c# web services

I want to use more fully fleshed out javascript frameworks with my already asp ajax enabled c# web app. My first project will consist of populating a treeview dynamically using the yahoo yui js framework and a custom c# web service.

There are two or more asynchronous web services that I will need to build. One will be responsible for building the tree and sending it back in xml or json so that I can build the tree again on the clients browser. The other method(s) will be responsible for altering the tree. I will need to move nodes to different parent nodes, delete selected nodes, or insert nodes under a specific node.

I can break it down into just a couple of functions: remove, insert, and move (which would just call the two previously declared functions in order after caching a node to be "moved" before deleted)

I'm going to start with the c# web services end using asp.net's new ajax implementation. Not sure how difficult it will be, but it seems to have a big enough following.

c# web services overview
Exposing web services to client script - the methods that I would call from javascript to modify the tree's nodes.

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Update:
I found a couple of fairly decent articles on codeguru.

Web services using .Net and Javascript

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Update: I've found an excellent tutorial on asp.net web services for beginners..
codesource.net