What Is Windows Azure Blob Storage Service

Azure BLOB storage is persistent Cloud data storage that serves a variety of purposes. Mike Forest shows the basics of how to use it, from offset through to snapshots and metadata; both from .NET, and by using the free tool, Cerebrata Azure Explorer.

Windows Azure Blob storage service can exist used to store and retrieve Binary Large Objects (BLOBs), or what are more commonly known as files. In this introduction to the Windows Azure Blob Storage service we volition embrace the difference betwixt the types of BLOBs you tin can shop, how to get files into and out of the service, how you can add metadata to your files and more.

There are many reasons why yous should consider using Hulk storage. Perhaps you desire to share files with clients, or off-load some of the static content from your web servers to reduce the load on them. However, if you lot are using Azure's Platform as a Service (PaaS), also known equally Deject Services, y'all'll most probable exist very interested in BLOB storage because it provides persistent data storage. With Cloud Services yous get dedicated virtual machines to run your code on without having to worry about managing those virtual machines. Dissimilar the hard drives found in Windows Azure Virtual Machines (the Infrastructure every bit a Service -IaaS- offering from Microsoft), the hard drives used in Cloud Services instances are not persistent. Because of this, any files y'all want to accept effectually long term should be put into a persistent shop, and this is where BLOB storage is and then useful.

Where Do We Showtime?

BLOB Storage, along with Windows Azure Tables and Windows Azure Queues brand up the 3 Windows Azure Storage services. Azure tables are a non-relational, cardinal-value-pair storage machinery and the Queue service provides basic bulletin-queuing capabilities. All three of these services store their information within a Windows Azure Storage Account which we will need to become started. At the time of writing, each account can concord up to 200 TB of information in any combination of Tables, Queues or BLOBs and all iii can be accessed via public HTTP or HTTPS REST based endpoints, or through a diverseness of client libraries that wrap the REST interface.

To go started using the BLOB service, we'll first need to take a Windows Azure account and create a Storage Account. Y'all can get a free trial account or, if you have a MSDN Subscription, you can sign upwardly for your Windows Azure benefits in order to try out the examples included in this commodity. After you have signed upward for your Azure account, you tin then create a storage account that can then exist used to store BLOBs.

To create a storage account, log in to the Windows Azure management portal at https://manage.windowsazure.com. Later on you log in to the portal you can quickly create a Storage Business relationship by clicking on the large NEW icon at the bottom left hand of the portal.

From the expanding carte select the 'Data Services' selection, then 'Storage' and finally, 'Quick Create'.

You volition at present demand to provide a name for your storage account in the URL textbox. This name is used equally part of the URL for the service endpoint then information technology must be globally unique. The portal will indicate whether the proper name is bachelor whenever yous interruption or finish typing. Adjacent, you select a location for your storage account by selecting one of the data center locations in the dropdown. This location volition be the primary storage location for your information, or more simply, your account will reside in this Data Middle. If you have created 'affinity groups', which is a friendly proper name of a collection of services you desire to run in the same location, you lot volition as well run across that in your drop downwardly listing. If you accept more than one Windows Azure subscriptions related to your login address, you lot may also see a dropdown listing to enable you to select the Azure subscription that the account will belong to.

All storage accounts are stored in triplicate, with transactionally-consistent copies in the primary data center. In improver to that redundancy, you can also choose to have 'Geo Replication' enabled for the storage account. 'Geo Replication' ways that the Windows Azure Tabular array and BLOB data that yous place into the account will non merely be stored in the primary location but will also be replicated in triplicate to another information eye within the aforementioned region. So, if you select 'West US' for your chief storage location, your account volition too have a triplicate copy stored in the Due east US information eye. This mapping is done automatically by Microsoft and yous tin can't command the location of your secondary replication, but it will never be exterior of a region so you don't have to worry about your Westward Usa based account somehow getting replicated to Europe or Asia as part of the Geo Replication feature. Storage accounts that take Geo Replication enabled are referred to every bit geo redundant storage (GRS) and price slightly more accounts that practice non accept it enabled, which are called locally redundant storage (LRS).

One time you take selected the location and provided a name, you can click the 'Create Storage Business relationship' action at the bottom of the screen. The Windows Azure portal volition then generate the storage account for you within a few moments. When the business relationship is fully created, you will encounter a condition of Online. By selecting the new storage business relationship in the portal, you lot tin can retrieve i of the access keys we will need in order to work with the storage business relationship.

Click on the 'Manage Access Keys' at the bottom of the screen to display the storage account name, which you provided when y'all created the account, and ii 512 scrap storage access keys used to authenticate requests to the storage business relationship. Whoever has these keys will have complete control over your storage account short of deleting the entire account. They would accept the ability to upload BLOBs, alter table data and destroy queues. These account keys should exist treated as a surreptitious in the same style that you would guard passwords or a individual encryption key. Both of these keys are agile and will piece of work to access your storage account. It is a good practice to apply one of the keys for all the applications that employ this storage account and then that, if that key becomes compromised, you can use this dialog to regenerate the primal you oasis't been using, then update the all the apps to apply that newly regenerated key and finally regenerate the compromised key. This would prevent anyone abusing the account with the compromised key.

Your storage account is now created and we have what we need to work with information technology. For now, get a re-create of the Primary Admission Fundamental by clicking on the copy icon next to the text box.

What Kind of BLOB is that?

Any file blazon can be stored in the Windows Azure BLOB Storage service, such as Image files, database files, text files, or virtual difficult bulldoze files. However, when they are uploaded to the service they are stored as either a Page Hulk or a Block BLOB depending on how you programme on using that file or the size of the file you demand to work with.

Page BLOBs are optimized for random reads and writes then they are most ordinarily used when storing virtual hard drive files for virtual machines: In fact, the Page BLOB was introduced when the commencement virtual drive for Windows Azure was appear: the Windows Azure Cloud Drive (at the time they were known every bit Windows Azure 10-Drives). Nowadays, the persisted disks used by Windows Azure Virtual Car (Microsoft's IaaS offer) too apply the Page BLOB to store their data and Operating System drives. Each Page BLOB is made up of one or more 512-byte pages of data, upward to a total size limit of 1 TB per file.

The majority of files that you lot upload would benefit from beingness stored every bit Block BLOBs, which are written to the storage account equally a serial of blocks so committed into a single file. We tin can create a large file by breaking information technology into blocks, which tin can be uploaded meantime and then and then committed together into a single file in one operation. This provides united states with faster upload times and better throughput. The client storage libraries manage this procedure past uploading files of less than 64 MB in size in a single functioning, and uploading larger files across multiple operations by breaking downwardly the files and running the concurrent uploads. A Block BLOB has a maximum size of 200 GB. For this commodity nosotros will be using Block BLOBs in the examples.

Upload a File Already!

With a storage account created, and our access key available, we can apply any of the three Windows Azure storage services including Hulk storage from outside of Windows Azure. Of course, you lot'll want a way of viewing your Blob storage in the same way you await at any other file system. We'll show y'all how a bit subsequently, only if you're developing an application, your outset business organisation will probably be to have the means to upload files automatically from code. We will therefore now look at the code that is required to upload a file, starting with a simple console application that uploads a file using the ii.0 Windows Azure .Internet client library in C#.

Using Visual Studio create a new C# Console application.

When the standard console application is created from the template, it will not have a reference to the storage customer library. We will add it using the Package Manager (NuGet).

Right-click on the projection, and select 'Manage NuGet Packages' from the context menu.

This will load upward the Package Managing director UI. Select the 'Online' tab from the Packet Director dialog, and search for 'Azure Storage'. As of the fourth dimension of this writing version 2.0.5.1 was available. Select the Windows Azure Storage bundle and click 'Install'.

If y'all adopt to manage your packages via the Package Managing director Console, you can also type Install-Package WindowsAzure.Storage to achieve the aforementioned event. The Package Manager volition add the references needed past the storage client library. Some of these references won't exist utilized when simply working with Blob storage. Below you tin can come across that several assembly references were added, but specifically the Microsoft.WindowsAzure.Configuration and Microsoft.WindowsAzure.Storage assemblies are what we will be working with in this case.

Open up the programme.cs file and add together the following using statements:

using Microsoft . WindowsAzure . Storage ;

using Microsoft . WindowsAzure . Storage . Auth ;

using Microsoft . WindowsAzure . Storage . Blob ;

Then add this code to the Main method:

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cord accountName = "YOUR_ACCOUNT_NAME";

cord accountKey = "YOUR_ACCOUNT_KEY";

try

{

StorageCredentials creds = new StorageCredentials ( accountName , accountKey ) ;

CloudStorageAccount account = new CloudStorageAccount ( creds , useHttps : true ) ;

CloudBlobClient client = account . CreateCloudBlobClient ( ) ;

CloudBlobContainer sampleContainer = client . GetContainerReference ("samples") ;

sampleContainer . CreateIfNotExists ( ) ;

CloudBlockBlob blob = sampleContainer . GetBlockBlobReference ("APictureFile . jpg") ;

using ( Stream file = System . IO . File . OpenRead ("MiniAzure . jpg") )

{

blob . UploadFromStream ( file ) ;

}

catch ( Exception ex )

{

Console . WriteLine ( ex ) ;

}

Console . WriteLine ("Washed . . . press a key to end .") ;

Console . ReadKey ( ) ;

Alter the lawmaking to add the storage account name for the accountName variable and the storage account access key from when you created the account in the portal for the accountKey variable. Also, substitute the file name used with the OpenRead method with a file that you wish to upload. I'd suggest an image or something pocket-sized for this example. For real applications, you lot will want to accept the account name and cardinal in a configuration file, or passed in and then that you are not hard-coding these values.

The account name and cardinal values are used to create a StorageCredential instance, which is then used to create an example of the CloudStorageAccount object. The CloudStorageAccount object represents a storage account that you will be accessing. From this object y'all can obtain references to BLOBs, tables and queues inside the storage account. Note that when nosotros create the instance of the CloudStorageAccount, we specify 'true' for the useHttps constructor argument. This will cause all of our performance calls to our storage account to exist encrypted with SSL. Because all wire-level communications are therefore encrypted, and all requests are signed using the credentials provided in the StorageCredential object, nosotros tin can have some confidence that our operations are secure from prying optics.

Since we are using BLOB storage, nosotros then create an instance of a CloudBlobClient object to provide the client interface that is needed to work with BLOBs. Using the CloudBlobClient object nosotros and then get a reference to a container. A container is much similar a base directory off the root of a hard drive. In this example, the container we are getting a reference to is named "samples". On the next line, we call CreateIfNotExists which will actually cause the client library to telephone call out to the public REST endpoint in Windows Azure to bank check if the container exists and, if non, volition create the container. This provides u.s. a location to upload our file to.

The last portion of the code gets a reference to a block BLOB inside the container we created. This file doesn't exist yet, we are just creating a reference to it every bit a CloudBlockBlob object. We volition then use this to upload the file by providing a file stream of our file to the UploadFromStream method. The client library will so ship up the file, creating the file in our Azure storage account. Note that many of the customer library methods support the asynchronous programming pattern using Begin/Finish versions. For instance, to asynchronously start an upload you lot tin call BeginUploadFromStream.

The client library may make more than one telephone call to the Residue API to upload the file if it is fairly large. You lot can control the size of file that is sent upwardly as a unmarried operation past setting the SingleBlobUploadThresholdInBytes property. This defaults to 32 MB and tin be prepare as high at 64 MB. Annihilation over that 64 MB mark volition exist automatically broken into smaller blocks and uploaded. If a file does go broken downwards by the client library for upload, it volition use a single thread by default to perform the upload. You can set up the ParallelOperationThreadCount property to indicate how many threads you would like the client library to use to concurrently upload your file. Just be sure to be careful that if you are asynchronously uploading a lot of files and setting the ParallelOperationThreadCount option fairly loftier, you may see some 'bottlenecking' and deadening throughput.

Ahhh, Where Did the File Go?

When you lot run the code provided higher up, y'all actually won't see much happening. If the file uploaded with no errors and so y'all'll simply come across "Washed… press a key to end." appear in your console. Did it piece of work? Do you now have a file in your storage account? This is where it is handy to take a way of viewing, copying, and deleting files in BLOB storage simply as y'all would in a file organization, which is exactly what Azure Explorer from Cerebrata is fabricated for.

Download and install Azure Explorer for free at http://www.cerebrata.com/labs/azure-explorer . This is a click-once deployed application, and then you'll be notified of updates to the awarding as they are released.

The interface for Azure Explorer looks a lot like Windows Explorer in Windows 8. You lot see the ribbon interface at the height and the local estimator drives listed (C:, D:, etc.). Y'all can apply this tool to motion files around your computer also; yet, the existent ability is under that Azure Storage Accounts node circled in red. Right-click on the 'Azure Storage Accounts' Node and select "Add Account".

Add the storage business relationship proper noun and the access primal to the dialog. These are the same values that you retrieved from the portal when you created the account, and the values you used for the accountName and accountKey variables in your lawmaking. Yous tin can test that your values are right using the 'Test Connection' button. Once y'all get a expert connection, click 'OK'. Some of you may be tempted to try using the access key you lot see above to mess with my storage business relationship, but that won't get yous too far. The key is nonetheless larger than you see in the dialog and I've already regenerated the access keys.

Now if you aggrandize the Azure Storage Accounts node, you'll encounter the business relationship you just added. By then drilling into that tree view you'll meet the container that we created through our lawmaking, and the file that nosotros uploaded. If y'all live in London, or any of the not bad cities that happen to fall into the UTC time zone, the modified date on the file will expect right; notwithstanding, if y'all live in one of the other time zones than you'll notice that information technology doesn't quite lucifer up with your appointment time. Windows Azure services shop everything in UTC and will study all dates in that time zone as well. Please conduct this in mind.

By using Azure Explorer, we can

upload new files
download files that are in our storage account
delete files
rename files

In fact, most of the operations you'd await to be able to do to manage files on a file system are bachelor for Blob storage via Azure Explorer, including drag and driblet. The file tin can even be opened past double-clicking on information technology, causing it to exist downloaded to a temporary directory and opened with an application on your machine registered to work with the file type you selected.

Cool! How do I Share Files with Others?

One of the benefits of using BLOB storage is so that the content can easily exist shared with others. Every file that you identify into Hulk storage can actually exist reached via a URL. If y'all right-click on the file in Azure Explorer, you tin can select 'Copy Path'.

This volition copy the URL of the file onto your clipboard. The URL will wait something like this: https://reallyimportantdata.blob.core.windows.net/samples/APictureFile.jpg .

In theory we can just hand out that URL to anyone we want to share the file with; yet, this is not the case with the Hulk we simply uploaded. If we paste that URL into a browser you'll see that y'all get a HTTP 404 response: File Non Institute.

What?! We see that the file exists by using Azure Explorer, and then why doesn't the URL work? Past default when containers are created they are created as private containers unless specified otherwise. This ways that simply those people who have the business relationship credentials, or a peculiarly-generated URL created using those credentials, may access the file.

If we right-click on the storage business relationship node, and so we can select 'New Blob Container', which will show united states of america a dialog we can utilize to create a new container, including the ability to select the access level for the content of the container. We can select from Private, Blob admission or Container access. If we set the property to 'Container' then anonymous callers can iterate through, and view, all of the BLOBs inside a container, though they tin can't admission the contents of other containers within a storage account. If the holding is set to 'Blob', then the anonymous callers can only get BLOBs that they accept a directly URL for, or can judge at.

Create a new container and so utilize Azure Explorer to copy the file that nosotros uploaded from the private container over to the public container, or but add any file from the local calculator past dragging information technology into the new public container. You can drag and drop the file from 1 container to the other, or apply the context menus for Copy and Paste only like you would with Windows Explorer. If we select the 'Copy Path' option from the file in the new public container and attempt to reach the Hulk via the URL, nosotros will now find that we get the file served to u.s..

If we wanted to apply code to gear up a BLOB Container to have specific permissions, we would practice so by using the BlobContainerPermissions object. Here is an case of altering the lawmaking we have already used, except that nosotros fix the permission level on information technology directly after nosotros create the container.

CloudBlobContainer sampleContainer = client . GetContainerReference ("samples") ;

sampleContainer . CreateIfNotExists ( ) ;

sampleContainer . SetPermissions ( new BlobContainerPermissions ( ) {

PublicAccess = BlobContainerPublicAccessType . Container

} ) ;

When setting the PublicAccess property on the BlobContainerPermissions object initializer, we chose between 'Container' and 'Blob'. This determines the level of access to the content of the container that bearding requests volition get. These options correspond to the 'Blob' and 'Container' options that we had when we utilize Azure Explorer to create the container.

When we are hosting public files that will be individually accessed by anonymous clients who know what they are looking for it is a proficient idea to set the container to the 'Blob' access permissions. A very common example of this would be if nosotros utilize Blob storage to keep all of our JavaScript, CSS and image files for a website. The HTML returned from our server volition have direct URL locations of the BLOBs so the clients do not need to iterate through the contents of a container. However, if a customer may non know the verbal URL of a file and may demand to see all of the files within a container then set the access permissions to 'Container' admission.

What is application/octect-stream?

If nosotros take a look at the file that we take uploaded from code to the account using Azure Explorer, we'll notice that i of the detail columns is "Content Type". It likely says "application/octet-stream" for the file.

The content type is returned as a HTTP Header when clients asking the file out of BLOB storage, just equally it is when files are served from most web servers. The specific content type of application/octet indicates that the file is a binary file but the data isn't exactly that useful beyond that. Modern browsers can decipher the actual type of file when it requests the file, which is why, when we requested this file via the browser, it pulled up the moving picture for us to see. Unfortunately, not all file types may go recognized and less intelligent clients might have a hard time deciding what to practise with the file it is receiving. It would be ameliorate if we correctly ready the content type and then that the clients requesting the file know what they are getting. There are a couple of ways we can ready this value.

If we are uploading Blob using the client library we can prepare the ContentType by setting the ContentType property. As we have seen the default is application/octet-stream. The lawmaking would await like this:

CloudBlockBlob hulk = sampleContainer . GetBlockBlobReference ("APictureFile . jpg") ;

blob . Backdrop . ContentType = "prototype / png";

Now when we run our upload lawmaking, we'll run into that the content type is ready correctly. If nosotros needed to update the content type on files that already exist in the container without re-uploading the actual file, we can update their properties by getting a reference to the Hulk. With this reference, we tin fetch the current values, set the property that we want to update and call SetProperties on the Hulk.

CloudBlockBlob blob = sampleContainer . GetBlockBlobReference ("APictureFile . jpg") ;

blob . FetchAttributes ( ) ;

blob . Backdrop . ContentType = "epitome / png";

blob . SetProperties ( ) ;

Be very careful to ensure y'all phone call FetchAttributes: This volition brand a phone call to the Remainder API to call back all the metadata and properties for the BLOB, just non the content of the file. If y'all omit the call to FetchAttributes, then y'all could lose other belongings values because it volition overwrite all of the backdrop when yous telephone call SetProperties.

If we only needed to modify the content blazon of just a few files, or whatsoever other holding for a Blob, we tin employ Azure Explorer to practise and so much more than conveniently. Select the file yous'd like to modify in Azure Explorer, right-click and select 'Properties' just similar you would do from Windows Explorer. Alternatively, you can select a file and click on the 'Properties' icon in the ribbon menu. A dialog volition announced that has several tabs, including a "Properties" tab.

From here y'all tin easily gear up any of the property values and select 'Utilize' to update the Hulk.

Getting Our Data Back

And so far we have uploaded files and pulled them back using a Browser or Azure Explorer, but what if nosotros demand to pull the code back downwards using the customer library? This is accomplished in much the same manner equally when nosotros uploaded it. We will go a reference to the blob and then employ that reference to write to a filestream.

CloudBlockBlob hulk = sampleContainer . GetBlockBlobReference ("APictureFile . jpg") ;

using ( Stream outputFile = new FileStream ("Downloaded . jpg", FileMode . Create ) )

{

blob . DownloadToStream ( outputFile ) ;

}

Behind the scenes, the client library is making a call to the Balance API to recollect the content of the file. This may result in one or more than calls to the Residue API only as it did when we uploaded it, depending on the size of the file. The slap-up thing most the client library is that it abstracts abroad all this complexity for you.

When you are developing, or just managing a private container for your ain personal files, you lot will find that a storage tool like Azure Explorer will be much more convenient to quickly pull downwardly files. Using Azure Explorer yous can quickly drag and drop any of the files yous see to your desktop or another location and the tool will download the file to that location. You lot tin also use the Download icon on the ribbon bill of fare as well.

Giving BLOBs Significant

I of the really slap-up features of Hulk storage is that we can add metadata to a BLOB. This lets usa provide some additional information to a Blob to give information technology context. For example, we might add a DocumentSource value to a Hulk so as to indicate where a Hulk came from, or mayhap give a Word document a metadata value for the writer of the document. These metadata values can and so exist looked at either in code or from tools like Azure Explorer. Metadata for a Hulk are Key-Value pairs of data. The keys must adhere to the C# Identifier naming conventions and are instance in-sensitive, simply they do retain the casing they were created with. The whole metadata item (fundamental and value together) cannot exceed 8K in size.

We can add metadata to BLOBs when they are created or later on, as part of an update. The post-obit lawmaking would gear up a Source metadata value before nosotros uploaded our epitome in the previous example:

CloudBlockBlob hulk = sampleContainer . GetBlockBlobReference ("APictureFile . jpg") ;

blob . Properties . ContentType = "epitome / png";

blob . Metadata . Add ("Source", "Mike Wood") ;

using ( Stream file = System . IO . File . OpenRead ("MiniAzure . jpg") )

{

blob . UploadFromStream ( file ) ;

}

If we wanted to edit the MetaData that was already on an existing Blob, the code would wait very similar to the lawmaking that updated the Content Type.

CloudBlockBlob blob = sampleContainer . GetBlockBlobReference ("APictureFile . jpg") ;

blob . FetchAttributes ( ) ;

blob . Metadata ["Source"] = "Michael Forest";

blob . SetMetadata ( ) ;

Notice that we once once more demand to phone call FetchAttributes so that all the electric current BLOB backdrop and metadata is pulled down. We then change what we desire and call SetMetadata to push the alter back upwards to the BLOB.

We can add together metadata to BLOBs and even BLOB containers. This is a groovy mode to assist provide pregnant to our containers and files, thereby assuasive united states of america to provide context to them that the calling lawmaking can use. As well merely like with ContentType, we can access and modify the metadata for a Hulk or container from Azure Explorer by using the Metadata tab on the Properties dialog.

Practise not become metadata values in BLOB storage confused with embedded file properties as they are non the same. For case, if nosotros use Windows Explorer to look at the properties for a MP3 file or JPG file yous might see details that include the Anthology name for the song or the shutter speed used to take the picture. These are embedded details of the file itself. The metadata nosotros add to the BLOBs are dissever and only accept significant within BLOB storage.

What is this Snapshot tab for?

When we were looking at the properties and metadata, you may accept noticed that there was a tab within Azure Explorer that was for snapshots. Nosotros have the adequacy in Blob storage of taking a snapshot of a Hulk, which preserves the content of a Blob at a particular time. Nosotros could, for example, utilize this to go along a historical record of changes to a file over fourth dimension, with the power to retrieve an older version of that file.

We can create a snapshot of a BLOB fairly easily from code. Modifying the case nosotros had earlier for uploading a file, nosotros can alter the code to take a snapshot of the file that we already added. Then I'll upload another prototype to the aforementioned BLOB name which will effectively overwrite the image.

CloudBlockBlob blob = sampleContainer . GetBlockBlobReference ("APictureFile . jpg") ;

hulk . CreateSnapshot ( ) ;

using ( Stream file = Arrangement . IO . File . OpenRead ("STS134Launch . jpg") )

{

blob . UploadFromStream ( file ) ;

}

Now if nosotros endeavor to reach the regular BLOB URL, or try to open up the Blob straight from Azure Explorer, nosotros'll encounter that the image was indeed overwritten with the newer image. We tin can employ Azure Explorer to look at the properties for the APictureFile.jpg file to see that the snapshot tab has some information in information technology. For each snapshot on the Blob we will encounter the date and time that the snapshot was created and the URL that could be used to direct access the snapshot.

As you tin can see, Azure Explorer can easily manage snapshots likewise. You can download specific snapshots of a Hulk, create new ones or even promote an older snapshot to overwrite the current version. In this case the promotion will revert the file back to our original image.

While we are charged by how much information we store in the BLOB account information technology doesn't necessarily mean that we are charged per snapshot. In the example above, I replaced the original content with a completely different file; nonetheless, Hulk storage is smart enough to keep just a delta whenever possible. For example, if the file was a 4 MB text file and nosotros took a snapshot, when nosotros append another 2 MB to the cease of the file we will only exist charged for storing 6 MB of data, not 10 MB. That'due south 4 MB for the original and the snapshot, so some other 2 MB for the delta. Simply remember that the amount of storage is calculated using the current size of a Blob plus all of the deltas of any snapshots. For instance, a 2 MB current Blob has a snapshot that was 10 MB in size you may be getting charged at least ten MB and up to 12 MB depending on just how different the files were.

What near Nested Folders?

When developers piece of work with files they often also bargain with nested folder structures. Since Windows Azure BLOB storage has a much more flat structure it is important to point out the differences from what you may be used to on a file system. It may be common on a traditional file system to accept a binder structure such every bit \content\images\icons. These are distinct folders that are nested under each other and may contain files in addition to other folders. In Windows Azure Blob storage a container tin simply comprise BLOBs. Information technology cannot incorporate other containers; all the same, with a piffling sleight of hand we can provide the illusion of nested containers.

Go back and alter the code we worked with higher up and modify the GetBlockBlobReference method phone call line to the following:

CloudBlockBlob blob = sampleContainer . GetBlockBlobReference ( @"nestedcontainer / APictureFile . jpg") ;

Find that we added what appears to be a folder name and slashed delimiter to the name. At present when we run the code again you can refresh Azure Explorer to see that information technology appears we actually practice take a nested folder structure.

In reality, nosotros have a container named samples that contains 2 BLOBs. One Blob is named APictureFile.jpg and the other is named nestedcontainer/APictureFile.jpg. The forrard-slash character is within the Hulk proper name itself, and the nested folder structure is an illusion.

Using Azure Explorer, we tin can click on the New Folder icon in the ribbon when looking at a container and add a new folder: All the same, unless you put something into that folder y'all actually haven't created anything in the container. Over again, this is because nested folders really do not exist in BLOB storage.

When working with BLOB storage from code with the client library you can apply the CloudBlobDirectory class to simulate nested directories as well. If the following code was put into our console application it would become a reference to the nestedcontainer "directory" nosotros created before and list all of the BLOBs in it.

CloudBlobDirectory dir = sampleContainer . GetDirectoryReference ("nestedcontainer") ;

var files = dir . ListBlobs ( ) ;

foreach ( IListBlobItem detail in files )

{

Console . WriteLine ( item . Uri ) ;

}

You'll notice that the CloudBlobDirectory doesn't have a create method and that is considering we tin't really create a directory. Nosotros tin only create BLOBs that accept the appearance of being within a directory; however, using the CloudBlobDirectory object nosotros can drill down into our virtual nested directory structures. Behind the scenes what is really happening is that the client library is sending requests to the REST API that is filtering the BLOBs within a container to those that start the same and have a delimiter in them, in this case "nestedcontainer/".

More on Azure Explorer

With Azure Explorer, you can easily several storage accounts from an interface that is equally familiar as Windows Explorer. Certain, you tin practice some of the same operations from the web based Windows Azure portal, such every bit adding new BLOBs or editing metadata, the power to speedily move files between accounts or containers and working with snapshots only isn't as piece of cake as it is with Azure Explorer.

One really great feature of Azure Explorer is that yous tin use it to search your containers and accounts. You lot can even search across accounts and go a list of files with a specific file extension or those that match a regular expression. But select the node in the tree where you want the search to start from, and type in your search term in the search box. Once your results come up back, you can download all the files, motility them all to some other account and more than.

Summary

There are many means that BLOB storage tin aid your applications and processes, such as storing files off site, creating a file-sharing mechanism with partners or even share files with anyone.

The Windows Azure BLOB storage services provide many more features than the essentials that we've covered here. If yous are looking for places to acquire more, I'd like to suggest checking out the Windows Azure Training Kit as well as the documentation and 'How To' articles on WindowsAzure.com. Hither are a few topics that I think y'all'll desire to understand as y'all dive into employ Blob storage:

How to use an ETag on BLOBs to assist deal with concurrent edits.
How to utilise the Shared Access Signatures to create a unique URI for a Blob that will give anyone with that link access to a Blob based on some fourth dimension based policy. This is a groovy feature for giving express access to private BLOBs to people without giving them your account primal.
How to turn on and monitor storage account statistics and so that y'all can see how your BLOBs are beingness accessed.
How to leverage Retry policies when using the Client Library through the BlobRequestOptions parameter that tin be passed to nearly of the BLOB operations. This is very important for dealing with transient errors that might occur in distributed systems.
How to leverage the Windows Azure Content Delivery Network (CDN) to betrayal the BLOBs in your public containers to a earth-broad gear up of data centers so that your content is closer to your finish users, thereby making it quicker for them to admission.
Understanding how you are charged for using the Blob storage service. Currently you lot are charged by how much data you lot shop in your account besides as the number of transactions against your account. The corporeality of these charges take been going down as the deject vendors make file storage a article, but it is all the same important to sympathize how you are charged no affair how small the amounts are.

Equally you lot piece of work with learning more virtually the Hulk storage services I recommend continuing to use Azure Explorer. You'll find a storage tool indispensable if you work with Blob storage regularly. Cerebrata is always looking to improve their products and then experience free to contact them with your ideas and whatsoever issues you may meet. Also, if y'all discover that you need a few more than features than are offered past Azure Explorer you lot ought to look at the Azure Management Studio product from Cerebrata which is a more wide-ranging management tool roofing non simply Blob storage, merely also table storage, storage queues, and fifty-fifty managing your deployed compute nodes in Windows Azure.