De grondbeginselen van Cloud Computing, met informatie over onder andere Infrastructure-as-a-Service, Platform-as-a-Service, Software-as-a-Service, Private Clouds en Public Clouds.
1. The principles of Cloud computing
1.1 The concept of Cloud computing
What is Cloud computing?
Cloud computing is a method of running application software and storing related data in central computer systems and
providing customers or other users access to them through the internet.
What are the four main deployment models for Cloud computing?
The private Cloud is a Cloud that resides on a private network that runs on a data center that is exclusively used by one
organization. The data center may be owned, managed and run by either the organization itself, a third party or a
combination of the two.
The public Cloud delivers off-site services over the internet to customers, such as Office 365.
The community Cloud delivers services to a specific group of organizations and/or individuals that share a common goal. The
main goal for creating a community Cloud is the ease of sharing data, platforms and applications which otherwise would be
too expensive for just one individual.
The hybrid Cloud is a mix of private Clouds, public Clouds and community Clouds. It combines several private and public
Clouds solutions from several providers into one IT infrastructure. In this model, a clear choice has to be made what to buy
where. Choosing specific services for either private Cloud or public Cloud suitability is balancing security, privacy and
compliance versus price.
What are the three main service models for Cloud computing?
With Software-as-a-Service (SaaS), applications are hosted by third parties. Customers do not need to worry about the
development and management of these applications. The provider is responsible for updates and managing licenses, and
most service management parameters like scalability, availability, maintenance and service continuity. A customer pays by
means of a subscription or pay-per-use model. Sub-types, or maybe simply other names for SaaS, are ‘software on demand’,
‘hosted services’ and ‘application service provisioning’.
With Platform-as-a-Service (PaaS), customers can use computer platforms ‘on demand’ which can save costs in ownership,
management and maintenance. In a typical software development environment, platforms are used for the time the project
runs and a new project often has other or newer platform requirements.
Infrastructure-as-a-Service (IaaS) are sold by so called hardware service providers from which a customer can rent physical
or virtual hardware like storage, servers or internet connectivity. Services are sold according to a utility computing service
and billing model.
1.2 The evolution of Cloud computing
What are the main concepts from which Cloud computing developed?
The main concepts from which Cloud computing developed are the development of the internet, the move from mainframe
, computing to the present day myriad of personal devices with connection to the internet and the development of computer
networks.
What is the role of network and servers in Cloud computing?
With ever growing bandwidth and speed of the networks, server speed and capacity, and ever cheaper and smaller personal
devices to connect to the networks we entered the age of the internet and application hosting by Application Service
Providers (ASP). One of the present day variants of the Cloud service SaaS (Software-as-a-Service) is a direct derivative of
these ASP solutions.
What is the role of the internet in Cloud computing?
The internet makes it possible for everyone to access SaaS-applications, IaaS-infrastructures and PaaS-platforms. The
internet is the connecting factor between an end user and the Cloud.
What is the role of virtualization in Cloud computing?
The five different forms of virtualization…
Access virtualization: Allows access to any application from any device.
Application virtualization: Enables applications to run on many different operating systems and hardware platforms.
Processing virtualization: Makes one system seem like many, or many seem like one.
Network virtualization: Presents and artificial view of the network that differs from the physical reality.
Storage virtualization: Allows many systems to share the same storage devices, enables concealing the location of
storage systems and more.
…mean that hardware, applications and data can be located anywhere in the Cloud; we only need to access and use them.
What is the role of managed services in Cloud computing?
Having your services managed basically means that you turn IT services over to a third party. In the late 1990’s applications
were actually offered by providers, meaning that they were no longer owned by the customer. The first example of shared
managed services was delivered by ASP (Application Service Providers). Because of the bursting ‘internet bubble’ the ASP
never became the big thing and slowly developed into one of the major Cloud service models: SaaS.
1.3 The Cloud computing architectures
What is the difference between a single purpose and multipurpose architecture?
A single purpose architecture, such as a physical server, takes much more time to (re)install than a multipurpose
architecture such as a new dedicated virtual platform.
What is the Service Oriented Architecture?
A Service Oriented Architecture is basically a collection of services that communicate with each other. This communication
may be simply passing of data between two or more services or a jointly managed activity. Connecting the services in many
cases involves web services using XML. One could say there would be no Cloud without SOA.
, 1.4 The benefits and limitations of Cloud computing
What are the main drivers for Cloud computing?
The main drivers for Cloud computing are:
- Reduced cost - Shared resources
- Automated - Agility and scalability
- Flexibility - Back to core business
- More mobility - More IT functionality for a lower price
What are the main limitations of Cloud computing?
Internet access: no internet access means no Cloud access.
Security: Cloud data centers can be high security and highly managed, but also low security and badly managed. How
to check if this is the case?
Privacy: because of uncertainty where your data is stored in combination with varying national and international
legislation on privacy, you never know who can access your data.
Service Level Agreement: does your agreement allow for flexibility and scalability?
Vendor lock-in: application migration to another Cloud computing provider.
2. Implementing and managing Cloud computing
2.1 The building of a local Cloud environment
Describe the main components of a local Cloud environment and how are they interconnected?
The main hardware components of a local Cloud environment are:
Blade server arrays
Local Area Network (LAN)
Storage
Load balancer
The main software components of a local Cloud environment are:
Virtualization software, such as VMWare.
Cloud Application software, such as CRM, Office 365, et cetera.
Database software, such as Oracle, Microsoft SQL, et cetera.
Middleware (a set of intermediaries for the components in a distributed computing system).
Operating Systems, such as Linux, Windows and Mac OS.
In order to make maximum use of the interoperability of Cloud computing it is important to standardize the architecture by
using standard protocols and other building blocks that are location and vendor independent.
Describe the use of Virtual Private Network access to a Local Area Network.
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