Windows Azure offers three different Cache Offerings.

1. Cache Service Preview

2. In-Role Caching

3. Shared Caching

Cache Service is the newest and is in Preview right now. Considering that Shared Caching is soon to be deprecated (ref), the real choice is between the new Cache Service Preview and the tried and tested In-Role Caching. Both of these are fundamentally different services and have few unique characteristics. To know more about each of these services, please refer to the following.

Windows Azure Cache Service (Preview)

Windows Azure In-Role Cache

Free e-book – Introducing Windows Azure for IT Professionals

To help make a better informed decision on which of these offerings to choose from, I am putting together a feature comparison matrix. This matrix should provide you a quick reference to some of salient features of Windows Azure Caching and their availability in various Cache Offerings.

Cache Comparison Matrix

If you want to have any additional features included here for comparison, please let me know.

Hope this help!

You can find this blog, and lot of other interesting articles about Windows Azure on My Team Blog

Recently I came across multiple scenarios where the Service endpoints were showing Offline/Degraded in Traffic Manager. Those endpoints were valid, accessible and respective service was running fine, but still the end point was showing offline in Traffic Manager.

In the above screenshot, the respective endpoint is accessible fine, but the Traffic Manager is showing it as Degraded.

Interestingly, in all those scenarios, the reason was common. The endpoint in questions was returning a non http 200 response code (302/307 etc.).

The way Traffic Manager works is, it expects an Http 200 response from the endpoints you have configured, that too within 10 seconds. If this doesn’t happen, then monitoring system will either retries (in case of no response in 10 seconds) or assumes that the endpoint is not available.

From MSDN:

Traffic Manager only considers an endpoint to be Online if the return message is a 200 OK. If a non-200 response is received, it will assume the endpoint is not available and will count this as a failed check

The monitoring system performs a GET, but does not receive a response in 10 seconds or less. It then performs three more tries at 30 second intervals. This means that at most, it takes approximately 1.5 minutes for the monitoring system to detect when a service becomes unavailable. If one of the tries is successful, then the number of tries is reset. Although not shown in the diagram, if the 200 OK response(s) come back greater than 10 seconds after the GET, the monitoring system will still count this as a failed check.

In the above example, there was a redirection rule configured on the website which was returning http 302. And this the endpoint was showing Degraded. After removing the redirection, the Endpoint became Online again.

Though this looks like very obvious concept, but on a bad day, this could turn out to be really tricky (from past experiences).

Common Scenarios where you may run into this:

1. Any sort of Redirection Rule on the Endpoint (Default Page, SSL Redirection etc.)

2. Any custom Authentication mechanism or URL Rewrite rule which doesn’t return http 200 for the first request

3. Home page takes >10 seconds to load

Further references:

Details about the WATM probe and how it determines when the primary service is down and when to failover

Overview of how WATM works

How the different policies work, including details on how failover works

Hope this helps!

Cheers!

Best part is this book is absolutely Free to download for everyone! Thank you Microsoft Press!

I got the opportunity to write the chapter on Windows Azure Caching for this book. Hope some of you would find it useful. Please let us know about any feedback/inputs.

DOWNLOADS PDF  - here Companion Content - here Mobi file for Kindle - here ePub file - here

Whether you’re new to the Windows Azure platform or are already using it in your business, this book has something that should interest you. Most Windows Azure services are described in some detail, with screenshots used to demonstrate some of the multitude of capabilities of the platform. And for the experienced we have lots of under-the-hood insights and expert tips written by Microsoft insiders who develop, test, and use the Windows Azure platform.

Ref: http://blogs.msdn.com/b/microsoft_press/archive/2013/10/01/free-ebook-introducing-windows-azure-for-it-professionals.aspx 

Happy reading!

You can find this blog, and lot of other interesting articles about Windows Azure on My Team Blog

Few days ago(on 31st July), the Azure Caching libraries were updated to v2.1.0.0 (previous version was v2.0.0.0).

If you are trying to use Windows Azure Caching on your new project from past few days, and if it is mysteriously not working, not even for the simplest of the projects, then you may be running into a dependency scenario!

A lot of us may have probably missed that this new version of Azure Caching has a dependency on Azure SDK v 2.1

See the highlighted part (easy to miss if we are in a hurry ).

So what would happen if we try to use Azure Caching 2.1.0.0 with Azure SDK 2.0 or older?

You may run into following issues

1. Your project may appear to hang for a while (browser spinning etc.).

2. Eventually you may see errors like

Exception Details: System.Net.Sockets.SocketException: No such host is known

DataCacheException: ErrorCode<ERRCA0017>:SubStatus<ES0006>

Detailed exception:

Server Error in '/' Application.
 
No such host is known 
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 
 
Exception Details: System.Net.Sockets.SocketException: No such host is known
 
Source Error: 
 
 
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. 
Stack Trace: 
 
 

[SocketException (0x2af9): No such host is known]
   Microsoft.ApplicationServer.Caching.AsyncResultNoResult.EndInvoke() +202
   Microsoft.ApplicationServer.Caching.AsyncResult`1.EndInvoke() +40
   Microsoft.ApplicationServer.Caching.SocketConnectionFactory.EndConnect(IAsyncResult asyncResult) +75
   Microsoft.ApplicationServer.Caching.TcpClientChannelFactory.TcpConnectionCallback(IAsyncResult result) +182
[DataCacheException: ErrorCode<ERRCA0017>:SubStatus<ES0006>:There is a temporary failure. Please retry later. (One or more specified cache servers are unavailable, which could be caused by busy network or servers. For on-premises cache clusters, also verify the following conditions. Ensure that security permission has been granted for this client account, and check that the AppFabric Caching Service is allowed through the firewall on all cache hosts. Also the MaxBufferSize on the server must be greater than or equal to the serialized object size sent from the client.). Additional Information : The client was trying to communicate with the server: net.tcp://WebRole1:24233.]
   Microsoft.ApplicationServer.Caching.DataCache.ThrowException(ErrStatus errStatus, Guid trackingId, Exception responseException, Byte[][] payload, EndpointID destination) +767
   Microsoft.ApplicationServer.Caching.DataCache.ThrowException(ResponseBody respBody, EndpointID destination) +149
   Microsoft.ApplicationServer.Caching.DataCacheFactory.EstablishConnection(IEnumerable`1 servers, RequestBody request, Func`3 sendMessageDelegate, DataCacheReadyRetryPolicy retryPolicy) +1313
   Microsoft.ApplicationServer.Caching.<>c__DisplayClass5.<Initialize>b__2(RequestBody req) +198
   Microsoft.ApplicationServer.Caching.SocketClientProtocol.SendReceive(IVelocityRequestPacket request, Func`2 delegate, EndpointID& destination) +121
   Microsoft.ApplicationServer.Caching.SocketClientProtocol.Initialize(IEnumerable`1 servers) +1225
   Microsoft.ApplicationServer.Caching.DataCacheFactory.GetCache(String cacheName, CreateNewCacheDelegate cacheCreationDelegate, DataCacheInitializationViaCopyDelegate initializeDelegate) +1104
   Microsoft.ApplicationServer.Caching.DataCacheFactory.GetCache(String cacheName) +131
   Microsoft.Web.DistributedCache.DataCacheFactoryWrapper.CreateDataCacheFromFactory(DataCacheFactory factory, String cacheName) +63
   Microsoft.Web.DistributedCache.CacheHelpers.RunCacheCreationHooks(CacheConnectingEventArgs fetchingEventArgs, IDataCacheFactory dataCacheFactory, Object sender, EventHandler`1 fetchingHandler, EventHandler`1 fetchedHandler) +356
   Microsoft.Web.DistributedCache.DistributedCacheSessionStateStoreProvider.CreateInternalProvider(IHttpRuntime httpRuntime, SessionInitializationData initData, IDataCacheFactory dataCacheFactory, EventHandler`1 cacheFetching, EventHandler`1 cacheFetched) +447
   Microsoft.Web.DistributedCache.DistributedCacheSessionStateStoreProvider.GetInternalProvider() +315
   Microsoft.Web.DistributedCache.DistributedCacheSessionStateStoreProvider.CreateNewStoreData(HttpContext context, Int32 timeout) +59
   System.Web.SessionState.SessionStateModule.InitStateStoreItem(Boolean addToContext) +160
   System.Web.SessionState.SessionStateModule.CompleteAcquireState() +363
   System.Web.SessionState.SessionStateModule.BeginAcquireState(Object source, EventArgs e, AsyncCallback cb, Object extraData) +1269
   System.Web.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +12598974
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +288

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.18033 

Please note that only including the new package in your solution will NOT cause these issues. These symptoms will appear only when you are actually trying to ‘use’ caching features. Like, enabling the Azure Caching Session State provide, or instantiating the DataCache objects etc..

Okay, we know there is a dependency. But what do we do now?

Here are two easy options

1. Upgrade your Azure SDK to the latest version (v2.1) (this should be the right and recommended way)

Download Latest Azure SDK

2. If for some reason, you can not upgrade your Azure SDK at the moment, then you can manually install previous version of Azure Caching. (of course you will be missing on the new things v2.10.0 has to offer)

a. Go to Visual Studio –> Open your project where you want to install Azure Caching libraries 

b. Tools –> Library Package Manager –> Package Manager Console

c. This should bring up ‘Package Manager Console’ window

d. Run following command in that console window

>Install-Package Microsoft.WindowsAzure.Caching -Version 2.0.0.0

This should install the v2.0.0.0 of Azure Caching which you can use with your older versions of Azure SDK (<v2.1)

 

 

Hope this help!

You can find this blog, and lot of other interesting articles about Azure on My Team Blog

In my previous post about the same topic I mentioned there are multiple ways to enable your Web/Worker Role to consume service management API. Here is one more way where we will be leveraging the power of Azure Publish Settings file.

Publish Settings File contains information about your subscription. And that information, once consumed by tools like Visual Studio, let you seamlessly deploy application to Windows Azure. Among other information, it contains a management certificate, which really facilitate the authentication part when you are trying to ‘manage’ your subscription.

We will be leveraging this Management Certificate to get our application code, which is consuming Service Management API, work.

As you may already know, while consuming Service Management API, your code is fetching the management certificate from the local certificate store. Lets assume you are using This MSDN Sample, and you have GetStoreCertificate method which looks like this.

private static X509Certificate2 GetStoreCertificate(string thumbprint)
{
    List<StoreLocation> locations = new List<StoreLocation>
    { 
        StoreLocation.CurrentUser, 
        StoreLocation.LocalMachine
    };

    foreach (var location in locations)
    {
        X509Store store = new X509Store("My", location);
        try
        {
            store.Open(OpenFlags.ReadOnly | OpenFlags.OpenExistingOnly);
            X509Certificate2Collection certificates = store.Certificates.Find(X509FindType.FindByThumbprint, thumbprint, false);
            if (certificates.Count == 1)
            {
                return certificates[0];
            }
        }
        finally
        {
            store.Close();
        }
    }
    throw new ArgumentException(string.Format("A Certificate with Thumbprint '{0}' could not be located.", thumbprint));
}

As you can see, you are querying your local certificate stores (Current User, Local Machine) and searching for the certificate thumbprint. In my previous post, we discussed how to make your certificate available for this method to work.

Now, lets see how we can avoid all that

1. Download the Azure Publish Settings File ( https://windows.azure.com/download/publishprofile.aspx )

2. Open this file in Notepad –>you will find something like ManagementCertificate=”…….SomeReallyLongString…..” –> copy this string value

3. Now modify your GetStoreCertificate method as following

private static X509Certificate2 GetStoreCertificate(string thumbprint)
{            
    X509Certificate2 certificate = new X509Certificate2((Convert.FromBase64String(".....SomeReallyLongString.....")));
    return certificate;         
}

Note: You would definitely want to wrap this around a nice try/catch block and will remove the now un-necessary parameter ‘thumbprint’ and follow other good programming practices.

4. Compile and deploy the project to Windows Azure –> it should work nicely

Let’s try to understand why this has worked.

It is the Publish Settings File which is doing the trick. When you downloaded this file (Step 1), there was a new management certificate got created on the Portal. This certificate was represented in the Publish Settings File (MyFileName.publishsettings)by

ManagementCertificate=”…SomeReallyLongString…”

All we did was pass on this string in our code and all was well since this certificate is already present in the management portal.

Read more about Publish Settings File

What is good about this method:

1. Easier to manage. No startup task or any change in Visual Studio is required

2. No need to create a new certificate separately

3. Cleaner code

What is not-so-good:

The main concerned could be that, by-default you have no control over the management certificate which is created by Windows Azure for you. You may want to use your own customized certificate.

To create Publish Settings File using your own certificate, please refer This MSDN Forum

Hope this helps!

There were some great updates to Windows Azure were released earlier today!  Some of them are

• SQL Databases: Support for Automated SQL Export and a New Premium Tier SQL Database option
• Traffic Manager: New support for managing Windows Azure Traffic Manager in the HTML Portal
• AutoScale: Support for Windows Azure Mobile Services, AutoScale rules for Service Bus Queue Depth, Alerts on AutoScale actions
• Virtual Machines: Updates to the IaaS management experiences in the Management Portal

For more details, please read Scott Gu’s blog

Windows Azure July Updates

http://weblogs.asp.net/scottgu/archive/2013/07/23/windows-azure-july-updates-sql-database-traffic-manager-autoscale-virtual-machines.aspx 

Cheers!

Recently on our Team Blog, I posted about using Service Management API from code running in Windows. Reposting it here as well for easier access.

My team blog

It is not un-common to have the need of enabling your Web Role / Worker Role to consume the Azure Service Management API. Here is a step-by-step guide on how you could do that

For Service Management API to work for you, you need to satisfy following pre-conditions

1. Have a valid SSL Certificate. This certificate has to be present on the Azure Portal

2. This certificate (or some information of this certificate) needs to be accessible to your Web/Worker Role.

Here is a step-by-step guide on how you achieve this.

1. Get a valid SSL Certificate:

a. You can get the certificate from your Enterprise CA or from any third party vendor

b. Or you can create your own self-signed certificate using IIS (probably the easiest way if you have local IIS configured)

Start –> Run –> type ‘inetmgr’ –> this will open IIS Manager –> select the root node in left panel –> double click on ‘Server Certificate’ icon in middle panel  –> ‘Create Self-Signed Certificate’ in the extreme right side panel –> Go through the wizard, that all and you have your own self signed certificate)

c. Save the certificate file (.pfx): In IIS Manager, double click on the certificate which you just created –> in the Certificate properties window, go to Details tab –> click ‘Copy to File’ –> Next –> select ‘Yes, export the Private key’ –> Next –> select ‘Personal Information Exchange.. ’ –> Next –> give a Password –> Next –> Browse to the file location –> Next –> Finish

2. Upload this certificate to the Azure portal

a. To do that, save the certificate in .cer format from IIS manager.

Use the same steps as above, except that this time select ‘Export without private key’ when asked.

b. Upload this .cer file to Azure Management Portal

in the Azure Portal –> got to Settings –> Management Certificate –> Upload

3. Attach the certificate with the solution using a startup task

This step will make the certificate available in the Local Certificate Store at the instance once you have deployed your application to Azure. Your application code should then be able to fetch necessary certificate details when it is consuming Service Management API

a. Create a new folder in Visual Studio, lets name it Startup

b. Copy the .pfx file in the Startup folder

c. Create a new .cmd file in the Startup folder, lets call it AddCertiticate.cmd

d. Add following command to the AddCertificate.cmd

CERTUTIL -f –p PasswordOfTheCertificate -importpfx "Startup\NameOfTheCertificate.pfx

e. Go to properties of AddCertificate.cmd and the certificate pfx –> ensure ‘Copy to output directory’ is set to ‘Copy Always’

f. Add the following in the service definition file (.csdef)

<Startup>  
  <Task commandLine="Startup\AddCertiticate.cmd" executionContext="elevated" taskType="simple"> </Task>
</Startup>

UPDATE [27/07/2013]: Here is an another way to do ‘Step 3’ without creating the startup task. thanks Gaurav Mantri.

In this method, we will manually upload the certificate to the Cloud Service, configure the certificate thumbprint in Visual Studio, and deploy the project! No need to create the startup task.

a. Go to the Azure Portal –> Cloud Service –> go to the service where you will be deploying

b. Certificate –> Upload –> Browse to the .pfx file and upload it –> Copy the Thumbprint once done

c. In Visual Studio –> go to the cloud project –> Roles –> WebRole1 (or the name you have given) –> right click –> Properties –> Certificates

d. Add Certificate –> give any name you want –> give the store location (generally it is ‘Local Store | My’ unless you have customized it during certificate creation/import) –> add the thumbprint which you have copied from the portal two steps ago

e. save, build and publish.

With this our setup is ready. Now there is one last issue to deal with. When your code executes on the VM, it would need to access local certificate store in order to pull the certificate information which you are uploading with the package. By default, the azure application pool account, Network Service, does not have privilege to access the local certificate store.

So we need to add those privileges for Network Service

4. Enabling application pool account (Net work Service) to access local certificate store

a. Add the following command AddCertificate.cmd

startup\WinHttpCertCfg.exe -g -c LOCAL_MACHINE\MY -s "NameOfTheCertificate" -a "Network Service"

Ref: WinHttpCertCfg 

b. As you have noticed, we are using WinHttpCertCfg.exe So we would need to add that as well in our solution

c. Download the WinHttpCertCfg.exe from here –> Copy it to Startup folder –> Ensure ‘Copy Always’ is selected in Properties for this exe

Download WinhttpCertCfg.exe

With this, now you can compile and publish the solution and your code to consume Service Management API should run without any issue. Please note that these steps are only putting the infrastructure in place. You still need to write the code to consume the Service Management APIs.

References:

Introduction

List of Operations

There are more than one ways to active this. In my coming posts I will try to talk about what could be the alternatives.

Hope this helps!

Some of the Azure developers/administrator often misunderstand “Linking a resource” to a cloud service. Many times I see people asking, I have linked a SQL Azure DB/Storage to my cloud service, still my data is not getting transferred. Most of you already know what really linking resources mean, but still I felt like giving this quick explanation for the benefits of all.

Linking a resource does not mean that your Cloud Service is connected to that resource (SQL Azure DB, Storage etc.). It simply means that now you can monitor the resource and the Cloud Service together in an easier way.

This does not mean that your Cloud Service will be able to interact with the resource. Weather you Link the resource or not, you must write the code in your Cloud Service application to interact with the resource.

The same explanation is provided right on the Azure Portal

(Azure Portal –> Select the Service in question –> Linked Resources – > click on the Question Mark “?”)

“

To show your cloud service's dependencies on other resources, you can link Windows Azure SQL Database instances and storage accounts to the cloud service and monitor their usage on the cloud service dashboard. (To see Total Requests for a linked storage account, you must turn on monitoring for it.)

You can scale a linked SQL Database instance along with cloud service roles on the Scale page.

Tip

You also can monitor, manage, and scale the database in SQL Databases. Get started using SQL Database

"Linking" a resource doesn't connect your app to the resource. You must add connection strings to your code. Unlinking a resource doesn't affect the resource or the connections.

“ 

Hope this help!

Cheers!

Thanks to Microsoft, here are yet another set of free Microsoft eBooks! Visit this post by Eric Ligman

http://blogs.msdn.com/b/mssmallbiz/archive/2013/06/18/huge-collection-of-free-microsoft-ebooks-for-you-including-office-office-365-sharepoint-sql-server-system-center-visual-studio-web-development-windows-windows-azure-and-windows-server.aspx

Here you can find previous batch of free eBooks

http://blogs.msdn.com/b/asgoyal/archive/2012/08/25/learning-resources-free-microsoft-press-e-books.aspx

Spread the word!

Cheers!

While learning various storage models for Windows Azure, I was looking for a simple ‘Hello world’ application which will only write to Blob Storage. It turned out that such simple application was not so easy to find on internet for a newbie, it was at least to me.

So I am sharing one such code snippet which will do a write to Blob storage. This can be used to learn the interaction with Blob storage as your very first step and also it can be used to debug your existing applications deployed in cloud.

A detailed reference can be found here in MSDN

http://www.windowsazure.com/en-us/develop/net/how-to-guides/blob-storage/ 

public override bool OnStart()
{

   // create a local file to upload
   var fileStream1 = System.IO.File.Create(@"hello.txt");
   fileStream1.Close();


 
   // Retrieve storage account from connection string.
   CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
         CloudConfigurationManager.GetSetting("StorageConnectionString"));
 
    

   // Create the blob client.
   Microsoft.WindowsAzure.Storage.Blob.CloudBlobClient blobClient = 
                    storageAccount.CreateCloudBlobClient();

 
   

   // Retrieve reference to a previously created container.
   CloudBlobContainer container = 

                       blobClient.GetContainerReference("mycontainer");
   container.CreateIfNotExists();
 
 
            

    // Retrieve reference to a blob named "myblob".
    CloudBlockBlob blockBlob = 

                     container.GetBlockBlobReference("OnStartEvent " + "_" 
                     + System.DateTime.Now.ToString() 
                     + "_" + RoleEnvironment.CurrentRoleInstance.Id.ToString());
 
            

   // Create or overwrite the "myblob" blob with contents from a local file.
   using (var fileStream = System.IO.File.OpenRead(@"hello.txt"))
   {
            blockBlob.UploadFromStream(fileStream);
   }
 
 
 
   return base.OnStart();
 
 }

The prerequisites are 

1. You should have a valid Windows Azure subscription 

                                              (get your 30 days free trial here)

2. You have created a Storage on the portal (Azure Portal –> New –> 

                                 Data Services –> Storage –> Quick Create)

3. Have configured a connection string in your config file 

                                          (web.config or app.config)

<configuration>
<appSettings>
<add key="StorageConnectionString" 
value="DefaultEndpointsProtocol=https;
         AccountName=[AccountName];
         AccountKey=[AccountKey]" />
</appSettings>
</configuration>

Now you should be able to build and perform this simple interaction with Azure Blob Storage. To see the storage data, you can use 

Azure Storage Explorer

or

Visual Studio (if using Azure SDK 2.0) 

Hope this helps!