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
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
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
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?
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