Saving data instantly, onClose, save button? Which is better in this situation

In my GWT application, I have been saving everything that the user does instantly to the datastore in the background whenever they make changes. So far this has been fine because the things that the user can change aren't being changed a whole lot.

But now I have added a series of check boxes that the user can check & uncheck:

Would it be proper to save everything instantly to the database everytime the user checks/unchecks a box? The thing that's on my mind is reducing the amount of times my web application has to go to the server to save data. Facebook, Google, (and many many others) use a "Save" button whenever a user makes changes to a large amount of fields (say, to their user information).

I am trying to stay away from having a Save button, and so the thought came to mind about saving these values whenever the user closed or refreshed the page. I d开发者_StackOverflow社区on't know if that's proper either (what if there is a loss of power, and their system shuts down!), but I know that I could use it like this:

public void onClose(CloseEvent<Window> event) {
    //save changes to the datastore
}

I'm torn between the three methods and don't know which path to take! Any information will be helpful

Thank you!

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Your current system follows a really excellent design pattern which a lot of apps (web- and otherwise) are picking up lately: Eliminate the manual operation of 'saving'. I think you should stick with it.

That said, if you want to reduce the number of round-trips and server load, you can do a couple of things: You could restrict the number of saves-in-progress to one, so that if the user makes a change while you're waiting for a 'save' request to complete, you wait until that request completes before sending a new one. Or, you could start a timer when the user makes a change, and commit any changes when the timer expires - this is pretty much how GMail's auto-save of draft messages works.

Either way, don't rely on a close event to trigger sending state to the server: If the user's browser crashes, the close event won't fire and they'll lose all their changes.