Overview of Emerging Technologies: IV AND V
Cloud Computing and its Service Models
Introduction to Cloud
computing
Cloud computing is a general term for anything that involves
delivering hosted services over the internet. ... The name cloud computing was
inspired by the cloud symbol that's often used to represent the internet in
flowcharts and diagrams.
What is exactly in cloud
computing?
Simply put, cloud computing is the delivery of computing
services—including servers, storage, databases, networking, software,
analytics, and intelligence—over the Internet (“the cloud”) to offer faster
innovation, flexible resources, and economies of scale.
Cloud computing is the on-demand availability of computer system resources, especially data storage (cloud storage) and computing power, without direct active management by the user. Large clouds often have functions distributed over multiple locations, each location being a data center. Cloud computing relies on sharing of resources to achieve coherence and economies of scale, typically using a "pay-as-you-go" model which can help in reducing capital expenses but may also lead to unexpected operating expenses for unaware users.
History
The cloud symbol was used to represent networks of computing equipment
in the original ARPANET by as early as
1977, and the CSNET by 1981—both predecessors to the
Internet itself. The word cloud was used as a metaphor for
the Internet and a standardized cloud-like shape was used to denote a network
on telephony schematics. With this
simplification, the implication is that the specifics of how the endpoints of a
network are connected are not relevant to understanding the diagram.
The term cloud was used to refer to platforms for distributed computing as early as 1993, when Apple spin-off General Magic and AT&T used it in describing their (paired) Telescript and PersonaLink technologies. In Wired's April 1994 feature "Bill and Andy's Excellent Adventure II", Andy Hertzfeld commented on Telescript, General Magic's distributed programming language:
"The beauty of Telescript ... is that now, instead of just
having a device to program, we now have the entire Cloud out there, where a
single program can go and travel to many different sources of information and
create a sort of a virtual service. No one had conceived that before.
The example Jim White [the designer of Telescript, X.400 and ASN. uses now is a date-arranging service where a software agent goes to the flower store and orders flowers and then goes to the ticket shop and gets the tickets for the show, and everything is communicated to both parties."[
Early history
During the 1960s, the initial concepts of time-sharing became
popularized via RJE (Remote
Job Entry); this terminology was mostly associated with large
vendors such as IBM and DEC. Full-time-sharing
solutions were available by the early 1970s on such platforms as Multics (on GE
hardware), Cambridge CTSS, and the earliest UNIX ports (on DEC hardware). Yet,
the "data center" model where users submitted jobs to operators to
run on IBM's mainframes was overwhelmingly predominant.
In the 1990s, telecommunications companies, who previously offered primarily dedicated point-to-point data circuits, began offering virtual private network (VPN) services with comparable quality of service, but at a lower cost. By switching traffic as they saw fit to balance server use, they could use overall network bandwidth more effectively.[citation needed] They began to use the cloud symbol to denote the demarcation point between what the provider was responsible for and what users were responsible for.
Cloud computing extended this boundary to cover all servers as well as the network infrastructure. As computers became more diffused, scientists and technologists explored ways to make large-scale computing power available to more users through time-sharing.[citation needed] They experimented with algorithms to optimize the infrastructure, platform, and applications to prioritize CPUs and increase efficiency for end users.
The use of the cloud metaphor for virtualized services dates at least
to General Magic in
1994, where it was used to describe the universe of "places" that mobile
agents in the Telescript environment
could go. As described by Andy
Hertzfeld:
2000s
In July 2002, Amazon created
subsidiary Amazon Web Services,
with the goal to "enable developers to build innovative and
entrepreneurial applications on their own." In March 2006 Amazon
introduced its Simple Storage Service (S3), followed
by Elastic Compute Cloud (EC2)
in August of the same year. These products pioneered the usage of server virtualization to
deliver IaaS at
a cheaper and on-demand pricing basis.
In April 2008, Google released the beta
version of Google App Engine. The
App Engine was a PaaS (one of the first of its kind)
which provided fully maintained infrastructure and a deployment platform for
users to create web applications using common languages/technologies such
as Python, Node.js and PHP.
The goal was to eliminate the need for some administrative tasks typical
of an IaaS model,
while creating a platform where users could easily deploy such applications
and scale them to demand. In early 2008, NASA's Nebula, enhanced
in the RESERVOIR European Commission-funded project, became the first
open-source software for deploying private and hybrid clouds, and for the
federation of clouds.
Service models
Cloud computing service
models arranged as layers in a stack
Though service-oriented architecture advocates
"Everything as a service" (with the
acronyms EaaS or XaaS, or simply aas),
cloud-computing providers offer their "services" according to
different models, of which the three standard models per NIST are
Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software
as a Service (SaaS). These
models offer increasing abstraction; they are thus often portrayed
as layers in a stack:
infrastructure-, platform- and software-as-a-service, but these need not be
related. For example, one can provide SaaS implemented on physical machines
(bare metal), without using underlying PaaS or IaaS layers, and conversely one
can run a program on IaaS and access it directly, without wrapping it as SaaS.
Infrastructure as a service
(IaaS)
Main article: Infrastructure
as a service
"Infrastructure as a service" (IaaS) refers to online services
that provide high-level API used to abstract various
low-level details of underlying network infrastructure like physical computing
resources, location, data partitioning, scaling, security, backup, etc.
A hypervisor runs the virtual
machines as guests. Pools of hypervisors within the cloud operational system
can support large numbers of virtual machines and the ability to scale services
up and down according to customers' varying requirements.
Linux containers run in isolated partitions of a single Linux
kernel running directly on the physical hardware.
Linux cgroups and namespaces are the
underlying Linux kernel technologies used to isolate, secure and manage the
containers. Containerisation offers higher performance than virtualization
because there is no hypervisor overhead. IaaS clouds often offer additional
resources such as a virtual-machine disk-image library,
raw block storage,
file or object storage,
firewalls, load balancers, IP
addresses, virtual local area networks (VLANs),
and software bundles.
The NIST's
definition of cloud computing describes IaaS as "where the consumer is
able to deploy and run arbitrary software, which can include operating systems
and applications. The consumer does not manage or control the underlying cloud
infrastructure but has control over operating systems, storage, and deployed
applications; and possibly limited control of select networking components
(e.g., host firewalls)."
IaaS-cloud providers supply these resources on-demand from their large
pools of equipment installed in data
centers. For wide-area connectivity,
customers can use either the Internet or carrier
clouds (dedicated virtual private networks).
To deploy their applications, cloud users install operating-system images and
their application software on the cloud infrastructure. In this model, the
cloud user patches and maintains the operating systems and the application
software. Cloud providers typically bill IaaS services on a utility computing
basis: cost reflects the amount of resources allocated and consumed.
Platform as a service (PaaS)
Main article: Platform as a service
The NIST's
definition of cloud computing defines Platform as a Service as:
The capability provided to the consumer is to deploy onto the cloud
infrastructure consumer-created or acquired applications created using
programming languages, libraries, services, and tools supported by the
provider.
The consumer does not manage or control the underlying cloud
infrastructure including network, servers, operating systems, or storage, but
has control over the deployed applications and possibly configuration settings
for the application-hosting environment.
PaaS vendors offer a development environment to application developers.
The provider typically develops toolkit and standards for development and
channels for distribution and payment. In the PaaS models, cloud providers
deliver a computing platform,
typically including operating system, programming-language execution environment,
database, and web server.
Application developers develop and run their software on a cloud
platform instead of directly buying and managing the underlying hardware and
software layers. With some PaaS, the underlying computer and storage resources
scale automatically to match application demand so that the cloud user does not
have to allocate resources manually.
Some integration and data management providers also use specialized
applications of PaaS as delivery models for data. Examples include iPaaS
(Integration Platform as a Service) and dPaaS (Data Platform as a
Service). iPaaS enables customers to develop, execute and govern integration
flows.
Under the iPaaS integration model, customers drive the development and
deployment of integrations without installing or managing any hardware or
middleware. dPaaS
delivers integration—and data-management—products as a fully managed service. Under
the dPaaS model, the PaaS provider, not the customer, manages the development
and execution of programs by building data applications for the customer. dPaaS
users access data through data-visualization tools.
Software as a service (SaaS)
Main article: Software
as a service
The NIST's
definition of cloud computing defines Software as a Service as:
The capability provided to the consumer is to use the provider's
applications running on a cloud infrastructure.
The applications are accessible from various client devices through either a
thin client interface, such as a web browser (e.g., web-based email), or a
program interface.
The consumer does not manage or control the underlying cloud infrastructure
including network, servers, operating systems, storage, or even individual
application capabilities, with the possible exception of limited user-specific
application configuration settings.
In the software as a service (SaaS) model, users gain access to
application software and databases.
Cloud providers manage the infrastructure and platforms that run the
applications. SaaS is sometimes referred to as "on-demand software"
and is usually priced on a pay-per-use basis or using a subscription fee.
In the SaaS model, cloud providers install and operate application
software in the cloud and cloud users access the software from cloud clients.
Cloud users do not manage the cloud infrastructure and platform where the
application runs. This eliminates the need to install and run the application
on the cloud user's own computers, which simplifies maintenance and support.
Cloud applications differ from other applications in their scalability—which
can be achieved by cloning tasks onto multiple virtual
machines at run-time to meet changing work demand. Load
balancers distribute the work over the set of virtual
machines. This process is transparent to the cloud user, who sees only a
single access-point. To
accommodate a large number of cloud users, cloud applications can be multitenant,
meaning that any machine may serve more than one cloud-user organization.
The pricing model for SaaS applications is typically a monthly or yearly
flat fee per user, so prices become scalable and adjustable if users are added
or removed at any point. It may also be free. Proponents claim that SaaS gives
a business the
potential to reduce IT operational costs by outsourcing hardware
and software maintenance and support to the cloud provider.
This enables the business to reallocate IT operations costs away from
hardware/software spending and from personnel expenses, towards meeting other
goals.
In addition, with applications hosted centrally, updates can be released
without the need for users to install new software. One drawback of SaaS comes
with storing the users' data on the cloud provider's server. As a result,[citation needed] there
could be unauthorized access to
the data. Examples of applications offered as SaaS are games and
productivity software like Google Docs and Word Online. SaaS applications may be
integrated with cloud
storage or File hosting services,
which is the case with Google Docs being integrated with Google
Drive and Word Online being integrated with Onedrive.
Mobile "backend"
as a service (MBaaS)
Main article: Mobile backend as a service
In the mobile "backend" as a service (m) model, also known
as backend as a service (BaaS), web
app and mobile
app developers are provided with a way to link their
applications to cloud
storage and cloud computing services with application programming
interfaces (APIs) exposed to their applications and custom software development kits (SDKs).
Services include user management, push
notifications, integration with social networking services[83] and
more. This is a relatively recent model in cloud computing, with most
BaaS startups dating from
2011 or later but trends indicate that these services are gaining
significant mainstream traction with enterprise consumers.
Serverless computing or
Function-as-a-Service (FaaS)
Main article: Serverless computing
Serverless computing is a cloud computing code execution model in which
the cloud provider fully manages starting and stopping virtual
machines as necessary to serve requests, and requests are
billed by an abstract measure of the resources required to satisfy the request,
rather than per virtual machine, per hour. Despite the name, it does not
actually involve running code without servers. Serverless computing is so
named because the business or person that owns the system does not have to
purchase, rent or provide servers or virtual machines for the back-end code
to run on.
Function as a service (FaaS) is a service-hosted remote procedure call
that leverages serverless computing to enable the deployment of individual
functions in the cloud that run in response to events. FaaS is considered
by some to come under the umbrella of serverless computing,
while some others use the terms interchangeably.
Deployment models
Cloud computing types
Private cloud
Private cloud is cloud infrastructure operated solely for a single
organization, whether managed internally or by a third party, and hosted either
internally or externally. Undertaking a private cloud project requires
significant engagement to virtualize the business environment, and requires the
organization to reevaluate decisions about existing resources. It can improve
business, but every step in the project raises security issues that must be
addressed to prevent serious vulnerabilities. Self-run data
centers are generally capital intensive.
They have a significant physical footprint, requiring allocations of
space, hardware, and environmental controls. These assets have to be refreshed
periodically, resulting in additional capital expenditures. They have attracted
criticism because users "still have to buy, build, and manage them"
and thus do not benefit from less hands-on management, essentially
"[lacking] the economic model that makes cloud computing such an
intriguing concept".
Public cloud
For a comparison of cloud-computing software and providers, see Cloud-computing comparison
Cloud services are considered "public" when they are delivered
over the public Internet, and they may be offered as a paid subscription, or
free of charge. Architecturally, there are few differences between public-
and private-cloud services, but security concerns increase substantially when
services (applications, storage, and other resources) are shared by multiple
customers.
Most public-cloud providers offer direct-connection services that allow
customers to securely link their legacy data centers to their cloud-resident
applications.
Several factors like the functionality of the solutions, cost,
integrational and organizational aspects
as well as safety & security are influencing
the decision of enterprises and organizations to choose a public cloud or on-premises solution.
Hybrid cloud
Hybrid cloud is a composition of a public cloud and a private
environment, such as a private cloud or on-premises resources, that remain
distinct entities but are bound together, offering the benefits of multiple
deployment models. Hybrid cloud can also mean the ability to connect
collocation, managed and/or dedicated services with cloud resources. Gartner defines
a hybrid cloud service as a cloud computing service that is composed of some
combination of private, public and community cloud services, from different
service providers.
A hybrid cloud service crosses isolation and provider boundaries so that
it can't be simply put in one category of private, public, or community cloud
service. It allows one to extend either the capacity or the capability of a
cloud service, by aggregation, integration or customization with another cloud
service.
Varied use cases for hybrid cloud composition exist. For example, an
organization may store sensitive client data in house on a private cloud
application, but interconnect that application to a business intelligence
application provided on a public cloud as a software service.
This example of hybrid cloud extends the capabilities of the enterprise
to deliver a specific business service through the addition of externally
available public cloud services. Hybrid cloud adoption depends on a number of
factors such as data security and compliance requirements, level of control
needed over data, and the applications an organization uses.
Another example of hybrid cloud is one where IT organizations use
public cloud computing resources to meet temporary capacity needs that can not
be met by the private cloud. This capability enables hybrid clouds to employ
cloud bursting for scaling across clouds. Cloud bursting is an application
deployment model in which an application runs in a private cloud or data center
and "bursts" to a public cloud when the demand for computing capacity
increases. A primary advantage of cloud bursting and a hybrid cloud model is
that an organization pays for extra compute resources only when they are
needed.
Cloud bursting enables data centers to create an in-house IT
infrastructure that supports average workloads, and use cloud resources from
public or private clouds, during spikes in processing demands. The
specialized model of hybrid cloud, which is built atop heterogeneous hardware,
is called "Cross-platform Hybrid Cloud". A cross-platform hybrid
cloud is usually powered by different CPU architectures, for example, x86-64
and ARM, underneath. Users can transparently deploy and scale applications
without knowledge of the cloud's hardware diversity.
This kind of cloud emerges from the rise of ARM-based system-on-chip for
server-class computing.
Hybrid cloud infrastructure essentially serves to eliminate limitations
inherent to the multi-access relay characteristics of private cloud networking.
The advantages include enhanced runtime flexibility and adaptive memory
processing unique to virtualized interface models.
Others
Community cloud
Community cloud shares
infrastructure between several organizations from a specific community with
common concerns (security, compliance, jurisdiction, etc.), whether managed
internally or by a third-party, and either hosted internally or externally. The
costs are spread over fewer users than a public cloud (but more than a private
cloud), so only some of the cost savings potential of cloud computing are
realized.
Distributed cloud
A cloud computing platform can be assembled from a distributed set of
machines in different locations, connected to a single network or hub service.
It is possible to distinguish between two types of distributed clouds:
public-resource computing and volunteer cloud.
Public-resource computing—This type of distributed cloud results from an
expansive definition of cloud computing, because they are more akin to
distributed computing than cloud computing. Nonetheless, it is considered a
sub-class of cloud computing.
Volunteer cloud—Volunteer
cloud computing is characterized as the intersection of public-resource
computing and cloud computing, where a cloud computing infrastructure is built
using volunteered resources. Many challenges arise from this type of
infrastructure, because of the volatility of the resources used to build it and
the dynamic environment it operates in. It can also be called peer-to-peer
clouds, or ad-hoc clouds. An interesting effort in such direction is
Cloud@Home, it aims to implement a cloud computing infrastructure using
volunteered resources providing a business-model to incentivize contributions
through financial restitution.
Multi cloud
Main article: Multicloud
Multi cloud is the use of multiple cloud computing services in a single
heterogeneous architecture to reduce reliance on single vendors, increase
flexibility through choice, mitigate against disasters, etc. It differs from
hybrid cloud in that it refers to multiple cloud services, rather than multiple
deployment modes (public, private, legacy).
Poly cloud
Poly cloud refers to the use of multiple public clouds for the purpose
of leveraging specific services that each provider offers. It differs from
Multi cloud in that it is not designed to increase flexibility or mitigate
against failures but is rather used to allow an organization to achieve more
that could be done with a single provider.
Big data cloud
The issues of transferring large amounts of data to the cloud as well as
data security once the data is in the cloud initially hampered adoption of
cloud for big data, but now that much data
originates in the cloud and with the advent of bare-metal
servers, the cloud has become a solution for use cases
including business analytics and geospatial analysis.
HPC cloud
HPC cloud refers to the use of cloud computing services and
infrastructure to execute high-performance computing (HPC)
applications. These applications consume considerable amount of computing
power and memory and are traditionally executed on clusters of
computers. In 2016 a handful of companies, including R-HPC, Amazon Web Services, Univa, Silicon Graphics
International, Sabalcore, Gomput, and Penguin
Computing offered a high performance computing cloud. The
Penguin On Demand (POD) cloud was one of the first non-virtualized remote HPC
services offered on a pay-as-you-go basis.
Penguin Computing launched its HPC cloud in 2016 as alternative to Amazon's EC2
Elastic Compute Cloud, which uses virtualized computing nodes.
What are the basic service
models of cloud computing?
There are three main service models of cloud computing
– Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and
Software as a Service (SaaS).
What are the 3 main service
models of cloud computing?
IaaS, PaaS and SaaS are the three most popular types of cloud
service offerings. (They are sometimes referred to as cloud service models or
cloud computing service models.
|
IaaS |
Paas |
SaaS |
|
It provides a virtual data center to store information and create
platforms for app development, testing, and deployment. |
It provides virtual platforms and tools to create, test, and deploy
apps. |
It provides web software and apps to complete business tasks. |
|
It provides access to resources such as virtual machines, virtual
storage, etc. |
It provides runtime environments and deployment tools for
applications. |
It provides software as a service to the end-users. |
|
It is used by network architects. |
It is used by developers. |
It is used by end users. |
|
IaaS provides only Infrastructure. |
PaaS provides Infrastructure+Platform. |
SaaS provides Infrastructure+Platform +Software. |
What are the 4 types of
cloud computing?
Overview. There are 4 main types of cloud computing: private
clouds, public clouds, hybrid clouds, and multiclouds. There are also 3 main
types of cloud computing services: Infrastructure-as-a-Service (IaaS),
Platforms-as-a-Service (PaaS), and Software-as-a-Service (SaaS).
Cloud Service Models
There are the following three types of cloud service models -
Infrastructure
as a Service (IaaS)
Infrastructure as a Service (IaaS)
IaaS is also known as Hardware as a Service (HaaS). It is a
computing infrastructure managed over the internet. The main advantage of using
IaaS is that it helps users to avoid the cost and complexity of purchasing and
managing the physical servers.
Characteristics of IaaS
There are the following characteristics of IaaS -
Resources are available as a service
Services are highly scalable
Dynamic and flexible
GUI and API-based access
Automated administrative tasks
Example: DigitalOcean, Linode, Amazon Web Services (AWS), Microsoft
Azure, Google Compute Engine (GCE), Rackspace, and Cisco Metacloud.
To know more about the IaaS
Platform as a Service (PaaS)
PaaS cloud computing platform is created for the programmer to develop,
test, run, and manage the applications.
Characteristics of PaaS
There are the following characteristics of PaaS -
Accessible to various users via the same development application.
Integrates with web services and databases.
Builds on virtualization technology, so resources can easily be scaled
up or down as per the organization's need.
Support multiple languages and frameworks.
Provides an ability to "Auto-scale".
Example: AWS Elastic Beanstalk, Windows Azure, Heroku, Force.com,
Google App Engine, Apache Stratos, Magento Commerce Cloud, and OpenShift.
To know more about PaaS
Software as a Service (SaaS)
SaaS is also known as "on-demand software". It is a software
in which the applications are hosted by a cloud service provider. Users can
access these applications with the help of internet connection and web browser.
Characteristics of SaaS
There are the following characteristics of SaaS -
Managed from a central location
Hosted on a remote server
Accessible over the internet
Users are not responsible for hardware and software updates. Updates are
applied automatically.
The services are purchased on the pay-as-per-use basis
Example: BigCommerce, Google Apps, Salesforce, Dropbox, ZenDesk,
Cisco WebEx, ZenDesk, Slack, and GoToMeeting.
To know more about the SaaS
Difference between IaaS,
PaaS, and SaaS
The below table shows the difference between IaaS, PaaS, and SaaS -
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