大家好，我们知道Windows Azure平台上我们可以将自己的数据存在各式各样的结构中，例如Blob适合大文件和二进制流文件，Table适合存储一些较有结构层次的数据，Queue适合作为不同Role之间的通信消息存储，SQL Azure适合大型的关系数据库。这几种结构中SQL Azure作为一个独立的部分和其他3种有少许不同，SQL Azure本质上来收是一个分布式的SQL Server，除开Federation上的一些问题，其他部分和普通的SQL Server类似。而Blob，Table，Queue统称为Azure Storage，是一种云端的存储方式，Azure Storage中数据通常是比较安全的，Azure会将你的数据备份3份，一旦发生任何故障，Fabric control都会帮助你自动创建新的备份，所以不必担心因为断电或者硬件问题造成的数据丢失或错误。
看到这里可能有些读者就比较疑惑了，之前你提到Azure会帮助我们做到自我备份，那么你还写这样一篇文章来说备份做什么呢? 其实不是这样的，Azure能帮你做到的是物理备份，用意是防止数据丢失，保证服务的稳定。对于你来说，你并不需要知道Azure是怎样为你的数据备份的，你能看到只是你自己数据而已。试想一下，就算你有3份备份在Azure storage上，如果此时你不小心误操作一些数据，Azure会按时间将你错误的数据统统复制3份去替代原先正确的数据，这样的话就前功尽弃了。
这里我们提到的是逻辑意义上的备份，在你的数据非常重要且敏感的情况下，多做一份逻辑备份是非常有必要的，这里我们举一个例子来说明如何在Azure的平台上通过代码来做到逻辑备份，当然你也可以设置定时备份这样的功能。写代码之前还是那句话，需要安装一些Azure组件在你的机器里，这些是必不可少的准备工作：
Azure 账号和 Storage账号（下文将会提到），没有的话可以去注册一个或者使用试用版，目前Azure看起来是已经登录中国了，大家可以关注一下。
[本示例完整源码下载(0分)] http://download.csdn.net/detail/aa466564931/5483345
首先我们创建一个Web Role，首先设计好你的UI，最最简单的是放置一个按钮就可以了，当然为了让我的页面看起来更佳美观和好用，我们还是放置更多一些的内容在页面上，首先说Blob的备份。
HTML代码：
<asp:Label ID="lbContent" runat="server" ForeColor="Red"></asp:Label>
<br />
<br />
<div style="border: 2px solid;">
<div style="font-style:italic;font-weight:bold">
Back up Blob Storage
Name Rule:
<p>
- Container names must start with a letter or number, and can contain only letters, numbers, and the dash (-) character.
</p>
<p>
- Every dash (-) character must be immediately preceded and followed by a letter or number; consecutive dashes are not permitted in container names.
</p>
<p>
- All letters in a container name must be lowercase.
</p>
<p>
Container names must be from 3 through 63 characters long.
</p>
<p> Check:
<a href="http://msdn.microsoft.com/en-us/library/windowsazure/dd135715.aspx">http://msdn.microsoft.com/en-us/library/windowsazure/dd135715.aspx</a> </p>
</div>
<br />
<br />
Source Container Name:
<asp:TextBox ID="tbSource" runat="server"></asp:TextBox>
<br />
Backup Container Name:
<asp:TextBox ID="tbCopies" runat="server"></asp:TextBox>
<br />
<asp:Button ID="btnBackup" runat="server" Text="Back up your Blob"
onclick="btnBackup_Click" />
<br />
<br />
<asp:Label ID="lbBackup" runat="server" ForeColor="Red"></asp:Label>
</div>
这里也提到当你创建Blob container时候必须遵守的一些命名规范（全为小写，长度3-63，禁止特殊字符除了“-”）。
继续添加一个按钮：
<asp:Button ID="btnUpload" runat="server" Text="Upload Resources to Storage"
onclick="btnUpload_Click" />
接下来我们在Azure项目中写入我们的Azure账号信息，右键点击Azure项目-左侧配置（settings）- 添加配置（Add Settings）- 类型选择连接字符串（connection string）- 点击最右侧的按钮 弹出设置Storage对话框 Account name为你的账号 Account key为你的密码，账户和密码可以在你的Azure的账户中心找到，这里如果你需要更详细的信息，请参照：
http://www.windowsazure.com/en-us/manage/services/storage/how-to-create-a-storage-account/
http://www.windowsazure.com/en-us/develop/net/how-to-guides/blob-storage/#configure-access
如果你是老用户，则可以跳过这一段。这里我们将这个connection string名字设为StorageConnections。（自定义）
接着让我们通过代码来创建一个Azure account因为我们不需要每次连接storage的时候都去重新创建一边Account，那么我们将account设为一个全局变量：
private CloudStorageAccount account;
List<string> nameList = new List<string>() { "MSDN.jpg", "Microsoft.jpg" };
protected void Page_Load(object sender, EventArgs e)
{
lbBackup.Text = string.Empty;
lbContent.Text = string.Empty;
account = CloudStorageAccount.FromConfigurationSetting("StorageConnections");
}
nameList只是我们需要备份的文件名，与创建account的过程无关。
接着是初次上传文件的代码, 也就是需要被备份的原始数据 （2张图片）：
/// <summary>
/// Upload resources to Storage.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
protected void btnUpload_Click(object sender, EventArgs e)
{
try
{
FileDataSource source = new FileDataSource("files");
CloudBlobClient client = account.CreateCloudBlobClient();
CloudBlobContainer container = client.GetContainerReference("blob");
container.CreateIfNotExist();
var permission = container.GetPermissions();
permission.PublicAccess = BlobContainerPublicAccessType.Container;
container.SetPermissions(permission);
bool flag = false;
foreach (string name in nameList)
{
if (!source.FileExists(name, "image"))
{
flag = true;
CloudBlob blob = container.GetBlobReference(name);
string path = string.Format("{0}/{1}", "Files", name);
blob.UploadFile(Server.MapPath(path));
FileEntity entity = new FileEntity("image");
entity.FileName = name;
entity.FileUrl = blob.Uri.ToString();
source.AddFile(entity);
lbContent.Text += String.Format("The image file {0} is uploaded successes. <br />", name);
}
}
if (!flag)
lbContent.Text = "You had uploaded these resources. The blob container name is 'blob', table name is 'files'";
else
lbContent.Text += "The blob container name is 'blob', The table name is 'files'";
}
catch (Exception ex)
{
lbContent.Text = ex.Message;
}
}
好了，接下来是备份按钮的代码，这里我创建了一个StorageManager类，用来检测Blob container和Blob是否存在，不存在则是无法备份了：
StorageManger.cs
public class StorageManager
{
/// <summary>
/// Check CloudBlobContainer is exists.
/// </summary>
/// <param name="container"></param>
/// <returns></returns>
public static bool CheckIfExists(CloudBlobContainer container)
{
try
{
container.FetchAttributes();
return true;
}
catch (StorageClientException e)
{
if (e.ErrorCode == StorageErrorCode.ResourceNotFound)
return false;
else
throw;
}
}
/// <summary>
/// Check CloudBlob is exists.
/// </summary>
/// <param name="blob"></param>
/// <returns></returns>
public static bool CheckIfExists(CloudBlob blob)
{
try
{
blob.FetchAttributes();
return true;
}
catch (StorageClientException e)
{
if (e.ErrorCode == StorageErrorCode.ResourceNotFound)
return false;
else
throw;
}
}
}
backup按钮：
protected void btnBackup_Click(object sender, EventArgs e)
{
try
{
if (tbSource.Text.Trim().Equals(string.Empty) && tbCopies.Text.Trim().Equals(string.Empty))
{
lbBackup.Text = "Source TextBox and Copies TextBox can not be empty";
return;
}
string sourceContainerName = tbSource.Text.Trim();
string copiesContainerName = tbCopies.Text.Trim();
CloudBlobClient client = account.CreateCloudBlobClient();
CloudBlobContainer sourceContainer = client.GetContainerReference(sourceContainerName);
if (!StorageManager.CheckIfExists(sourceContainer))
{
lbBackup.Text = "The source blob container is not exists";
return;
}
CloudBlobContainer copiesContainer = client.GetContainerReference(copiesContainerName);
copiesContainer.CreateIfNotExist();
var permission = copiesContainer.GetPermissions();
permission.PublicAccess = BlobContainerPublicAccessType.Container;
copiesContainer.SetPermissions(permission);
foreach (var blob in sourceContainer.ListBlobs())
{
string uri = blob.Uri.AbsolutePath;
string[] matches = new string[] { "blob/" };
string FileName = uri.Split(matches, StringSplitOptions.None)[1].Substring(0);
CloudBlob sourceBlob = sourceContainer.GetBlobReference(FileName);
CloudBlob copiesBlob = copiesContainer.GetBlobReference(FileName);
copiesBlob.CopyFromBlob(sourceBlob);
lbBackup.Text += String.Format("The image file {0} is backup successes. Copies container name is {1} <br />", FileName, copiesContainerName);
}
}
catch (StorageClientException ex)
{
if (ex.ExtendedErrorInformation.ErrorCode.Equals("OutOfRangeInput"))
lbBackup.Text = "Please check your blob container name.";
else
lbBackup.Text = ex.Message;
}
catch (Exception all)
{
lbBackup.Text = all.Message;
}
}
备份成功的blob会新创建好一个Blob，并且放在同一个BlobContainer下，你可以使用Storage Explorer检查一下是否备份成功了。
刚才我们提到的是Blob的备份，blob你可以想象就是一个个单独的文件的备份，比较简单和直观，如果我们需要Table storage这种有一定结构性的数据该怎么办呢？也很简单，首先我们需要为Table Storage建立一个类库，这样调用和阅读起来都比较方便。接着建立好一个实体类，这里你可以想象成数据库里表结构对应实体类，不过唯一的不同是这个实体类需要继承TableServiceEntity类，并且给两个特殊key赋值，PartitionKey和RowKey，Rowkey你可以想象成是你的列的主键，这是不可以重复的，而partitionkey是作为你的Table的分区键使用的，对Table storage来说会有更好的性能。代码如下：
public class FileEntity : TableServiceEntity
{
/// <summary>
/// No parameters constructor
/// </summary>
public FileEntity()
{
PartitionKey = "all";
RowKey = string.Format("{0:10}-{1}", DateTime.MaxValue.Ticks - DateTime.Now.Ticks, Guid.NewGuid()).Replace("-", "");
}
/// <summary>
/// With parameters constructor
/// </summary>
/// <param name="partitionKey"></param>
public FileEntity(string partitionKey)
{
PartitionKey = partitionKey;
RowKey = string.Format("{0:10}-{1}", DateTime.MaxValue.Ticks - DateTime.Now.Ticks, Guid.NewGuid()).Replace("-", "");
}
public string FileName
{
get;
set;
}
public string FileUrl
{
get;
set;
}
}
还需要一个用来创建查询的context类：
public class FileContext : TableServiceContext
{
public FileContext(string baseAddress, StorageCredentials credentials)
: base(baseAddress, credentials)
{
}
/// <summary>
/// Get all entities of table storage "files".
/// </summary>
public IEnumerable<FileEntity> GetEntities
{
get
{
var list = this.CreateQuery<FileEntity>("files");
return list;
}
}
/// <summary>
/// Get all entities of table storage "files_backup".
/// </summary>
public IEnumerable<FileEntity> GetBackupEntities
{
get
{
var list = this.CreateQuery<FileEntity>("files_backup");
return list;
}
}
}
最后我们可以建立Datasource类，方便view层和data层之间的相互调用（具体的方法都在这里，包括查询table，添加row，校验方法等等）
public class FileDataSource
{
private static CloudStorageAccount account;
private FileContext context;
private string tableName;
public FileDataSource(string tableName)
{
// Create table storage client via cloud account.
account = CloudStorageAccount.FromConfigurationSetting("StorageConnections");
CloudTableClient client = account.CreateCloudTableClient();
client.CreateTableIfNotExist(tableName);
this.tableName = tableName;
// Table context properties.
context = new FileContext(account.TableEndpoint.AbsoluteUri, account.Credentials);
context.RetryPolicy = RetryPolicies.Retry(3, TimeSpan.FromSeconds(1));
context.IgnoreResourceNotFoundException = true;
context.IgnoreMissingProperties = true;
}
/// <summary>
/// Get all entities method.
/// </summary>
/// <returns></returns>
public IEnumerable<FileEntity> GetAllEntities()
{
var list = from m in this.context.GetEntities
select m;
return list;
}
/// <summary>
/// Get table rows by partitionKey.
/// </summary>
/// <param name="partitionKey"></param>
/// <returns></returns>
public IEnumerable<FileEntity> GetEntities(string partitionKey)
{
var list = from m in this.context.GetEntities
where m.PartitionKey == partitionKey
select m;
return list;
}
/// <summary>
/// Get specify entity.
/// </summary>
/// <param name="partitionKey"></param>
/// <param name="fileName"></param>
/// <returns></returns>
public FileEntity GetEntitiesByName(string partitionKey, string fileName)
{
var list = from m in this.context.GetEntities
where m.PartitionKey == partitionKey && m.FileName == fileName
select m;
if (list.Count() > 0)
return list.First<FileEntity>();
else
return null;
}
/// <summary>
/// Add an entity.
/// </summary>
/// <param name="entity"></param>
public void AddFile(FileEntity entity)
{
this.context.AddObject(this.tableName, entity);
this.context.SaveChanges();
}
/// <summary>
/// Add multiple entities.
/// </summary>
/// <param name="entities"></param>
public void AddNumbersOfFiles(List<FileEntity> entities)
{
if (entities.Count() > 0)
{
int totleNumbers = entities.Count();
int uploadTimes = entities.Count() / 100;
if ((entities.Count() % 100) > 0)
uploadTimes += 1;
for (int i = 0; i < uploadTimes; i++)
{
if (i == uploadTimes - 1)
{
for (int j = i * 100; j < totleNumbers; j++)
{
this.context.AddObject(this.tableName, entities[j]);
}
this.context.SaveChanges();
}
else
{
for (int j = i * 100; j < (i + 1) * 100; j++)
{
this.context.AddObject(this.tableName, entities[j]);
}
this.context.SaveChanges();
}
}
}
}
/// <summary>
/// Make a judgment to check file is exists.
/// </summary>
/// <param name="filename"></param>
/// <param name="partitionKey"></param>
/// <returns></returns>
public bool FileExists(string filename, string partitionKey)
{
IEnumerable<FileEntity> list = from m in this.context.GetEntities
where m.FileName == filename && m.PartitionKey == partitionKey
select m;
if (list.Count()>0)
{
return true;
}
else
{
return false;
}
}
}
Table storage的按钮方法（同Blob，实现细节有少许不同，使用到了我们刚刚创建的TableStorageManager类库中的方法添加和查询Table Storage）
protected void btnBackupTable_Click(object sender, EventArgs e)
{
try
{
if (tbTabelSource.Text.Trim().Equals(string.Empty) && tbTableCopies.Text.Trim().Equals(string.Empty))
{
lbBackupTable.Text = "Source TextBox and Copies TextBox can not be empty";
return;
}
string sourceTableName = tbTabelSource.Text.Trim();
string copiesTableName = tbTableCopies.Text.Trim();
CloudTableClient client = account.CreateCloudTableClient();
if (!client.DoesTableExist(sourceTableName))
{
lbBackupTable.Text = "The source table is not exists";
return;
}
FileDataSource tableDataSource = new FileDataSource(sourceTableName);
List<FileEntity> sourceList = tableDataSource.GetAllEntities().ToList<FileEntity>();
client.DeleteTableIfExist(copiesTableName);
FileDataSource tableDataCopies = new FileDataSource(copiesTableName);
tableDataCopies.AddNumbersOfFiles(sourceList);
lbBackupTable.Text = String.Format("The source table {0} is backup successes. Copies table name is {1}", sourceTableName, copiesTableName);
}
catch (StorageClientException ex)
{
if (ex.ExtendedErrorInformation.ErrorCode.Equals("OutOfRangeInput"))
lbBackupTable.Text = "Please check your blob container name.";
else
lbBackupTable.Text = ex.Message;
}
catch (Exception all)
{
lbBackupTable.Text = all.Message;
}
}
而Storage的另一个对象Queue来说通常是作为消息机制而存在的，所以我们一般不会对Queue做备份工作，如果你确实需要对Queue进行备份，参考Blob的代码，并且将Blob container改为Queue的相对读取和创建的方法即可。
示例图片：
1 点击上传资源按钮. (需要被备份的对象) blob container名字为blob, table名字为files
2. 点击备份blob按钮 备份成功的blob container名字为blob-copy2
3. 在Azure storage explorer工具中可以快速找到备份blob对象
4. 点击table storage按钮 备份 新的table storage叫做filesCopy
5.同样可以再Storage Explorer找到备份对象 你可以与源对象进行比较
