consume web services with a rails app?

I want to do a proof-of-concept showing how to consume data from an
xml web service provided by a partner company.

I have had a lot of difficulty finding examples of consuming xml web
services (plenty of info on providing xml web services).

I'm looking for the correct way to architect such a web app, using MVC
and Rails as I will not be requiring a database on my side of the
fence.

What you're going to want to use is a library called soap4r, it has
another library called wsdl2ruby.

http://dev.ctor.org/soap4r (read it all, but there is a long list of
good how-to's)

It will generate some files for you that make it easier to consume the
web service...

There should be 4 files and you'll need to require things at the top
of each. I wanted to be able to run my test ruby script as well as my
rails implementation concurrently (well without changing the require
statements every time anyway) so I did something like this...

require File.expand_path(File.dirname(__FILE__) + "../../../config/
environment")
require "#{RAILS_ROOT}/lib/soap/customer_details.rb"
require "#{RAILS_ROOT}/lib/soap/customer_detailsMappingRegistry.rb"
require 'soap/rpc/driver'

class WsGetCustAcctDtls < ::soap::RPC::Driver

Things are put here from wsdl2ruby...

And after that you just need to be able to query your web service.
This is what my WSDLNameClient.rb file (the ruby file that wsdl2ruby
generates) looks like:

http://pastie.textmate.org/private/u1yw8kyfi7ysopnh5mwrzq

The authentication stuff in there was specific to the web service I
was consuming, I had to build up a header and pass it in, etc... it
was a pita.

I'm not an expert, but I did end up getting it working after a lot of
googling and playing around with it. Here is an article that helped
me. but check out all the how-to's in that first link.

http://www.brendonwilson.com/blog/2006/04/02/ruby-soap4r-wsdl-hell/

Hopefully knowing the libraries you're supposed to be using will help
your googling too. Good luck!

-Jon Kinney
Inacom Information Systems
Ruby on Rails Developer

Kind of depends on what you really mean by "xml web service".

If they're exposing a SOAP interface, then you probably want to use
the soap4r gem.

If they're exposing a interface according to the XML RPC standard,
Ruby has built-in support for that too: http://ruby-doc.org/stdlib/libdoc/xmlrpc/rdoc/index.html

If they're exposing a REST XML service according to Rails
conventions :-), then you can use ActiveResource directly inside of
your Rails app. The interface is similar (but a subset) of
ActiveRecord, so it will feel pretty natural inside of a Rails app.

If it's a proprietary XML standard, then using something like
XmlSimple (which Rails includes by default) let's you slurp up an XML
doc into a hash pretty easily, and you can attack it from there.

Hope this helps?

Jeff

softiesonrails.com
purpleworkshops.com

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