How can I save multiple files locally in Silverlight?

Question

My problem is I have a LOB application that can possibly save multiple files (number of files only known at runtime) based on user inputs. Saving this as a single file and having the user break them apart, or zipping them up as a single file is not an option unfortunately.

SaveFileDialog seems suited to only save 1 file at a time. Third party controls may be an option but I have yet to find any that serve this purpose. Thanks!

Answer 1

The browser security model guidelines (outside of Silverlight) prohibit web application logic (script or otherwise) from having direct access to the local file system.

Consider what havoc a malicious web site could wreak on your computer if web application script could write arbitrary files to arbitrary locations on the local hard disk!

For this reason, Silverlight isolates your code away from the local file system. Silverlight manages the Open File or Save File dialogs, but your web app code never gets to see the full path of the file names directly for security reasons. The Silverlight dialog only supports working with one filename / path at a time.

Silverlight does offer isolated storage on the local machine in which your web app could write multiple files. However, as noted in comments, isolated storage is isolated in both directions - it keeps the web app isolated from the local file system, and that makes it difficult for the end user to access the contents of the isolated storage outside of the browser. (Difficult enough to make it infeasible for nontechnical users, but not difficult enough to call isolated storage "secure" from malicious snooping).

Short of writing your own native executable browser extension (for each different browser brand and version you wish to support) (or non-sandboxed javascript plugin for some browsers), I don't think there is a way for a web app to push data into multiple local files convenient to use outside of the browser in one user action.

Answer 2

Since this is an LOB in the intranet zone have you considered asking your users to install the app as OOB with Elevated trust. This would allow you to write files to the users Documents folder without the SaveFileDialog.

The other option is to zip the files with a single SaveFileDialog call.

There are no other Silverlight oriented solution.