Cloud for Service Oriented Architecture (Cloud4SOA)

The cloud consists of an interoperability framework and platform to facilitate user- centric, semantically enhanced, service-oriented applications design, deployment and distribution (T. Anderson, 2010). “Cloud” is essentially a metaphor for the Internet, and

62 “cloud computing” uses the Internet to access applications, data or services that are stored or running on remote servers (T. Anderson, 2010). Any company that provides its services over the Internet can be called a cloud computing company.

2.9.4.1 Generic Cloud Computing PaaS architecture

There is no single structure to represent cloud computing, for example, there are over 150 different representations on Google (2011). However, review of eighteen architectures that focused on Cloud computing interoperability resulted in the Cloud4SoA Consortium proposing an architecture depicted in Figure 2-13.

Figure 2-13: Generic Cloud computing PaaS architecture (Cloud4SoA consortium, 2011)

The following list introduces these layers (Cloud4SoA consortium):

ƒ Virtual/infrastructure Layer - Infrastructure-as-a-Service (IaaS): This layer is concerned with the provision of physical and virtualized resources. Effectively, a company can outsource its hardware needs to another organisation. The users of IaaS companies rent and access over the Internet items such as off-site server, storage, and networking hardware. This enables them to reduce maintenance costs and wasted office space. Amazon, Red Hat, Microsoft and VMWare are some of the many organisations that offer IaaS (Ludwig, 2011).

ƒ PaaS and Middleware layers: The layers provide the appropriate tools for the

deployment of applications, and they enable the configuration and management of the infrastructure. The user company can adopt a variety of solutions for developing and deploying applications over the Internet, such as virtualized servers and operating systems. Again this has the potential to save the user

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company money on hardware and simplifies collaboration between a widely dispersed workforce. Some of the biggest PaaS providers are Microsoft Azure and Google App Engine (Ludwig, 2011).

ƒ Front-end Layer - Software-as-a-Service (SaaS): The Software-as-a-Service

layer is the one the user company is most likely to use. The portal is the usual means of access. For example, an application located on a remote server that can be accessed over the Internet would be considered as SaaS. Typical examples include Netflix, Cisco’s WebEx and Salesforce’s CRM (Ludwig, 2011). The portal accessing the e-eovernment knowledge base in this thesis could be viewed as a SaaS.

Also included in Figure 2-13 is the suggestion made by Charlton (2009) that a description of Cloud services should include deployment and management, and a semantic layer to provide platform-neutral specifications to overcome issues associated with portability and semantics.

2.9.4.2 Cloud4SOA

Cloud4SOA is a three year European project Seventh Framework Programme (FP7)

initiative funded to the value of €2.74 million (Cloud4SOA, 2010). The project’s

fundamental aims and objectives are to contribute towards Cloud interoperability by embracing the following research and innovation related activities:

ƒ Identify and analyse semantic interoperability problems: A comprehensive

analysis on both IaaS and PaaS layers is to be undertaken, which will seek stakeholder experience, requirements and feedback. The product of this exercise will be the design and construction of a cloud semantic interoperability framework; which in turn will act as a roadmap for creating similar user-oriented platforms.

ƒ Construct reference architecture: It is intended that the most problematic

semantic interoperability issues will be addressed by constructing an open, generic architecture for a semantically interoperable Cloud. The approach will adopt a service-oriented architecture, using lightweight semantics, and user- centric design and development principles.

ƒ Develop a proof of concept platform: The Cloud4SOA Reference Architecture will

be applied in different scenarios and environments across the European economic and business communities.

64 In June 2011, the final version of the Cloud4SOA Reference Architecture was made public (Cloud4SoA consortium, 2011). The purpose of the architecture is to resolve semantic incompatibilities that arise between heterogeneous Cloud computing Platforms. To some extent, it builds on the knowledge derived from the generic Cloud architecture. The reference architecture is shown in Figure 2-14.

Figure 2-14: Abstract view of Cloud4SOA Reference Architecture (Cloud4SoA consortium, 2011)

The three horizontal layers have the following roles (Cloud4SoA consortium, 2011):

ƒ Front-end Layer: The focus of Cloud4SOA is user-centric, and its purpose is to

provide the application developers with easy access to the Cloud4SOA functionalities. It facilitates the seamless interaction to both Cloud-based application developers and Cloud PaaS providers.

ƒ The SOA Layer: The core functionalities offered by the Cloud4SOA system are

implemented in this layer, for example: service discovery, announcement and deployment. The SOA Layer consists of a set of tools that utilises the semantic annotation expressed in the Semantic Layer and the functionalities of the Distributed Repository to provide services, for example: security, discovery, deployment, recommendation and migration services. The SOA Layer also acts as an intermediary to the services offered by the other layers.

ƒ Distributed Repository: In this layer, the technical infrastructure is put in place. Its main components provide mechanisms for search and discovery, and database support.

ƒ The Semantic and Governance layers extend across and impact all the horizontal

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ƒ Semantic Layer: The semantic models and tools offered by Cloud4SOA are to be

found in this layer. Their purpose is to resolve semantic interoperability conflicts that are raised between different PaaS offerings.

ƒ Governance Layer: It is essentially a toolkit for monitoring the lifecycle of

Cloud4SOA services. The Cloud4SOA Governance Layer is responsible for implementing and maintaining EU governance policies in Cloud4SOA platforms.