Cloud Computing : Fundamental Concepts and Models

Fundamental Concepts and Models
Manash Kumar Mondal
Rani Rashmoni Green University
Code: MSCCS401
M.K.Mondal (mkmkucse@gmail.com) Rani Rashmoni Green University M.Sc CS. 2025 1 / 63

Contents
1 Roles
2 Boundaries
3 Cloud Characteristics
4 Cloud Delivery Models
5 Cloud Deployment Models

Roles
Roles

Roles
Cloud Provider
Organisation, provides cloud-based IT resources.
Responsible for making cloud services available to cloud consumers, as per
agreed upon SLA guarantees.
Management and administrative duties to ensure the on-going operation of
the overall cloud infrastructure.
Owns the IT resources that are made available for lease by cloud consumers
”Resell” IT resources leased from other cloud providers.

Roles
Cloud Consumer
An organisation (or a human)
Has a formal contract or arrangement with a cloud provider
Uses IT resources made available by the cloud provider.
Uses a cloud service consumer to access a cloud service

Roles
Cloud Provider and Cloud Consumer
Figure: A cloud consumer (Organisation A) interacts with a cloud service from a cloud
provider (that owns Cloud A). Within Organisation A, the cloud service consumer is
being used to access the cloud service.

Roles
Cloud Service Owners
The person or organization that legally owns a cloud service
Can be the cloud consumer, or the cloud provider that owns the cloud within
which the cloud service resides.
Cloud consumer organizations can develop and deploy cloud services in clouds
owned by third parties for the purpose of making the cloud services available
to the general public.

Roles
Cloud Consumer As Cloud Service Owner
Figure: A cloud consumer can be a cloud service owner when it deploys its own service in
a cloud.

Roles
Cloud Consumer As Cloud Service Owner
Figure: A cloud provider becomes a cloud service owner if it deploys its own cloud
service, typically for other cloud consumers to use.

Roles
Cloud Auditor
A third-party that conducts independent assessments of cloud environments
The evaluation of security controls, privacy impacts, and performance.
Provides an unbiased assessment (and possible endorsement) of a cloud
environment
to help strengthen the trust relationship between cloud consumers and cloud
providers.

Roles
Cloud Broker and Cloud Carrier
Cloud Broker
The responsibility of managing and negotiating the usage of cloud services
between cloud consumers and cloud providers.
Mediation services - inter-mediation, aggregation, and arbitrage.
Cloud Carrier
Provides the wire-level connectivity between cloud consumers and cloud
providers.
Network and telecommunication providers.

Boundaries
Boundaries

Boundaries
Organisational Boundary
Represents the physical perimeter that surrounds a set of IT resources owned
and governed by an organization.
Does not represent the boundary of an actual organization, only an
organisational set of IT assets and IT resources.
Clouds have an organisational boundary.

Boundaries
Organisational Boundary of Consumer and Provider
Figure: Organizational boundaries of a cloud consumer (left), and a cloud provider
(right), represented by a broken line notation.

Boundaries
Trust Boundary
When an organization assumes the role of cloud consumer to access
cloud-based IT resources, it needs to extend its trust beyond the physical
boundary of the organization to include parts of the cloud environment.
A logical perimeter that typically spans beyond physical boundaries to
represent the extent to which IT resources are trusted.
When analysing cloud environments, it is most frequently associated with the
trust issued by the organization acting as the cloud consumer.

Boundaries
Trust boundary and Organisational Boundary
Figure: An extended trust boundary encompasses the organisational boundaries of the
cloud provider and the cloud consumer.

Cloud Characteristics

On-demand Usage
A cloud consumer can autonomously access cloud-based IT resources
Gives the cloud consumer the freedom to self-provision these IT resources
Once configured, usage of the self-provisioned IT resources can be automated
- no further human involvement.
Also known as “on-demand self-service usage,”
enables the service-based and usage-driven features found in mainstream
clouds.

Ubiquitous Access
Represents the ability for a cloud service to be widely accessible.
Require support for a range of devices, transport protocols, interfaces, and
security technologies.
To enable this level of access generally requires that the cloud service
architecture be tailored to

Multitenancy and Resource Pooling
Multitenacy
The characteristic of a software program that enables an instance of the program
to serve different consumers (tenants) whereby each is isolated from the other, is
referred to as multitenancy.
A cloud provider pools its IT resources to serve multiple cloud service
consumers by using multitenancy models
Relies on the use of virtualization technologies
IT resources can be dynamically assigned and reassigned, according to
demands.

Multitenancy and Resource Pooling cont.
Resource Pooling
Resource pooling allows cloud providers to pool large-scale IT resources to serve
multiple cloud consumers.
Different physical and virtual IT resources are dynamically assigned and
reassigned according to demand
Statistical multiplexing.
Resource pooling is achieved through multitenancy technology

Single-tenant vs Multitenat Environments
Figure: Single-tenant: each cloud consumer
has a separate IT resource instance.
Figure: Multitenant: A single instance of an
IT resource, such as a cloud storage device,
serves multiple consumers.

Elasticity
The automated ability of a cloud to transparently scale IT resources, as
required in response to runtime conditions or as pre-determined by the cloud
consumer or cloud provider.
Closely associated with the Reduced Investment and Proportional Costs
benefit.
Cloud providers with vast IT resources can offer the greatest range of
elasticity.

Measured usage
Represents the ability of a cloud platform to keep track of the usage of its IT
resources, primarily by cloud consumers.
Based on what is measured, the cloud provider can charge a cloud consumer
only for the IT resources actually used and/or for the time-frame during
which access to the IT resources was granted.
It is closely related to the on-demand characteristic.
Not only tracking statistics for billing purposes.
Also encompasses the general monitoring of IT resources and related usage
reporting (for both cloud provider and cloud consumers)
Measured usage is also relevant to clouds that do not charge for usage
(Private Cloud)

Resiliency
A form of failover that distributes redundant implementations of IT resources
across physical locations.
IT resources can be pre-configured so that if one becomes deficient,
processing is automatically handed over to another redundant
implementation.
Redundant IT resources within the same cloud (but in different physical
locations) or across multiple clouds.
Increase both the reliability and availability of their applications by leveraging
the resiliency of cloud-based IT resources.

An Example: Resiliency
Figure: A resilient
system in which
Cloud B hosts a
redundant
implementation
of Cloud Service
A to provide
failover in case
Cloud Service A
on Cloud A
becomes
unavailable.

Cloud Delivery Models

Represents a specific, pre-packaged combination of IT resources offered by a
cloud provider.
Three common cloud delivery models widely established and formalised:
Infrastructure-as-a-Service (IaaS)
Platform-as-a-Service (PaaS)
Software-as-a-Service (SaaS)
N.B
A cloud delivery model can be referred to as a ’cloud service delivery model’
because each model is classified as a different type of cloud service offering.

Extended Cloud Delivery Models
Many specialised variations of the three base cloud delivery models have
emerged, each comprised of a distinct combination of IT resources.
Storage-as-a-Service (STaaS)
Database-as-a-Service (DBaaS)
Security-as-a-Service (SECaaS)
Communication-as-a-Service (CaaS)
Integration-as-a-Service
Testing-as-a-Service (TaaS)
Process-as-a-Service
Business Process-as-a-Service (BPaaS)

Infrastructure-as-a-Service (IaaS)
IaaS
A self-contained IT environment comprised of infrastructure-centric IT resources
that can be accessed and managed via cloud service-based interfaces and tools.
Environment may include
Environment may include hardware, network, connectivity, operating systems, and
other “raw”IT resources.
vs. Traditional hosting or outsourcing environment
IT resources are typically virtualized and packaged into bundles that simplify
up-front runtime scaling and customization of the infrastructure.

Infrastructure-as-a-Service (IaaS) (Cont...)
Provide cloud consumers with a high level of control and responsibility over
its configuration and utilization.
Not pre-configured, placing the administrative responsibility directly upon the
cloud consumer.
Designed for cloud consumers that require a high level of control over the
cloud-based environment they intend to create.
Sometimes cloud providers will contract IaaS offerings from other cloud
providers in order to scale their own cloud environments.

The types and brands of the IT resources provided by IaaS products offered
by different cloud providers can vary.
IT resources are generally offered as freshly initialized virtual instances.
A central and primary IT resource within a typical IaaS environment is the
virtual server.
Virtual servers are leased by specifying server hardware requirements, such as
processor capacity, memory, and local storage space.

Figure: A cloud consumer is using a virtual server within an IaaS environment. Cloud
consumers are provided with a range of contractual guarantees by the cloud provider,
pertaining to characteristics such as capacity, performance, and availability.

Platform-as-a-Service (PaaS)
PaaS
A pre-defined “ready-to-use”environment typically comprised of already
deployed and configured IT resources.
Pre-packaged products and tools
PaaS relies on the usage of a ready-made environment that establishes a set of
pre-packaged products and tools used to support the entire delivery lifecycle of
custom applications.

Platform-as-a-Service (PaaS) (Cont...)
Reason for investing in PaaS environment
Wants to extend on-premise environments into the cloud for scalability and
economic purposes.
Uses the ready-made environment to entirely substitute an on-premise
environment.
Wants to become a cloud provider and deploys its own cloud services to be
made available to other external cloud consumers.

Pros.
Spared from the administrative burden of setting up and maintaining the bare
infrastructure IT resources provided via the IaaS model.
Cons.
Conversely, the cloud consumer is granted a lower level of control over the
underlying IT resources that host and provision the platform.
Examples
Google App Engine offers a Java and Python-based environment.

Figure: A cloud consumer is accessing a ready-made PaaS environment. The question
mark indicates that the cloud consumer is intentionally shielded from the implementation
details of the platform.

Software-as-a-Service (SaaS)
SaaS
A software program positioned as a shared cloud service and made available as a
“product”or generic utility represents the typical profile of a SaaS offering.
Used to make a reusable cloud service widely available (often commercially)
to a range of cloud consumers.
An entire marketplace exists around SaaS products that can be leased and
used for different purposes and via different terms.

Software-as-a-Service (SaaS) (Cont...)
Characteristics
A cloud consumer is generally granted very limited administrative control
over a SaaS implementation.
It is most often provisioned by the cloud provider, but it can be legally owned
by whichever entity assumes the cloud service owner role.
Example
An organization acting as a cloud consumer while using and working with a
PaaS environment can build a cloud service that it decides to deploy in that
same environment as a SaaS offering.
The same organization then effectively assumes the cloud provider role as the
SaaS-based cloud service is made available to other organizations that act as
cloud consumers when using that cloud service.

Software-as-a-Service (SaaS) (Cont...)
Figure: The cloud service consumer is given access the cloud service contract, but not to
any underlying IT resources or implementation details.

Comparing Cloud Delivery Models

Typical activities carried out by cloud consumers and cloud
providers

Examples of IaaS, PaaS, SaaS
Figure: Examples of IaaS, PaaS, SaaS

Comparing IaaS, PaaS, SaaS
Figure: Comparing IaaS, PaaS, SaaS

IaaS + PaaS
Concept
A PaaS environment will be built upon an underlying infrastructure comparable to
the physical or virtual servers and other IT resources provided in an IaaS
environment.
The reasoning behind leasing an IaaS
Economically eﬀicient
May be he first cloud provider is close to exceeding its existing capacityby
serving other cloud consumers
cloud consumer imposes a legal requirement for data to be physically stored in
a specific region (different from where the first cloud provider’s cloud resides)

IaaS+PaaS: Architecture
Figure: A PaaS environment based on the IT resources provided by an underlying IaaS
environment.

An Example: IaaS+PaaS

IaaS+PaaS+SaaS: Architeture
Figure: A simple layered view of an architecture comprised of IaaS and PaaS
environments hosting three SaaS cloud service implementations.

Cloud Deployment Models

Deployment Models
Deployment Models
Represents a specific type of cloud environment, primarily distingused by
ownership, size and access
Public Cloud
Comunity Cloud
Private Cloud
Hybrid Cloud

Public Clouds
A publicly accessible cloud environment owned by a third-party cloud
provider.
The IT resources are provisioned via cloud delivery models
Offered to cloud consumers at a cost or are commercialized via other
revenues (such as advertisement).
The cloud provider is responsible for the creation and on-going maintenance

Public Clouds (Cont...)
Figure: Organizations act as cloud consumers when accessing cloud services and IT
resources made available by different cloud providers.

Community Clouds
Similar to a public cloud except that its access is limited to a specific
community of cloud consumers.
May be jointly owned by the community members or by a third-party cloud
provider that provisions a public cloud with limited access.
The member cloud consumers of the community typically share the
responsibility for defining and evolving the community cloud.

Community Clouds (Cont...)
Figure: An example of a “community”of organizations accessing IT resources from a
community cloud.

Pivate Clouds
Owned by a single organization.
Enables an organization to use cloud computing technology as a means of
centralizing access to IT resources by different parts, locations, or
departments of the organization.
When a private cloud exists as a controlled environment, the problems
described in the Risks and Challenges section do not tend to apply.
Using a private cloud can change how organizational and trust boundaries are
defined and applied.
The administration may be carried out by internal or outsourced staff.

Pivate Clouds (Cont...)
With a private cloud, the same organization is technically both the cloud
consumer and cloud provider.
Roles
A separate organizational department typically assumes the responsibility for
provisioning the cloud - The cloud provider
Departments requiring access to the private cloud - The cloud consumer role

Community Clouds (Cont...)
Figure: A cloud service consumer in the organization’s on-premise environment accesses
a cloud service hosted on the same organization’s private cloud via a virtual private
network.

On-premise vs. Cloud-based
Even though the private cloud may physically reside on the organization’s
premises, IT resources it hosts are still considered “cloud-based”as long as
they are made remotely accessible to cloud consumers.
IT resources hosted outside of the private cloud by the departments acting as
cloud consumers are therefore considered “on-premise”in relation to the
private cloud-based IT resources.

Hybrid Clouds
Hybrid Clouds
A cloud environment comprised of two or more different cloud deployment models.
Example
A cloud consumer may choose to deploy cloud services processing sensitive
data to a private cloud.
Less sensitive cloud services to a public cloud.
The result of this combination is a hybrid deployment model.
This architectures is complex and challenging to create and maintain due to
the potential disparity in cloud environments and the fact
The management responsibilities are typically split between the private cloud
provider organization and the public cloud provider.

Hybrid Clouds (Cont...)
Figure: An organization using a hybrid cloud architecture that utilizes both a private and

Other Deployement Models
Virtual Private Cloud
lso known as a “dedicated cloud”or“hosted cloud,”
This model results in a self-contained cloud environment hosted and
managed by a public cloud provider, and made available to a cloud consumer.
Inter-Cloud
Based on an architecture comprised of two or more inter-connected clouds.

Summary of Key Points
A public cloud is owned by a third party and generally offers commercialized
cloud services and IT resources to cloud consumer organizations.
A private cloud is owned by an individual organization and resides within the
organization’s premises.
A community cloud is normally limited for access by a group of cloud
consumers that may also share responsibility in its ownership.
A hybrid cloud is a combination of two or more other cloud deployment
models.

Acknowledgement
Thank you!

Cloud Computing : Fundamental Concepts and Models

More Related Content

More from Manash Kumar Mondal (20)

Recently uploaded (20)

Cloud Computing : Fundamental Concepts and Models