c/S, b/s concept

c/S is a distributed system structure, it is based on a simple request/response protocol, in the C/S mode, the server only centrally manage the data, and computing tasks scattered on the client, the client and the server through the network protocol to communicate. P client sends data requests to the server, the server transmits the data to the client for calculation, the advantage of this mode makes full use of the performance of the client, and greatly improves the computing power.

The b/S (BROWSER/SERVER) structure is the browser and server structure. It is a change or an improved structure of C/s structure with the rise of internet technology. In this structure, the user interface is implemented by the WWW browser, very few transaction logic in the front-end (Browser) implementation, but the main transaction logic in the server-side (server) implementation, the formation of the so-called three-layer 3-tier structure. This greatly simplifies the client computer load, reduces the cost and effort of system maintenance and upgrade, and reduces the total cost of users (TCO).

Cloud computing is a business computing model. It distributes computational tasks across a large pool of computer-based resources, enabling various applications to acquire computational power, storage space, and information services as needed.

Four types of cloud deployment models

1. Public cloud. Owned by an organization, its cloud infrastructure provides cloud services to the public or to a large industry group. (e.g. Google)
2. Private cloud. Cloud infrastructure specifically runs services for an organization. It can be managed by the organization or a third party, either on-site (on-premises) or off-site (off-premises).

3. Community Cloud. A cloud infrastructure is shared by several organizations to support a particular community. A community is a group (such as a mission, security requirement, policy, or compliance consideration) that has a common aspiration and pursuit. It can be managed by the organization or a third party, either on-site (on-premises) or off-site (off-premises).

4. Hybrid Cloud. Cloud infrastructure consists of two or more clouds (private, community, or public) that exist independently, but are bundled with standard or proprietary technologies that facilitate portability of data and applications (such as cloud bursting technology for load sharing between clouds).

Three types of cloud service models

Iaas:infrastructure-as-a-service (infrastructure as a service)

The first layer is called IaaS, sometimes called Hardware-as-a-service, and a few years ago if you want to run some business applications in your office or on your company's website, you need to buy servers or other high-level hardware to control your local applications and get your business up and running.
But with IaaS now, you can outsource your hardware to other places. IaaS will provide off-site servers, storage and network hardware that you can rent. Save on maintenance costs and office space, companies can use these hardware at any time to run their applications.
Some large IaaS companies include Amazon, Microsoft, VMWare, Rackspace and Red Hat. However, these companies have their own expertise, such as Amazon and Microsoft provide you with not only IaaS, they will also rent their computing power to you to host your site.

Paas:platform-as-a-service (Platform as a service)

The second layer is called PAAs, which is sometimes called middleware. All the development of your company can be done at this level, saving time and resources.
PAAs offers a variety of solutions for developing and distributing applications on the web, such as virtual servers and operating systems. This saves you money on the hardware and makes it easier to collaborate between decentralized studios. Web application management, application design, application virtual hosting, storage, security and application development collaboration tools, etc.
Some large PAAs providers have Google App engine,microsoft azure,force.com,heroku,engine Yard. Recent companies have Appfog, Mendix and standing Cloud

Saas:software-as-a-service (software as a service)

The third layer is called SaaS. This layer is a layer of daily contact with your life, most of which is accessed through a Web browser. Any application on a remote server can be run over the network, which is SaaS.
The services you consume are completely accessible from websites such as Netflix, MOG, Google Apps, Box.net, Dropbox or Apple's icloud. Although these Web services are used for business and entertainment or both, this is part of cloud technology.
Some of the SaaS applications used for business include Crm,adp,workday and SuccessFactors of Citrix's Gotomeeting,cisco Webex,salesforce.

This article from "No Twin Cities" blog, declined reprint!

c/S, b/s concept