update magento currency rates using custom php file

I'm trying to use a custom file to update currency rates using cURL from my local bank and insert the data into the currency database table. 开发者_StackOverflow中文版Do I have to create a module to do that, or can I do that without creating a module? I intend to use cron too. Does anyone have any advice on how to achieve this, and are there any tutorials?

Thanks..

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Best way to create custom mangento api as changing currency rates is not implemented in default magento api. Here is a simple tutorial that you can follow to implement the custom api http://www.magentocommerce.com/wiki/doc/webservices-api/custom-api