Demystifying the Cloud-eBook

Demystifying the Cloud An introduction to Cloud Computing

Version 1.1 – August 2010

Janakiram MSV Cloud Computing Strategist

www.janakiramm.net | [email protected]

This guide explains the concepts of Cloud Computing in simple terms. The first three chapters introduce the key concepts and the terminologies of the Cloud. The remaining chapters cover the major implementations of the Cloud Computing including Amazon Web Services, Microsoft Windows Azure Platform and Google App Engine. This is targeted towards the beginners and intermediate developers with a basic understanding of web technologies.

Disclaimer

This eBook was authored prior to my employment with Amazon Web Services. The views, terminology, architecture and references depicted in this material are my own and do not represent those that of my employer.

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Chapter 1

Defining the Cloud

Evolution of Cloud Computing

Evolution of ISP

There are multiple factors that led to the evolution of Cloud Computing. One of

the key factors is the way Internet Service Providers (ISP) matured over a period of

time. I am borrowing this analogy from Forrester Research.

Evolution of ISP

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From the initial days of offering basic Internet connectivity to offering software as

a service, the ISPs have come a long way. ISP 1.0 was all about providing Internet

access to their customers. ISP 2.0 was the phase where ISPs offered hosting

capabilities. The next step was co-location through which the ISPs started leasing

out the rack space and bandwidth. By this, companies could host their servers

running custom, Line of Business (LoB) applications that could be accessed over the

web by its employees, trading partners and customers. ISP 3.0 was offering

applications on subscription resulting in the Application Service Provider (ASP)

model. The latest Software as a Service or SaaS, is a mature ASP model. The next

logical step for ISPs would to embrace the Cloud.

1.2 The Programmable Web

Web Services made the web programmable. They enabled the developers to look at

the Internet a class library or an object model. Protocols like Simple Object Access

Protocol (SOAP), Representational State Transfer (REST), JavaScript Object

Notation (JSON) and Plain Old XML (POX) fueled the growth of APIs on the web.

Today every popular search engine, social networking site and syndication portal

has APIs offered to developers.

Virtualization

Virtualization is the most discussed term among CIOs and IT decision makers.

Through Virtualization, the data center infrastructure can be consolidated from

hundreds of servers to just tens of servers. All the physical server roles like Web

Servers, Database Servers and Messaging Servers run as virtualized instances. This

results in lower Total Cost of Ownership (TCO) and brings substantial savings on the

power bills and reduced cost of cooling equipment.

Though the evolution of ISP, programmable web and virtualization are independent

trends, they contribute to the evolution of Cloud Computing.

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Understanding Cloud Computing

If you are wondering what is so special about the ‘Cloud’ in Cloud Computing, here

is the explanation. Traditionally, developers and architects used a picture of cloud

to illustrate a remote resource connected via the web. Eventually cloud became

the logical connector between the local and remote resources on the Internet.

Most of the developers get confused when they encounter the term Cloud

Computing. According to them, their Web Services are already hosted on the Cloud

and that can be potentially called as Cloud Services. While there is some truth in

this argument, it is a not very accurate way of describing Cloud Computing. Let’s

look at Cloud Computing through the eyes of a developer.

Think Web Services

Most of the developers are familiar with Web Services. Web Services are based on a

few simple concepts. Every Web Service accepts a request and returns a response

(even if there is no explicit return value, a HTTP 200 OK return value is considered

as a response). They are units of code that can be invoked over the web. Typically,

Web Services accept one or more input parameters and invoke processing logic

which will result in an output. Web Services are a part of web applications that run

on a typical stack that has hardware, a Server OS, application development

platform. For a while, think how you can expose every layer that is powering your

web application as a Web Service.

Web Services Stack

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Cloud OS

Visualize a scenario where the hardware and the Operating System (OS) are

exposed as a Web Service over the public Internet. Based on the principles of Web

Services, we could send a request to this service along with a few parameters.

Since the OS is expected to act as an interface to the CPU and the devices, we can

potentially invoke a service that accepts a ‘job’ that will be processed by the OS

and the underlying hardware. Technically, this Web Service has just turned the OS

+ H/W combination into a ‘Service’. We can start consuming this service by

submitting CPU intensive tasks to this new breed of Web Service. What do you call

an OS that is exposed on the web as a service? May be a Cloud OS? We will answer

this in the coming sections.

Exposing the hardware and the OS as a Service

Cloud FX

Developers always develop and deploy their applications on the application

development platforms. Some of the most popular application development

platforms are .NET and Java. In the last scenario, we have seen how the OS + H/W

combination is offered as a service. Now, imagine a scenario where the application

development platform is offered to you as a service. Through this, you will be able

to develop and test your applications on a low end, inexpensive notebook PC but

will able to ‘submit’ my code to run on the most powerful hardware infrastructure.

It is the same programming language, SDK and the runtime that runs on your

development environment. If the hardware, OS, the language runtime and the SDK

are offered to you as a service, what would you call this? A Cloud Platform or may

be Cloud FX? We will address this in the next section.

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Exposing the Runtime + SDK as a Service

Cloud Application

Today, most of the traditional desktop applications like word processors and

spreadsheet packages are available over the web. These new breed of applications

just need a browser and offer high fidelity with the desktop software. This

fundamentally changes the way software is deployed and licensed. You need not

double click setup.exe to install an Office suite on your desktop. Just subscribe to

the applications and the features that you need and only pay for what you use. This

is almost equivalent to exposing the application as a service.These applications

may be called as Cloud Applications. We will take a relook at this later.

Web App as a Service

Welcome to the World of Services

Infrastructure as a Service

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In the previous section we discussed the Cloud OS. All that the Cloud OS offers is

the infrastructure services. You may choose to use REST API to manage this OS or

use SSH or Remote Desktop console. Technically, when you are able to delegate a

program to execute on a remote OS running on the Web, you are leveraging

Infrastructure as a Service (IaaS). This is different from classic web hosting. Web

hosting only hosts web pages and cannot execute code that needs low level access

to the OS API. Web hosting cannot dynamically scale on demand. IaaS enables you

to run your computing task on virtually unlimited number of machines. Remember

that through IaaS, you have just moved a server running in your backyard into the

Cloud. You pretty much own the managing, patching, securing and the health of

the remote servers. Amazon EC2 is an example of commercial IaaS offering.

Cloud OS = Infrastructure as a Service

Platform as a Service

Platform as a Service or PaaS goes one level above the Cloud OS. Through this,

developers can leverage a scalable platform to run their applications. The

advantage of PaaS is that the developers need not worry about installing,

maintaining, securing and patching the server. The PaaS provider takes the

responsibility of the infrastructure and exposes the platform alone as a service.

Through this, the developers can achieve higher level of scalability, reliability and

availability of their applications. Microsoft Azure and Google App Engine are

examples of PaaS.

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Cloud FX = Platform as a Service

Software as a Service

Software as a Service (SaaS) is a silent revolution in the world of traditional

software products. With the availability of Intel Atom based Netbooks and

abundant bandwidth, most of the applications are moving to the Cloud to be

offered as services. Consumers can now use inexpensive devices that are capable

of connecting to the web to get their work done. This reduces the upfront

investment in software and brings the Pay-as-you-go model. Google Apps,

Salesforce.com and Microsoft Online Services are examples of SaaS.

Cloud App = Software as a Service

What does Cloud Computing mean to you?

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IT Professionals and System Administrators

For IT Professionals, Cloud Computing is all about consolidation and outsourcing the

infrastructure. They are typically focused on the Infrastructure as a Service. IT

Pros will move away from managing individual servers in their Data Centers to using

a unified console to manage, track and monitor the health of the remote server

instances running on the Cloud.

IaaS is the focus area of IT Pros and system administrators

Developers and Architects

Platform as a Service is an offering meant for developers and architects. They

need to design applications keeping the statelessness of the Cloud. Architects

should start thinking about the patterns that will make the applications seamlessly

scale on-the-fly across hundreds of servers.

PaaS is the focus area of developers and architects

Consumers

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Consumers will experience the Cloud through a variety of applications that they

will use in their day to day life. If you have ever used Google Docs or Microsoft Live

Mesh, you have already leveraging the Cloud. Consumers will subscribe to Software

as a Service offerings.

SaaS delivers software through a subscription for the consumers

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Chapter 2

The Tenets of the Cloud

The 4 Key Tenets

I want to quickly recap the definition of Cloud Computing. It is all about

outsourcing your infrastructure and applications to run on a remote resource. The

‘remote resource’ phrase in the definition can be misleading and creates an illusion

that running your web app on a server hosted abroad is Cloud Computing. So, what

qualifies the ‘remote resource’ to be called as the Cloud?

Here are the 4 key capabilities that the Cloud Computing offers:

Elasticity

This is the most important attribute of the Cloud. You might start running your

application on just a single server. But in no time, Cloud Computing enables

you to scale your application to run on 100’s of servers. Once the traffic and

usage of your application decreases, you can scale down to 10’s of servers. All

this happens almost instantly and the best thing is your application and your

customers don’t even realize that. This dynamic capability to scale up and

scale down is called Elasticity. Elasticity brings an ‘illusion of Infinity’. Though

nothing is infinite in this world, your application can get any number of

resources as it demands. This is the biggest unique selling point of the Cloud.

Now, think of web hosting. When you want to add another server to your web

application, your hoster has to manually provision that for you. Adding

additional servers and configuring the network topology introduces additional

time lag that your business cannot afford. Most of the Cloud Computing vendors

offer an intuitive way of manipulating your server configuration and topology.

Elasticity is the single most important attribute of the Cloud.

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Elasticity of Cloud Computing

Pay-By-Use

Elasticity and Pay-By-Use attributes go hand in hand. When you are scaling up

your application by adding more resources, you know how much it is going to

cost you. Pay-By-Use is a boon for the startups. As an entrepreneur, you got to

balance your investment between human resources and IT resources. The

biggest benefit of Pay-By-Use is that it reduces the CAPEX and turns your IT

investment into OPEX. The analogy that I typically use is that of Cable or DTH

TV subscription. During the season of Cricket World Cup or NBA, you would

want to subscribe to the sports channels and unsubscribe that moment the

event is over. With Pay-By-Use, you can subscribe and unsubscribe to the IT

infrastructure based on your needs and you only pay for what you use. This is

the most optimal way of spending your IT budget.

Self Service

When you are able to enjoy the capability of scaling up and scaling down and

only pay for what you use, you never want to wait for someone in the

datacenter to add an additional server to your application. Cloud can deliver its

promise only when there is Self Service. Through this, you can control the

resources all by yourself without an intermediary. When you add a new CPU

core, a server instance or add extra storage, you do it by yourself by using the

Console offered by the Cloud provider. This results in reduction in IT support

and maintenance. Today most of the organizations have dedicated IT teams to

provision a new machine, storage, collaboration portal and mailboxes as a part

of on-boarding the new employees. Through Self Service, a fairly non-technical

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person can achieve these tasks and you don’t need certified system

administrators to do this. For example, when you sign up with Google Apps, it is

very simple and intuitive to configure the mailboxes for the employees. With

more and more applications moving the Cloud, Self Service becomes the

preferred way of configuring and managing the IT infrastructure.

Server Configuration @ ElasticHosts.com

ElasticFox for managing Amazon Web Web Services

Programmability

This is a critical parameter of the Cloud. The Cloud makes the developers

extremely important. Developers are familiar with the concepts of

multithreading where they spawn new threads to achieve scalability and the

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responsiveness of the application. They incorporate logic to create additional

threads on demand. The programmability aspect of the Cloud adds a new

dimension to the development. Developers can now create additional machines

and add it to the applications on demand. They can treat the entire data

center, servers and machines as an object model that be programmed. They

can now do a For-Each loop on every server instance and decide what do with

each instance. Amazon Web Services have the most mature API for

programmatically controlling the Cloud based resources. Azure started

supporting the management API that lets developers programmatically deploy

and manage Azure applications. By leveraging these APIs, developers are

building applications to manage the infrastructure and some of these frontends

run on iPhone and Windows Mobile. Now, imagine clicking a button on your

mobile phone to add a dozen servers to your application. Thanks to the Cloud!

Developers are important more than ever!

AWS SDK for .NET

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Azure Tools for Eclipse

iPhone App to manage AWS

So, let’s summarize what we just discussed. Cloud Computing has 4 key tenets –

1) Elasticity, 2) Pay-By-Use, 3) Self Service, and 4) Programmability.

Hosting vs. Cloud Computing

Revisiting the on-going debate of hosting vs. Cloud Computing, let’s see what

attributes hosting model exposes. Hosting can never meet the promise of

elasticity. Even if it does, it won’t match the economics of the Cloud. Hosting does

offer some level of Self Service but not to an extent of manipulating the server

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configuration on the fly! Pay-By-Use attribute is emulated by some hosting

companies. But, it is not a norm in the hosting business. Programmability is too

expensive to be supported by hosters as they cannot invest in the SDK and tools to

manage the infrastructure. So, it is clearly evident that hosting is not the same as

Cloud Computing.

Having understood the key attributes of the Cloud, you might start wondering how

you can bring these capabilities to your data center in the enterprise. The reality is

that these capabilities can be applied to your data center and officially that is

called as the Private Cloud. It is time for us to discuss various implementations of

the Cloud. We will look at 4 different mechanisms the way Cloud can be

implemented.

Hosting vs. the Cloud

The 4 Implementations of the Cloud

Public Cloud

This is the most popular incarnation of the Cloud. Many businesses and individuals

realize Cloud through the Public Cloud implementation. It needs a huge investment

and only well established companies with deep pockets like Microsoft, Amazon and

Google can afford to set them up. Public Cloud is implemented on thousands of

servers running across hundreds of data centers deployed across tens of locations

around the world. The best thing about Public Cloud is that the customers can

choose a location for his application to be deployed. This will reduce the latency

when the consumers access the application. For example, a London based business

can choose to deploy their app at the Europe data center and an American

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company prefers a data center in North America. With the geographical spread,

Public Clouds like Amazon Web Services and Microsoft Windows Azure also offer

Content Delivery Network (CDN) features. Through this, static content will be

automatically replicated across all the data centers around the globe thus

increasing the scalability and availability of the applications.

Public Cloud

Private Cloud

Simply put, Private Clouds are normal data centers within an enterprise with all

the 4 attributes of the Cloud – Elasticity, Self Service, Pay-By-Use and

Programmability. By setting up a Private Cloud, enterprises can consolidate their IT

infrastructure. They will need fewer IT staff to manage the data center. They will

also realize reduced power bills because of the low electricity consumption and

lesser cooling equipment needs. Private Cloud empowers employees within an

organization through Self Service of their IT needs. It becomes easy to provision

new machines and quickly assign them to project teams. Private Cloud borrows

some of the best practices of Public Cloud but limited to an organizational

boundary. Private Cloud can be setup using a variety of offerings from vmWare,

Microsoft, IBM, SUN and others. There are also some of the Open Source

implementations like Eucalyptus and Ubuntu Enterprise Cloud. We will discuss more

of Private Cloud in the coming episodes.

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Private Cloud

Hybrid Cloud

There are scenarios where you need a combination of Private Cloud and Public

Cloud. Due to the regulations and compliance issues in few countries, sensitive

data like citizen information, patient medical history, and financial transactions

cannot be stored in servers that physically not located within the political

boundaries of a country. In some scenarios, the enterprise customers want to get

best of the both worlds by logically connecting their Private Cloud and the Public

Cloud. Through this, they can offer seamless scalability by moving some of the on-

premise and Private Cloud based applications to the Public Cloud. Security plays a

critical role in connecting the Private Cloud to the Public Cloud. Realizing its

importance, Amazon Web Services has recently announced Virtual Private Cloud

(VPC) that securely bridges Private Cloud and Amazon Web Services. It is almost

like extending your infrastructure beyond the organizational boundary and the

firewall in a secure way. Microsoft’s recent announcement of Windows AppFabric

brings the concept of Hybrid Cloud to Microsoft’s future customers.

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Hybrid Cloud

Community Cloud

Community Cloud is implemented when a set of businesses have a similar

requirement and share the same context. This would be made available to a set of

select organizations. For example, the Federal government in US may decide to

setup a government specific Community Cloud that can leveraged by all the states.

Through this, individual local bodies like state governments will be freed from

investing, maintaining and managing their local data centers. Similarly, the

Reserve Bank of India (RBI) may setup a Community Cloud for all the financial

institutions that share common goals and requirements. So, a Community Cloud is a

sort of Private Cloud but goes beyond just one organization.

Community Cloud

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Chapter 3

The Anatomy of the Cloud

Introduction to Virtualization

Virtualization is abstracting the hardware to run virtual instances of multiple guest operating systems on a single host operating system. You can see Virtualization in action by installing Microsoft Virtual PC, VMware Player or Sun VirtualBox. These are desktop virtualization solutions that let you install and run an OS within the host OS. The virtualized guest OS images are called Virtual Machines. The benefit of virtualization is realized more on the servers than on the desktops.

Server Virtualization

There are many reasons for running Virtualization on the servers running in a traditional data center. Here are a few:

Mean Time To Restore

It is far more flexible and faster to restore a failed web server, app server or a database server that is running as a virtualized instance. Since these instances are physical files on the hard disk for the host operating system, just copying over a replica of the failed server image is faster than restoring a failed physical server. Administrators can maintain multiple versions of the VMs that come handy during the restoration. The best thing about this is that whole copy and restore process can be automated as a part of disaster recovery plan.

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Maximizing the server utilization

It is very common that certain servers in the data center are less utilized while some servers are maxed out. Through virtualization, the load can be evenly spread across all the servers. There are management software offerings that will automatically move VMs to idle servers to dynamically manage the load across the data center.

Reduction in maintenance cost

Virtualization has a direct impact on the bottom line. First, by consolidating the data center to run on fewer but powerful servers, there is a significant cost reduction. The power consumed by the data center and the maintenance cost of the cooling equipment comes down drastically. The other problem that virtualization solves is the migration of servers. When the hardware reaches the end of the lifecycle, the physical servers need to be replaced. Backing up and restoring the data and the installation of software on a production server is very complex and expensive. Virtualization makes this process extremely simple and cost effective. The physical servers will be replaced and the VMs just get restarted without any change in the configuration. This has a lot of impact on the IT budgets.

Efficient management

All major virtualization software have a centralized console to manage, maintain, track and monitor the health of physical servers and the VMs running on these servers. Because of the simplicity and the dynamic capabilities, IT administrators will spend less time in managing the infrastructure. This results in better management and cost savings for the company.

Virtualization on the Server

Let’s understand more about the server virtualization. Typically the OS is designed to act as an interface between the applications and the hardware. It is not specifically designed to run the guest OS instances on top of it.

OS manages the applications

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In fact, in the server virtualization scenario, the host OS is not very significant. It is just confined to booting up and running the VMs. Given the fact that the OS is not ideal for running multiple VMs and has a little role to play, there is a new breed of software called Hypervisor that takes over the OS. Hypervisor is an efficient Virtual Machine Manager (VMM) that is designed from the ground up to run multiple high performant VMs. So, a Hypervisor is to VMs what an OS is to processes.

A Hypervisor can potentially replace the OS and can even boot directly from a VM. This is called bare metal approach to virtualization. These Hypervisors have low footprint of few megabytes (vmWare ESXi is just 32MB in size!) and have an embedded OS with them. Hypervisors are assisted by the hardware virtualization features built into the latest Intel and AMD CPUs. This combination of hardware and Hypervisor turns the server into a lean and mean machine to host multiple VMs. The VM that is used by the Hypervisor to boot as a host is called a paravirtualized VM. This concept makes virtualization absolutely powerful. Imagine a server booting in few seconds and the required paravirtualized (host) VM gets copied over a gigabit Ethernet to run multiple guest VMs. This turns the datacenter to be very dynamic and agile. The Hypervisor can be controlled by a central console and can be instructed about the host VM to boot and the guest VMs to be run on it.

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A look at the Hypervisor market

Citrix XenServer

This product is based on the proven, open source Hypervisor called Xen. Xen’s paravirtualization technology is widely acknowledged as the fastest and most secure virtualization software in the industry and it is enhanced by taking full advantage of the latest Intel® VT and AMD-V™ hardware virtualization assist capabilities. This product is free and can be downloaded from Citrix.com.

VMware ESXi

This product is another bare metal Hypervisor from the virtualization leader, VMware. This is one of the best Hypervisors with just 32MB footprint. ESXi ships with Direct Console User Interface (DCUI) that provides basic UI required for administering and managing the Hypervisor. Through its standard Common Information Model (CIM) system, it also exposes the APIs to control the infrastructure.

Microsoft Hyper-V Server

This is a free Hypervisor from Microsoft based on the same Hypervisor that ships with Microsoft Windows Server Hyper-V edition. This is best suited for Virtual Desktop Infrastructure (VDI) because of its compatibility with Windows Vista and

Bare Metal Virtualization

Figure 3. Hypervisor manages the VMs

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Windows 7. Hyper-V does not have any local GUI but can be managed from System Center Virtual Machine Manager (SCVMM).

Virtualization and the Cloud

The architecture that we discussed forms the heart and soul of Cloud Computing. Here is how –

Elasticity

We know that the key attribute of the Cloud is Elasticity, which is the ability to scale up and scale down on the fly. This capability is achieved only through virtualization. Scaling up is technically adding more server VMs to an application and scaling down is detaching the VMs from the application.

Self Service The next attribute is Self Service. The Hypervisor comes with an API and the required agents to manage it remotely. This functionality can surface through the Self Service portals that the Cloud vendor offers. So, when you move a slider to increase the number of servers in your web tier, you are essentially talking to the Hypervisor to action that request. Pay-By-Use Pay-By-Use is the next attribute of the Cloud. By leveraging the management and monitoring capabilities of the Hypervisor, metering the usage of resources like the CPUs, RAM and storage can be easily achieved. Programmable Infrastructure Programmable Infrastructure is the last key tenet of the Cloud. We already saw how the API wired into Hypervisors can be leveraged. Developers can directly talk to the Hypervisor through the native APIs or Web Services exposed by the Cloud vendors. Through this, they can take the control of the VMs. It is very obvious that the Cloud is heavily relying on virtualization and efficient Hypervisors to achieve its goal.

Dissecting the Cloud Now that we know how Virtualization forms the core of the Cloud, let’s me put things in perspective. Let’s see what actually goes inside the Cloud. Geographic location

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We start deciding where to physically run our application. Most of the Cloud providers give you an option to host your application at a specific location. Depending on the customer base and the expected user location, you can choose a location. This will ensure that all your components like storage, compute and database services are hosted within the same data center. This will reduce the latency and makes the application more responsive.

Geographically spread Cloud data centers

Data Center Though you do not have a direct choice in this, your app will be deployed at a data center physically located at a place that you have chosen. These data centers typically run thousands of powerful servers that offer a lot of storage and computing power.

Server You never know which physical server is responsible for running your code and the application. In most of the cases, the app that you deployed may be powered by more than one server running within the same data center. You cannot assume that

A Cloud data center runs hundreds of servers

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the same physical server will run the next instances of your app. Servers are treated as a commodity resource to host the VMs. There is no affinity between a VM and a physical server. Each server in the data center is optimally utilized at any given point.

Each server runs the Hypervisor and the VM(s)

Virtual Machine This is the layer that you will directly interact with. In Platform as a Service (PaaS), you may not realize that you are dealing with a VM but in reality most of the Cloud implementations will host your code or app on a VM. VMs are essential to respect the 4 tenets of the Cloud. Your application runs on a VM that is managed by the Hypervisor running across all the servers. These VMs are moved across servers based on the server utilization. There is no guarantee that the VM that you launch will run on the same physical server. There will be a load balancer which will ensure that your applications are scalable by exploiting the power of all the VMs associated with your application.

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Under the hood of a server

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Chapter 4

Introducing Amazon Web Services Overview of Amazon Web Services

Amazon Web Services is one of the early and also the most successful

implementations of the Public Cloud. Many well known online properties leverage

AWS. Amazon initially started offering a Cloud based Message Queuing service

called Amazon Simple Queue Service or SQS. They eventually added services like

Mechanical Turk, Simple Storage Service (S3), Elastic Compute Cloud (EC2), A CDN

service called CloudFront, a flexible and distributed database service called

SimpleDB. Amazon recently announced the availability of MySQL in the Cloud

through a service called Relational Data Service (RDS).

Amazon Web Services

Given that Amazon offers the core capabilities to run a complete web application

or a Line of Business application, it is obvious that it is Infrastructure as a Service

(IaaS). AWS is truly the platform of the platforms. You can choose an OS, App

server and the programming language of your choice. AWS SDK and API is available

for most of the popular languages including Java, .NET, Python and Ruby.

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AWS API Bindings

Let’s take a closer look at some of the major Cloud service offerings from Amazon:

S3

Amazon’s Simple Storage Service or S3 is a great way to store data on the Cloud

that can be accessed by any application with access to the Internet. S3 can store

any arbitrary data as objects accompanied by metadata. These objects can be

organized into buckets. Every bucket and object has a set of permissions defined in

the Access Control List (ACL). The objects stored in S3 can be anything from a

document, a media file, serialized objects or even Virtual Machine images. Each

object can be 5GB in size while the metadata can be up to 2KB. All the objects can

be accessed using simple REST or SOAP calls. This makes S3 an ideal storage

solution to centrally store and retrieve data across multiple clients. S3 can also be

treated as a virtual file system to provide persistence storage capabilities to

applications.

Amazon Physical Infrastructure

EC2 Your Application

SOAP or REST based API

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Simple Storage Services

EC2

In simple terms, EC2 is hiring a server running at a remote location. These servers

are actually Virtual Machine images running on top of Amazon’s powerful data

centers. Amazon calls these virtualized server instances as Amazon Machine Images

or AMI. These instances come in different sizes that you can choose from. Please

refer to http://aws.amazon.com/ec2/#instance for more details on the instance

types. There are many pre-configured AMIs that you can choose from. The typical

workflow on EC2 is that you choose a pre-configured AMI, launch that AMI,

customize it by adding additional software and by loading an app and finally, save

that AMI as your custom AMI on S3. You can launch multiple instances of your AMI

and attach them to an IP called the Elastic IP. Because of the dynamic capability of

launching multiple instances of the same AMIs to scale up and terminating them to

scale down, it is called Elastic Compute Cloud.

http://bucket.s3.amzonaws.com/object Bucket

Object

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Elastic Compute Cloud

SQS

SQS is the message queue on the Cloud. It supports programmatic sending of

messages via web service applications as a way to communicate over the Internet.

Message Oriented Middleware (MOM) is a popular way of ensuring that the messages

are delivered once and only once. Moving that infrastructure to the web by

yourself is expensive and hard to maintain. SQS gives you this capability on-demand

and through the pay-by-use model. SQS is accessible through REST and SOAP based

API.

Simple Message Queue

CloudFront

When your web application is targeting the global users, it makes sense to serve

the static content through a server that is closer to the user. One of the solutions

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based on this principle is called Content Delivery Network (CDN). But this

infrastructure of geographically spread servers to serve static content can be very

expensive. CloudFront is CDN as a service. Amazon is leveraging its data center

presence across the globe by serving content through these edge locations.

CloudFront utilizes S3 by replicating the buckets across multiple edge servers.

Amazon charges you only for the data that is served through CloudFront and there

is no requirement for upfront payment.

Cloud Front

SimpleDB

If S3 offers storage for arbitrary binary data, SimpleDB is a flexible way to store

Name/Value pairs on the Cloud. This dramatically reduces the overhead of

maintaining a relational database continuously. SimpleDB is accessed through REST

and HTTP calls and can be easily consumed by any client that can parse a HTTP

response. Many Web 2.0 applications built using AJAX, Flash and Silverlight can

easily access data from SimpleDB. It is the only service from Amazon that is free up

to a specific threshold.

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Simple DB

RDS

Amazon RDS offers relational database on the Cloud. It is based on the popular

MySQL database. When you are moving a traditional Line of Business application to

the Cloud and want to maintain high fidelity with the existing systems, you can

choose RDS. The advantage of RDS is that you do not install, configure, manage and

maintain the DB server. You only consume it and Amazon takes care of the rest.

Routine operations like patching the server and backing up the databases are taken

care and you only consume the service. RDS is priced on Pay-as-you-go model and

there is no upfront investment required. It is accessible through the REST and SOAP

based API.

Relational Database Services

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Scenarios

Scalable Web Application

If you are an aspiring entrepreneur and want to go-live with your app without an

upfront investment, Amazon is the place to go. By running your web app on

Amazon, you can dynamically scale you application on demand and only pay for

what you use. This can be the best playground for you to determine the server

capacity needs and asses the peak traffic patterns before the commercial launch of

your web app.

Line of Business Application

If your enterprise has to open up an internal LOB application to its employees and

trading partners, it can extend the application to the Cloud by leveraging a

concept of AWS called Virtual Private Cloud (VPC). This is achieving the Hybrid

Cloud capabilities by partially moving an application to the Cloud while still

running the sensitive and proprietary part of the LOB application secured behind

the firewall. VPC enables organizations to securely extend itself to the Cloud.

Data Archival

Data that is not very frequently accessed but may be required due to data

retention policies can be easily archived on Amazon S3. By building a simple,

searchable frontend, this data can be searched and retrieved on-demand. Moving

the data to the Cloud will ensure that is available from any where and any time.

High-Performance Computing On Demand

For many enterprises, there is an occasional requirement of high performance

computing. Investing in high-end servers is not an optimal solution because they

may not be utilized after the task is done. With AWS, companies can virtually ‘hire’

as much computing power as they need and pay only for what they used. This will

eliminate the expensive proposition of investing in the infrastructure.

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Scalable Media Delivery

A TV channel might want to start delivering the recorded shows to its global

audience. Since most of the content is static, they can leverage the CDN

capabilities. Signing up with services like Akamai and LimeLight can be expensive.

Because the media content is already stored on S3, it is very easy and cost

effective to leverage Amazon’s CloudFront to deliver the media content through

the geographically spread edge locations.

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Chapter 5

Introduction to Microsoft

Windows Azure Platform

Overview of Windows Azure Platform

At a high level, Windows Azure Platform has 4 key services in it. The first one is

Windows Azure which is the Cloud OS from Microsoft. The second service is the

AppFabric which enables the integration of on-premise services with the Cloud.

The third service is a Database on the Cloud called SQL Azure which is based on

Microsoft SQL Server. The latest addition to the platform is a service Codenamed

“Dallas” which is a marketplace to publish, discover, consume and analyze premier

content.

Though Windows Azure Platform is designed for the developers building

applications on the Microsoft platform, this can also be leveraged by developers

building applications on Java and PHP environments. Microsoft is investing in the

right set of tools and plug-ins for Eclipse and other popular developer

environments.

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Windows Azure Platform

I will first explain each of the components of Windows Azure Platform and then

walk you through the scenarios for deploying applications on this platform.

Windows Azure

Windows Azure is the heart & soul of the Azure Platform. It is the OS that runs on

each and every server running in the data centers across multiple geographic

locations. It is interesting to note that Windows Azure OS is not available as a retail

OS. It is a homegrown version exclusively designed to power Microsoft’s Cloud

infrastructure. Windows Azure abstracts the underlying hardware and brings an

illusion that it is just one instance of OS. Because this OS runs across multiple

physical servers, there is a layer on the top that coordinates the execution of

processes. This layer is called the Fabric. In between the Fabric and the Windows

Azure OS, there are hundreds of Virtual Machines (VM) that actually run the code

and the applications. As a developer, you will only see two services at the top of

this stack. They are 1) Compute and, 2) Storage.

Windows Azure architecture

You interact with the Compute service when you deploy your applications on

Windows Azure. Applications are expected to run within one of the two roles called

Web Role or Worker Role. Web Role is meant to host typical ASP.NET web

applications or any other CGI web applications. Worker Role is to host long running

processes that do not have any UI. Think of the Web Role as an IIS container and

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the Worker Role as the Windows Services container. Web Role and Worker Role can

talk to each other in multiple ways. The Web Role can also host WCF Services that

expose a HTTP endpoint. The code within Worker Role will run independent of the

Web Role. Through the Worker Role, you can port either .NET applications or

native COM applications to Windows Azure.

When you run an application, you definitely need storage to either store the simple

configuration data or more complex binary data. Windows Azure Storage comes in

three flavors. 1) Blobs, 2) Tables and, 3) Queues.

Blobs can store large binary objects like media files, documents and even serialized

objects. Table offers flexible name/value based storage. Finally, Queues are used

to deliver reliable messages between applications. Queues are the best mechanism

to communicate between Web Role and Worker Role. The data stored in Azure

Storage can be accessed through HTTP and REST calls.

Figure 3. Compute & Storage Service

So, we just discussed that Windows Azure offers a Compute and Storage service.

Compute service is consumed by deploying a Web Application in a Web Role and

long running process in the Worker Role. Storage can be consumed through Blobs,

Tables and Queues.

AppFabric

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Windows Azure platform AppFabric was earlier called the .NET Services. This

service enables seamless integration of services that run within an organization

behind a firewall with those services that are hosted on the Cloud. It forms a

secure bridge between the legacy applications and the Cloud services. AppFabric

also brings the federated identity to the Cloud based applications. The two key

components of AppFabric are 1) Service Bus and, 2) Access Control.

AppFabric connecting on-premise to the Cloud

Service Bus provides a secure connectivity between on-premise and Cloud services.

It can be used to register, discover and consume services irrespective of their

location. Services hosted behind firewalls and NAT can be registered with the

Service Bus and these services can be then invoked by the Cloud Services. The

Service Bus abstracts the physical location of the Service by providing a URI that

can be invoked by any potential consumer.

Access Control is a mechanism to secure your Cloud services and applications. It

provides a declarative way of defining rules and claims through which callers can

gain access to Cloud services. Access Control rules can be easily and flexibly

configured to cover a variety of security needs and different identity-management

infrastructures. Access Control enables enterprises to integrate their on-premise

security mechanisms like Active Directory with the Cloud based authentication.

Developers can program Access Control through simple WCF based services.

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SQL Azure

SQL Azure is Microsoft SQL Server on the Cloud. Unlike Azure Storage, which is

meant for unstructured data, SQL Azure is a full blown relational database engine.

It is based on the same DB engine of MS SQL Server and can be queried with T-SQL.

Because of it’s fidelity with MS SQL, on-premise applications can quickly start

consuming this service. Developers can talk to SQL Azure using ADO.NET or ODBC

API. PHP developers can consume this through native PHP API. Through the

Microsoft SQL Azure Data Sync, data can be easily synchronized between on-

premise SQL Server and SQL Azure. This is a very powerful feature to build hubs of

data on the Cloud that always stay in sync with your local databases. For all

practical purposes, SQL Azure can be treated exactly like a DB server running in

your data center without the overhead of maintaining and managing it by your

teams. Because Microsoft is responsible for installation, maintenance and

availability of the DB service, business can only focus on manipulating and

accessing data as a service. With the Pay-as-you-go approach, there is no upfront

investment and you will only pay for what you use.

SQL Azure

Microsoft Codenamed “Dallas”

This service is an exchange setup by Microsoft for parties that can publish useful

data/content and parties that can consume this data in their applications. For

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example, Public Sector can publish interesting and useful census data and some

company in the healthcare business might be just looking for this data. This

company can search and discover the census dataset and pay for what they

consume. Data can be published in a variety of forms including BLOBS, CSV files,

Spreadsheets and RSS feeds. The dataset published on Dallas can be consumed

directly through tools like Microsoft Excel or can be integrated into custom

applications by calling the REST based API. So, this turns into a marketplace of

data publishers and data consumers. Through an add-in for Excel 2010 called

PowerPivot (previously known as Project “Gemini”), end users can directly

consume the data in Microsoft Excel.

Figure 5. Microsoft Codename “Dallas” service

To summarize what we just discussed, Windows Azure Platform Services consist of

Windows Azure, AppFabric, SQL Azure and a project Codenamed “Dallas”.

Scenarios for Microsoft Windows Azure Platform

Scalable Web Application

Because Windows Azure Platform is based on the familiar .NET platform, ASP.NET

developers can design and develop web applications on fairly inexpensive machines

and then deploy them on Azure. This will empower the developers to instantly

scale their web apps without worrying about the cost and the complexity of

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infrastructure needs. Even PHP developers can enjoy the benefits of elasticity and

pay-by-use attributes of the platform.

Compute Intensive Application

Windows Azure Platform can be used to run process intensive applications that

occasionally need high end computing resources. By leveraging the Worker Role,

developers can move code that can run across multiple instances in parallel. The

data generated by either Web Role or On-Premise applications can be fed to the

Worker Roles through Azure Storage.

Centralized Data Access

When data has to be made accessible to a variety of applications running across the

browser, desktop and mobile, it makes sense to store that in a central location.

Azure Cloud based storage can be great solution for persisting and maintaining data

that can be easily consumed by desktop applications, Silverlight, Flash and AJAX

based web applications or mobile applications. With the Pay-as-you-grow model,

there is no upfront investment and you will only pay for what you use.

Hybrid Applications (Cloud + On-Premise)

There may be a requirement for extending a part of an application to the Cloud or

building a Cloud façade for an existing application. By utilizing the AppFabric

services like Service Bus and Access Control, on-premise applications can be

seamlessly and securely extended to the Cloud. AppFabric can enable the Hybrid

Cloud scenario.

Cloud Based Data Hub

Through SQL Azure, companies can securely build data hubs that will be open to

trading partners and mobile employees. For example, the Inventory of a

manufacturing company can be securely hosted on the Cloud which is always in

sync with the local inventory database. The Cloud based DB will be opened up for

B2B partners to directly query and place orders. SQL Azure and the SQL Azure Data

Sync will enable interesting scenarios.

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Chapter 6

Google App Engine

Google App Engine is a platform to deploy and run web applications on Google’s

infrastructure. It comes with a dynamic web server with full support for common

web technologies. It offers a transactional data store for persisting data.

Developers can integrate their web application with Google Accounts through the

APIs. The biggest advantage of running web applications on GAE is the scalability

that it offers. Your web application will be as scalable as some of the popular

Google services like search.

Your web app running along with Google properties

Google App Engine currently supports Python and Java environments. Java

developers will be able to deploy and run JSPs and Servlets while Python

developers can use standard library. Since GAE runs in a sandbox, not all

operations are possible. For example, opening and listening on sockets is disabled.

The applications running on GAE live in a sandbox that provides multi-tenancy and

isolation across applications.

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Components of Google App Engine

The next logical layer is a set of APIs and Services to support the web application

developers. This layer has a persistent Datastore, User Authentication services,

Task Scheduler and Task Queue, URL Fetch, a Mail component, MemCache and

Image Manipulation. All these services are exposed through native API bindings. For

example, Java developers will be able to use JDO/JPA to talk to the datastore.

Let’s take a closer look at some of the services provided by GAE.

Java Runtime – GAE is based on Java 6 VM and Servlet 2.5 Container. The datastore

can be accessed through the JDO/JPA API. It supports JSR 107 for MemCache API.

Mail can be accessed through javax.mail API. Javax.net.URLConnection provides

access to URLFetch service. Apart from core Java language, other dynamic

languages based on Java like JRuby and Scala.

Python Rumtime – GAE comes with a rich set of API and tools for developing web

applications based on Python. It supports Python 2.5.2 and Python 3 is being

considered for the future releases. You can also take advantage of a wide variety

of mature libraries and frameworks for Python web application development, such

as Django. The Python environment provides rich Python APIs for the datastore,

Google Accounts, URL fetch, and email services. App Engine also provides a simple

Python web application framework called webapp to make it easy to start building

applications.

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Datastore – App Engine comes with a very powerful data storage that can scale

dynamically. It also features a query engine and support for transactions. The

datastore is different from traditional relational databases. The objects stored in

datastore are called “Entities” which are “schemaless”. These entities have a set

of properties that can be queried using a SQL like grammar like GQL or Google

Query Language. The datastore is strongly consistent and supports optimistic

concurrency control.

User Authentication – One of the advantages of using GAE is its integration with

Google Accounts. This empowers the developers to leverage Google’s secure

authentication engine for their custom applications. While a user is signed in to the

application, the app can access the user's email address, as well as a unique user

ID. The app can also detect whether the current user is an administrator, making it

easy to implement admin-only areas of the app.

Google Accounts integration with App Engine

URL Fetch – This service will fetch external web pages using the high bandwidth

that many other Google applications use.

Mail – This will enable developers to programmatically send email messages from

custom web applications.

MemCache – The Memcache service provides applications with a high performance

in-memory key-value cache that is accessible by multiple instances of the

application. Memcache is useful for data that does not need the persistence and

transactional features of the datastore, such as temporary data or data copied

from the datastore to the cache for high speed access.

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Image Manipulation – Through this service, developers can manipulate images. With

this API, you can resize, crop, rotate and flip images in JPEG and PNG formats.

Scheduled Tasks – Scheduled Tasks are also called “cron jobs”. Other than running

interactive web applications, GAE can also schedule tasks that can be invoked at a

specific time.

To get started on Google App Engine, download the Eclipse plug-in and the SDK.

The SDK emulates the GAE environment locally and enables you to design, develop

and test applications on your machine before finally deploying on GAE.

About the author -

Janakiram MSV is the Web Services Evangelist at Amazon Web

Services (AWS) in India. He helps developers, IT professionals,

customers and partners understand the value and use the

service offerings of AWS cloud platform. His responsibilities

include enabling ISVs, SIs and enterprises with the skills to

move their IT infrastructure and applications to the Cloud. In his previous role, he

was the Technology Architect – Cloud at Microsoft Corporation where he was

responsible for architecting enterprise solutions on the Microsoft Cloud Computing

platform. Janakiram is a Microsoft Certified Professional on the Windows Azure

Platform. He worked for Microsoft Corporation for over 10 years during which he

played various roles that involved selling, marketing and evangelizing the

Microsoft Application Platform and Tools to customers and partners in India. He

has been a regular speaker at events like Microsoft TechEd, Microsoft Developer

Days, Great Indian Developer Summit, JAX India and Foss.in. Janakiram’s blog can

be found at http://www.janakiramm.net

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