Cloud computing describes the provision of IT infrastructures. These can consist of servers, storage, software, databases, network components, and artificial functionalities (AI). The IT infrastructures mentioned are not installed on the respective end device, but are available on the Internet for flexible and demand-oriented use; The corresponding services are accessed exclusively via interfaces and protocols.

In 2011, the National Institute of Standards and Technology (NIST) published a comprehensive, widely accepted definition that describes the service models, delivery models, and essential characteristics of cloud computing.

Cloud computing – the essential characteristics

• On-demand self-service – Users independently access services from the cloud that are available when needed.
• Broad network access – The respective services from the cloud can be accessed via various heterogeneous end devices and the installed software; these are considered standard tools and enable access via the network used.
• Resource pooling – Computing power, network, or storage space are resources that can be accessed by multiple users/customers as needed (physically and virtually) without restrictions.
• Rapid elasticity – From the user’s perspective, virtual resources can be scaled very quickly and almost indefinitely, which is why they are released accordingly (quickly and elastically), in some cases automatically.
• Measured service – Cloud systems automatically control and optimize resource usage, which can then be analyzed, measured, and monitored accordingly.

 

Overview graphic on cloud computing. Image: Sam Johnston / CC BY-SA 3.0

 

Cloud computing – the public cloud and private cloud delivery models

The delivery model perspective describes how access to cloud services is regulated and who is authorized to access them (user and rights management).

Public cloud

The public cloud is accessible to the general public and provides services via the Internet.

Users can rent services such as computing power, infrastructure, storage space, or applications from a public cloud service provider, for example Google, Amazon, Apple, and Microsoft. The most common and well-known public cloud services include photo storage, data storage, photo editing, and streaming services. These services are usually unlocked or made accessible for a fee.

Private cloud

A private cloud is operated by a single company or organization; accordingly, only those persons who have been granted access by the organization or company have access to it. This form of cloud computing contradicts the general approach of a cloud in that the higher security requirements necessitate a much more capital-intensive purchase, for example for additional hardware and IT infrastructure. Although security standards are also provided in the public cloud, private cloud requirements are tailored to individual customer needs. This also increases the individual costs for security controls, maintenance, and management. Important: Access is usually via a VPN network, not via the traditional Internet – a private cloud is therefore considered relatively secure against attacks from the Internet in business circles.

Hybrid cloud

The hybrid cloud is a combination of two or more clouds, primarily from the public and private environments described above. For example, databases can be stored in a private cloud, while the software that processes this data is installed in a public cloud. In general, the term hybrid cloud refers to a mixed computing, storage, and services environment that can consist of an on-premises infrastructure, private cloud services, and a public cloud such as Amazon Web Services (AWS) or Microsoft Azure.

Editor’s note: Other hybrid forms or clouds with a specific focus include community clouds, distributed clouds, multi-clouds, virtual private clouds, big data clouds, and HPC clouds (HPC stands for high-performance computing).

Cloud computing – the service models

The service models of cloud computing can be roughly divided into three different types:

Software as a Service (SaaS)

Software as a Service – also known as software on demand – describes the availability and use of software or applications (apps) via the Internet. Users rent cloud-based apps via the Internet and can use them via a browser or client. Common examples include email, calendar, and office tools, such as the Microsoft Office 365 software package or Apple’s iCloud.

Platform as a Service (PaaS)

Generally speaking, this type of platform includes developer tools, database management, and tools related to business analytics. Users can develop software applications using the available online tools or run them within the cloud-based infrastructure. Typically, users develop cloud-based applications so that they can test them immediately on the Internet.

Important: *A PaaS provider should automatically provide all necessary resources, such as computing power, storage, network, middleware (message queuing or load balancing) and databases during deployment (development) of the application and scale them according to requirements, known as ‘fabric computing’. Built-in monitoring functions are also expected, which can be used to monitor the runtime behavior of the applications (*Computerwoche).

Infrastructure as a Service (IaaS)

IaaS provides users with the classic components that are usually installed in a data center. These include, for example, hardware, computing power, storage space, and network resources—all of which are available via the Internet and are usually configured and controlled independently by the user. Maintenance, on the other hand, is handled by the provider. Access to the resources is via private and public networks.

 

Requirements for cloud providers

 

Advantages and disadvantages of cloud computing

The advantages and disadvantages of using cloud computing can be clearly distinguished between private users and companies that use this technology.

Advantages for private users

No hardware is required (except for a PC, tablet, or smartphone) to store data or use the relevant application software.

• This means that there are no external data carriers that private users can lose, misplace, damage, or have stolen.
• Your own hardware does not usually need to be adapted or upgraded, as most cloud services are browser-based or provide access via an application (smartphone/tablet/PC/Mac).
• The respective cloud services can be used independently of the device and on the go, provided you have internet access.
• Documents, images, music, or videos can also be made available to third parties via file sharing.

Disadvantages for private users

• The security of data stored in the cloud is a general weakness of cloud computing. The corresponding infrastructure must be intensively maintained and secured, which involves high technical and financial costs. Hacker attacks on the servers of cloud providers usually target personal user data, which is naturally stored there.
• Data protection is also a disadvantage. Although the data stored, how it is used and passed on is specified in the terms of use of the service/provider and generally complies with the applicable data protection guidelines, this is diluted by the specific location of the provider’s headquarters (e.g., outside the EU).

Advantages for companies

• For companies, the use of cloud computing has a particularly positive impact in the form of significant cost savings. Costly investments in hardware, software, and the necessary personnel are eliminated—provided that the company has carried out an operating cost analysis. If this is the case, there is no long-term capital commitment in terms of accounting.
• In the case of a public cloud, the cloud provider takes care of updates to the hardware and software used, eliminating the need for labor-intensive monitoring and maintenance of the services. With a private cloud, on the other hand, the costs for monitoring, maintenance, and service increase.
• Scalability, i.e., the flexible adaptation of the scope of use to actual requirements, is an immense advantage. In this context, it is also possible to link or connect multiple locations to the IT infrastructure that has already been leased.
• Cloud computing enables location-independent, collaborative work on projects and access to company-related data by employees with the appropriate authorizations. However, cloud solutions for private users now also offer this option.

Disadvantages for companies

• By using cloud services, companies effectively place themselves in a position of dependency on the provider. If a provider does not adequately take care of updates, security, and data protection for the services provided, this has a direct negative impact on the customers, i.e., the companies.
• By outsourcing certain IT areas to a cloud provider, a company automatically minimizes its internal expertise in the same area.
• If a company’s internal processes are outsourced to the cloud, it also becomes dependent on the required internet connection.
• The use of data storage (data outsourcing) in other EU countries is a sensitive issue, especially when it comes to sensitive, company-related data, and is simply prohibited by many companies.

Image rights: Cloud requirements for cloud providers: knowis AG