UNIT 5

LECTURE 3

Inter Cloud

Inter Cloud is a service-oriented architectural framework for cloud federation that supports utility- driven interconnection of clouds.

It is composed of a set of decoupled elements that interact via a market-oriented system to enable trading of cloud assets such as computing power, storage, and execution of applications.

As depicted in above Figure the Inter Cloud model comprises two main elements:

·         Cloud Exchange

·         Cloud Coordinator

    Cloud Exchange: This is the market-making component of the architecture. It offers services that allow providers to find each other in order to directly trade cloud assets, as well as allowing parties to register and run auctions. In the former case, Cloud Exchange acts as a directory service for the federation. In the latter case, it runs the auction. For offering such services to the federation, Cloud Exchange implements a Web service-based interface that allows data centers to join and leave the federation; to publish resources they want to sell; to register their resource requirements so that parties interested in selling providers are able to locate potential buyers for their resources; to query resource offers that match specific requirements; to query requirements that match available resources from a party; to with draw offers and requests from the coordinator; to offer resources in auctions ;to register bids; and to consult the status of a running auction.

Cloud Coordinator: This component manages domain-specific issues related to the federation. This component is present on each party that wants join   the federation. Cloud Coordinator has front-end components (i.e., elements that interact with the federation) as well as back-end components (i.e., components that interact with the associated data center).Front-end components interact with the Cloud Exchange and with other coordinators. The former allows data centers to announce their offers and requirements, where as the latter allows the Coordinator to learn about the current state of the data center to decide whether actions from the federation are required or not. Therefore, wherever the Coordinator detects that extra resources are required by the data center, it triggers the process of discovery of potential providers (by interacting with the cloud federation). Once potential providers are discovered and the preferred one is selected, the Coordinator contacts the remote Coordinator and negotiates. Similarly, when the Coordinator detects that local resources are underutilized, they can publish an offer for resources in the Cloud Exchange or they can look for matches among requirements registered in the Exchange service.

Negotiation between parties follows the Alternate Offers protocol. The value that each Coordinator is willing to pay for a resource, as well as the value for which each Coordinator wants to sell resources, is not defined by the federation; instead, each Coordinator is free to value resources according to utilization and profit estimation (or any other criteria that a federation member wants to consider), and they are also free to reject offers that are not attractive for them. This flexibility of providers in deciding how and when to buy or sell resources, how many of them, when, and for what price is a big motivator for providers to join an Inter Cloud federation. Providers are free to refuse to buy or sell resources if they disagree with the price; similarly, they may opt for using the method that seems more profitable to them (e.g., auction or fixed price).

Moreover, Inter Cloud acts primarily in the operational layer. That means that issues related to security, VM images, and networking are not handled by the framework. Similarly, providers’ obligations and expectations for joining the federation are also not addressed by the framework. Therefore, existing approaches for these layers, or even new solutions for them, can be applied in the Inter Cloud without changes to its architecture.

THIRD PARTY CLOUD SERVICE

One of the key elements of cloud computing is the possibility of composing services that belong to different vendors or integrating them into existing software systems. The service-oriented model, which is the basis of cloud computing, facilitates such an approach and provides the opportunity for developing a new class of services that can be called third-party cloud services.

Besides this general definition, there is no specific feature that characterizes this class of service. Therefore, in this section, we describe some examples of third-party services.

METACDN

MetaCDN provides users with a Content Delivery Network (CDN) service by leveraging and harnessing together heterogeneous storage clouds. It implements a software overlay that coordinates the service offerings of different cloud storage vendors and uses them as distributed elastic storage on which the user content is stored.

The architecture of Meta CDN is shown in Figure. The MetaCDN interface exposes its services through users and applications through the Web; users interact with a portal, while applications take advantage of the programmatic access provided by means of Web services.

The main operations of MetaCDN are the creation of deployments over storage clouds and their management. The portal constitutes a more intuitive interface for users with basic requirements, while the Web service provides access to the full capabilities of MetaCDN and allows for more complex and sophisticated deployment.

In particular, four different deployment options can be selected:

• ·         Coverage and performance-optimized deployment.
• ·         Direct deployment.
• ·         Cost-optimized deployment.
• ·         QoS optimized deployment.

A collection of components coordinate their activities in order to offer the services we described. These constitute the additional value that MetaCDN brings on top of the direct use of storage clouds by the users. Of particular importance are three components:

• ·         MetaCDN Manager
• ·         MetaCDN QoS Monitor
• ·         Load Redirector

The Manager is responsible for ensuring that all the content deployments are meeting the expected QoS. It is supported in this activity by the Monitor, which constantly probes storage providers and monitors data transfers to assess the performance of each provider. Content serving is controlled by the Load Redirector, which is in charge of redirecting user content requests to the most suitable replica given the condition of the systems and the options specified during the deployment.

SPOT CLOUD

Spot Cloud has already been introduced as an example of a virtual market place. By acting as an intermediary for trading compute and storage between consumers and service providers, it provides the two parties with added value. For service consumers, it acts as a market directory where they can browse and compare different IaaS service offerings and select the most appropriate solution for them. For service providers it constitutes an opportunity for advertising their offerings. In addition, it allows users with available computing capacity to easily turn themselves into service providers by deploying the run time environment required by SpotCloud on their infrastructure.

The two previously presented examples give an idea of how different in nature third-party services can be:

·       MetaCDN provides end users with a different service from the simple cloud storage offerings;

·    SpotCloud does not change the type of service that is finally offered to end users, but it enriches it with additional features that result in more effective use of it.

These are just two examples of the market segment that is now developing as a result of the consolidation of cloud computing as an approach to a more intelligent use of IT resources.