Testing Telerik ZIPLibrary

The ZIP library I've been testing came with Telerik WPF Controls bundle. I assume that its interface and usage does not differ significantly if at all in Telerik Silverlight, WinForm and ASP.NET libraries.

Start using the library with adding the reference to Telerik.Windows.Zip.

Files can be compressed by calling either Add or AddStream methods of ZipPackage class. The second method allows choosing between compression algorithms.


private static void TestCompress()
{
    using (var compressedFile = File.Create(@"c:\temp\documents.zip"))
    {
        using (var zipPackage = ZipPackage.Create(compressedFile))
        {
            //zipPackage.Add(
            //    Directory.GetFiles(@"c:\temp").Where(
            //        item => new[] { ".doc", ".docx" }.Contains(Path.GetExtension(item))));

            foreach (var file in Directory.GetFiles(@"c:\temp").Where(
                    item => new[] { ".doc", ".docx" }.Contains(Path.GetExtension(item))))
            {
                zipPackage.AddStream(
                    File.OpenRead(file), 
                    Path.GetFileName(file), 
                    ZipCompression.Deflate64, 
                    DateTime.Now);
            }
        }
    }
}

File extraction is performed through accessing ZipPackageEntries collection of the ZipPackage.

private static void TestDecompress()
{
    const string SourceCompressedFile = @"C:\temp\documents.zip";

    using (var sourceStream = File.OpenRead(SourceCompressedFile))
    {
        using (var zipPackage = ZipPackage.Open(sourceStream))
        {
            foreach (var zipPackageEntry in 
                zipPackage.ZipPackageEntries.OrderByDescending(item => item.FileNameInZip))
            {
                Console.WriteLine(zipPackageEntry.FileNameInZip);

                using (var openInputStream = zipPackageEntry.OpenInputStream())
                {
                    using (var outputStream = 
                        File.Create(@"c:\temp\aa\" + zipPackageEntry.FileNameInZip))
                    {
                        openInputStream.CopyTo(outputStream);
                    }
                }
            }
        }
    }
}

The compression ratio is acceptable -- slightly below the WinZip's level and almost on par with the Windows' level.

Dec. 21, 2012: The following pair of methods shows how to work with strings. Note that Base64 conversion is used for handling zero bytes. Due to that do not expect getting any significant gain, or even any gain at all, on strings shorter than 1K.


private static string CompressString(string source)
{
    using (var memoryStream = 
        new MemoryStream())
    using (var outputStream = 
        new ZipOutputStream(memoryStream, ZipCompression.Default))
    using (var writer = 
        new StreamWriter(outputStream))
    {
        writer.Write(source);
        writer.Flush();
        return Convert.ToBase64String(memoryStream.ToArray());
    }
}

private static string DecompressString(string source)
{
    using (var memoryStream = 
        new MemoryStream(Convert.FromBase64String(source)))
    using (var inputStream = 
        new ZipInputStream(memoryStream))
    using (var reader = 
        new StreamReader(inputStream, Encoding.UTF8))
    {
        return reader.ReadToEnd();
    }
}

Creating SQL Server database backup using the Microsoft.SqlServer.Management.Smo

Assemblies to be referenced can be found in C:\Program Files\Microsoft SQL Server\100\SDK\Assemblies. The "100" part in the path may need to be changed to reflect the SQL Server version in use.

Microsoft.SqlServer.ConnectionInfo
Microsoft.SqlServer.Management.Sdk.Sfc
Microsoft.SqlServer.Smo
Microsoft.SqlServer.SmoExtended

A backup can be created in either sync or async mode. Below is a basic console implementation built around  the Backup class of the library.

using System;
using Microsoft.SqlServer.Management.Smo;

namespace SqlServerBackupStudy
{
    public class Program
    {
        public static void Main(string[] args)
        {
            TestCreateBackup(
                ".", 
                "MyDatabase", 
                @"c:\backup\test_backup.bak");

            Console.Write("\n\nAny key...");
            Console.ReadKey();
        }

        private static void TestCreateBackup(
            string serverName, 
            string databaseName, 
            string backupPath)
        {
            try
            {
                var server = new Server(serverName);

                var backup = new Backup
                    {
                        Database = databaseName, 
                        Initialize = true
                    };

                backup.Devices.Add(new BackupDeviceItem(
                            backupPath,
                            DeviceType.File));

                backup.SqlBackup(server);
            }
            catch (Exception ex)
            {
                Console.WriteLine(
                    "{0}\n{1}", 
                    ex.GetType(), 
                    ex.Message);
            }
        }
    }
}

Microsoft.SqlServer.Management.Smo.FailedOperationException can be caused by non-existent or unreachable server or database, as well as by invalid backup path. My guess that insufficient disk space should cause same exception.

It is important to understand that in case of DeviceType.File the destination path is meant to be a path on the machine that runs the SQL Server. In other words, do not expect creating backup of a remote database on your local drive. This may change eventually.

Database restoring routine uses the Restore class, and otherwise looks almost identical to the backup routine.



private static void TestRestoreFromBackup(
    string serverName, 
    string databaseName, 
    string backupPath)
{
    try
    {
        var server = new Server(serverName);

        var restore = new Restore
            {
                Database = databaseName
            };

        restore.Devices.Add(new BackupDeviceItem(
            backupPath,
            DeviceType.File));

        restore.SqlRestore(server);
    }
    catch (Exception ex)
    {
        Console.WriteLine(
            "{0}\n{1}",
            ex.GetType(),
            ex.Message);
    }
}

The exception may have one and more inner exception levels. The lowest one is the most instructive. Here is an example of three levels of exception.

1. Restore failed for server [server]
2. An exception occurred while executing a Transact-SQL statement or batch.
3. Cannot open backup device '...'. Operating system error 3(The system cannot find the path specified.).\r\nRESTORE DATABASE is terminating abnormally.

Also one has to ensure that the target database is not in use. Otherwise the following exception would pop up.

Exclusive access could not be obtained because the database is in use.\r\nRESTORE DATABASE is terminating abnormally.