History of cloud computing
I. Start up for the cloud.
Cloud can be considered as a model where related user can get on demand access to the shared resources as well as applications, servers’ storage or may any hardware device over the internet or the network. Consumer or user cannot get the hardware access directly, only owned and managed by provider. Use can access allocated services and resources by using browser anywhere.
II. Cloud computing and other same configurations
There are a lots of multi-tenant implementations that are same or similar to cloud computing. We can understand t these terms better by disfiguring each with cloud computing.
Applications service provider (ASP):
The founder of tele-computing Jostein Eike land releaser the term ASP in 1996 .ASP was considered as organization of computing because they were hosting and managing multiple application. Customer can use their services anytime, anywhere by using internet.
The term utility computing was started in the era of mainframe computing in 1969s.It was also the innovation of the mainframe computer. Mainframe computer was much more expensive and physically unpacifiable therefor mainframe manufacturer started the form unitality computing where they offered databases storage and computing power to banks, companies and large organizations.
III. Tools of cloud computing
Cloud computing deal with some tools and component as its infrastructure and resources with applications that can be accessed through self-service portals a panel.
§ Clients: A clients is a software application, platform or may be device from where user or consumer can access their cloudy services.
§ Cloud network: Cloud network is an interconnection of resources or services between the user.
§ Cloud application programming interface: A cloud application programming interface CAPI is a set of rules, tools and instruction that provides abstractions over a specific provider cloud.
IV. Types of cloud computing
Cloud computing can be categorized as public cloud, private cloud, hybrid could and community cloud.
§ The public clouds: This is a general type of cloud used and access by general messes. Normally small organization use this type of cloud a start their system with cloud after then they can extend services as per their need by paying according to the services. This type of cloud is highly managed by cloud service provider.
§ The private cloud: This type of cloud computing infrastructure is used by single organization and resources; services and access cannot be shared with other organization. Private cloud computing is more expensive then public cloud computing but more secure the then public cloud.
§ The community clouds: The community clouse is types of cloud that can be shared among the multiple organization s with a common tie. This type of cloud is generally managed and controlled by a third party offering the cloud service.
§ The hybrid cloud: The hybrid cloud is concerned as another types of cloud computing. In this type of cloud computing various internal or external services provider provides service to multiple organization.
Introduction to virtualization
I. Introduction:Virtualization is core component environment of cloud computing. It is also considered as new dimension into the field of information technology. We can run, test and experiment large multiple and various large-scale application with virtual environment. In this topic we will learn Virtual environment providers organization and benefits provided by virtualization.
II. Benefits of virtualization:
Although there are a lot of advantages of virtualization. Some core advantages of virtualizing are as follows.
§ Maximizing resources: It is easy to maximize their resources and services as per their requirement.
§ Reducing hardware cost: Virtualization is a better way to reduce the hardware cost. We can use any one hardware for the multiple infrastructure that can may reduce our hardware cost.
§ Enjoying benefits of OS services: Virtualization is can help us to install multiple operating system into one PC or one platform which may lead us for research and experimental purposes.
§ Increasing system security: Virtualization also leads us to implement security into the system.
I. Virtualizations Structure
Virtualization is accomplished through the software hypervisor or virtual machine monitor (VMM). The software used into two different structure of virtualizations.
§ Hosted structure
§ Bare-motel Structure
II. Virtualization provider companies
There are a lot of companies and organizations are working to implement the virtualization technology and providing as their services. Some names from them are: Microsoft, VMware and Oracle.
§ Microsoft- In the industry of software an IT based services Microsoft is considered as frontrunners. Microsoft is also working for virtualization services. Some of the major virtualization baes services of Microsoft are: Virtual PC, Virtual Server 2005 and Hyper V.
§ VMware – Over the years, the organization VMware introduced as virtualization services provider. They are providing much more virtualization services as their area of working. Major service of VMware is: VMware workstation and VMware server.
§ Oracle – Oracle is also considered as the vendor of IT based industry. The organization oracle is currently working on many IT based topics and the virtualization is also one of them. The virtualization services of the oracle are Oracle VM virtual box.
CC (Cloud computing) services
I. Introduction :
Cloud computing services provider companies or organizations are offering wide range of services. According to the services module and usages it can be categorized into three main types:
Figure 1: Delivering structure of the service of cloud computing over the network 
§ SaaS (Software as a service)- It is an on-demand service where user or customer pay per use of application in an independent platforming SaaS user can access application or software as per their package anytime and anywhere by using the browser or light ware client’s application and user or customer didn’t need to install the software on their PC. In SaaS all computing resources are managed by the vendor.
§ PaaS (Platform as a service)- This type of service is generally used by developer or programmers. PaaS provide environment for programming language executional operating system, a web server and a database to the developer to development, testing and running of their programs. In this module or types user ca only manage mentioned resources at above all other high-level resource are managed by vendor. 
§ IaaS (Infrastructure as a service)- This type of module or type offers computing structure, infrastructure and all computing resources including virtualization, networking and more as well as the resources of SaaS and PaaS at a virtual environment to the multiple onerously all the resources of the module is managed by vendor but user or customer also can be a manager or responsible. This type of module or type is mostly used by System administrators. 
§ XaaS (Anything as a service) - This is a recent evolution to cloud computing services. In XaaS, X is figure as anything which can be any cloud computing services or as well as the mix of all resources of all three services. This module or type is also known as ‘Everything-as-a-Service’. This type of services is also managed and controlled by vendor but user and customer can also be a responsible. 
Data Security in Cloud computing Security, other challenges and protection of data in cloud computing will be discussed into two phases.
I. Discussion Phase -
As per the development and advancement of technology and cloud computing everything we are doing into the cloud computing. The most important factor in this is the data. The study of of data security in cloud computing can be considered as the most important factor then the actual topic of cloud computing. The number of Data is increasing day by day and getting importance. Therefor the data security is conceded as the main object in cloud computing. In this phase we will discuss some major issue and challenges with data in cloud computing.
§ Security risk: Cloud computing is totally depending in internet, anything we do internet can be risky with security threats. Internet is considered as the main source od attacker to do something unethically. Therefor cloud computing and the data stored in cloud may face alts of security attacked which are as follow. 
o Unauthorized discovery
o Accidental or malicious deletion
o Denial of services attacks
§ Data Availability: The second concern after the security risk data availability is another challenge with data on stored in cloud. When user or customer start the services, there are chances of unexpected downtime may create. Lake of proper internet may lead to the unavailability of data on the cloud sometime. And an attacker can perform man in the middle attack to damage the routine. 
II. Protection Phase –
In this phase we will briefly discuss some important mechanisms of protection can be used for data security in cloud computing.
§ Data encryption:
Data encryption is most important way to protect data from being understood or used by unrelative users. Even if unfortunately, any unauthorized or unrelative party got the access of the data in cloud, they con not read or use it. The data stored on cloud can be encrypt with algorithm and a key the encrypted form of data in cloud is mentioned “ciphertext”.
There are two mostly used way to encrypt the data.
1) Asymmetric encryption: In this type of encryption some unique keys are compulsorily used for encryption of data as well as decryption. Keys are categorized as public and private keys.
2) Symmetric encryption: This is the old technique of encryption and decryption. In this type of encryption some shared secrete keys are used to encrypt and decrypt the data.
§ Backing up the data:
After the encryption and decryption of data, it is also considered as important mechanism in the protection of data in cloud. Backing up the data is another better way to protect the data and backed up data also must be protected either by using encryption decryption method.
§ Data integrity:
At early discussed mechanism of data protection with encryption and decryption we make sure that the data in the cloud cannot be understood by unrelative user. But in data integrity, encrypted data on the cloud cannot modified by unrelative or unauthorized parties either it is in underway or in rest. If precariously seems data is modified, to detect if the data is modified, user must to have the origin authentication. 
§ Cloud Data Management Interface:
Cloud Data Management Interface (CDMI) is a modern mechanism in the phase of protection of data in the cloud. With the implementation of CDMI user can transferred their data securely and easily from previous to new one vendor. 
References :Cloud Computing -Black Book (PG#3). ISBN:978-93-418-7 Edition : 2015.Cloud Computing -Black Book (PG#16). ISBN:978-93-418-7 Edition : 2015. Cloud Computing -Black Book (PG#35). ISBN:978-93-418-7 Edition : 2015. Cloud Computing Guidelines (PG#3)http://www.motc.gov.qa/sites/default/files/cloud_computing_ebook.pdf Three Cloud Computing Service Models .Source: https://doublehorn.com/saas-paas-and-iaas-understanding/ Cloud Computing Services ModelsSource : https://www.youtube.com/watch?v=36zducUX16w Cloud Computing Services Models Source: https://www.youtube.com/watch?v=36zducUX16w Types of Cloud Computing Services Source:http://www.gaditek.com/blog/types-of-cloud-computing-services Cloud Computing -Black Book (PG#184). ISBN:978-93-418-7 Edition : 2015. Cloud Computing -Black Book (PG#184). ISBN:978-93-418-7 Edition : 2015. Cloud EncryptionSource : https://searchstorage.techtarget.com/definition/cloud-encryption-cloud-storage-encryption   Cloud Computing -Black Book (PG#191,192,193,194). ISBN:978-93-418-7 Edition : 2015.