how to write a web services for my asp.net web application

I have an asp.net mvc3 website, I need to update the database periodically, for example, get some web resources from another site and use that as my dat开发者_StackOverflow中文版a. I think I should write some web services to do the job since the service should be running all the time, but I don't know where to start, is this hard? Where can I find the right tutorials for this job..

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If you need to update the data periodically, here are some questions you need to consider:

• Will the data updates be driven by user input? If so, the web application will update the data, there are numerous ways this can be accomplished, I assume you have some sort of method established to communicate with your data store?

• Will the data be updated by another data source? If so, consider using SSIS or some other ETL tool, if the data can be "batched", i.e. loaded nightly or hourly

• Thirdly, I'm not sure what your scenario is, from the question its pretty broad, you could use a Windows Service as an option if you are more comfortable populating your data via C#/VB.NET as opposed to something like SSIS. The Windows Service can periodically perform an action on your behalf.

Finally, maybe update your question a bit, "update database periodically" is very vague.