0. Fundamental Concepts and Models
Cloud Computing
Lecture Note 2
Fundamental Concepts and Models
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1. Roles and Boundaries – 1/2
Cloud provider
A organization that provides cloud-based IT resources as-a-service
Responsible for making cloud services available to cloud customers under SLA and guaranteeing required management/administrative duties delivered in order to ensure the on-going operation of the overall cloud infrastructure
Makes the IT resources (owned or leased) available to other cloud customers for lease
Cloud customer
A organization or an individual that signs for a formal contract or arrangement with a cloud provider for IT resource lease
Cloud service consumer: consumers of service provided by a cloud consumer
Cloud service owner
The individual or organization that legally owns a cloud service
= a cloud consumer or a cloud provider depending on who actually provides the service
Cloud Service Consumer
Cloud Service Owner
Cloud Service Owner
Cloud X
Cloud Consumer
Cloud Provider

2. Roles and Boundaries – 2/2
Cloud resource administrator
The individual or organization responsible for administrating a cloud-based IT resource (including cloud service)
= (members of ) the cloud consumer or cloud provider
Cloud resource administrator  cloud service administrator  cloud resource  cloud service
Additional roles (as supplementary roles defined by NIST Cloud Computing Reference Architecture)
Cloud auditor : a third-party contractor for independent assessment of cloud environments evaluating security controls, privacy impacts, performance and so on
Cloud broker : a party responsible for managing and negotiating the usage of cloud service between cloud customers and cloud providers including intermediation, aggregation, arbitrage
Cloud carrier : the party responsible for providing the wire-level connectivity between cloud consumers and cloud providers – network and telecommunication providers in general
Organizational boundary
Physical perimeter that surrounds a set of IT resources that are owned and governed by an organization
Trust boundary
A logical perimeter that typically spans beyond physical boundaries to represent the extent to which IT resources are trusted
Trust Boundary
Organizational Boundary
Organizational Boundary
Cloud Consumer
Cloud X
Cloud Provider

3. Cloud Characteristics – 1/2
Common cloud service requirements
A specific set of characteristics in order to enable the remote provisioning of scalable and measured IT resources in an effective manner
Cloud provider – provides each of such characteristics
Cloud consumer – evaluates each of such characteristics to select a proper cloud platform to lease
On-demand usage, ubiquitous access, multitenancy (and resource pooling), elasticity, measured usage, resiliency (not by NIST)
On-demand usage
The ability to automate the usage of the self-provisioned IT resources requiring no further human involvement by the cloud consumer or cloud provider once configured
Characteristics enabling the service-based and usage-driven features found in mainstream clouds
Ubiquitous access
The ability for a cloud service to be widely accessible
Characteristics enabling guaranteed access to the given cloud service whenever and wherever
Need to support for a range of devices, transport protocols, interface and security technologies
Multitenancy (and resource pooling)
The characteristics of a software program enabling an instance of the program to service different consumers (tenants) whereby each is isolated form the other
IT resource pooling to service multiple cloud service consumers by using multitenancy model based on virtualization technologies so that IT resources can be dynamically assigned or reassigned according to cloud service consumer demands – logical rather than physical boundaries

4. Cloud Characteristics – 2/2
Elasticity
The automated ability of a could to transparently scale IT resources as required in response to runtime conditions or as pre-determined by the cloud consumer/provider
A core justification for the adoption of could computing for cloud consumers – closely associated with the reduced initial investment and proportional costs benefits
Measured usage
The ability of a cloud platform to keep track of the actual usage of its IT resources by each cloud consumer with which the cloud provider charges the cloud consumer
The ability to enabling the on-demand characteristics of cloud computing platform
The feature required for IT resource monitoring purpose as well for cloud providers
Resiliency (not defined by NIST)
The ability to recover from an unexpected failure allowing a degree of loss (data, connection, etc.) – vs. tolerance which does not allow any loss
A form of failover that distributes redundant implementations of IT resources across physical locations
The feature increasing the availability of the given cloud platform (vs. reliability vs. fidelity)
Single-Tenancy Storage Example
Multi-Tenancy Storage Example
Logical Storage
of Consumer A
Logical Storage
of Consumer B
Logical Storage
of Consumer A
Logical Storage
of Consumer B
Physical Storage A
Physical Storage B
Common Physical
Storage Pool

5. Cloud Delivery Models – 1/3
Three basic delivery models: Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS), Software- as-a-Service (SaaS)
Specialized variations: Storage-as-a-Service, Database-as-a-Service, Security-as-a-Service, Testing-as-a- Service, Communication-as-a-Service, Integration-as-a-Service, Process-as-a-Service, etc.
Infrastructure-as-a-Service (IaaS)
Provides a self-contained IT environment comprised of infrastructure –centric IT resources that can be accessed and managed via cloud service-based interfaces and tools
Offers typically virtualized and packaged IT resources including hardware, network, connectivity, operating systems and other raw IT resources (vs. traditional hosting with physical IT resources)
Allows simple up-front runtime scaling and customization of the given infrastructure
Provides cloud customers with a high level of control and responsibility over its configuration and utilization
Preferred by those cloud customers that want a high level of control over the cloud-based environment with a proper level of administrative ability – delivered without pre-configuration in general
IaaS provided by the cloud customer of the other cloud providers – a sort of sub-lease
Typical IT resources offered by IaaS environments include:
Virtual server : specified by processing power, memory capacity, local storage space
Virtual storage : specified by capacity in GB or TB unit generally in large scale with no QoS guarantee
Virtual network : specified by bandwidth, QoS
Requires cloud customers to configure IT resources for their own after lease

6. Cloud Delivery Models – 2/3
Platform-as-a-Service (PaaS)
Provides a pre-defined “ready-to-use” environment typically comprised of already deployed and configured IT resource
Relies on (and is defined by) 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
Primary reasons for cloud customers to rely on PaaS include:
To extend on-promise environments into the cloud for scalability and economic purpose
To substitute the ready-made environment for the entire on-promise environment at once
To deploy its own cloud services to be made available to other cloud customers
For short-term lease of many different platforms for the purpose of special needs (e.g., software development – No. of OSs  No. of OS versions)
Releases cloud customers from the administrative burden of setting up and maintaining the bare infrastructure IT resources at the cost of less control over the underlying IT resources
Software-as-a-Service (SaaS)
Provides the lease service of software programs
Provides a reusable cloud service widely available (often commercially) to a range of cloud consumers for various purpose and different terms
Allows very limited administrative control over a SaaS implementation for cloud customers
Can be provided by the cloud consumers of other cloud providers
Very practical cloud delivery model for those software programs that are not always in use – e.g., white box testing software (vs. DBMS)

7. Cloud Delivery Models – 3/3
Cloud Service Consumer
Cloud Service Consumer
Cloud Service Consumer
PaaS
IaaS
SaaS
Virtual Platform Resource
(HW, Network, OS, MW, SW, App, etc.)
Virtual Infra Resource
(HW, Network, OS)
Software Program (DnP/Streaming)
Cloud X

8. Cloud Delivery Model Comparison
Typical Level of Control Granted to Cloud Consumer
Typical Functionality Made Available to Cloud Consumer
SaaS
Usage and usage-related configuration
Access to front-end user-interface
PaaS
Limited administrative
Moderate level of administrative control over IT resources relevant to cloud consumer’s usage of platform
IaaS
Full administrative
Full access to virtualized infrastructure-related IT resources and possibly to underlying physical IT resources
Cloud Delivery Model
Common Cloud Consumer Activities
Common Cloud Provider Activities
SaaS
Uses and configures cloud service
Implements, manages and maintains cloud service
Monitors usage by cloud consumers
PaaS
Develops, tests, deploys and manages cloud services and cloud- based solutions
Pre-configures platform and provisions underlying infrastructure, middleware and other needed IT resources as necessary
IaaS
Sets up and configures bare infrastructure, and installs, manages, and monitors any needed software
Provisions and manages the physical processing, storage, networking and hosting required

9. Cloud Delivery Models Hierarchy & Combined Models
PaaS Customers
PaaS
SaaS Customer
SaaS
Cloud Y
PaaS
Virtual Server
IaaS
IaaS Customers
IaaS
Cloud Z
SaaS
Virtual Platform
PaaS
PaaS Customers
PaaS
SaaS
Cloud X
IaaS
SaaS Customer
SaaS

10. Cloud Deployment Models – 1/2
Type of cloud environment distinguished by ownership, size and access
Public cloud, community cloud, private cloud, hybrid cloud (cf. virtual private cloud & inter-cloud)
Public clouds
A cloud environment publicly accessible and owned by a third-party cloud provider
Both service and IT resources created and maintained by the provider of the given public cloud
Amazon, Google, Microsoft, Yahoo, Rackspace, Salesforce, Zoho, etc.
Community clouds
A cloud environment similar to a public cloud except that its access is limited to a specific community of cloud consumers
The responsibility for defining and evolving the community cloud typically shared by the members of the given consumer community
Private clouds
A cloud environment privately accessible and owned by a single (and large in general) organization
A cloud platform located inside a trust boundary – both the provider and consumers of the private cloud are the members of the same organization under the same final decision maker
IT resources technically located within the organization’s physical boundary (= on-premise), but utilized under cloud-based technology
Possible outsourcing for the actual administration duty of a private cloud environment
Hybrid clouds
A cloud environment comprised of two or more different cloud deployment models
Complex and challenging architecture/technology required for maintaining multiple security zones

11. Cloud Deployment Models – 2/2
Public Cloud Customers
Public Cloud Customers
Public Cloud Customers
Public Cloud Customers
Public Cloud Customers
Cloud Service
Cloud Service
Cloud Service
Cloud Service
Cloud Service
Cloud X
Cloud X
Cloud X
Public
Community
Private
Cloud Provider’s Boundary
Cloud Provider(Community)’s Boundary
Cloud Provider’s Boundary
Private Cloud Service
Private Cloud Customers
Cloud X
Public Cloud Service
Cloud X
Virtual
Private
Private Cloud Service
Private Cloud Customers
Hybrid
Public Cloud Service
Public Cloud Customers
Public
Virtual Private
Boundary
Cloud Provider’s Boundary
Cloud Provider’s Boundary

12. Cloud Computing
End of Lecture Note
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