cloud computing 014 - uniroma1.it · cloud computing • cloud computing, like other technologies,...

Introduction to Cloud Computing

Roberto Beraldi

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

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…

Cloud computing

• Cloud computing, like other technologies, such as cluster, grid, aims at allowing access to large amounts of computing power in a fully virtualized manner, by aggregating resources and offering a single system view.

• Cloud computing has been coined as an umbrella term to describe a category of sophisticated on-demand computing services initially offered by commercial providers, such as Amazon, Google, and Microsoft.

What CC can provide?

• Infrastructure

• Platform

• Software

• API

• STorage

• Desktop

• X

as a service (IaaS)

as a service (PaaS)

as a service (SaaS)

as a service (APIaaS)

as a service (STaaS)

as a service (DaaS)

as a service (XaaS)

Main characteristics of CC

• Pay-per-use

– no ongoing commitment, utility prices;

• Elastic capacity and the illusion of infinite resources;

• 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

From mainframes to clouds

• Providers of CC can operate their

infrastructures at very high utilization rate

• Something similar to what happened with

Mainframes.

– They had to operate at very high utilization rates

simply because they were very expensive and

costs should be justified by efficient usage

Provisioning

Provisioning for peak load

Underprovisioning, case 1

Underprovisioning case 2

Types of Cloud Computing

(IaaS) Infrastructure as a Service

(SaaS)Software as a Service

XaaS (PaaS) Platform as a Service

INFRASTRUCTURE AS A SERVICE

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

Virtualization - 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.

Virtualization - isolation

Virtualization – 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.

Virtualization – application mobility

Virtualization - consolidation

• Virtualization makes it possible to consolidate

individual workloads onto a single physical

platform, reducing the total cost of ownership.

Virtual machines

• Virtual machine is a logic machine implemented via

software (ML) running on a physical machine (MF)

• Two main types

• No native emulation ML≠MF

• Native emulation. ML=MF

Process virtual machine

• Runs a SW process

• Examples Java Virtual Machine

• Common Language Runtime (CLR)/.NET

Virtual machine and interoperabiity

• Java Virtual Machine (JVM)

– ISA: Macchina a stack (zero-register)

JVM

MF1 MF2 MFn

Java

• “write once run

everywhere”

System 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

• Process : SO = Supervisor : Hypervisor

System virtual machine

• Full virtualization

– OS without modification (VMWare)

– OS legacy

• Paravirtualization

– OS must be modified

– Higher effciency

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 privilegedlevel. 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 Istruzione non privilegiata

verde = User Mode

rosso = System Mode

Istruzione privilegiata

p.e. CLI, Clear Interrupts

2trap

VMM

time

2’

Livello User Livello Kernela. 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), also called a 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 ESX

Type-2 hypervisor (hosted)

• Runs on top of a Hosting OS

• Guest OS unchanged (full virtualization)

• Often used on clients

Example of VMM: Virtual Box

• It usually runs on Desktop computers

• VMM runs as an application hosted by an OS

• Software-based virtualization

• Lower performance, easy to install VM (demo)

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.

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

IaaS: deployment model

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)

Platform as a Service

• A cloud platform offering an environment on which developers create and deploy applications

• Developers do have access to a SDK that allows to develop a new application and to deploy it in the cloud

• Impact on the programming model

• Google’s app engine, Windows Azure, and many more…

PaaS – example: GAE

• Cloud service for running web applications on the

Google data center

• Do one thing well

– 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

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

– Advanced frameworks can be used, e.g., Django

WEB AppHTTP Requests

WEB Server

WSGI Protocol

GAE: supported language

• Java

– JVM, Java servlet, …

– SDK Eclipse extension

• Python

– Standard library (without ‘unsecure’ calls)

• Go

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

– 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 .

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

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

SOFTWARE AS A SERVICE

Types of Cloud Computing

(IaaS) Infrastructure as a Service

(SaaS)Software as a Service

XaaS (PaaS) Platform as a Service

Access to Cloud computing

• A service is delivered through two access points:

• Standard web browsing (HTTP) and

• Programmatic access (Rest,XML-RPC,SOAP, etc. over HTTP)

Programmatic Service Access

(many methods)

Web URL

(standard HTTP methods)

web browerHTTP

Application

HTTP

Rest,XML-RPC,etc

Service

PaaS

IaaS

SaaS

What is a service?

SERVICE

INT

ER

FAC

E

--------

--------

--------

--------

Interface definition (e.g., WSDL)

Technology A

Technology B

Technology C

Web API (aka API as a Service)

• Delivering basic building blocks as ‘services’

for other programs

• Services can be offered via simpler protocols

– JSON, JSON-RPC, REST, JSONP,…

Web API (aka API as a Service)

Web-API

• Based of RPC/HTTP

• Two main data representations

– JSON

– XML

• Protocols

– XML-RPC

– JSON-RPC

– SOAP

– REST

Web API: RPC over Internet• RPC calls mapped onto HTTP (GET or POST)

• Synchronous call

• Asynchronous call– with callbacks

• External data representation– JSON (Java Simple Object Notation)

• http://www.json.org/json-it.html

– XML

• Protocols– REST, SOAP, JSONP, JSON-RPC, XML-RPC,…

JSON

• Two fundamental structures:

See JSON Lint

XML in a nutshell

• XML (eXtensible Markup Language) is a language derived fromSGML (Standard Generalized Markup Language), from whichHTML also derives.

• The key notion in the markup language familty is a markup,something that describes some aspect of the data

• In HTML markups define the appearance of the document,whereas in XML they define the meaning of the data

XML in a nutshell

• An XML document is a tree

• Data appear inside elements

• An element not only contains the data itself but alsoinformation describing the meaning of the data

Example

Il Signore degli Anelli, di John Ronald Reuel Tolkien,

Bompiani.

Title

Author

Editor

Example

<book>

<title>

Il Signore degli Anelli

</title>

<author>

John R. R. Tolkien

</author>

<editore>

Bompiani

</editor>

</book>

Title

Author

Editor

Book Elements

Tips : Browser allows to see the structure of the document

Elements and attribute

<title>


</title>

Data

Tag

<title pages=“345”>


</title>

Attribute (key/value pair)

Well formed document

Valid document

• Document that follows composition rules

about the its structure

• Two solutions

• Document Type Definition

– Easier, less ‘powerfull’

• XML Schema

– More complex, more powerfull

WFD and validation

XML

DocumentSyntax check

Semantic

checkGrammar

XML-RPC

Overview of XML-RPC

• Data Model

– Scalar

– Struct

– Array

• Messages

– Request message

– Response message

– Error message

Scalar types

Tag Type Example

<i4> or <int> four-byte signed integer -12

<boolean> 0 (false) or 1 (true) 1

<string> string hello world

<double> double-precision signed floating point

number

-12.214

<dateTime.iso8601> date/time 20101504T09:30:00

<base64> base64-encoded binary eW91IGNhbid0IHJlYWQgdGhpcyE=

Struct type

<struct>

<member>

<name>lowerBound</name>

<value><i4>18</i4></value>

</member>

<member>

<name>upperBound</name>


</member>

</struct>

Array type

<array>

<data>


<value><string>Egypt</string></value>

<value><boolean>0</boolean></value>

<value><i4>-31</i4></value>

</data>

</array>

Request message

• Root element: methodCall

• contains a MethodName element and a params

element

• MethodName contains the name of the procedure

being called

• Params is a list of values for the parameters

Example

<?xml version="1.0"?>

<methodCall>

<methodName>XXX</methodName>

<params>

<param>


</param>

<param>

<value><double>12.3</double></value>

</param>

</params>

</methodCall>

Example<?xml version="1.0"?>

<methodCall>

<methodName> XXX</methodName>

<params>

<param>


</param>

<param>


</param>

</params>

</methodCall>

methodCall

XXX

methodName

params

param valuei4

param valuedouble

123

12.3

Example<?xml version="1.0"?>

<methodCall>

<methodName>Scuola XXX</methodName>

<params>

<param>


</param>

<param>


</param>

</params>

</methodCall>

methodCall

XXX

methodName

params

param valuei4

param valuedouble

123

12.3

methodName

params

paramparam

doublei4

methodCall

Complete request message

POST /xmlrpc HTTP 1.0

User-Agent: …

Host: …

Content-type: text/xml

Content-length: ..

<?xml version=“1.0”?>

<methodCall>

<methodName>Circle_Area</methodName>

<params><param><value><double>12.2</double></value><param><params>

</methodCall>

Reply message

<?xml version="1.0"?>

<methodResponse>

<params>

<param>


</param>

</params>

</methodResponse>

Fault message<?xml version="1.0"?>

<methodResponse>

<fault>

<value>

<struct>

<member>

<name>faultCode</name>

<value><int>4</int></value>

</member>

<member>

<name>faultString</name>

<value><string>Too many parameters.</string></value>

</member>

</struct>

</value>

</fault>

</methodResponse>

JSON-RPC 2.0

• JSON-RPC is a stateless, transport agnostic,

light-weight remote procedure call (RPC)

protocol

• Much like XML-RPC

– No formal grammar

– Definition of request object and reply object

• New feature: batch requests, notification

Some example

--> {"jsonrpc": "2.0", "method": "subtract", "params": [42, 23], "id": 1}

<-- {"jsonrpc": "2.0", "result": 19, "id": 1}

-->{"jsonrpc": "2.0", "method": "subtract", "params": [23, 42], "id": 2}

<-- {"jsonrpc": "2.0", "result": -19, "id": 2}

-->{"jsonrpc": "2.0", "method": "subtract", "params": {"subtrahend": 23, "minuend": 42}, "id": 3}


--> {"jsonrpc": "2.0", "method": "subtract", "params": {"minuend": 42, "subtrahend": 23}, "id": 4}


JSON-RPC call batch

--> [{"jsonrpc": "2.0", "method": "sum", "params": [1,2,4], "id": "1"},{"jsonrpc": "2.0", "method": "notify_hello", "params": [7]},{"jsonrpc": "2.0", "method": "subtract", "params": [42,23], "id": "2"},{"foo": "boo"},{"jsonrpc": "2.0", "method": "foo.get", "params": {"name": "myself"}, "id": "5"},{"jsonrpc": "2.0", "method": "get_data", "id": "9"} ]<-- [{"jsonrpc": "2.0", "result": 7, "id": "1"},{"jsonrpc": "2.0", "result": 19, "id": "2"},{"jsonrpc": "2.0", "error": {"code": -32600, "message": "Invalid Request."}, "id": null},{"jsonrpc": "2.0", "error": {"code": -32601, "message": "Method notfound."}, "id": "5"},{"jsonrpc": "2.0", "result": ["hello", 5], "id": "9"}]

JSONP (JSON with Padding)

GET

….

<javasxcript scr=xxx&callback=f>

….

f(JSON data)

Used in JavaScript

Allows to overcome the cross-

domain problem

Uses a callback function

REST

• Method calls are mapped to HTTP request

(Get, Post)

• Method name is a parameter of the call

• Reply is usually formatted as JSON or XML

SOAP

• It’s by far the most verbose protocol

• Service is described in WSDL file

• Messages as XML documents formatted

according to a specific schema

Tool utili per il debugging

RPC over Internet: example

…

http://api.wunderground.com/api/http://api.wunderground.com/api/http://api.wunderground.com/api/http://api.wunderground.com/api/KEYKEYKEYKEY////FEATUREFEATUREFEATUREFEATURE/[/[/[/[FEATUREFEATUREFEATUREFEATURE…]/q/…]/q/…]/q/…]/q/QUERYQUERYQUERYQUERY....FORMATFORMATFORMATFORMAT

Features

geolookupconditions forecast

types= JSON, XML

Example

http://api.wunderground.com/api/[API_KEY]/conditions/q/rome.json

….

location ID

http://api.wunderground.com/api/[API_KEY]/conditions/q/rome.json?callback=f

JSONP

Example of XML reply

http://api.wunderground.com/api/[APIKEY]/conditions/q/zmw:00000.1.16240.xml

Interoperability

Chrome Developer tool

Static call

• Using JS src you can “make a call” and display

results on the screen

•

Static call

Dynamic Call

Dynamic call

1. Dynamically create a HTML element and append in

the head section

2. Call the URL with callback function

Dynamic call

• Show the current temperature on the screen

Using jQuery

Additional example

Example: Geocoding API

Example: Geocoding API (json)

Example: Geocoding API (xml)

Example: reverse Geocoding (json)

Example: Reverse geocoding (xml)

Google’s JavaScript API (vers. 3)

Example

Example:

Geolocation in HTML5

Example: Flickr ®

Flickr: request, reply message format

http://api.flickr.com/services/xmlrpc/

http://api.flickr.com/services/soap/

WEB-API

http://api.flickr.com/services/rest/

Example: rest call

Example

• Reply is wrapped through jsonFlickrApi

callback name

• To avoid this, set nojsoncallback=1 option

json format

Asynchronous RPC: AJAX

Sicurezza:

Cross domain non è

consentito

Example: using AJAX

Example: searching photos

Example: searching data

Key photo contains photo details

Example: searching photo

Every photo has a link

[mstzb] defines the size

Example: searching photos

Other example

http://api.wordreference.com/{api_version}/{API_key}/{dictionary}/{term}

http://api.wordreference.com/{api_version}/{API_key}/JSON/{dictionary}/{term}

Example

Example: Twitter API

Exercise

• Write a simple JS program for the TTT game

• Hint:

– use a table for button formatting

– Use a single handler to make modification

Other web API

• http://openweathermap.org/api

• EditGrid

• Dropbox is a free (up to 2GB), web-based cloud storage mechanism– file backup service

– data sharing

– Data sync among different clients

– Mobile applications

Android

iPhone

iPad

Blackberry

Windows

Linux

MAC

.mp3

.avi.jpg

REST / JSON

STorage as a Service

Questions?

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