XML feed downloaded into a local XML file then processing the local XML file

I'm trying to write an app which has the following functionality:

• a local XML file is used to provide data for the display,


• summary XML feed is used to compare dates with the local XML file, and the full XML feed is only downloaded into a local XML file if the summary date is more recent,


• if no network connection, or no download is needed, then use the local XML file.

My aim is to minimize unnecessary network traffic, and cope with situations where there is no network connection at all. The processing of the XML data is not a problem, just the transfer of the XML feed to a local file, if it has been created, and how to achieve this in more than 1 activity.

Please can anyone offer some tips to provide this functionality?

Thanks in advance.....Phil