[IronPython] Updating WebServices samples

Christian Muirhead christian.muirhead at resolversystems.com
Mon May 12 12:50:19 CEST 2008

Jimmy Schementi wrote:
 > I’m actually using this stuff in a talk next month, so I guess *someone*
 > has to get it working. =P Christian , if you are working on this, by all
 > means continue, otherwise when I make progress I’ll let you know

Fair enough! :)

Well, I had a go at doing this in the weekend, and after a bit of 
mucking around implementing GetCustomMember and Call methods, I realised 
that all I really need is the WsdlProvider part. And then that a lot of 
the stuff the WsdlProvider is doing (adding properties to the code dom 
for the to-be-generated assembly to enable access to types defined in 
the WSDL) is much easier done in Python than in C#.

So I did that instead. The interface is different - something like this:

 >>> import wsdlprovider as wsdl
 >>> url = 
 >>> math = wsdl.GetWebServiceAssembly(url)
 >>> ws = math.MathService()
 >>> ws.Add(40, 2.5)

It turned out that modifying the CodeDom wasn't really necessary - if 
you return the assembly instead of the proxy type, you can just treat it 
as a module, and the constructors for parameters to service methods are 
available already. And if you don't already know the name of the proxy 
type, you can use wsdlprovider.FindProxyType, which rummages through the 
assembly to find something that inherits from SoapHttpClientProtocol.

It doesn't unify the interfaces as much as they were in the C# code, but 
that's not that important for the stuff I'm writing.

There were a couple of questions that occurred to me when I was doing it 
in C# (before I remembered that I'd rather code in Python).

* While I can replace attribute injectors with GetCustomMember and 
friends in classes that I'm defining (like WebServiceHelper), 
DynamicWebServiceHelpers also registers injectors for string (for 
pluralisation) and XmlElement (convenient child element access). This is 
a bit like C#'s extension methods (or if I'm feeling uncharitable, Ruby 
class monkeypatching, since I don't think it's namespaced). How would I 
get this effect (particularly for the SimpleXmlHelper stuff) in IP2? 
(Although given the rubyesqueness, maybe I wouldn't want it! ;)

In Python, I guess I'd create a transparent wrapper for XmlElement that 
delegates from __getattr__ (for real XmlElement attributes) and then 
falls back to the cleverness allowing named child element access. But 
that wouldn't automatically affect every XmlElement - I'd have to 
manually wrap any elements as I returned them from my wrapper.

* The properties that WsdlProvider adds to the CodeDom before generating 
an assembly are implemented using a call to Ops.GetDynamicTypeFromType. 
I couldn't work out the corresponding call in IP2. How would I do that?

I haven't tried to port the SimpleXmlHelper and pluralisation to Python 
yet - it's less useful to me.

Not sure what the focus of your talk is, Jimmy, but hopefully this is 
some help?


> ~js
> On 5/9/08 8:46 AM, "Dino Viehland" <dinov at exchange.microsoft.com> wrote:
>     And ICallable is the same - you can now mark a method w/ SpecialName
>     and call it "Call" and it'll be invoked when you're calling the
>     object.  You can even have multiple overloads, all strongly typed,
>     etc...
>     -----Original Message-----
>     From: users-bounces at lists.ironpython.com
>     [mailto:users-bounces at lists.ironpython.com] On Behalf Of Sanghyeon Seo
>     Sent: Friday, May 09, 2008 6:39 AM
>     To: Discussion of IronPython
>     Subject: Re: [IronPython] Updating WebServices samples
>     2008/5/9 Christian Muirhead <christian.muirhead at resolversystems.com>:
>     >  Is there any chance that someone has updated these to work with
>     the IP2
>     >  architecture? If not, how much work would people expect it to be?
>     The errors
>     >  I saw when I quickly tried to compile the C# were primarily about
>     not being
>     >  able to find the IAttributesInjector and ICallable interfaces - do
>     these
>     >  exist in the same form in the new architecture?
>     I think IAttributesInjector -- which was hacky, IMO -- has been
>     replaced by defining GetBoundMember method and marking the method with
>     SpecialNameAttribute.
>     Details are here:
>     http://blogs.msdn.com/srivatsn/archive/2008/04/12/turning-your-net-object-models-dynamic-for-ironpython.aspx
>     --
>     Seo Sanghyeon
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Christian Muirhead
Senior Developer
Resolver Systems
christian.muirhead at resolversystems.com
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