## 3 e-Health Cloud Challenges
### Technical Challenges
In other words, the configuration of cloud services to meet different requirements must be achieved with minimum effort and cost. * **Interoperability:** services for the e-Health Cloud can be provided from multiple cloud service providers. For example, one provider may provide storage and processing services for high resolution medical images while another provider may provide storage and other services for storing patient electronic records or data mining and analysis services. The main issue here is interoperability which involves defining an agreed-upon framework or some open protocols/APIs that enable easy servers and data integration among different cloud service providers [44]. The common framework or protocol should also include mechanisms for secure information exchange and services' integration. The issue of interoperability is also faced when integrated e-Health Cloud services are provided from both local and external clouds. For example, some e-health functions can be developed by integrating some local and external services. These e-Health Cloud services cannot be formed easily unless there is a good degree of interoperability among the local and external service providers. A good degree of interoperability can also facilitate easy migration among different available systems. Data migration between an old local application and a new e-Health Cloud can be simplified if open protocols and APIs are provided. One approach is to utilize the concept of Service-Oriented Architecture (SOA) [45,46] for implementing the e-Health Cloud. SOA aims to make services available and easily accessible through standardized models and protocols without having to worry about the underlying infrastructures, development models or implementation details. This helps achieve interoperability and loose coupling among e-Health Cloud components and also among e-Health Cloud users. * **Security:** the e-Health Cloud services can be provided by multiple cloud service providers and be used by multiple healthcare providers. The cloud service providers provide a number of recourses that are collected in a virtualized pool to be utilized by healthcare providers. High security concerns are usually associated with open environments which are provided by a number of service providers and shared among a number of service consumers. A healthcare provider that owns IT applications within its premises can apply and monitor proper security policies and controls for identity and access control managements. However with open environments, it is very important to provide cloud services which support suitable and adequate access control and authentication mechanisms in addition to mechanisms to secure the transfer of such data to and from clients and service providers. That is essential since data must be kept secure in the multi-tenant clouds where it is stored along with other healthcare providers' data. In addition, it is necessary to make sure that the service provider itself cannot access or use the healthcare providers' data. Another issue is the need for efficient security mechanisms for the e-Health Cloud. While there are several ways to apply strong security measures, these impose high computation and communication costs rendering them inefficient in distributed open environments such as the Cloud. In addition, another issue is the wide range of security requirements among healthcare providers, thus an organization's security requirements and policies may not be fully reflected in cloud services [47]. * **Privacy**: privacy is an important CC issue that could prevent the full utilization of its capabilities for different types of organizations and applications [48]. Privacy is particularly one of the main concerns in e-Health systems [49, 50]. When using the Cloud for e-Health services, this concern is amplified. The concerns here involve the ability to protect patient's records from each other, other healthcare providers and the cloud service providers.