Introduction to PaaS and IaaS Cloud Computing

Roberto Beraldi

Models for Cloud Computing

(IaaS) Infrastructure as a Service

(SaaS)Software as a Service

XaaS (PaaS) Platform as a Service

Models for cloud computing

CC in a nutshell

• Cloud computing is a way to use Information

Technology infrastructures without the need to

install specific HW related to the infrastructures

being used.

• IT infrastructure can be as simple as a single raw

virtual machine, …

… more abstract as a sw platform used to develop

and running applications on several machines,

…or a sw application

What CC can provide?

• Infrastructure

• Platform

• Software

• API

• STorage

• X

as a service (IaaS)

as a service (PaaS)

as a service (SaaS)

as a service (APIaaS)

as a service (STaaS)

as a service (XaaS)

Main characteristics of CC

• Pay-per-use

– no ongoing commitment, utility prices

• Elastic capacity and the illusion of infinite resources

• Multitentancy

– Same instance of an application to serve multiple clients

• Resources that are abstracted or virtualized Resources provided as a Service and with a self-service Interface

– provides users the ability to upload, build, deploy, schedule, manage, and report on their business services on demand.

Factors enabling cloud computingHardware

HW virtualization

Multi-core chipsIn

tern

et

Tech

no

log

ies

Distrib

ute

d

Co

mp

utin

g

Web 2.0

Web Services

Mashups

SoA

Utility computing

Grid Computing

..

System Management

Autonomic Computing

Data Center Automation

Cloud

computing

Cloud actors

Platform as a Service

• A cloud platform offering an environment on which developers create and deploy applications– E.g., decide the size of the VM, where they are

located, etc.

• Different Programming Languages– PHP

– Java

– Ruby

• Different DB

• Web based console to create application (with dashboard)

Platform as a Service

• Developers can use an IDE to develop the

application and use either an SDK or CLI to

deploy the application

• Impact on the programming model

• Main players:

– Google’s app engine, OpenShift, Windows Azure,

and many more…

PaaS – example: GAE

• Cloud service for running web applications on the Google data center

• GAE is one of the most interesting and complete PaaS

– Simple configuration

– Transparent scalability

• “infinite” number of applications, req/sec storage

– Security

• All applications run inside a sandbox, do not have direct access to file system, cannot open other connections

• Different programming languages

GAE console

Lots of service

• Compute– App Engine

– VM

• Storage– BigTable

– SQL

– Datastore

• Operations– Monitoring

– Debugging

– Etc.

• Tools– Deployment Manager

– Development

• Big Data

SDK

GAE architecture

• Google App Engine speaks with web applications

through the Web Server Gateway Interface (WSGI)

standard protocol

• App Engine and SDK includes the webapp2

framework that implements WSGI

WEB AppHTTP Requests

WEB Server

WSGI Protocol

GAE: supported language

• Java

– JVM, Java servlet, …

– SDK Eclipse extension

• Python

– Standard library (without ‘unsecure’ calls)

• Go

• PHP (new)

LAB: Hello Word in GAE

• What we need:

– Google account

– GAE registration

• Plafond free (10 app)

– Register a new application

• The application ID will be used to deploy the application

– SDK

– Use the language

• Python 2.7 (no support for 3.x)

Hello Word in GAE

helloworld.py

app.yaml

Code

ConfSimulator

“Google Cloud”Deploy

Web-based Admin console

Step 1

Step 3

Step 2

Step 4

Hello Word in GAE

• Define a handler for the HTTP requests as a class that extends webapp2.RequestHandler class (MainPage)– Attributes : response, request (instance of class Request, Response)

– Methods: get,post, etc.. (to override)

• Map HTTP get request to get method (also post, put, etc..)

• Write data to HTTP response through self.response

• app is a global name that must assigned to the application

helloworld.py

Code

Step 1

app.yaml

Conf

“Google Cloud”Deploy

Web-based Admin console

Step 3

Step 4

• An application name helloword must be registered with the google engine– helloworld.appspot.com

appcfg.py update .

Dashboard

GAE architecture (simplified view)

App Eng

Front End

App Eng

Front End

App Eng

Front End

App Server

Loa

d

Ba

lan

cer

App Server App Server

API layer

APP APP APP

Other

Google

Service

HTTP Requests

Python GAE architecture

Python

VM

Standard

Lib

App

Read-only

File system

Source: Google App Engine – Guido van Rossum

REQ/REP

DATASTOREMEMCACHE

BigTable

URLfetch

mail

images

ServicesSandbox

CGI

Python GAE architecture (scaling)

Python

VM

Standard

Lib

App

Read-only

File system

Source: Google App Engine – Guido van Rossum

REQ/REP

DATASTOREMEMCACHE

BigTable

URLfetch

mail

images

ServicesSandbox

CGI

.

.

Example: PHP

• an app that handles customer requests might

include separate modules to handle other

tasks, such as:

– API requests from mobile devices

– Internal, admin-like requests

– Backend processing such as billing pipelines and

data analysis

Appication modules instances

GAE and mobile apps

OpenShift• OpenShift Online by Red Hat is a Platform as a Service (PaaS) that provides

developers and IT organizations with an auto-scaling, cloud application platform for deploying new applications on secure, scalable resources with minimal configuration and management overhead.

• Languages– Java, Ruby, and PHP. Integrated developer tools, such as Eclipse integration, JBoss Developer

Studio, and Jenkins, support the application life cycle.

• Database– MySQL, PostgreSQL, MongoDB, and SQLite.

• OpenShift Online provides disk space, CPU resources, memory, network connectivity, and an Apache or JBoss server to create, deploy, and manage applications in the cloud.

• Management web console

• CLI, very powerful for coding debugging etc

Source: online documentation

OpenShift: basic System components

Subscription plan

Example: create and application

GEARCLIENT

git to pull

git commit

PaaS example2: Windows Azure

• It is a set of integrated cloud technologies each

providing a specific set of services to application

developers

• Windows Azure provides developer-accessible

services for creating applications

• Strongly integrated with Visual studio

– Development fabric simulator

– Development storage simulator

Windows azure

• Two execution models for applications – Web hosting: Web Site

– PaaS: Cloud Service

• IaaS: Virtual Machines

http://www.windowsazure.com/en-us/develop/net/fundamentals/intro-to-windows-azure/

DeployementWeb Portal

1. Register (Live-id)

Conf(n.inst. =3)

Fabric

Controller

Service

.cspkg

Service

Service

Service

2. Create Hosted-Service

http://xxxx.cloudapp.net

3. Package upload

.csconf + .cspkg

Microsoft azure

• Lots of services are added during the years

– Computation

• VM,Cloud Services,Batch,RemoteApp

– Web and mobile device

• Backend for mobile app

– Data and storage

– Data analysis

• Machine learning

– Internet of Things

– …

INFRASTRUCTURE AS A SERVICE

Cloud computing in a nutshell

(by an analogy)

• Electricity is “virtual” entity – (many sources, we do not care from where we receive it,…)

• “Pay-as-you-go” – Elastic

Production Distribution Utilization

CC: Virtual computing power

CPU

cycles

Storage

Memory

Provider Utilization

Virtual machine

control panel

User decides the size on the VM…

IaaS

• A cloud infrastructure enables on-demand provisioning of servers running several choices of operating systems and a customized software stack.

• Cloud computing services are usually backed by large-scale data centers composed of thousands of computers.

• Such data centers are built to serve many users and host many disparate applications.

• Offers virtualized resources (computation, storage, and communication) on demand

IaaS: deployment models

Virtualization, main idea

• Memory:– Virtual Memory (>=Physical memory)

• Multitasking:– Several processes concurrently on the same HW, see the same

ISA. HW is shared thanks to an OS than manages critical instructions.

• Virtual Machine:– ‘60 from IBM on mainframes

– Abandoned with the advent of PCs, now again used for cloud computing

– Even different ISA on the same CPU

– Used to run different OS (not processes)

– Achieved through a Virtual Machine Monitor

Isolation

• Through virtualization, workload isolation is achieved since all program instructions are fully confined inside a VM, which leads to improvements in security.

• Better reliability is also achieved because software failures inside one VM do not affect others.

• Moreover, better performance control is attained since execution of one VM should not affect the performance of another VM.

Isolation

Application mobility

• Workload migration, also referred to as application mobility, targets at facilitating hardware maintenance, load balancing, fault tolerance and disaster recovery.

• It is done by encapsulating a guest OS state within a VM and allowing it to be suspended, fully serialized, migrated to a different platform, and resumedimmediately or preserved to be restored at a later date.

• A VM’s state includes a full disk or partition image, configuration files, and an image of its RAM.

Application mobility

HW consolidation

• Virtualization makes it possible to consolidate

individual workloads onto a single physical

platform, reducing the total cost of ownership.

Interface of a computing system

Virtual Machine

• Virtual Machine is a logic machine (ML) whose ISA is

implemented exploiting software running on a

physical machine (MF)

• Two main types:

– Native. ML=MF

• Same ISA. Indeed instructions of the MF are in large part executed

on the real CPU. Sensitive instruction are trapped.

– Emulation ML≠MF (different ISA)

• HW emulation

• Language level emulation (java)

Emulation

• HW emulation:

– ISA is different from real CPU

• Sparc emulates IA32

– Installation of different OS

• Language specific VM

– JVM

– CLR

Native emulation Virtual machine

• Same machine as the physical machine

“Efficient, isolated duplicate of a real

machine”)

• Virtualization is realized by a Virtual Machine

Monitor (VMM) o hypervisor

Native emulation

• Full virtualization

– OS without modification (e.g., VMWare’s ESX,

ESXi)

– OS legacy

• Para virtualization

– OS must be modified (e.g., Open source’s XEN)

– Higher efficiency

Resources

• Xen and the Art of Virtualization, Pratt et al. SOSP

2003.

• The Architecture of Virtual Machines, Smith, J.E.; R.

Nair, IEEE Computer, May 2005, Volume: 38 , Issue: 5

• A Comparison of Software and Hardware Techniques

for x86 Virtualization, K. Adams, O. Agesen. ASPLOS

2006.

Classical virtualization

• “A classical VMM executes guest operating system

directly, but at a reduced privileged level. The VMM

intercepts traps from the de-privileged guest, and

emulates the trapping instruction against a virtual

machine state”[*]

[*]”A camparison of Software and Hardware Techniques

for x86 Virtualization”, K.Adams, O.Agesen, ASPLOS

2006

Classical virtualization, esempio

1

3

4

5

Guest OS Not privileged instruction

green= User Mode

red= System Mode

Privileged instruction

e.g.. CLI, Clear Interrupts

2trap

VMM

time

2’

User level Kernel levela. CPU executes a kernel

instruction of the Guest OS

while being in user mode

b. CPU generates a trap

c. Control passes to the VMM

that emulates the instruction

d. 2’ is different of 2, but is

produces the same effect (

(for example,

CLI�VCPU.IF=0)

Hw virtualizazion

Hardware virtualization allows running multiple operating systems and software

stacks on a single physical platform.

The virtual machine monitor (VMM), hypervisor, mediates access to the

physical hardware presenting to each guest operating system a virtual machine

(VM), which is a set of virtual platform interfaces

Type-1 hypervisor (bare metal)

• Guest OS runs unchanged

• Used to build a “Hardware Server” (cloud computing)

• Hyper-V(Microsoft) , VMWare’s ESX

Type-2 hypervisor (hosted)

• Runs on top of a Hosting OS

• Often used on clients

Example of VMM: Virtual Box

• It usually runs on Desktop computers

• VMM runs as an application hosted by an OS

• Lower performance, easy to install VM

HW assisted virtualization

• Processors are designed to help virtualization

• For example, Intel-VT and AMD-V provide

additional instructions that help virtualization

• Hypervisors can use these instructions to

improve the performance

– Linux KVM, Microsoft Hyper-V, Microsoft Virtual

PC, Xen, etc. use these features

IaaS provider’s point of view

• A key challenge IaaS providers face when

building a cloud infrastructure is managing

physical and virtual resources, namely servers,

storage, and networks, in a holistic fashion.

• The orchestration of resources must be

performed in a way to rapidly and dynamically

provision resources to applications.

IaaS provider’s point of view

• The software toolkit responsible for this orchestration is called a virtual infrastructure

manager (VIM).

• This type of software resembles a traditional operating system (“cloud operating system”)—but instead of dealing with a single computer, it aggregates resources from multiple computers, presenting a uniform view to user and applications.

VIM and hypervisor

physical

servers

Hypervisor Hypervisor HypervisorVIM

Virtualization

platform

Virtual

server

Automated scaling

VIMhypervisor hypervisor

1)User request a new VM

That joins the existing 3 VM

1

2

2) VIM allocates the new VM

3

3) User increases the load

request

4

Usage and administrator

portal

Physical server 1 Physical server 2

Automated scale

listener

Example: automated scaling

VIMhypervisor hypervisor

Physical server 1 Physical server 2

Automated scale

listener

Example: OpenNebula

• Interface to Public Clouds: it offers a driver to

manage the life cycle of virtualized resources

obtained from external cloud providers.

• In case of spikes in demand, extra load can be

offloaded to rented resources. To the

applications, the use of leased resources must

ideally be transparent

Example: OpenStack

OpenStack is a cloud operating system that

controls large pools of compute, storage, and

networking resources throughout a datacenter,

all managed through a dashboard that gives

administrators control while empowering their

users to provision resources through a web

interface.

Example of IaaS

• Windows azure

– Different machine with different size and OS

– Different geographical region where the machine

is located

– Free trial (requires registration with VISA)

Main Amazon Web Service offering

• Elastic Cloud Computing (EC2)– Amazon Elastic Compute Cloud (Amazon EC2) is a web

service that provides resizable compute capacity in the cloud.

• Amazon Simple Storage Service (Amazon S3)– Amazon S3 provides a simple web services interface

that can be used to store and retrieve any amount of data, at any time, from anywhere on the web.

• Amazon Simple Queue Service (Amazon SQS)– offers a reliable, highly scalable hosted queue for

storing messages as they travel between computers

Current offer

Amazon Web Services (EC2)

• Rich set of VM

• General purpose– baseline level of CPU performance with the ability to burst above the

baseline

• Compute Optimized, GPU, etc…

• Reserved Instance– Amazon EC2 Reserved Instances allow to reserve Amazon EC2

computing capacity for 1 or 3 years

• Dedicated Instance– run in a VPC (Virtual Private Cloud) on hardware that's dedicated to a

single customer.

• Cluster networking

• Spot Instance– allow to bid on spare Amazon EC2 computing capacity.

Price (depends on the location)

Microsoft Azure vs Amazon AWS

• Short story: AWS is superior to Windows

Azure

• Long story: see

– http://www.computerworlduk.com/it-

vendors/microsoft-azure-vs-amazon-aws-public-

cloud-comparison-which-cloud-is-best-for-

enterprise-3624848/

New trends: Containers

Each virtual machine includes the

application, the necessary binaries and

libraries and an entire guest operating

system - all of which may be tens of GBs

in size.

Containers

Containers include the

application and all of its

dependencies, but

share the kernel with

other containers. They

run as an isolated

process in userspace on

the host operating

system.

Same OS!

Runs only on Linux

Much faster

Mobile Cloud Computing

• Exploiting ‘cloud’ approach to boost the

performance of an application, reduce the energy

consumption, increase the computation power

• Example: ‘CloneCloud’

– The system is a flexible application partitioner and

execution runtime that enables unmodified mobile

applications running in an application-level virtual

machine to seamlessly off-load part of their execution

from mobile devices onto device clones operating in a

computational cloud.

CloneCloud: main idea

Mobile-to-mobile offloading

Questions?