tailieunhanh - Provenance for the Cloud

Depending on the route, the walk may go through more than one police area. Organisers are normally required to log route details with the operational departments of each separate police force. It may be appropriate to check with the police that your route is considered safe from a crime perspective and take advice about your plans. It is generally the case nowadays that although the police may assist with the development of your event and give advice, they no longer provide a free presence on the day other than their normal beat presence. Any special. | Provenance for the Cloud Kiran-Kumar Muniswamy-Reddy Peter Macko and Margo Seltzer Harvard School of Engineering and Applied Sciences Abstract The cloud is poised to become the next computing environment for both data storage and computation due to its pay-as-you-go and provision-as-you-go models. Cloud storage is already being used to back up desktop user data host shared scientific data store web application data and to serve web pages. Today s cloud stores however are missing an important ingredient provenance. Provenance is metadata that describes the history of an object. We make the case that provenance is crucial for data stored on the cloud and identify the properties of provenance that enable its utility. We then examine current cloud offerings and design and implement three protocols for maintaining data provenance in current cloud stores. The protocols represent different points in the design space and satisfy different subsets of the provenance properties. Our evaluation indicates that the overheads of all three protocols are comparable to each other and reasonable in absolute terms. Thus one can select a protocol based upon the properties it provides without sacrificing performance. While it is feasible to provide provenance as a layer on top of today s cloud offerings we conclude by presenting the case for incorporating provenance as a core cloud feature discussing the issues in doing so. 1 Introduction Data is information and as such has two critical components what it is its contents and where it came from its ancestry . Traditional work in storage and file systems addresses the former storing information and making it available to users. Provenance addresses the latter. Provenance sometimes called lineage is metadata detailing the derivation of an object. If it were possible to fully capture provenance for digital documents and transactions detecting insider trading reproducing research results and identifying the source of system break-ins would .

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