Cloud Computing

Cloud Computing

Definition:

Cloud Computing is a pay-per-use model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g. networks, servers, storage, applications and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.

Cloud computing is using the internet to access someone else's software running on someone else's hardware in someone else's data center. (Lewis Cunningham)

Source: (http://solmagazine.wordpress.com/2012/10/28/journey-to-the-cloud)

This cloud model promotes availability and is composed of five essential characteristics, three service models, and four deployment models.

Five Key Characteristics of Cloud Computing

1. On-demand self-service: A consumer can unilaterally provision computing capabilities, such as server time and network storage, as needed automatically without requiring human interaction with each service’s provider.
2. Broad Network Access: Capabilities are available over the network and accessed through standard mechanisms that promote use by heterogeneous thin or thick client platforms (e.g., mobile phones, laptops, and PDAs).
3. Resource Pooling: The provider’s computing resources are pooled to serve multiple consumers using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand. There is a sense of location independence in that the customer generally has no control or knowledge over the exact location of the provided resources but may be able to specify location at a higher level of abstraction (e.g., country, state, or datacenter). Examples of resources include storage, processing, memory, network bandwidth, and virtual machines.
4. Rapid Elasticity: Capabilities can be rapidly and elastically provisioned, in some cases automatically, to quickly scale out and rapidly released to quickly scale in. To the consumer, the capabilities available for provisioning often appear to be unlimited and can be purchased in any quantity at any time.
5. Measured Service: Cloud systems automatically control and optimize resource use by leveraging a metering capability at some level of abstraction appropriate to the type of service (e.g., storage, processing, bandwidth, and active user accounts). Resource usage can be monitored, controlled, and reported providing transparency for both the provider and consumer of the utilized service.

Three Service Models: (Software, Platform, Infrastructure Model - SPI Model)

1. Software as a Service (SaaS): 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 a thin client interface such as a web browser (e.g., web-based email). 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. Today SaaS is offered by companies such as Google, Salesforce, Microsoft, Zoho, linkedin, Gmail, Exact-online etc.
2. Platform as a Service (PaaS): The capability provided to the consumer is to deploy onto the cloud infrastructure consumer-created or acquired applications created using programming languages 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 application hosting environment configurations. PaaS providers offer a predefined combination of OS and application servers, such as LAMP platform (Linux, Apache, MySql and PHP), restricted J2EE, Ruby etc. Google’s App Engine, Force.com, EngineYard, Microsoft Azure etc are some of the popular PaaS examples.
3. Infrastructure as a Service (IaaS): The capability provided to the consumer is to provision processing, storage, networks, and other fundamental computing resources 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, deployed applications, and possibly limited control of select networking components (e.g., host firewalls). Some common examples are Amazon, GoGrid, 3 Tera, Rackspace, Cloud Virtual Private Server etc. 

Four Deployment Models

1. Private cloud: The cloud infrastructure is operated solely for an organization. It may be managed by the organization or a third party and may exist on premise or off premise.

2. Community cloud: The cloud infrastructure is shared by several organizations and supports a specific community that has shared concerns (e.g., mission, security requirements, policy, and compliance considerations). It may be managed by the organizations or a third party and may exist on premise or off premise.

3. Public cloud: The cloud infrastructure is made available to the general public or a large industry group and is owned by an organization selling cloud services.

4. Hybrid cloud: The cloud infrastructure is a composition of two or more clouds (private, community, or public) that remain unique entities but are bound together by standardized or proprietary technology that enables data and application portability (e.g., cloud bursting for load-balancing between clouds).

The NIST Model

      The United States government is a major consumer of computer services and, therefore, one of the major users of cloud computing networks. The U.S. National Institute of Standards and Technology (NIST) have a set of working definitions that separate cloud computing into service models and deployment models. Those models and their relationship to essential characteristics of cloud computing are shown in Figure 

The NIST Model

Cloud Architecture:

Cloud computing architecture refers to the components and sub-components required for cloud computing.

These components typically consist of a front end platform (fat client, thin client, mobile device), back end platforms (servers, storage), a cloud based delivery, and a network (Internet, Intranet, Inter-cloud). Combined, these components make up cloud computing architecture.

The Cloud Computing architecture comprises of many cloud components, each of them are loosely coupled. We can broadly divide the cloud architecture into two parts:

1.Front End

2.Back End

The following diagram show the graphical view of cloud computing architecture:

Cloud Architecture

—FRONT END

Front End refers to the client part of cloud computing system. It consists of interfaces and applications that are required to access the cloud computing platforms, e.g., Web Browser.

—BACK END

Back End refers to the cloud itself. It consists of all the resources required to provide cloud computing services. It comprises of huge data storage, virtual machines, security mechanism, services, deployment models, servers, etc.

The Cloud Cube Model:

—The Open Group maintains an association called the Jericho Forum whose focus is how to protect cloud networks. The group has an interesting model that attempts to categorize a cloud network based on four dimensional factors.

—The four dimensions of the Cloud Cube Model are shown in Figure and listed here:

The Jericho Forum's Cloud Cube Model

1. Physical location of the data: Internal (I) / External (E) determine your organization's boundaries.

—This is the dimension that defines the physical location of the data: where does the cloud form you want to use exist - inside or outside your organization’s boundaries.—If it is within your own physical boundary then it is Internal.

—If it is not within your own physical boundary then it is External.

2. Ownership: Proprietary (P) / Open (O) is a measure of not only the technology ownership, but of interoperability, ease of data transfer, and degree of vendor application lock-in.

—Proprietary – Single supplier

—Open – Many supplier

3. Security boundary: Perimeterised (Per) / De-perimiterised (D-p): is a measure of whether the operation is inside or outside the security boundary or network firewall.
—Perimeterised implies continuing to operate within the traditional IT perimeter, often signalled by “network firewalls”. Private Clouds are Perimeterised.

Collaborative Clouds are best de-perimeterised

4. Sourcing: Insourced or Outsourced means whether the service is provided by the customer or the service provider.

Insourced: the service is provided by your own staff under your control

Outsourced: the service is provided by a 3rd party

Taken together, the fourth dimension corresponds to two different states in the eight possible cloud forms: Per (IP, IO, EP, EO) and D-p (IP, IO, EP, EO).

Perimeterised (per) – (Internal Proprietary, Internal Open, External Proprietary, External Open)

De-perimiterised (D-p) – (Internal Proprietary, Internal Open, External Proprietary, External Open)

Benefits of Cloud Computing:

1.On-demand self-service

2.Broad network access

3.Resource pooling, Almost Unlimited Storage

4.Rapid elasticity

5.Measured Service

6.Lower overall costs, no need for capital expenditure at all

7.Ease of utilization, Less personnel training is needed

8.Quality of Service

9.Reliability

10.Outsourced IT management

11.Simplified maintenance and upgrade

12.Minimize licensing new software, Automatic software updates

13.Disaster recovery

14.Work from anywhere

15.Quick Deployment

Disadvantages of Cloud Computing:

1.Technical Issues

2.Possible downtime

3.Security issues - How safe is your data?

4.Lack of support

5.Prone to Attack

6.Not everything fits into the cloud

7.Dependency and vendor lock-in

8.You may not get all the features

Cloud Computing Security Threats:

Nine critical threats to cloud security (ranked in order of severity): 

1.Data Breaches

2.Data Loss

3.Account Hijacking

4.Insecure Interfaces and APIs

5.Denial of Service

6.Malicious Insiders

7.Abuse of Cloud Services

8.Insufficient Due Diligence

9.Shared Technology Issues 

Common Defense Used in Cloud:

1.Encryption

2.Digital Signature

3.Identity and Access Management

4.Single Sign on

5.Cloud based Security Groups: A security group acts as a virtual firewall that controls the traffic for one or more instances.

6.Remote User Multi-Factor Authentication

7.Audit Logging / Intrusion Detection

8.Data, Application Security