>Do you think, should I implement it fully online or partial online (only upload the transaction intervally) ?

This depends on your needs... and the amount of money you are going to invest in the system for its continued operation. Dial-up is considerably cheaper than a continuous connection.

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>1. The outlet may need to know the "real time" warehouse's stock status.

Dial-up the internet and hit a web service - pass the parameters (item id?)

>2. Outlet may only need to upload their sales records by batch.
>3. HQ may upload outlets' stock adjustment, transfer and etc by batch.
>4. HQ, warehouse, and outlet want to have a local copy of it's own data.

All could be done at close of business for the day?


>
>Do you think, i should place all of the database/tables in web hosting too?

Your preference - it could be cheaper, and you can add users/nodes easier. Also no upgrades to nodes.

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>What if, I have desktop application as usual, then upload all updated data to web host after a period of time?

Your choice again - I think you need to determine the needs of the application, the proposed budget, the operating budget, etc. This will help you determine which route to take.

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>Do you think web services is the right way to go, or I upload the table to web host and then run ASP that will update the uploaded data?
>
Web services are the future - and the now. They work. Use them if they fit your needs.