SOA and Cloud Computing

Cloud Computing Hype
Why is everyone talking about cloud computing? Drawn-out, expensive IT projects that are planned and implemented with few benefits for the business stakeholders are commonplace. In contrast, cloud computing offers business users the chance to immediately implement services with usage-based billing that are tailored to their requirements, often without the need to consult with the IT department.

However, aspects including security, architecture, availability, and standards are often not evaluated. Cloud consumers find themselves at the mercy of the cloud provider. Scenarios that require changing cloud providers after a cloud provider goes bankrupt, and the associated moving of data and/or applications, have not yet been sufficiently tested. Business continuity should play a key role from the start of a cloud evaluation process.

One of the greatest challenges here is the integration of existing data and systems into the cloud solution. Without integration spanning clouds and on-premise systems, processes can only be executed in isolation, leading to cloud-specific silos of isolated solutions. Important information for users is not available across processes and systems. Problems that would have occurred in the company's internal IT are now shifted to the cloud provider. To prevent "legacy clouds" or solutions that are hard to maintain, it is important to manage the entire architecture proactively and, in particular, the integration into the cloud. Even if cloud providers want us to believe otherwise, not every aspect of IT can be outsourced to cloud solutions!

Cloud Computing Definition and Criteria
Cloud computing is a model for usage-based network access to a common pool of configurable computing resources (e.g. networks, servers, storage systems, applications, and services) that can be provided and used quickly. IP-based services are requested via self-service and used online independently. A prerequisite for this is a broadband Internet connection with low latency. The IT resources are bundled into pools and provided as required. Billing is based on the services used.

Concepts in Cloud Computing
In cloud computing, the following models are differentiated on the basis of horizontal scaling:

• Infrastructure-as-a-Service (IaaS) - provides a hardware platform as a service, such as Amazon EC2 or Oracle Compute Service (now in preview)

• Platform-as-a-Service (PaaS) - provides a software platform as a service, such as Google Apps Engine or Oracle Java Cloud

• Software-as-a-Service (SaaS) - allows applications and functions to be outsourced by virtualizing cloud providers' hardware and software and providing the functions as services, such as Salesforce CRM [REF-1] or Oracle Sales Cloud

In deployment models, distinctions are made according to availability and installation location. Public clouds are services that are available to the public on the Internet. Private clouds are internal company services. Hybrid clouds and community clouds represent mixtures of these models, such as when Amazon computing power is used in the event of a failure or overload of an internal company cloud application.

Large companies for which IT plays a central role or represents a competitive advantage often build internal company cloud solutions in their own data centers. Small and medium enterprises frequently use public cloud services. A further distinguishing feature is the applications' focus. In the business-to-business segment, private clouds are predominantly used, while the majority of the business-to-consumer segment uses public clouds .