Dynamic Web Service SmartObject Service

Hmm. It might be possible, but that poses some significant challenges which is why I chose not to do it. The basic problem is that with a webservice, you don't know (and shouldn't need to) how a webmethod is implemented.

Currently, the service object just looks at the webmethod signature to generate the proxy using the WSDL, but trying to support custom objects as parameters really would require a greater understanding of the actual code within the webmethod which we don't have access to from the WSDL.

For example, let's say I have a class called Order which has 20 different public properties/fields of value types and some additional number of custom objects also. And let's say I have a method like:

[WebMethod]
public OrderDetail GetOrderDetails( Order order )
{
  OrderRepository.GetOrderDetails( order.Id );
}

Since I only look at the signature and don't know how Order is actually used, I'd have to translate this to a SmartObject service that looked something like:

Except replace the ... with all 20 of the public properties of the class which would be really clunky as you can see that all we really need is id. But it would work, you'd just have a lot of parameters you would have to pass in empty values for.

But now assume that the implementation isn't what I have above, but is instead:

Here, the method is using a User object (another custom object let's say) and the orderDate to return all order details (this example is just to highlight the challenges and doesn't necessarily make sense). Now assuming we use the same logic we are using for return values then we'd ignore User since we only go one level deep on objects and only support value types so we'd end up not letting you pass in User in our SmartObject call which would mean order.User would be null, which would mean the webmethod doesn't return the value you would expect.

We could instead say, well let's just traverse the entire object graph to create our parameter list. But then we'd get a smartobject method that looked something like:

And our smartobject method would quickly grow to have a huge number of parameters.

When I wrote the SmartObject service, my first thought on a way around this would be to have some kind of schema file in addition to the WSDL for the WebService which would specify what parameters are expected in a situation like that, but that seems like it would be a significant amount of work to implement and requires a deep understanding of the actual webmethod implementation. And it seems to me that if you have that deep of an understanding then you probably have access to the code, so a better alternative would seem to be to just create another webmethod which accepts only the value types required to implement the request. So you'd then have code like:

[WebMethod]
public OrderDetail GetOrderDetails( Order order )
{
  OrderRepository.GetOrderDetails( order.User, order.orderDate );
}

[WebMethod]
public OrderDetail GetOrderDetailsForUserName( string userName, DateTime orderDate )
{ 
  User user = new User();
  user.UserName = userName;

  GetOrderDetails( user, orderDate );
}

If you have any thoughts on ways to overcome the challenges posed, I am certainly open to suggestions.

Got the Broker installed and set up the smartobject to go with it.

When the workflow runs I get the following error in the process instance - taken from the Host Server Log:

"1401486","2008-08-14 12:53:34","Debug","General","15","GeneralDebugMessage","ProcessInstance.HandleException","15 DestinationRule: Message: Exception has been thrown by the target of an invocation.; ServiceName: DirectivesSupport; ServiceGuid: 3a6e06ed-4105-4e66-b27c-71bbe0caa4a3; InnerExceptionMessage: ;
    at SourceCode.Workflow.Runtime.Extenders.WinWFExtender.OnExecute(Object context, XmlElement data, ResolverManager resolverManager)
   at SourceCode.Workflow.Runtime.Extenders.ResolverExtenderBase.Execute(Object context, String data)
   at K2AppDomainManager.ExecuteExtender(String name, String data, Object ctxt)
   at K2AppDomainManager.ExecuteExtender(String name, String data, Object ctxt)
   at SourceCode.KO.ProcessInstance.ExecuteExtender(Guid code, State state, ContextType ctxt, Object ctxtobj, Int32 objid, String ctxtname, Guid ecode)","","","i3Workflow:c:program filesk2 blackpearlHost ServerBin","1401486","63a6be964a254b468592598d3c7a0645",""

Am I missing something somewhere?

I have registered the service broker in both a development and test environment. In both environemnts when I go to add the service I enter the url of the web service and when I press next I get a valiation error dialog box that says:

 "Could not load file or assembly 'file:///C:Documents and Settingsk2svcLocal SettingsTempl7uxpdap.dll' or one of its dependencies. The system cannot find the file specified."

The actual file name changes each time I try this process. Can you tell me what might be causing this problem?

I made this change and recieved the same error. I restarted the K2 Service and still the same result.

I will work with it some more on Monday as I will be out for the next few days.

Thanks for your quick response!!!!

Hi,

I'm running into problems using this service for custom objects.  I did a simple hello world return as a string and the service worked fine, but returning a custom object fails with this error.  I've tried a couple different custom objects and all fail this way.  The web service tests fine, but no luck through K2 and this service.  Any ideas?

Hi danalstr,

Did you figure this one out?  We're seeing this issue now too.

Thanks,

JDK

Hi All,

I download the dynamic webservice and added into K2 workspace, created the service instance with webservice Url, but when i try the access through context browser i am not getting any webmethods in that.

Please help me out! 

Any body confirm, does this support Arraylist or Dataset return date type from webservice's webmothod?

It does support arrays so you could convert your arraylist to an array and return that. 

The project comes with source code so you can see exactly what it supports and enhance it with additional features.