IE reading/writing on client end

Is there a way to read and write files on a client's computer using a web based application? Basically I need to create a internal app that will take two input CSV files and convert it into an output CSV file that is written to the same location 开发者_如何学运维as the input files on the client's computers.

Since this is an internal app, I don't have to worry about security. I can easily write a C# app for this but I want to create a ASP.NET app (or any other format). I even looked into creating a HTA application.

Can anyone point me on the right direction to achieve this?

Thanks.

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If you want to do it on the client, you will have to write an ActiveX control. You might be able to use Flash or Silverlight, if their security model allows it (I'm not sure).