Compressing Cache in Local Storage

   Hi dswersky;
Actually, DevForce already has a built-in class under IdeaBlade.Core.Ionic.Zlib.GZipStream to provide EntityCacheState compression capabilities.

Using this page, http://drc.ideablade.com/xwiki/bin/view/Documentation/code-sample-save-restore-chained-streams, as a guidance. I was able to modify the functions just a little bit so it uses IsolatedStorageFile for Silverlight.

      public void SaveCompressedEncryptedFile(EntityManager em, byte[] key, string fileName) {
        var provider = new AesManaged { Key = key, IV = key };
        using (IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication()) {
          using (IsolatedStorageFileStream isfs = new IsolatedStorageFileStream(fileName, 
            System.IO.FileMode.Create, isf)) {
            using (CryptoStream cs = new CryptoStream(isfs, provider.CreateEncryptor(), CryptoStreamMode.Write)) {
              using (GZipStream gz = new GZipStream(cs, CompressionMode.Compress)) {
                em.CacheStateManager.SaveCacheState(gz);
              }
            }
          }
        }
      }

      public void RestoreCompressedEncryptedFile(EntityManager em, byte[] key, string fileName) {
        var provider = new AesManaged { Key = key, IV = key };
        using (IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication()) {
          using (IsolatedStorageFileStream isfs = new IsolatedStorageFileStream(fileName,
            System.IO.FileMode.Open, isf)) {
            using (CryptoStream cs = new CryptoStream(isfs, provider.CreateDecryptor(), CryptoStreamMode.Read)) {
              using (GZipStream gz = new GZipStream(cs, CompressionMode.Decompress)) {
                em.CacheStateManager.RestoreCacheState(gz, RestoreStrategy.Normal);
              }
            }
          }
        }
      }

Hope this helps.