I am just getting into XML, XSDs, and webservices, so my questions may be pretty naïve. I would appreciate advice or references.

I am coding a web service that allows users to select multiple calculations that they want to perform. The service generates an XSD that defines the data it needs to perform the desired calculations. The user submits the required data as XML and the service returns their results.

I am providing two webservice methods. Since the calculations require specific range and structure in their parameters, I want the constrained data structure that XML and XSDs provide. I am not sure what classes to use to pass XML and XSDs back and forth in my two web service methods, outlined below:

1. ¿XsdReturnType? getDataRequirements(string calculationIDs)

The user submits a delimited list of IDs for the calculations that they want to perform and a single XSD describing the parameters needed for all the calculations is returned.

What should the return type be, a string, an XML document, or something else?

I want to provide service subscribers with an XSD so they can validate their data before submitting calculation parameters to the web service method that performs calculations.

2. getCalculationResults(string calculationIDs, ¿XMLtype? parameters)

This method would calculate their results. The user passes in their calculation IDs again and the XML for their data parameters. I validate their data on my end using the same XSD. Should I use XMLDocument, string, or something else to pass in the XML parameters?

I'd appreciate any sage advice that any web service veterans have.