Store Data when Your App Has Restricted Permissions

Problem : You need to save application and user data even when the app has no permission to access the local computer, such as when it’s running from the Internet security zone.

Solution: Use Isolated Storage. This is kind of like a virtual file system that .NET associates with an assembly, user, application domain, application (when using ClickOnce only), or a combination of these items. By using Isolated Storage, you can give programs the ability to store information without giving them access to the real file system.Here’s a simple example that creates a subdirectory and a text file:

using System;
using System.IO;
using System.IO.IsolatedStorage;

namespace IsolatedStorageDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Run with command line arg -r to remove isolated storage for this app/user");

            //get the isolated storage for this appdomain + user
            using (IsolatedStorageFile file =
                    IsolatedStorageFile.GetUserStoreForDomain())
            {
                //setup directory
                if (!file.DirectoryExists("Dummy"))
                {
                    file.CreateDirectory("Dummy");
                }
                Console.WriteLine("Accesses:");
                //read and write to a file in the directory
                using (IsolatedStorageFileStream stream =
                       file.OpenFile(@"Dummy\accesses.txt",
                       System.IO.FileMode.OpenOrCreate))
                using (TextReader reader = new StreamReader(stream))
                using (TextWriter writer = new StreamWriter(stream))
                {
                    string line = null;
                    do
                    {
                        line = reader.ReadLine();
                        if (line != null)
                        {
                            Console.WriteLine(line);
                        }
                    } while (line != null);

                    writer.WriteLine(DateTime.Now.ToString());
                }
                if (args.Length > 0 && args[0] == "-r")
                {
                    Console.WriteLine( "Removing isolated storage for this user/app-domain");
                    file.Remove();
                }
            }

            Console.ReadKey();
        }
    }
}

					    

After a few runs, the output looks like this:

Run with command line arg -r to remove isolated storage
for this app/user
Accesses:
7/4/2009 4:02:08 PM
7/4/2009 4:02:16 PM
7/4/2009 4:02:22 PM
7/4/2009 4:02:28 PM