ReST is used in a number of cloud storage protocols, and also for managing cloud computing infrastructures. Youll also find SOAP (or Simple Object Access Protocol) as a management protocol to implement remote procedure calls over the Internet.
A number of efforts are underway to define standard APIs for clouds. While not open, VMwares vCloud API appears promising for IaaS. vCloud supports hybrid clouds, through which VMs can transparently migrate between sites containing virtualized infrastructure.
Another useful PaaS solution is Engine Yard. Engine Yard focuses on applications developed using the Ruby on Rails application environment, and permits hosting within Engine Yards private cloud or within Amazons EC2 (discussed shortly). Ruby on Rails is an open source web framework developed with the Ruby language.
Rackspace Cloud Servers is another IaaS solution which competes with EC2. Rackspace focuses on simplicity, making it very easy to get a VM up and running within their infrastructure. Like Amazon, you scan easily scale your infrastructure over a set of servers that very in size and performance (using either Linux or Windows VMs).
Each of the IaaS solutions operate in a pay-as-you-go model (both examples here rely on the Xen hypervisor). When your servers are running, youre charged an hourly fee. If desired, your compute capacity can scale with demand, making it very simple, and in many cases, very cost efficient.
Its also possible to build a private compute cloud that implements Amazons EC2 interface. Eucalyptus is an open source project that allows you to build private clouds, and also hybrid clouds that interface to Amazon for the public portion.
Mozy is one of the most popular in the consumer space. Rather than focus on generic storage, Mozy provides remote storage with a backup application that automatically copies data into their public cloud for storage. Within their infrastructure, Mozy implements encryption to protect your data.
One of the most well known cloud storage providers is Amazon, with their Simple Storage Service offering (called Amazon S3). Amazon provides an API in a variety of languages that permit programmatic access to their public storage cloud (using a ReST or SOAP API). A unique aspect of their storage is that access occurs through HTTP, such that stored objects can be accessed as HTTP URLs like any other web file (assuming a user is authorized to view the files).
The Nirvanix Storage Delivery Network is another example of a public storage cloud. Nirvanix implements an interesting set of features. In addition to implementing a public storage cloud, Nirvanix also provides a hybrid solution, permitting a fully managed private and public cloud storage solution.
Finally, EMCs Atmos is a deployable cloud storage solution which may be used as private cloud storage, or to develop a public or hybrid cloud storage offering. Atmos was designed for massive scalability on a global scale, while providing cost effective storage for unstructured data.
Representational State Transfer
VMwares vCloud API
Salesfore.com Software as a Service http://www.salesforce.com/saas/
Google App Engine
Engine Yard Platform as a Service
Ruby on Rails Web Application Environment http://rubyonrails.org/
Amazon Elastic Compute Cloud (Infrastructure as a Service)
Rackspace Cloud Server (Infrastructure as a Service)
Eucalyptus Private Cloud Software (Enterprise Edition)
Eucalyptus Open Source Cloud Platform
Mozy Online Backup
Amazon Simple Storage Service
Nirvanix Storage Delivery Network
EMC Atmos Cloud Storage