Improving Operational Agility and Efficiency involved in Load Balancing and Scaling using Windows Azure - by Marlabs Cloud and Mobile CoE.

1. Improving
Operational Agility
and Efficiency
involved in Load
Balancing and Scaling
using Windows
Azure
Cloud & Mobile COE, Marlabs
Auto scaling is a way to automatically scale up or down the
number of compute resources based on user-defined
policies, Key Performance Indicators (KPI), health status
checks, and schedules. If your application needs more
computing power, you can launch additional compute
instances on-demand and use them for as long as you want,
and then terminate them when they are no longer needed

2. Improving Operational Agility and Efficiency involved in Load 1
Balancing and Scaling using Windows Azure
Cloud & Mobile COE, Marlabs
Version 1.0
http://www.marlabs.com

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Balancing and Scaling using Windows Azure
Table of Contents
Introduction .................................................................................................................................................. 3
The Business Need for Auto Scaling.............................................................................................................. 3
Example Scenarios for Auto Scaling .......................................................................................................... 3
Major benefits of using Auto Scaling ........................................................................................................ 4
Operational Agility ................................................................................................................................ 4
Elastic Scalability ................................................................................................................................... 4
Guard the Budget .................................................................................................................................. 4
Cost Savings .......................................................................................................................................... 4
Notifications .......................................................................................................................................... 5
Windows Azure Autoscaling Application Block (WASABi) ............................................................................ 5
Major functionalities of Windows Azure .................................................................................................. 5
Instance Scaling..................................................................................................................................... 5
Throttling .............................................................................................................................................. 5
Notifying................................................................................................................................................ 5
Custom action ....................................................................................................................................... 5
Adding Autoscaling Application Block to Host Application........................................................................... 6
Hosting the Autoscaling Application Block in a Windows Azure Worker Role ............................................. 7
Instantiate and Run the Scaler .................................................................................................................. 7
Import Namespaces .............................................................................................................................. 7
Resolve an instance of Autoscaler class................................................................................................ 7
Edit Autoscaling Application Block Configuration..................................................................................... 8
Author Rule Configuration File ............................................................................................................... 11
Author Service Configuration File ........................................................................................................... 12
Quick Steps to Add and Use Autoscaling Application Block ....................................................................... 12
Windows Azure Compute Resources to Host Autoscaling Application Block............................................. 13

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Introduction
Cloud computing is the set of technologies and infrastructure capabilities being offered in a service
based consumption model. Windows Azure is Microsoft’s Cloud computing offering to build and deploy
applications on a Pay-per-use basis. Cloud computing with Microsoft Windows Azure platform lets the
customers to focus on delivering services to their customers rather than managing technology
infrastructure. One of the key benefits of using Cloud computing is the ability for on-demand scalability
of the applications deployed in Cloud. Dynamic provision for load balancing and scaling can dramatically
reduce operational overheads, time, and costs and can improve efficiency of the applications deployed
over the Cloud. Microsoft’s patterns & practices team is providing an Auto Scaling solution for Windows
Azure that will provides dynamic provision for auto scaling based on the rules defined by the users for
the applications scalability needs and organizational strategy.
What is Auto Scaling?
Auto scaling is a way to automatically scale up or down the number of compute resources based on
user-defined policies, Key Performance Indicators (KPI), health status checks, and schedules. If your
application needs more computing power, you can launch additional compute instances on-demand and
use them for as long as you want, and then terminate them when they are no longer needed.
The Business Need for Auto Scaling
Auto Scaling is an extremely important service when we are building cloud based applications. Since
cloud computing is a pay-per-use utility service and provides on-demand scalability, dynamic
provisioning for scale up and scale down of cloud resources are very important functionality for cloud
based applications. Dynamic provisioning for auto scaling can provide better scalability and can also
guard organizational budget for cloud deployments. Auto Scaling balances between costs and
performance to business organizations when they are moving to cloud.
Example Scenarios for Auto Scaling
The following are the few example scenarios where Auto Scaling service can provide business values.

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 You can instruct the Auto Scaling service to launch an additional compute instances whenever
CPU usage is high for a pre-defined time.
 You can instruct the Auto Scaling service to terminate few compute instances whenever CPU
usage is low for a pre-defined time.
 You can instruct the Auto Scaling service to terminate few compute instances over the weekend
when traffic is expected to be low.
 You can instruct the Auto Scaling service to launch an additional compute instances over the
evening time of week days when traffic is expected to be high.
 You can instruct the Auto Scaling service to launch an additional compute instances when
messages on your application’s queue service is very high.
 You can configure the Auto Scaling service for receiving email notifications whenever compute
usage is very high or low.
The above conditions are just few example scenarios, but the Auto Scaling can provide business values
to many situations based on the behavior of your applications and the organizational strategy. This can
reduce lot of manual tasks involved in load balancing and scaling and can staying on budget. Auto
Scaling will help the enterprises to save both time and money and can improve business agility. Auto
Scaling is a ‘must have’ service when organizations are moving their applications onto Cloud.
Major benefits of using Auto Scaling
The following are the key features and benefits of using an Auto Scaling service
Operational Agility
Auto Scaling service can reduces lot of manual tasks involved in load balancing and scaling which will
enables the overall operational agility and better productivity.
Elastic Scalability
Auto Scaling service can dynamically add compute resources when application usage rises and remove it
when usage drops.
Guard the Budget
Organizations can guard their financial budget for C loud based applications. They can define and control
the number of computing instances using well defined conditions.
Cost Savings
Auto Scaling service can save usage costs of compute resources by terminating underused instances
automatically and launching new instances when applications need more compute resources.

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Notifications
The Auto Scaling service can also use for receiving notifications and alerts about the load situations and
health statuses.
Windows Azure Autoscaling Application Block (WASABi)
The Windows Azure Autoscaling Application Block (WASABi) lets the cloud developers to add and
manage automatic scaling behavior to Windows Azure applications that provides all the functionality
needed to define and monitor autoscaling behavior in a Windows Azure application or a group of
Windows Azure applications. The Windows Azure Autoscaling Application Block is a part of the Microsoft
Enterprise Library provided by the Microsoft patterns & practices team. The Windows Azure Autoscaling
Application Block can automatically scale Windows Azure applications based on the rules defined in
configuration files specifically for the hosted Windows Azure application. The block will read the rules
and monitor Windows Azure applications and scale-up or scale-down the applications based on the
rules. The Autoscaling Application Block can be hosted on a Windows Azure worker role application or in
an on-premises application. The Enterprise Library provides a GUI based configuration tool that can be
used for edit configuration settings for the Autoscaling Application Block.
Major functionalities of Windows Azure
The following are the key functionalities of Autoscaling Application Block
Instance Scaling
The Autoscaling Application Block varies the number of role instances in order to accommodate
variations in the load on the application. Instance scaling actions can span multiple host
services/subscriptions.
Throttling
Instead of spinning off new instances, the block limits or disables certain expensive operations in your
application when the load is above certain thresholds.
Notifying
Instead of performing instance scaling or throttling, the user may elect to simply receive notifications
about the load situations with no automatic scaling taking place.
Custom action
We can build extensions using the extensibility features provided by Autoscaling Application Block.

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Adding Autoscaling Application Block to Host Application
The Autoscaling Application Block is available as a NuGet package .The following steps will add the
Autoscaling Application Block onto your host application.
1. Add a reference to the Autoscaling Application Block assembly. In Microsoft Visual Studio, right-click
your project node in Solution Explorer, and then click Manage NuGet Packages.
2. Click the Online button, and then in the Search Online box, type WASABi.
3. Click the Install button for the Enterprise Library 5.0 – Windows Azure Autoscaling Application Block –
Beta package.
4. Read and accept the license terms for the packages listed.
The NuGet package will add the all necessary assemblies and references to your project that you need to
use the Autoscaling Application Block. The NuGet package will also add the XML schema files for the
autoscaling rule definitions and autoscaling service information.

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Hosting the Autoscaling Application Block in a Windows Azure
Worker Role
Autoscaling Application Block needs a host to run. The Autoscaling Application Block can be hosted on a
Windows Azure worker role application or in an on-premises application. The following step by step
instructions will help you to host the Autoscaling Application Block onto Windows Azure Worker Role.
Instantiate and Run the Scaler
The following steps will instantiate and run the Autoscaling Application Block in a Windows Azure
Worker Role.
Import Namespaces
Import the following namespaces to the Worker Role class
using Microsoft.Practices.EnterpriseLibrary.Common.Configuration;
using Microsoft.Practices.EnterpriseLibrary.WindowsAzure.Autoscaling;
Resolve an instance of Autoscaler class
The Autoscaler class is the main entry point for the Autoscaling Application Block from your host
application. The following code block instantiates the Autoscaler class and call its start method for
monitoring the Autoscaling behavior.
Autoscaler scaler = EnterpriseLibraryContainer.Current.GetInstance<Autoscaler>();
scaler.Start();
The following code block shows implementation of Worker Role class
public class WorkerRole : RoleEntryPoint
{
private Autoscaler autoscaler;
public override void Run()
{
autoscaler = EnterpriseLibraryContainer.Current.GetInstance<Autoscaler>();
autoscaler.Start();
while (true)
{
Thread.Sleep(10000);
Trace.WriteLine("Working", "Information");
}
}

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public override bool OnStart()
{
// *** AzureAutoScale-Start ***
//Set Max number of concurrent connections
ServicePointManager.DefaultConnectionLimit = 12;
DiagnosticMonitorConfiguration dmc = DiagnosticMonitor.GetDefaultInitialC
onfiguration();
dmc.Logs.BufferQuotaInMB = 4;
dmc.Logs.ScheduledTransferPeriod = TimeSpan.FromSeconds(30);
dmc.Logs.ScheduledTransferLogLevelFilter = LogLevel.Verbose;
DiagnosticMonitor.Start("Microsoft.WindowsAzure.Plugins.Diagnostics.Conne
ctionString", dmc);
// *** AzureAutoScale-End ***
return base.OnStart();
}
}
When you call the Start method of the Autoscaler class, the block will look for rule and service
information, and will start to monitor hosted services and will perform the auto scaling based on the
rules defined in the rule store.
Edit Autoscaling Application Block Configuration
You can add ad edit the Autoscaling application block configuration using Enterprise Library
Configuration tool. To install the Enterprise Library Configuration tool, do the following steps
1. In Visual Studio, on the Tools menu, click Extension Manager.
2. In the Extension Manager dialog, click Online Gallery, and then in the Search Online Gallery box, type
Enterprise Library Config.
3. Make sure that you can see version 5.0.505 of the EnterpriseLibrary.Config package. Then click the
Download button.
4. Read the license and then click Install.
5. Click the Restart Now button to restart Visual Studio and complete the installation.
To edit the Autoscaling application block configuration using Enterprise Library Configuration tool, right
click on the app.config file in the project that will be hosting the block and click Edit configuration file.

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In the Enterprise Library Configuration tool, open the Blocks menu, and then click Add Autoscaling
Settings.

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The enterprise library configuration tool allows editing Autoscaling settings, Rule store information and
the Service information store. The Rule Store settings contain the storage information about Rules
configuration file and the Service Information Store settings contain the storage information about
Service configuration file. Typically, if you host the Autoscaling Application Block in a worker role, you
will store the data points, rule definitions, and service information in Windows Azure storage.

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Author Rule Configuration File
The rule configuration file contains the rules that will be used for the scaler to scale up and scale down
the hosted service. There are two types of rules available in the Autoscaling Application Block -
constraint rules and reactive rules. Constraint rules are associated with a time table and reactive rules
are associated with KPI and conditions. The below code block shows the sample rule configuration which
contains both constraint rules and reactive rules.
<?xml version="1.0" encoding="utf-8"?>
<rules xmlns="http://schemas.microsoft.com/practices/2011/entlib/autoscaling/rules">
<constraintRules>
<rule name="default" description="default" rank="1" enabled="true">
<actions>
<range target="WebRole1" min="1" max="4"/>
</actions>
</rule>
<rule name="peakbusinesstime" enabled="true" rank="100">
<timetable duration="02:00:00" startTime="13:26:00" utcOffset="-07:00">
<weekly days ="Friday"/>
</timetable>
<actions>
<range target="WebRole1" min="4" max="8"/>
</actions>
</rule>
</constraintRules>
<reactiveRules>
<rule name="Too Much CPU" enabled="true">
<when>
<greaterOrEqual operand="CPU_Last_15Minutes" than="60"/>
</when>
<actions>
<scale target="WebRole1" by="2" />
</actions>
</rule>
<rule name="Too Less CPU" enabled="true">
<when>
<lessOrEqual operand="CPU_Last_15Minutes" than="30"/>
</when>
<actions>
<scale target="WebRole1" by="-2" />
</actions>
</rule>
</reactiveRules>
<operands>
<performanceCounter alias="CPU_Last_15Minutes" performanceCounterName="Processor
(_Total)% Processor Time" source="HighCPUWorkerRole" aggregate="Average" timespan="0
0:15:00"/>
</operands>
</rules>

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The above rule configuration contains two constraint rules – a default rule and a rule for peak business
time on every Fridays. The rank specified in the rule configuration is just a priority for each role. The
‘utcOffset’ value is using to convert the configured local time to UTC time using by the Windows Azure.
The reactive rules contain the rules for KPI based on the CPU utilization.
Author Service Configuration File
The service configuration file contains the information for Windows Azure subscriptions and hosted
service(s) to monitoring for auto scaling. This tells the Scaler that which hosted service(s) should
monitor. The below code blocks show the sample service configuration file.
<?xml version="1.0" encoding="utf-8" ?>
<serviceModel xmlns="http://schemas.microsoft.com/practices/2011/entlib/autoscaling/s
erviceModel">
<subscriptions>
<subscription name="something"
subscriptionId="b5fb8dfb-3e0b-xxxx-xxxx-xxxxxxxxxxxx"
certificateStoreLocation="LocalMachine"
certificateStoreName="My"
certificateThumbprint="FE5EB4279BC6354xxxxxxxxxxxxxxxxxxxxxxxxx">
<services>
<service name="myHostedServiceName" slot="Staging">
<roles>
<role name="WebRole1"
roleName="WebRole1"
wadStorageAccountName="wadStorageAccount"/>
</roles>
</service>
</services>
<storageAccounts>
<storageAccount name="wadStorageAccount" connectionString="DefaultEndpointsProtocol
=https;AccountName=myaccount;AccountKey=123xxxxxxxxx">
</storageAccount>
</storageAccounts>
</subscription>
</subscriptions>
</serviceModel>
Quick Steps to Add and Use Autoscaling Application Block
The following are the major quick steps to add and use Autoscaling Application Block
1. Add a reference to Autoscaling Application Block in host application.
2. Instantiates the Autoscaler class and call its start method for monitoring.
3. Edit app.config file of the host application using Enterprise Library configuration tool.
4. Configure the Autoscaling settings.

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5. Configure the Rule Store settings to specify the storage information of Rules configuration file.
6. Configure the Service Information Store to specify the storage information of Service
information configuration file.
7. Add Rules configuration XML file to specify the rules and conditions for scaling.
8. Add Service information XML file to specify Windows Azure subscription and hosted services to
monitoring the Autoscaling Application Block.
Windows Azure Compute Resources to Host Autoscaling
Application Block
The following compute resources are the essential components to host Autoscaling block
1. Windows Azure hosted service for Worker Role to host Autoscaling block.
2. BLOB storage account for store rule configuration and service information configuration.
Conclusion
Windows Azure is Microsoft’s offering for Cloud computing to help customers to build and deploy
applications on a Pay-per-use basis and providing on-demand scalability. This allows the customers to
fully focus on their applications rather than managing IT infrastructure. The Windows Azure Autoscaling
Application Block lets the Windows Azure customers to take full advantage of scalability offerings
provided by Windows Azure. This enables the customers to reduce number of management overheads
involved load balancing and scaling which will improve the business agility and can also reduce cost and
time.
Links
Windows Azure - http://www.microsoft.com/windowsazure/
Microsoft Patterns & Practice - http://entlib.codeplex.com/