Alternative views abound in the topology of cloud architecture solutions that range from the type of technology to the patterns of federation and distributed services. Six examples of these emerging approaches include:
· A build out cloud versus heterogeneous cloud ecosystem strategies. A build out cloud example like Google seeks a homogenous ecosystem approach that derives a consistency to the service framework. Rightscale and Elastra are examples of multi-cloud management systems that seek to manage provisioning across different physical cloud environments such as AWS, GoGrid and other resource utility cloud sources.
· Actor model versus god model hypervisor resource management perspectives. One mandates a distributed set of hypervisors and contiguous flow of services. The other a monitor of monitors command and control perspective that seeks to connect to a resource pool oriented set of services federated between a number of parties.
· Architectural semantic representation versus appliance container semantic representation standards development. Approaches based on RDF, OWL and other ontology’s both open and proprietary seek to evolve a meta standards definition of the physical architecture configuration. Examples of this are seen in Elastra and Eucalyptus API and Architecture nomenclature standards development. The extensibility of this can move into the software layer as example by Salesforce.com and NetApps meta model ontology’s for software customization for specific users of their SaaS. The core axiom in this approach is to define the architecture as a meta specification that can be provisions as a configuration (this approach has parallels to the concept of disposable software and service provisioning of commodity solutions.) The appliance approach is more a middle out approach that seeks to virtualize and containerize the workload itself, example of this is the OVF standard and vCloud initiative and vApp standard that seeks to create a standard for a virtual appliance. A key challenge in this approach is the extent of how aware the software application is to the virtual container and environment to best optimize the federated elastic qualities of the cloud. Ideally customers want software that can be portable across devices and resources and best use of distributed best sourced storage, compute and network integration resources. Today's n-tier architectures in Java , .Net and LAMP are largely blind to the physical separation of the web, application and database server architecture. The evolution of these as seen in Microsoft Azure Services+Resources cloud approach will see new architecture standards and approaches to federated services in the cloud.
· Stateless service representation versus stateful service representation strategy developments. Examples of stateless management are the thin client services that we see in Facebook, Myspace and other on-demand services that are hosted for wide scale services. The debate over stateful management is less clear in the cloud where the state representation of inflight transactions and long lived multi-actor collaborative services will require forms of composite services that manage the various event states of service users. The recent profile of Coghead, (now part of SAP) used BPM to manage some services in its framework. This edifice is a long suffering area of debate in Service orientation architecture around the level of service granularity and business logic encapsulation. Studying the boundary of federated security; the service API and how the business process orchestration will be provisioned inside a cloud service provider will drive out questions on state management from a business perspective.
· Federated Marketplace versus Integrated Application as a Platform ecosystem approaches. The core concept in this is the idea of IT software applications that are built and pre-configured to run in a on-demand hardware environment. By doing so the selection from a catalogue style interface and automated deployment and provisioning is in minutes rather than weeks and months. The federated marketplace as seen in examples of eTask and to some extent Mechanical Turk by AWS is similar to the concept of reverse auctioning where the platform is a digital market of suppliers and customers which exchange services. The solution is a hosting services platform environment bring together commercial exchange but does not contain any resources itself. largely what can be described as “eBay meets the SI”. The Integrated AasaP is seen in examples of Saleforce.com where the development of software is designed and built to run in the PaaS environment. Much like the famous Apple itunes Appstore , the application is a click and go interface that is available on demand. The power of this approach is to grow an ecology of applications that are like a catalogue of functional solutions for a customer. (A variant of this is the application does not necessarily have to be hosted in the PaaS cloud and just the API is “posted” in the catalogue pointing to the external PaaS.)
· Open Source versus proprietary meta tag browser and operating system architecture standards. An issue inherited from the open source Linux standard, Microsoft Windows and tag standards' not all browsers are made equal in the current competing world of Mozilla Firefox, Google chrome, Apple Safari and Microsoft explorer browser market. Why this is important in the cloud architecture can be seen in the subtle differences in use of cloud hosted application services that support specific browser formats affecting the interoperable reuse of services between open source and proprietary platforms and the choice of form factor browser. It is expected this to continue on in the Google Android platform and Microsoft Azure platforms following the early Apple apps development platform entry as these play out into the mobile market space.
What is clear is that the evolving debate of homogenous versus heterogeneous cloud frameworks; what and where to invest in a cloud platform is still emerging and the interoperability and portability standards and capabilities is far from over in terms of wide scale adoption.
What is at stake and the prize is the integration of hardware, software and business as a utility of use. The exploitation of such technology is abstracted from the point of use to enable freedom of choice and mobility. An aspiring goal of cloud computing is the speed of selection, provisioning and deployment of IT services increased manifold by the ability to define and deploy solutions into the “cloud”.