UNIT I

CLOUD ARCHITECTURE MODELS AND INFRASTRUCTURE

Cloud Architecture: System Models for Distributed and Cloud Computing - NIST
Cloud Computing Reference Architecture - Cloud deployment models - Cloud service
models.
CLOUD ARCHITETURE:
1. Explain in detail about Cloud Computing Architecture (Or) Explain the Various
Layered Cloud Architectural Development Design for Effective Cloud Computing
Environment. (Nov/Dec 2020)

Cloud Architecture Design

The cloud architecture design is the important aspect while designing a cloud. The
simplicity in cloud services attract cloud users to use it which makes positive business impact.
Therefore, to design such a simple and user - friendly services, the cloud architecture design
plays an important role to develop that.
Every cloud platform is intended to provide four essential design goals like scalability,
reliability, efficiency and virtualization.
To achieve this goal, certain requirements have to be considered. The basic requirements
for cloud architecture design are given as follows:
• The cloud architecture design must provide automated delivery of cloud services along
with automated management.
• It must support latest web standards like Web 2.0 or higher and REST or RESTful
APls.
• It must support very large - scale HPC infrastructure with both physical and virtual
machines.
• The architecture of cloud must be loosely coupled.
• It should provide easy access to cloud services through a self - service web portal.
• Cloud management software must be efficient to receive the user request, finds the
correct resources and then calls the provisioning services which invoke the resources
in the cloud.
• It must provide enhanced security for shared access to the resources from data centers.
• It must use cluster architecture for getting the system scalability.
• The cloud architecture design must be reliable and flexible.
• It must provide efficient performance and faster speed of access.

Today's clouds are built to support lots of tenants (cloud devices) over the resource pools

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and large data volumes. So, the hardware and software plays an important role to achieve that.

The rapid development in multicore CPUs, memory chips, and disk arrays in the hardware
field has made it possible to create data centers with large volumes of storage space instantly.
While development in software standards like web 2.0 and SOA have immensely helped to
developed a cloud services.

The Service Oriented Architecture (SOA) is also a crucial component which is used in the
delivery of Saas.

The web service software detects the status of the joining and leaving of each node server
and performs appropriate tasks accordingly. The virtualization of infrastructure allows for
quick cloud delivery and recovery from disasters. In recent cloud platforms, resources are
built into the data centers which are typically owned and operated by a third - party
provider.
Layered Cloud Architecture Design

The layered architecture of a cloud is composed of three basic layers called infrastructure,
platform and application. These three levels of architecture are implemented with
virtualization and standardization of cloud - provided hardware and software resources. This
architectural design facilitates public, private and hybrid cloud services that are conveyed to
users through networking support over the internet and the intranets. The layered cloud
architecture design is shown in Fig. 1.1
In layered architecture, the foundation layer is infrastructure which is responsible for
providing different Infrastructure as a Service (IaaS) components and related services.
It is the first layer to be deployed before platform and application to get laaS services and
to run other two layers.
• The infrastructure layer consists of virtualized services for computing, storage and
networking. It is responsible for provisioning infrastructure components like compute
(CPU and memory), storage, network and IO resources to run virtual machines or
virtual servers along with virtual storages.
• The abstraction of these hardware resources is intended to provide the flexibility to the
users. Internally, virtualization performs automated resource provisioning and
optimizes the process of managing resources.
The infrastructure layer act as a foundation for building the second layer called platform
layer for supporting PaaS services.
The platform layer is responsible for providing readily available development and
deployment platform for web applications to the cloud users without needing them to install
in a local device. This layer provides an environment for users to create their applications,
test operation flows, track the performance and monitor execution results.

Fig. 1.1 Layered cloud architecture design

The platform must be ensuring to provide scalability, reliability and security. In this layer,
virtualized cloud platform, acts as an "application middleware" between the cloud
infrastructure and application layer of cloud. The platform layer is the foundation for
application layer.
A collection of all software modules required for Saas applications forms the application
layer. This layer is mainly responsible for making on demand application delivery.
In this layer, software applications include day-to-day office management software's used
for information collection, document processing, calendar and authentication.
Enterprises also use the application layer extensively in business marketing, sales,
Customer Relationship Management (CRM), financial transactions and Supply Chain
Management (SCM). It is important to remember that not all cloud services are limited to a
single layer.
Many applications can require mixed - layers resources. After all, with a relation of
dependency, the three layers are constructed from the bottom-up approach. From the
perspective of the user, the services at various levels need specific amounts of vendor support
and resource management for functionality.
In general, Saas needs the provider to do much more work, PaaS is in the middle and IaaS
requests the least. The best example of application layer is the Salesforce.com's CRM service
where not only the hardware at the bottom layer and the software at the top layer is supplied
by the vendor, but also the platform and software tools for user application development
and monitoring.

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System Models for Distributed and Cloud Computing

2. Explain in detail about system models for distributed Cloud Computing.
Distributed and cloud computing systems are built over a large number of autonomous
computer nodes. These node machines are interconnected by SANs, LANs, or WANs in
a hierarchical manner.

With today's networking technology, a few LAN switches can easily connect hundreds
of machines as a working cluster. A WAN can connect many local clusters to form a very
large cluster of clusters. Massive systems are considered highly scalable, and can reach
web-scale connectivity, either physically or logically.

Massive systems are classified into four groups:

1. Clusters of Cooperative Computers

A computing cluster consists of interconnected stand-alone computers which work
cooperatively as a single integrated computing resource. In the past, clustered computer systems
have demonstrated impressive results in handling heavy workloads with large data sets.
1.1 Cluster Architecture
In Figure 1.15 shows the architecture of a typical server cluster built around a low-
latency, high-bandwidth interconnection network. This network can be as simple as a SAN (e.g.,
Myrinet) or a LAN (e.g., Ethernet). To build a larger cluster with more nodes, the interconnection
network can be built with multiple levels of Gigabit Ethernet, Myrinet, or lnfiniBand switches.
Through hierarchical construction using a SAN, LAN, or WAN, one can build scalable clusters with
an increasing number of nodes. The cluster is connected to the Internet via a virtual private
network (VPN) gateway.
All resources of a server node are managed by their own OS. Thus, most clusters have
multiple system images as a result of having many autonomous nodes under different OS
control.

1.2 Single-System Image:

Cluster designers desire a cluster operating system or some middle-ware to support SSI
at various levels, including the sharing of CPUs, memory, and I/O across all cluster nodes. An SSI
is an illusion created by software or hardware that presents a collection of resources as one
integrated, powerful resource. SSI makes the cluster appear like a single machine to the user.
 A cluster with multiple system images is nothing but a collection of independent
computers.
1.3 Hardware, Software, and Middleware Support
Clusters exploring massive parallelism are commonly known as MPPs. Almost all HPC
clusters in the Top 500 list are also MPPs. The building blocks are computer nodes (PCs,
workstations, servers, or SMP), special communication software such as PVM or MPI, and a
network interface card in each computer node. Most clusters run under the Linux OS. The
computer nodes are interconnected by a high-bandwidth network (such as Gigabit Ethernet,
Myrinet, InfiniBand, etc.
Special cluster middleware supports are needed to create SSI or high availability (HA).
Both sequential and parallel applications can run on the cluster, and special parallel
environments are needed to facilitate use of the cluster resources. For example, distributed
memory has multiple images. Users may want all distributed memory to be shared by all servers
by forming distributed shared memory (DSM). Many SSI features are expensive or difficult to
achieve at various cluster operational levels. Instead of achieving SSI, many clusters are loosely
coupled machines. Using virtualization, one can build many virtual clusters dynamically, upon
user demand.
1.4 Major Cluster Design Issues
Unfortunately, a cluster-wide OS for complete resource sharing is not available yet.
Middleware or OS extensions were developed at the user space to achieve SSI at selected
functional levels. Without this middleware, cluster nodes cannot work together effectively to
achieve cooperative computing. The software environments and applications must rely on the
middleware to achieve high performance. The cluster benefits come from scalable performance,
efficient message passing, high system availability, seamless fault tolerance, and cluster-wide job
management, as summarized in Table 1.3.
2. Grid Computing Infrastructures

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Unit-I CCS335-Cloud Computing

In the past 30 years, users have experienced a natural growth path from Internet to web
and grid computing services. Internet services such as the Telnet command enables a local
computer to connect to a remote computer. A web service such as HTTP enables remote access
ofremote web pages. Grid computing is envisioned to allow close interaction among applications
running on distant computers simultaneously. Forbes Magazine has projected the global growth
of the IT-based economy from $1 trillion in 2001 to $20 trillion by 2015. The evolution from
Internet to web and grid services is certainly playing a major role in this growth.

2.1 Computational Grids

Like an electric utility power grid, a computing grid offers an infrastructure that couples
computers, software/middleware, special instruments, and people and sensors together. The grid
is often con-structed across LAN, WAN, or Internet backbone networks at a regional, national, or
global scale. Enterprises or organizations present grids as integrated computing resources. They
can also be viewed as virtual platforms to support virtual organizations. The computers used in a
grid are primarily workstations, servers, clusters, and supercomputers. Personal computers,
laptops, and PDAs can be used as access devices to a grid system.
In Figure 1.16 shows an example computational grid built over multiple resource sites
owned by different organizations. The resource sites offer complementary computing resources,
including workstations, large servers, a mesh of processors, and Linux clusters to satisfy a chain
of computational needs. The grid is built across various IP broadband networks including LANs
and WANs already used by enterprises or organizations over the Internet. The grid is presented
to users as an integrated resource pool as shown in the upper half of the figure.
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2.2 Grid Families

Grid technology demands new distributed computing models, software/middleware
support, network protocols, and hardware infrastructures. National grid projects are followed by
industrial grid plat-form development by IBM, Microsoft, Sun, HP, Dell, Cisco, EMC, Platform
Computing, and others. New grid service providers (GSPs) and new grid applications have
emerged rapidly, similar to the growth of Internet and web services in the past two decades.
In Table 1.4, grid systems are classified in essentially two categories: computational or
data grids and P2P grids.

3. Peer-to-Peer Network Families

An example of a well-established distributed system is the client-server architecture. In
this scenario, client machines (PCs and workstations) are connected to a central server for
compute, e-mail, file access, and database applications. The P2P architecture offers a distributed
model of networked systems. First, a P2P network is client-oriented instead of server-oriented.
In this section, P2P systems are introduced at the physical level and overlay networks at the
logical level.
3.1 P2P Systems
In a P2P system, every node acts as both a client and a server, providing part of the system
resources. Peer machines are simply client computers connected to the Internet. All client
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machines act autonomously to join or leave the system freely. This implies that no master-slave
relationship exists among the peers. No central coordination or central database is needed. In
other words, no peer machine has a global view of the entire P2P system. The system is self-
organizing with distributed control.
Figure 1.17 shows the architecture of a P2P network at two abstraction levels. Initially, the
peers are totally unrelated. Each peer machine joins or leaves the P2P network voluntarily. Only
the participating peers form the physical network at any time. Unlike the cluster or grid, a P2P
network does not use a dedicated interconnection network. The physical network is simply an ad
hoc network formed at various Internet domains randomly using the TCP/IP and NAI protocols.
Thus, the physical network varies in size and topology dynamically due to the free membership
in the P2P network.
3.2 Overlay Networks
Data items or files are distributed in the participating peers. Based on communication or
file-sharing needs, the peer IDs form an overlay network at the logical level. This overlay is a
virtual network

FIGURE 1.17
The structure of a P2P system by mapping a physical IP network lo an overlay network built with virtual
links.

formed by mapping each physical machine with its ID, logically, through a virtual mapping as
shown in Figure 1.17. When a new peer joins the system, its peer ID is added as a node in the
overlay network. When an existing peer leaves the system, its peer ID is removed from the overlay
network automatically. Therefore, it is the P2P overlay network that characterizes the logical
connectivity among the peers.
There are two types of overlay networks: unstructured and structured. An unstructured
overlay network is characterized by a random graph. There is no fixed route to send messages or
files among the nodes. Often, flooding is applied to send a query to all nodes in an unstructured
overlay, thus resulting in heavy network traffic and nondeterministic search results. Structured
overlay net-works follow certain connectivity topology and rules for inserting and removing
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nodes (peer IDs) from the overlay graph. Routing mechanisms are developed to take advantage
of the structured overlays.
3.3 P2P Application Families
Based on application, P2P networks are classified into four groups, as shown in Table 1.5.
The first family is for distributed file sharing of digital contents (music, videos, etc.) on the P2P
network. This includes many popular P2P networks such as Gnutella, Napster, and BitTorrent,
among others. Collaboration P2P networks include MSN or Skype chatting, instant messaging,
and collaborative design, among others.
3.4 P2P Computing Challenges
P2P computing faces three types of heterogeneity problems in hardware, software, and
network requirements. There are too many hardware models and architectures to select from;
incompatibility exists between software and the OS; and different network connections and
protocols

make it too complex to apply in real applications. We need system scalability as the workload
increases. System scaling is directly related to performance and bandwidth. P2P networks do
have these properties. Data location is also important to affect collective performance. Data
locality, network proximity, and interoperability are three design objectives in distributed P2P
applications.
3. Internet clouds :The idea is to move desktop computing to a service-oriented platform
using server clusters and huge databases at data centers. Cloud computing leverages
its low cost and simplicity to benefit both users and providers. Machine virtualization
has enabled such cost-effectiveness. Cloud computing intends to satisfy many user
Virtualized resources from data centers to form an Internet cloud, provisioned with
hardware, software, storage, network, and services for paid users to run their
applications.
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NIST Cloud Computing Reference Architecture

4. Explain about the NIST Cloud Computing reference architecture. (May-2022)

The reference architecture model given by the National Institute of Standards and
Technology (NIST). The model offers approaches for secure cloud adoption while
contributing to cloud computing guidelines and standards.

The NIST team works closely with leading IT vendors, developers of standards, industries
and other governmental agencies and industries at a global level to support effective cloud
computing security standards and their further development. It is important to note that
this NIST cloud reference architecture does not belong to any specific vendor products,
services or some reference implementation, nor does it prevent further innovation in cloud
technology.

Fig. 1.2 : Conceptual cloud reference model showing different actors and
entities

From Fig. 3.2.1, note that the cloud reference architecture includes five major actors :

• Cloud consumer
• Cloud provider
• Cloud auditor
• Cloud broker
• Cloud carrier
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Each actor is an organization or entity plays an important role in a transaction or a process,

or performs some important task in cloud computing. The interactions between these actors
are illustrated in Fig. 1.3.

Fig. 1.3: Interactions between different actors in a cloud

Now, understand that a cloud consumer can request cloud services directly from a
CSP or from a cloud broker. The cloud auditor independently audits and then contacts
other actors to gather information. We will now discuss the role of each actor in detail.

Cloud Consumer

A cloud consumer is the most important stakeholder. The cloud service is built to support
a cloud consumer. The cloud consumer uses the services from a CSP or person or asks an
organization that maintains a business relationship. The consumer then verifies the service
catalogue from the cloud provider and requests an appropriate service or sets up service
contracts for using the service. The cloud consumer is billed for the service used.
Some typical usage scenarios include :

Example 1 : Cloud consumer requests the service from the broker instead of directly
contacting the CSP. The cloud broker can then create a new service by combining
multiple services or by enhancing an existing service. Here, the actual cloud provider is not
visible to the cloud consumer. The consumer only interacts with the broker. This is
illustrated in Fig. 1.4.

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Fig. 1.4 : Cloud broker interacting with cloud consumer

Example 2 : In this scenario, the cloud carrier provides for connectivity and transports
cloud services to consumers. This is illustrated in Fig. 1.5.

Fig. 1.5 : Scenario for cloud carrier

In Fig. 1.2.4, the cloud provider participates by arranging two SLAs. One SLA is with the
cloud provider (SLA2) and the second SLA is with the consumer (SLAl). Here, the cloud
provider will have an arrangement (SLA) with the cloud carrier to have secured, encrypted
connections. This ensures that the services are available for the consumer at a consistent level
to fulfil service requests. Here, the provider can specify the requirements, such as flexibility,
capability and functionalities in SLA2 to fulfil essential service requirements in SLAl.

Example 3 : In this usage scenario, the cloud auditor conducts independent evaluations
for a cloud service. The evaluations will relate to operations and security of cloud service
implementation. Here the cloud auditor interacts with both the cloud provider and consumer,
as shown in Fig. 1.6.

Fig. 1.6 : Usage scenario involving a cloud

auditor
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In all the given scenarios, the cloud consumer plays the most important role. Based on the
service request, the activities of other players and usage scenarios can differ for other cloud
consumers. Fig. 1. 7 shows an example of available cloud services types.
In Fig. 1.7 note that Saas applications are available over a network to all consumers. These
consumers may be organisations with access to software applications, end users, app
developers or administrators. Billing is based on the number of end users, the time of use,
network bandwidth consumed and for the amount or volume of data stored.

Fig. 1.7: Example of cloud services available to cloud consumers

PaaS consumers can utilize tools, execution resources, development IDEs made available
by cloud providers. Using these resources, they can test, develop, manage, deploy and
configure many applications that are hosted on a cloud. PaaS consumers are billed based on
processing, database, storage, network resources consumed and for the duration of the
platform used.
Unit-I CCS335-Cloud Computing

On the other hand, IaaS consumers can access virtual computers, network - attached
storage, network components, processor resources and other computing resources that are
deployed and run arbitrary software. IaaS consumers are billed based on the amount and
duration of hardware resources consumed, number of IP addresses, volume of data stored,
network bandwidth, and CPU hours used for a certain duration.

Cloud Provider

Cloud provider is an entity that offers cloud services to interested parties. A cloud provider
manages the infrastructure needed for providing cloud services. The CSP also runs the
software to provide services and organizes the service delivery to cloud consumers
through networks.
Saas providers then deploy, configure, maintain and update all operations of the
software application on the cloud infrastructure, in order to ensure that services are
provisioned and to fulfil cloud consumer service requests. Saas providers assume most of
the responsibilities associated with managing and controlling applications deployed on the
infrastructure. On the other hand, Saas consumers have no or limited administrative controls.
PaaS cloud providers manage the computing infrastructure and ensure that the
platform runs the cloud software and implements databases, appropriate runtime software
execution stack and other required middleware elements. They support development,
deployment and the management of PaaS consumers by providing them with necessary tools
such as IDEs, SDKs and others. PaaS providers have complete control of applications,
settings of the hosting environment, but have lesser control over the infrastructure lying
under the platform, network, servers, OS and storage.
Now, the IaaS CSP aggregates physical cloud resources such as networks, servers, storage
and network hosting infrastructure. The provider operates the cloud software and makes all
compute resources available to IaaS cloud consumer via a set of service interfaces, such as VMs
and virtual network interfaces. The IaaS cloud provider will have control over the physical
hardware and cloud software to enable provisioning and possible infrastructure services.
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Fig. 1.8 : Major activities of a cloud provider

The major activities of a cloud provider include :

• Service deployment: Service deployment refers to provisioning private, public, hybrid

and community cloud models.
• Service orchestration: Service orchestration implies the coordination, management of
cloud infrastructure and arrangement to offer optimized capabilities of cloud services.
The capabilities must be cost-effective in managing IT resources and must be
determined by strategic business needs.
• Cloud services management: This activity involves all service-related functions
needed to manage and operate the services requested or proposed by cloud consumers.
• Security: Security, which is a critical function in cloud computing, spans all layers in
the reference architecture. Security must be enforced end-to-end. It has a wide range
from physical to application security. CSPs must take care of security.
• Privacy: Privacy in cloud must be ensured at different levels, such as user privacy, data
privacy, authorization and authentication and it must also have adequate assurance
levels. Since clouds allow resources to be shared, privacy challenges are a
big concern for consumers using clouds.

lcloud Auditor

The cloud auditor performs the task of independently evaluating cloud service controls
to provide an honest opinion when requested. Cloud audits are done to validate standards
conformance by reviewing the objective evidence. The auditor will examine services provided
by the cloud provider for its security controls, privacy, performance,
and so on.
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Cloud Broker

The cloud broker collects service requests from cloud consumers and manages the use,
performance, and delivery of cloud services. The cloud broker will also negotiate and manage
the relationship between cloud providers and consumers. A cloud broker may provide services
that fall into one of the following categories :
• Service intermediation : Here the cloud broker will improve some specific
capabilities, and provide value added services to cloud consumers.
• Service aggregation : The cloud broker links and integrates different services into
one or more new services.

• Service Arbitrage : This is similar to aggregation, except for the fact that services
that are aggregated are not fixed. In service arbitrage, the broker has the liberty to
choose services from different agencies.

Cloud Carrier
The cloud carrier tries to establish connectivity and transports cloud services between a
cloud consumer and a cloud provider. Cloud carriers offer network access for consumers,
by providing telecommunication links for accessing resources using other devices (laptops,
computers, tablets, smartphones, etc.). Usually, a transport agent is an entity offering
telecommunication carriers to a business organization to access resources. The cloud provider
will set up SLAs with cloud carrier to ensure carrier transport is consistent with the level of
SLA provided by the consumers. Cloud carriers provide secure and dedicated high - speed
links with cloud providers and between different cloud
entities.
Actor Definition
A person or organization that maintains a business relationship
Cloud Consumer
with, and uses service from, Cloud Providers.
A person, organization, or entity responsible for making a service
Cloud Provider
available to interested parties.
An intermediary that provides connectivity and transport of cloud
Cloud Carrier
services from Cloud Providers to Cloud Consumers.
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A party that can conduct independent assessment of cloud

Cloud Auditor services, information system operations, performance and
security of the cloud implementation.
An entity that manages the use, performance and delivery of
Cloud Broker cloud services, and negotiates relationships between Cloud
Providers and Cloud

3. Explain in detail about Cloud Computing Deployment Model with a neat diagram.
Nov/Dec 2021(Nov/Dec 2022)
Cloud Deployment Models
A cloud deployment models are defined according to where the computing infrastructure
resides and who controls the infrastructure. The NIST have classified cloud deployment
models into four categories namely,
• Public cloud
• Private cloud
• Hybrid cloud
• Community cloud

They describe the way in which users can access the cloud services. Each cloud deployment
model fits different organizational needs, so it's important that you pick a model that will suit
your organization's needs. The four deployment models are characterized based on the
functionality and accessibility of cloud services. The four deployment models of cloud
computing are shown in Fig. 1.9.

Fig. 1.9: Four deployment models of cloud computing

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Public Cloud

The public cloud services are runs over the internet. Therefore, the users who want cloud
services have to have internet connection in their local device like thin client, thick client,
mobile, laptop or desktop etc. The public cloud services are managed and maintained by the
Cloud Service Providers (CSPs) or the Cloud Service Brokers (CSBs). The public cloud services
are often offered on utility base pricing like subscription or pay- per-use model. The public
cloud services are provided through internet and AP!s. This model allows users to easily access
the services without purchasing any specialize hardware or software. Any device which has
web browser and internet connectivity can be a public cloud client. The popular public cloud
service providers are Amazon web services, Microsoft azure and Google app engine, Salesforce
etc.

Advantages of public cloud

1. It saves capital cost behind purchasing the server hardware's, operating systems
and application software licenses.
2. There is no need of server administrators to take care of servers as they are kept at
CSPs data center and managed by them.

3. No training is required to use or access the cloud services.

4. There is no upfront or setup cost is required.

5. A user gets easy access to multiple services under a single self - service portal.

6. Users have a choice to compare and select between the providers.

7. It is cheaper than in house cloud implementation because user have to pay for that they
have used.
8. The resources are easily scalable.

Disadvantages of public cloud

1. There is lack of data security as data is stored on public data center and managed by third
party data center vendors therefore there may be compromise of user's confidential
data.
2. Expensive recovery of backup data.
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3. User never comes to know where (at which location) their data gets stored, how that
can be recovered and how many replicas of data have been created.
Private Cloud
The private cloud services are used by the organizations internally. Most of the times it run
over the intranet connection. They are designed for a single organization therefore anyone
within the organization can get access to data, services and web applications easily through
local servers and local network but users outside the organizations cannot access them. This
type of cloud services are hosted on intranet therefore users who are connected to that intranet
get access to the services. The infrastructure for private cloud is fully managed and maintained
by the organization itself.
It is much more secure than public cloud as it gives freedom to local administrators to
write their own security policies for user's access. It also provides good level trust and privacy
to the users. Private clouds are more expensive than public clouds due to the capital
expenditure involved in acquiring and maintaining them. The well-known private cloud
platforms are Openstack, Open nebula, Eucalyptus, VMware private cloud etc.
Advantages of private cloud

1. Speed of access is very high as services are provided through local servers over
local network.
2. It is more secure than public cloud as security of cloud services are handled by local
administrator.
3. It can be customized as per organizations need.

4. It does not require internet connection for access.

5. It is easy to manage than public cloud.

Disadvantages of private cloud

1. Implementation cost is very high as setup involves purchasing and installing

servers, Hypervisors, Operating systems.
2. It requires administrators for managing and maintaining servers.

3. The scope of scalability is very limited.

Hybrid Cloud

The hybrid cloud services are composed of two or more clouds that offers the benefits of
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multiple deployment models. It mostly comprises on premise private cloud and off- premise
public cloud to leverage benefits of both and allow users inside and outside to have access to
it. The Hybrid cloud provides flexibility such that users can migrate their applications and
services from private cloud to public cloud and vice versa. It becomes most favored in IT
industry because of its eminent features like mobility, customized security, high throughput,
scalability, disaster recovery, easy backup and replication across clouds, high availability
and cost efficient etc. The popular hybrid clouds are AWS with eucalyptus, AWS with VMware
cloud, Google cloud with Nutanix etc.
The limitations of hybrid cloud are compatibility of deployment models, vendor-lock in
solutions, requires a common cloud management software and management of
separate cloud platforms etc.

Community Cloud

The community cloud is basically the combination of one or more public, private or hybrid
clouds, which are shared by many organizations for a single cause. The community cloud
is setup between multiple organizations whose objective is same. The Infrastructure for
community cloud is to be shared by several organizations within specific community with
common security, compliance objectives which is managed by third party organizations or
managed internally. The well-known community clouds are
Salesforce, Google community cloud etc.

lcomparison between various Cloud Deployment Models

The comparison between different deployment models of cloud computing are given in
Table 1.3.1.

Public Community
s Feature Cloud Private Cloud Hybrid Cloud Cloud

Scalability Very High Limited Very High Limited

Security Less Secure Most Secure Very Secure Less Secure
Low to
3 Performance Medium Good Good Medium

Medium to
4 Reliability Medium High High Medium
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Upfront Cost Low Very High Medium Medium

Quality of
6 Service Low High Medium Medium

Intranet and
7 Network Internet Intranet Internet Internet

For general Organizations For general For

public internal staff public and Community
8 Availability organizations members
internal Staff

Openstack, Combin ation of salesforce

Windows VMware cloud, Openstack and community
9 Example Azure, CloudStack, AWS
AWS etc. Eucalyptus etc.

Table 1.3.1: Comparison between various Cloud Deployment Models

5. Explain in detail about the three cloud models at different service levels of the
cloud. (Or) Give the importance of cloud computing and elaborate the different
types of services offered by it. )Nov/Dec 202 l(Nov/Dec 2022).

Cloud Service Models

A Cloud computing is meant to provide variety of services and applications for users over
the internet or intranet.
The most widespread services of cloud computing are categorised into three service
classes which are called cloud service models or cloud reference models or working
models of cloud computing.
They are based on the abstraction level of the offered capabilities and the service model
of the CSPs. The various service models are :
• Infrastructure as a Service (IaaS)
• Platform as a Service (PaaS)
• Software as a Service (SaaS)

The three service models of cloud computing and their functions are shown in
Fig. 1.10.
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Fig. 1.10 : Cloud service models

From Fig. 1.10, we can see that the Infrastructure as a Service (IaaS) is the bottommost layer
in the model and Software as a Service (SaaS) lies at the top.
The IaaS has lower level of abstraction and visibility, while Saas has highest level of
visibility.
The Fig. 1.11 represents the cloud stack organization from physical infrastructure to
applications.
In this layered architecture, the abstraction levels are seen where higher layer services
include the services of the underlying layer.

Fig. 1.11: The cloud computing stack

As you can see in Fig. 1.4.2, the three services, IaaS, PaaS and Saas, can exist independent of
one another or may combine with one another at some layers. Different layers in every cloud
Unit-I CCS335-Cloud Computing

computing model are either managed by the user or by the vendor (provider).
In case of the traditional IT model, all the layers or levels are managed by the user because
he or she is solely responsible for managing and hosting the applications.
In case of laaS, the top five layers are managed by the user, while the four lower layers
(virtualisation, server hardware, storage and networking) are managed by vendors or
providers. So, here, the user will be accountable for managing the operating system via
applications and managing databases and security of applications.
The core middleware manages the physical resources and the VMs are deployed on top
of them. This deployment will provide the features of pay-per-use services and multi-tenancy.
Infrastructure services support cloud development environments and provide capabilities for
application development and implementation.
It provides different libraries, models for programming, AP!s, editors and so on to support
application development. When this deployment is ready for the cloud, they can be used
by end-users/ organisations.With this idea, let us further explore the different service models.
Infrastructure as a Service (IaaS)

• Infrastructure-as-a-Service (IaaS) can be defined as the use of servers, storage,

computing power, network and virtualization to form utility like services for users.
• It is a cloud service model that provides hardware resources virtualized in the
cloud. It provides virtual computing resources to the users through resource pool.
• In IaaS, the CSP owns all equipment, such as servers, storage disks, and
network infrastructure.

• Developers use the laaS service model to create virtual hardware on which
the applications and/ or services are developed.
• Developers can create virtual private storage, virtual private servers, and virtual
private networks by using laaS.
• The private virtual systems contain software applications to complete the laaS
solution. The infrastructure of laaS consists of communication networks, physical
compute nodes, storage solutions and the pool of virtualized computing resources
managed by a service provider.
• laaS provides users with a web-based service that can be used to create, destroy
and manage virtual machines and storage.

• Instead of purchasing extra servers, softwares, datacenter space or network

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equipment, IaaS enables on-demand provisioning of computational resources in the

form of virtual machines in cloud data center. Some key providers of IaaS are
Amazon Web Services (AWS), Microsoft Azure, GoGrid, Joyent, Rackspace etc. and
some of the private cloud softwares through which IaaS can be setup are Openstack,
Apache Cloud Stack, Eucalyptus, and VMware VSphere etc.

• In IaaS service delivery, workload is the fundamental component of the

virtualised client. It simulates the capacity of a physical server to perform
work. Hence, the work done is equal to the total number of Transaction Per Minute
(TPM).
• In the case of hosted applications, the client runs on a dedicated server inside a
server rack. It may also run on a standalone server.
• The user reserves an equivalent machine required to run workloads. The IaaS
infrastructure runs the instances of the server in the data centre offering the
service.

The resources for this server instance are drawn from a mix of virtualised systems,
RAID disks, network and interface capacity. These are physical systems partitioned into
logical

Fig. 1.12: Components in laaS service model (cloud security alliance)

The client in IaaS is allocated with its own private network. For example, Amazon EC2
enables this service to behave such that each server has its own separate network unless the
user creates a virtual private cloud. If the EC2 deployment is scaled by adding additional
networks on the infrastructure, it is easy to logically scale, but this can create an overhead
as traffic gets routed between logical networks.

In IaaS, the customer has controls over the OS, storage and installed applications, but has
Unit-I CCS335-Cloud Computing

limited control over network components. The user cannot control the underlying cloud
infrastructure. Services offered by IaaS include web servers, server hosting,
computer hardware, OS, virtual instances, load balancing, web servers and bandwidth
provisioning. These services are useful during volatile demands and when there is a
computing resource need for a new business launch or when the company may not want to
buy hardware or if the organisation wants toexpand.

Platform as a Service

• The Platform as a Service can be defined as a computing platform that allows the
user to create web applications quickly and easily and without worrying about
buying and maintaining the software and infrastructure.
• Platform-as-a-Service provides tools for development, deployment and testing the
softwares, middleware solutions, databases, programming languages and APis for
developers to develop custom applications; without installing or configuring the
development environment.
• The PaaS provides a platform to run web applications without installing them
in a local machine i.e. the applications written by the users can be directly run
on the PaaS cloud. It is built on the top of IaaS layer.
• The PaaS realizes many of the unique benefits like utility computing, hardware
virtualization, dynamic resource allocation, low investment costs and pre-
configured development environment. It has all the application typically required
by the client deployed on it. Some key providers of PaaS clouds are Google App
Engine, Microsoft Azure, NetSuite, Red hat Open shift etc.

• The PaaS realizes many of the unique benefits like utility computing, hardware
virtualization, dynamic resource allocation, low investment costs and pre-
configured development environment. It has all the application typically required
by the client deployed on it. Some key providers of PaaS clouds are Google App
Engine, Microsoft Azure, NetSuite, Red hat Open shift etc.
• The PaaS model includes the software environment where the developer can
create custom solutions using development tools available with the PaaS platform.
The components of a PaaS platform are shown in Fig. 1.13. Platforms can support
specific development languages, frameworks for applications and other
constructs. Also, PaaS provides tools and development environments to design
applications. Usually, a fully Integrated
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• Development Environment (IDE) is available as a PaaS service. For PaaS to be

a cloud computing service, the platform supports user interface development. It
also has many standards such as HTML, JavaScript, rich media and so on.
• In this model, users interact with the software and append and retrieve data,
perform an action, obtain results from a process task and perform other actions
allowed by the PaaS vendor.
• In this service model, the customer does not own any responsibility to maintain the
hardware and software and the development environment.
• The applications created are the only interactions between the customer and the
PaaS platform. The PaaS cloud provider owns responsibility for all the operational
aspects, such as maintenance, updates, management of resources and product
lifecycle.

Fig. 1.13 : Components of PaaS

A PaaS customer can control services such as device integration, session management,
content management, sandbox, and so on. In addition to these services, customer controls are
also possible in Universal Description Discovery and Integration (UDDI), and platform
independent Extensible Mark-up Language (XML) registry that allows registration and
identification of web service apps.
Let us consider an example of Google app engine.

The platform allows developers to program apps using Google's published APis. In this
platform, Google defines the tools to be used within the development framework, the file
system structure and data stores. A similar PaaS offering is given by Force.com, another
vendor that is based on the Salesforce.com development platform for the latter's Saas
offerings.Force.com provides an add - on development environment.
In PaaS, note that developers can build an app with Python and Google APL Here, the PaaS
vendor is the developer who offers a complete solution to the user. For instance, Google acts
Unit-I CCS335-Cloud Computing

as a PaaS vendor and offers web service apps to users. Other examples are : Google Earth,
Google Maps, Gmail, etc.
PaaS has a few disadvantages. It locks the developer and the PaaS platform in a
solution specific to a platform vendor. For example, an application developed in Python using
Google AP! on Google App Engine might work only in that environment.
PaaS is also useful in the following situations :

• When the application must be portable.

• When proprietary programming languages are used.
• When there is a need for custom hardware and software.

Major PaaS applications include software development projects where developers and users
collaborate to develop applications and automate testing services.
Part-A

1. List out the major functionalities of cloud computing. (or) Mention the characteristic
features of cloud. (Apr/May'17)(May-2022)
• The cloud will free users to focus on user application development and create business
value by outsourcing job execution to cloud providers. The computations (programs) are
sent to where the data is located, rather than copying the data to millions of desktops as
in the traditional approach.
• Cloud computing avoids large data movement, resulting in much better network
bandwidth utilization.
• Furthermore, machine virtualization has enhanced resource utilization, increased
application flexibility, and reduced the total cost of using virtualized data-center
resources.
• The cloud offers significant benefit to IT companies by freeing them from the low-level
task of setting up the hardware (servers) and managing the system software.
2. Write short notes on Research Compute Cloud (RC2) / Why do we need hybrid cloud?
[NOV/ DEC'16](Nov/Dec 2021)
Research Compute Cloud (RC2) shown below is a private cloud, built by IBM, that
interconnects the computing and IT resources at eight IBM Research Centers scattered
throughout the United States, Europe, and Asia. A hybrid cloud provides access to clients, the
partner network, and third parties. Public clouds promote standardization, preserve capital
investment, and offer application flexibility. Private clouds attempt to achieve customization
and offer higher efficiency, resiliency, security, and privacy. Hybrid clouds operate in the
middle, with many compromises in terms of resource sharing.
Unit-I CCS335-Cloud Computing

Fig: Private cloud

3. Define Platform as a Service (PaaS) Nov/Dec 2020

Platform as a service (PaaS) is a category of cloud computing services that provides a platform
allowing customers to develop, run, and manage applications without the complexity of
building and maintaining the infrastructure typically associated with developing and
launching an application. PaaS can be delivered in two ways: as a public cloud service from a
provider, where the consumer controls software deployment with minimal configuration
options, and the provider provides the networks, servers, storage, OS, 'middleware'. as
software deployed on a public infrastructure as a service.

4. Highlight the cloud platform services offered byPaaS services.

Cloud Name Languages and Programming Target Applications
Developer Tools Models and Storage Option
Supported by
Provider
Google App Python, Java, and MapReduce, web Web applications and
Engine Eclipse-based IDE programming on BigTable storage
demand
Salesforce.com's Apex, Eclipse-based Workflow, Excel-like Business applications
Force.com IDE, web-based formula, Web such as CRM
Wizard programming on
demand
Microsoft Azure NET, Azure tools for Unrestricted model Enterprise and web
MS Visual Studio applications
Amazon Elastic Hive, Pig, Cascading, MapReduce Data processing and
MapReduce Java, Ruby, Perl, e-commerce
Python, PHP, R, C++
Unit-I CCS335-Cloud Computing

Aneka. .NET, stand-alone Threads, task, NET enterprise

SOK MapReduce applications, HPC

Pros and Cons of cloud computing

5. Mention the six main challenges in cloud architecture development.(May-2022)
• Challenge 1-Service Availability and Data Lock-in Problem
• Challenge 2-Data Privacy and Security Concerns
• Challenge 3-Unpredictable Performance and Bottlenecks
• Challenge 4-Distributed Storage and Widespread Software Bugs
• Challenge 5-Cloud Scalability, Interoperability, and Standardization
• Challenge 6-Software Licensing and Reputation Sharing

6. Outline the key challenges associated in the process of storing images in

cloud.(Nov/Dec 2021).
As cloud grows in popularity, it has become common to deploy applications in the cloud
and provide them to end users. At the same time, the trend of using serverless architecture means
that an unspecified number of end users can seamlessly access resources in the cloud.
Getting started building an image upload feature Before diving into the GCP components
needed to implement this service, let's define our requirements:
• Use managed services as much as possible
• Enable only authenticated users to upload files
• Validate/filter the content uploaded by users.
7. How Hybrid Clouds are Formed?(May-2023)
Hybrid cloud refers to a mixed computing, storage, and services environment made up of on-
premises infrastructure, private cloud services, and a public cloud-such as Amazon Web
Services (AWS) or Microsoft Azure-with orchestration among the various platforms.
8. Mention the design goals of cloud platform.?(May-2023)
Cloud Platform Design Goals: The major goals of a cloud computing platform are scalability,
efficiency, VZ, and reliability. A cloud platform manager receives the user requests, finds the
resources, and calls the provisioning services to allocate the appropriate amount of resources for
the job.
Unit-I CCS335-Cloud Computing

9. Differentiate Public Cloud and Private Cloud .(Nov-2022)

10. what are the different layers?

The different layers of cloud computing are:

• Saas: Software as a Service (SaaS), it provides users access directly to the cloud
application without installing anything on the system.
• laaS: Infrastructure as a service, it provides the infrastructure in terms of hardware like
memory, processor speed etc.
• PaaS: Platform as a service, it provides cloud application platform for the developers

11. What are the different modes of software as a service (SaaS)?

• Simple multi-tenancy: In this each user has independent resources and are different
from other users, it is an efficient mode.
• Fine grain multi-tenancy: In this type, the resources can be shared by many but the
functionality remains the same.
12. How important is the platform as a service?

Platform as a service or PAAS is an important layer in cloud computing. It provides

application platform for providers. It is responsible for providing complete virtualization of the
infrastructure layer and makes it work like a single server.

13. What is a cloud service?

Cloud service is used to build cloud applications using the server in a network through
internet. It provides the facility of using the cloud application without installing it on the
Unit-I CCS335-Cloud Computing

computer. It also reduces the maintenance and support of the application which are
developed using cloud service.

14. List down the three basic clouds in cloud computing?

• Professional cloud
• Personal cloud
• Performance cloud

15. What are the resources that are provided by it?

!AAS ( Infrastructure As A Service) provides virtual and physical resources that are used
to build a cloud. It deals with the complexities of deploying and maintaining of the services
provided by this layer. Here the infrastructure is the servers, storage and other hardware
systems.

16. What are the business benefits involved in cloud architecture?

The benefits involved in cloud architecture is

• Zero infrastructure investment

• Just in time infrastructure
• More efficient resource utilization

17. What are the characteristics of cloud architecture that separates it from traditional
one?

The characteristics that make cloud architecture above traditional architecture is

According to the demand cloud architecture provides the hardware requirement Cloud
architecture is capable of scaling the resource on demand Cloud architecture is capable of
managing and handling dynamic workloads without failure

18. What are the building blocks?

• Reference architecture
• Technical architecture
• Deployment operation architecture