What is cloud computing?

Question

I never really understood where is the boundary that determines whether an application is in the "cloud" or not.

Examples:

• One of the first applications that appeared totally online are the emails, as today we have Gmail, Outlook, etc, fully accessible via browser. I have never seen anyone call this "cloud", but it would not be the case, since it works without having to install anything on the machine?

• If a business owner decides to free up external access to the ERP on their server, so that some people can access from their homes, does this already feature as a cloud? If not, what would it take for it to be a "cloud", put it on a third party server?

• A simple website, like a blog, could be considered a mini cloud application?

What is the boundary that determines whether something is "in the clouds" or not? What is cloud computing?

Answer 1

The term "cloud computing" originally referred to to a network architecture where several computers - not necessarily identical, or of equal capacity - collaborate in the accomplishment of a certain task. New computers can be freely introduced into the set, or removed from it, without the need to stop processing and/or reconfigure everything.

Nowadays it is most used in the context of Software as a Service (Saas)*, where you do not compute on(s) your computer(s), but rather hire someone to host the necessary systems - paying only for processing power, disk space, network connections... And true to the philosophy of the cloud, allowing yourself to increase or decrease the size of the contract (i.e. how much you pay, and how much resource is allocated to you) in an easy way.

*Or, as pointed out by Caputo, other types of service, but maintaining the characteristic of not "plastering" the system to the environment being executed.

Putting this in the context of your question:

• Both Webmail and other client-server applications (e.g., Viaweb - then Yahoo! Store - history’s first web application) are not considered "cloud" because there is no such feature of scheduling: the provider offers a fixed service and little customizable, and a certain amount of resources, and only. Sometimes there are different plans (e.g.: 1GB of email space, 5GB, etc) but it is rare to see something "on-demand" (where you pay more or less, month to month, as your need forecast).

• The example of ERP is similar - the service is fixed, the conditions are determined by the owner of the company... Transferring to a third-party server on its own doesn’t change anything (let’s say you hired one Private Virtual Server - VPS - at a fixed cost with fixed resources - this does not characterize cloud computing). What may happen is that this third-party provider offers hosting with cloud computing features (you choose how much space you will need and how much monthly transfer you pay proportionately, a little extra if you exceed the limit, etc).

• Again, the site would not be an example of cloud. But if the site is hosted on a server that charges proportionally to the network traffic used, or to the disk space used for blog posts/comments, that would be a cloud service.

In accordance with comment from the bfavaretto, there is no simple criterion to say whether something is "in the cloud" or not. Nowadays this expression is often used as a synonym for "in the web". But I would say that if the service does not allow to increase or decrease resource allocation without touching the settings [from the client’s point of view, the contractor], I wouldn’t call it "cloud" - though it’s described as such (and I wouldn’t mind it, after all a name is just a name...).

Addendum: in my reply I always referred to "a service that you hire", but in reality it is not necessary a contract with third parties for a platform to be considered "cloud": you can have a company with its own infrastructure (servers, co-located or hosted in their own dependencies) that organizes and makes available their computational resources in the form of cloud. Since the various systems installed in the internal network, the various departments of the company, etc, have resources allocated to them dynamically, and not static (the X server hosts application A, Y applications B and C, etc.; let’s deploy service D? we need to buy another server... etc.). It’s what we would call "private cloud" (private cloud).

Answer 2

According to the Wikipedia

Cloud Computing is delivering computing as a service instead of as a product, by which compatible features, software and information is provided to computers and other devices such as a utility (like the mains) over a network (usually the Internet) Clouds can be classified as public, private or hybrid.

Therefore Cloudcomputing is not the product delivered but the provision of services over a network.

These service models can be (according to the same Wikipedia article):

Infraestrtutura as a service (Infrastructure as a service (Iaas))

Iaas providers offer computers (physical or virtual machines) and other resources, load balance, fail over, ability to scale more or less services depending on customers' demand or need, storage with distributed backups, VLAN, firewalls.

Platform as a service (Platform as a service (Paas))

In the Paas model, cloud providers deliver a computing platform that usually includes the OS and a running environment of a programming language, databases, and Web servers. With this model, developers can deliver their applications without having to worry about the Hardware and Software layers and focus only on developing their products.

As an example we have Microsoft Azure, Google App Engine, which scale processing and storage without requiring manual intervention from the developer.

Software as a Service (Software as a service (Saas))

In this business model users have access to applications and their databases. Cloud providers provide the Iaas and Paas that run the application. Saas are generally considered "software on demand" as they are paid for per use.

In the Saas model providers install and manage applications and software users access their services and pay by period or by consumption.

So:

One of the first applications that emerged fully online are the emails, as today we have Gmail, Outlook, etc, fully accessible via browser. I’ve never seen anyone call this "cloud," but would be the case, since it works without having to install nothing in the machine?

Installing is not the deciding point, email can be considered a Saas and yes, it would be a Cloud because it is an application sold for you to use, under the responsibility of another company

If a business owner decides to free up external access to ERP in his server, so that some people can access from their homes, this already characterized as cloud? If not, what would be needed for this be a "cloud", put this on a third party server?

No, it would be dark if this company’s business was ERP and it sold access to it to other companies.

A simple website, like a blog, could be considered a mini cloud application?

No, because it does not provide any service to its users

Answer 3

In their examples, I consider them as serviços and each service provider chooses how to deliver them ( on which datacenter to host, how to do the software, etc...)

Already the computação na nuvem that’s when you run your application on a computer you hired as a service and doesn’t even see him.

But only this description does not characterize cloud as you need this service that is giving support to sua application support some properties such as scale on demand or aggregated services like firewall, routers, new disks, adjustable contractor band.

I consider the best current example of Cloud Computing the separate services that are offered by Amazon AWS