Overview of the Windows Azure CDN

The Windows Azure Content Delivery Network (CDN) caches Windows Azure blobs and the static content output of computer instances at strategically placed locations to provide maximum bandwidth for delivering content to users.

We can enable CDN delivery for our content providers using the following link:

https://windows.azure.com

CDN is an add-on feature to your subscription and has a separate billing plan.

The CDN offers the customer a global solution for delivering high-bandwidth content by caching the content at physical nodes in the United States, Europe, Asia, Australia and South America.

The list of CDN node locations is in the following link location:

http://msdn.microsoft.com/en-us/library/windowsazure/gg680302

The benefits of using the CDN to cache Windows Azure data include:

• Better performance and user experience for end users who are far from a content source, and are using applications where many "internet trips" are required to load content
• Large distributed scale to better handle instantaneous high load, say, at the start of an event such as a product launch.

To use the Windows Azure CDN we must have a Windows Azure subscription and enable the feature on the storage account or hosted service in the Windows Azure Management Portal.

Note: Enabling the CDN may take up to 60 minutes (from the https://windows.azure.com/) to propagate worldwide.

Getting Started with the Windows Azure CDN

This quick start guide will show us how to enable the Windows Azure Content Delivery Network (CDN) and begin caching our content.

Steps

1. First set up a Windows Azure subscription
2. Create new "Storage account" under Hosted Services, Storage accounts & CDN section.
3. Enable CDN on your content provider.
4. Access your CDN content.

The following steps are to enable CDN access to a storage account:

1. Login to the following link (Windows Azure Developer Portal):
   
   https://windows.azure.com
    
2. Create your storage account if you don't have one
3. Click on the CDN section under the "Hosted services, Storage Account& CDN" as in the following screen shot:
   
   
   

Now we have to create the "Endpoint" with our storage account, as in:

1. Click the "New Endpoint" button from the top left .
2. A new form will open where we need to choose our hosted service or storage account from the dropdown to create a New CDN end point
   
   
   

Now the endpoint has been created under the particular storage account.

Note: The configuration created for this endpoint is not immediately available; it can take up to 60 minutes for the registration to propagate through the CDN network worldwide. Users who try immediately to use the CDN domain name will get a 400 error until the configuration is updated worldwide.

Now we have a default http endpoint; it is:

az331053.vo.msecnd.net (see the following screen shot).



That's all you have to do to get the CDN functionality, but as you'll notice, the URL for the CDN is a bit ugly. In the next step, we'll get a cleaner URL by mapping a custom domain.

Step 2: Map a Custom Domain

Along with the Windows Azure CDN, today we've introduced functionality to map custom domains to either CDN URLs or storage accounts directly. I don't want the image URLs on my blog to have the domain az331053.vo.msecnd.net in them, so let's map to the custom domain cdn.nobreakpoint.wordpress.com and use that instead.

Below the CDN section in the portal, you should see another new section called "Custom Domains." It shows your normal blob endpoint as well as your CDN endpoint.

Now we have to configure a custom domain for the selected CDN network:

1. Click on "Add Domain" for the particular "end point"
   
   
    
2. A new form will open where you have to give Custom domain name

CNAME records must map a specific subdomain such as www.example.com or myblog.example.com. For example, contoso.com can only map to a CDN endpoint using a URI such as documents.contoso.com.

Like in the following image the blog URL is: nobreakpoint.wordpress.com but for mapping to a CDN endpoint we need to use like cdn. nobreakpoint.wordpress.com



To complete the registeration of this custom domain name you will be asked to verify that you own the domain.

To enable or validate this custom domain we must validate the ownership of the domain. To do this we must create the following CNAME record on the particular domain register website with the following data
Alias name: - 2f286ab3-702d-4252-8478-4f65246af5f7.cdn.nobreakpoint.wordpress.com
Points to host name: verify.azure.com

Once we have completed this step on the required domain registration website we have to return to the Management portal and click validate on the CDN ribbon to enable the custom domain.

Please see the following screen shot:



Without doing this if we try to validate this custom domain then we will get an error while validating.

Now the Cname redirect URL is:

2f286ab3-702d-4252-8478-4f65246af5f7.cdn.nobreakpoint.wordpress.com

Without validation also you can access your custom domain club with this end point:

http://cdn.nobreakpoint.wordpress.com/

If you no longer wish to cache a blob in the CDN, you can:

• Delete the blob from the public container
• Remove the Windows Azure CDN endpoint from your storage account in the Windows Azure Developer Portal.

Additional information

• At this time there is no charge for CDN access to your blobs while in CTP. Information on pricing for the Windows Azure CDN offering will be provided in the future.
• For best performance, we recommend caching blobs less than 10 GB in size.
• Windows Azure CDN access only works for anonymous access and for HTTP. HTTPS is not supported for CDN access.
• A custom domain name can be registered for only one storage account endpoint at a time. For example, one could not register the domain name "merlot.cohowinery.com" for two different Windows Azure CDN endpoints at the same time.

Conclusion

So in this article we have learned the CDN concept of Windows Azure.