Service Models
Infrastructure as a Service (IaaS)
IaaS provides an organization with the infrastructure required to run its business. This could include networks, computing resources such as storage or servers, and IT staffing. The organization does not manage or control the infrastructure, it can control over operating systems, programming frameworks and applications. For instance, a hospital may use the cloud for diagnostic imaging disaster recovery shown in (Figure 1). The organization has its own PACS and archive, but it purchases storage and network services to pass a copy of data to the cloud provider in case of lost data. The cloud service provider has little interaction with the daily events at the hospital and access to this data is limited to an as needed basis in the face of disaster.
Figure 1. Infrastructure as a service healthcare model (IaaS)
Platform as a Service (PaaS)
PaaS is a service model where organization manages the applications deployed, but not the underlying infrastructure. This is most common in developing software applications where engineers have access to development tools, databases and middleware and infrastructure software. Healthcare providers with IT development staff may leverage this model to develop a local electronic medical record.
Figure 2. Platform as a service healthcare model (PaaS)
Software as a Service (SaaS)
SaaS becomes a model for healthcare providers to quickly adopt new technologies without excessive capital costs or readiness efforts shown in (Figure 3). SaaS provides users with remote access to the application, normally through a web browser. Facilities don’t need to worry about storage or application management. Digital pathology, PACS or even email could be used through the cloud where the organization would only pay for the use of the application as pay-per-study or gigabyte model. SaaS can be quickly deployed and used without the need for any capital money, fulfilling maximum uptime and benefit from the technology.
Figure 3. Software as a service healthcare model (SaaS)
Cloud Deployment Models
The cloud can be provided in a many of different models, every one used in a specific environment and delivering different benefits to the user. Through these delivery models, healthcare facilities can pick which services best suit their requirements. With each model there are benefits and related risks that need to be considered in the facility’s cloud strategy.
Public Cloud Deployment
A public cloud is the most cost effective model of deployment. The public cloud is open to the general public and is completely managed by the cloud service provider. Users will buy the use of an application from a public cloud provider. Examples of public cloud are Amazon.com or salesforce.com. Users upload their information into this complete environment. The servers, storage and networking are shared among all subscribers and the applications are delivered over the Internet. Public cloud deployments are more risky, because they are open to anyone and the thought is that security and privacy violation are common with public clouds. Disaster recovery for healthcare organizations could be well managed to a public cloud model as there are limited access points to the data and storage is more cost effectively managed and access is only in the case of emergency shown in (Figure 4). Mission-critical systems do not need to rely on this data and so service level agreements (SLAs) can be minimal
Figure 4. Public cloud architecture
Community Cloud Deployment
A community cloud is a public cloud that serves many organizations that support a particular community of users. They may be managed by the organizations or a third party and may reside on-site or off it. For example a Linux community cloud would allow developers to share tools common to Linux development. The same risks are associated with community cloud as with public cloud, so consideration of security and privacy are important with community clouds.
Figure 5. Community cloud architecture
Private Cloud Deployment
Private cloud are operated just for one organization. They may be managed by the organization itself or by a third party and they may reside on-site or off it. Private clouds are expected to be the most suitable model adopted by healthcare providers, especially that cloud providers have demonstrated more on how to overcome the many challenges associated with other cloud models. With private clouds the ability to manage and control sensitive patient data remains within the organization shown in (Figure7).Private clouds are more expensive, but confidence in deployment is higher.
Figure 6. Private cloud architecture
Hybrid Cloud Deployment
A hybrid cloud combines two or more clouds but they stay unique entities. A hybrid cloud deployment will share technology, but the information, applications, etc., will not be shared. The use of tenants and namespaces provides separation of users while running on the same category. Healthcare providers may deploy a hybrid cloud for disaster recovery of diagnostic images or clinical systems shown in (Figure 6). Use of hybrid cloud come in less risk to organizations, as participants are more aware of who is using the services.