cloud computing (8-9): Although the term “the cloud” appears straightforward, the reality is that it is a single term used to describe a multitude of different services and technologies. A cloud may be implemented for a client in any of four different ways [public, private, hybrid, community]. [...] In general, the cloud service industry offers four types of services - Infrastructure as a Service, Software as a Service, Platform as a Service and, less commonly, Data as a Service. [...] These four types of clouds and four different services can be implemented in any number of combinations, for example software being provided in cloud-based platforms through rented infrastructure. (†466)
cloud service (8-9): Although the term “the cloud” appears straightforward, the reality is that it is a single term used to describe a multitude of different services and technologies. A cloud may be implemented for a client in any of four different ways [public, private, hybrid, community]. [...] In general, the cloud service industry offers four types of services - Infrastructure as a Service, Software as a Service, Platform as a Service and, less commonly, Data as a Service. [...] These four types of clouds and four different services can be implemented in any number of combinations, for example software being provided in cloud-based platforms through rented infrastructure. (†465)
community cloud (8): The final type of cloud is referred to as a “community cloud,” where a specified group of clients all share the same cloud service. In this way, the clients can ensure that their information is not being stored with other unknown organizations but can still gain the purported benefits of sharing the burden of cost. This implementation could also enable information sharing between organizations with shared interests or data uses. [Text includes citations] (†454)
Data as a Service (DaaS) (9): A fourth type of cloud service has been dubbed Data as a Service (DaaS). This type “is typically implemented within a SaaS, PaaS or IaaS solution and provides (often spatial) data within applications that support more specialized data discovery, access, manipulation, and use.” [Text includes citations] (†462)
hybrid cloud (7-8): The third type of cloud implementation that is available is a “hybrid” cloud. In this model, some of the infrastructure would be the shared space of the public model and some would be the isolated infrastructure of the private model. This model is appropriate when some client information is more sensitive, requiring storage in higher cost private space while less sensitive information can be kept in less expensive but more public space. [Text includes citations] (†453)
Infrastructure as a Service (IaaS) (8): Infrastructure as a Service (IaaS) refers to the provision of access to hardware (e.g. hard disks, servers, etc.). This service allows the client to rent, rather than purchase IT infrastructure on an as-needed basis, allowing it to easily and quickly increase infrastructure capacity when required. The most commonly promoted benefit of this service is the cost saving to the client who no longer needs to purchase and maintain infrastructure. This “rented” infrastructure can then be accessed remotely by members of the client organization. [Text includes citations] (†456)
Platform as a Service (PaaS) (8-9): The third type of cloud computing is Platform-as-a-Service (PaaS). This service provides the client with an environment for creating and running its own software. This has been done, for example, by Google in its Google Apps platform, which allows developers to create software that can run on devices using Google operating systems such as Android. This is again meant to save the client the cost of owning and running an environment that supports such activities. [Text includes citations] (†463)
private cloud (7): The next type of cloud service implementation is a “private” cloud. Again, this term describes the number of clients who access the infrastructure. In this model, only the client who is purchasing the service would have its information stored in the infrastructure, which would be physically isolated from that of other clients. This type of implementation can be provided remotely but it may also be provided at the client’s site. It may even be owned and administered by the client for its employees. This model, particularly if it is owned and maintained by the client itself, is more expensive than the public model, but can offer better guarantees of security and privacy. [Text includes citations] (†452)
public cloud (7): The first possible implementation is a “public” cloud. Here the word “public” does not refer to government agencies but rather to an infrastructure that is shared by all clients of a service provider. In this public cloud, all clients’ information is stored together, with only logical separations to distinguish one from the other. This form of cloud service is commonly accessed remotely. [Text includes citations] (†451)
service level agreement (9-10): Service Level Agreements (SLA), on the other hand tend to contain more specific terms relating to particular services. A study by IBM Research on SLAs identified terms such as “service guarantee metrics” which quantify “availability (e.g., 99.9%), response time (e.g., less than 50ms), disaster recovery and fault resolution time (e.g., within one hour of detection) and how compensation will be calculated and reimbursed for a fault in service. Availability or uptime can be offered based on a tiered payment structure. The SLAs also tend to offer service guarantees on a basis of time periods as well as at different granularities. For example, time periods may be measured in requests to the service per minute, hour, day, week, etc., and service interruption may be measured by service, data centre, etc. [Text includes citations] (†469)
Software as a Service (SaaS) (8): Software as a Service (SaaS) refers to a service which allows the client to remotely access software that is hosted on infrastructure owned and maintained by the service provider. This service enables a client organization to use software that might otherwise be too expensive to purchase, install, maintain, and update itself. [Text includes citations] (†459)
terms of service (9): The “Terms and Conditions (TaC),” “Terms of Service (ToS),” or similarly named document TaC may contain more general clauses that would encompass all of the services that a provider offers, such as conditions for service termination, legal protections for the service provider in terms of content uploaded by the client, and copyright terms. In general, these contracts describe the client’s obligations when using the service, and they are clearly meant to protect the service provider more than the client. [Text includes citations] (†467)
