Cloud computing is computing in the form of a service rather than a product. Shared resources, software, and data are provided to computers and other devices via a network (typically the Internet) that basically acts like a utility (like the electricity grid). The cloud provides computation, software, data access, and storage services that do not require end-user knowledge of the physical location and configuration of the system that delivers the services. This concept meets a wide-spread need of IT: a way to increase capacity or add capabilities on the fly without investing in new infrastructure, training new personnel, or licensing new software. Cloud computing encompasses any subscription-based or pay-per-use service that extends IT's existing capabilities in real time using the Internet. The services provided by cloud computing can be categorized in three different models:
IaaS – Infrastructure as a Service: The user can access and use virtual hardware resources such as desktop, server, network or memory. Choosing IaaS, users create their own cloud-based computer cluster and thereby account for the selection, installation, and operation of the software themselves.
PaaS – Platform as a Service: Cloud instances provide net access for programming or runtime environments using flexible and customizable computing and data capacities. PaaS can be used to develop your own software applications or execute them in a predefined environment provided and maintained by your service provider.
SaaS – Software as a Service – cloud instances provide net access to software applications offered by your service provider. These applications are operated in predefined and ready-to-use environments or infrastructures. SaaS is sometimes also described as "software on demand".
This document only relates to SaaS, that is, providing ARIS services in a cloud instance with access to these services via the Internet from anywhere. For this solution, we distinguish between three provisioning models:
Public cloud - Offers access to abstract IT infrastructures for the public Internet. Public-cloud service providers allow their customers to use or rent these infrastructures on a monetary basis with users only having to pay for actual usage (pay-as-you-go), without investing money in computing or data center infrastructures.
Private cloud - Offers access to abstract IT infrastructures within your own organization. The connection between the cloud instance and your home office network can be established via VPN (VPC at Amazon).
Local Cloud - Offers access to abstract IT infrastructures on your local computer. Most likely you only receive a predefined image or instance of the software for download and you need to run it locally on a virtualization platform (for example, VMWare or Virtual Box) hosted on your computer. The connection to that image or instance can be established using local network interfaces on your computer or the hosting application you are running the image or instance on.
The following sections provide more details on the two different concepts and all necessary configurations for PPM.