  
/usr/lib/ruby/1.8/webrick/httpserver.rb:104:in `service' /usr/lib/ruby/1.8/webrick/httpserver.rb:65:in`run’  
/usr/lib/ruby/1.8/webrick/server.rb:173:in `start_thread' /usr/lib/ruby/1.8/webrick/server.rb:162:in`start\_thread’  
/usr/lib/ruby/1.8/webrick/server.rb:95:in `start' /usr/lib/ruby/1.8/webrick/server.rb:92:in`start’  
/usr/lib/ruby/1.8/webrick/server.rb:23:in `start' /usr/lib/ruby/1.8/webrick/server.rb:82:in`start’  
/usr/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/webrick\_server.rb:67:in  
`dispatch' /usr/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/commands/servers/webrick.rb:59 /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:21:in`require’  
/usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active\_support/dependencies.rb:136:in  
`require' /usr/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/commands/server.rb:30 /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:21:in`require’  
/usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active\_support/dependencies.rb:136:in  
`require’  
script/server:3

/usr/lib/ruby/gems/1.8/gems/actionwebservice-1.1.0/lib/action\_web\_service/container/action\_controller\_container.rb:76:in  
`require_web_service_api' /usr/lib/ruby/gems/1.8/gems/actionwebservice-1.1.0/lib/action_web_service/container/action_controller_container.rb:50:in`web\_service\_api’  
/usr/lib/ruby/gems/1.8/gems/actionwebservice-1.1.0/lib/action\_web\_service/container/action\_controller\_container.rb:87:in  
`inherited_without_action_controller' /usr/lib/ruby/gems/1.8/gems/actionwebservice-1.1.0/lib/action_web_service/dispatcher/action_controller_dispatcher.rb:34:in`inherited’  
#{RAILS\_ROOT}/app/controllers/backend\_controller.rb:1  
/usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active\_support/dependencies.rb:129:in  
`load' /usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active_support/dependencies.rb:56:in`require\_or\_load’  
/usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active\_support/dependencies.rb:30:in  
`depend_on' /usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active_support/dependencies.rb:74:in`require\_dependency’  
/usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active\_support/dependencies.rb:87:in  
`const_missing' /usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active_support/dependencies.rb:120:in`const\_missing’  
/usr/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action\_controller/routing.rb:237:in  
`traverse_to_controller' generated/routing/recognition.rb:3:in`eval’  
/usr/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action\_controller/routing.rb:237:in  
`traverse_to_controller' generated/routing/recognition.rb:3:in`recognize\_path’  
/usr/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action\_controller/routing.rb:477:in  
`recognize!' /usr/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/dispatcher.rb:38:in`dispatch’  
/usr/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/webrick\_server.rb:115:in  
`handle_dispatch' /usr/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/webrick_server.rb:81:in`service’  
/usr/lib/ruby/1.8/webrick/httpserver.rb:104:in `service' /usr/lib/ruby/1.8/webrick/httpserver.rb:65:in`run’  
/usr/lib/ruby/1.8/webrick/server.rb:173:in `start_thread' /usr/lib/ruby/1.8/webrick/server.rb:162:in`start\_thread’  
/usr/lib/ruby/1.8/webrick/server.rb:95:in `start' /usr/lib/ruby/1.8/webrick/server.rb:92:in`start’  
/usr/lib/ruby/1.8/webrick/server.rb:23:in `start' /usr/lib/ruby/1.8/webrick/server.rb:82:in`start’  
/usr/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/webrick\_server.rb:67:in  
`dispatch' /usr/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/commands/servers/webrick.rb:59 /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:21:in`require’  
/usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active\_support/dependencies.rb:136:in  
`require' /usr/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/commands/server.rb:30 /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:21:in`require’  
/usr/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active\_support/dependencies.rb:136:in  
`require’  
script/server:3

This error occured while loading the following files:  
backend\_controller.rb

Request

Parameters: None

Show session dump

* * *

flash: !map:ActionController::Flash::FlashHash {}

Response  
Headers: {“cookie”=\>[], “Cache-Control”=\>“no-cache”}  
------------------ERROR-----------------

---

<div class="post-metadata">

**Author:** ![Bealach\_Na\_Bo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e19b73/32.png) [@Bealach\_Na\_Bo](https://www.ruby-forum.com/u/Bealach_Na_Bo)\
**Post date:** [April 18, 2006, 9:38am UTC](https://www.ruby-forum.com/t/should-perl-talk-to-rails-via-lwp/57991/7 "2006-04-18T09:38:53Z")

</div>

I’ve just solved the problem without really understanding why what I  
did solved the problem! I had not REMOVED the default  
app/apis/backend\_api.rb, but made a copy of it, edited the copy and  
renamed it to product\_api.rb. When I removed  
backend\_api.rb it worked.

Bealach

---

<div class="post-metadata">

**Author:** ![Bealach\_Na\_Bo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e19b73/32.png) [@Bealach\_Na\_Bo](https://www.ruby-forum.com/u/Bealach_Na_Bo)\
**Post date:** [April 18, 2006, 2:42pm UTC](https://www.ruby-forum.com/t/should-perl-talk-to-rails-via-lwp/57991/8 "2006-04-18T14:42:03Z")

</div>

A couple more questions guys.

I’ve got things set up so that the product example works fine and  
talks nicely to a  
Perl XMLrpc client - thanks for all your suggestions and putting me on  
the right track - life did get very good Derrick!

2 questions:

1. The default documentation (method names and return types) that  
appears when the user visits [http://localhost:3000/backend/invoke](http://localhost:3000/backend/invoke) is  
concise and correct, but a bit terse. How can I give my users a little  
more? Maybe even include an example for them on the same page. Do I  
manually insert this in the rendered view? Or is there, like most  
things Ruby that I am discovering, a much more elegant way of doing  
this using RDoc?

2. How do I go about providing full blown CRUD? If a user wants to  
insert 50 new books in my database using his/her Perl scripts, he/she  
will want to be able to send  
a hash or array of hashes and get some feedback (customized error codes  
etc.)

Bealach