Forum OpenACS Development: Re: Tcl Web Services Toolkit: TWiST

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Posted by Tom Jackson on

Here is an example auto-generated invoke procedure:

proc ::wsdb::operations::openacs::CheckEmailOperation::Invoke {
inputXMLNS
outputXMLNS
} {
variable conversionList
::xml::childElementsAsListWithConversions $inputXMLNS $conversionList
return [::wsdb::elements::openacs::CheckEmailResponse::new $outputXMLNS [::openacs::CheckEmail $Email]]
}

This tiny proc is the interface between the XML world and the Tcl world. This procedure could be completely hand written as long as it takes the same input (where to find the Tcl rep of the XML document and where to put the output document) and returns the same output (reference to the return document, a child of outputXMLNS).

In addition, the operation's namespace variable 'invoke' must be set to the fully qualified proc name.

From the point of view of the server, the size and complexity of the document isn't important. But obviously the underlying Tcl API which can handle complex data is beyond the scope of the interface: it is hidden inside the invoke procedure. This is the purpose of this interface, otherwise it would take a few seconds of thought to discover something you couldn't handle, and hacking would begin. The invoke procedure is independent of other parts of the tWSDL API. You can completely test this procedure without the need to run the SOAP server, therefore it is also independent of the binding or protocol. If someone adds a new binding, the invoke procedures remain valid.

One use case which I am working on is a complexType which contains a sequence of children all of the same type, such as a sequence of database rows. It works as expected, but I don't yet have a higher level API to write the code.

If you run the modelGroup::sequence::new API with 'puts' or 'log Notice' instead of 'eval', you can see what code is actually generated.