PYTHIA

Popularly used to distribute a variety of multimedia content items in today's Internet, HTTP-based web content delivery still suffers from various content delivery failures, including server failures [1], network failures [2] and routing failures [3]. Hindered by the expensive deployment cost, the conventional CDN can not deploy as many edge servers as possible to successfully deliver content items to all users under these delivery failures. In this paper, we propose a joint CDN and peer-assisted web content delivery framework to address the delivery failure problem. Different from conventional peer- assisted approaches for web content delivery, which mainly focus on alleviating the CDN servers' bandwidth load, we study how to use a browser-based peer-assisted scheme, namely WebRTC, to resolve content delivery failures. To this end, we carry out large-scale measurement studies on how users access and view webpages. Our measurement results demonstrate the challenges (e.g., peers stay on a webpage extremely short) that can not be directly solved by conventional P2P strategies, and some important webpage viewing patterns (e.g., predictability of users' webpage viewing time). Due to these unique characteristics, WebRTC peers open up new possibilities for helping the web content delivery, coming with the problem of how to utilize the dynamic resources efficiently. We formulate the peer selection that is the critical strategy in our framework, as an optimization problem, and design a heuristic algorithm based on the mea- surement insights to solve it. Our simulation experiments driven by the traces from Tencent QZone, one of the most popular social service platforms in China, demonstrate the effectiveness of our design: compared with non-peer-assisted strategy and random peer selection strategy, our design significantly improves the successful relay ratio of web content items under network failures, e.g., our design improves the content download ratio up to 60% even when users located in a particular region (e.g., city) where none can connect to the regional CDN server.

Energy-efficient content delivery networks using cluster shutdown

Content Delivery Networks (CDNs) deliver much of the world's web, video, and application content on the Internet today. A key component of a CDN is the mapping system that uses the DNS protocol to route each client's request to a ``proximal'' server that serves the requested content. While traditional mapping systems identify a client using the IP of its name server, we describe our experience in building and rolling-out a novel system called end-user mapping that identifies the client directly by using a prefix of the client's IP address. Using measurements from Akamai's production network during the roll-out, we show that end-user mapping provides significant performance benefits for clients who use public resolvers, including an eight-fold decrease in mapping distance, a two-fold decrease in RTT and content download time, and a 30% improvement in the time-to-first byte. We also quantify the scaling challenges in implementing end-user mapping such as the 8-fold increase in DNS queries. Finally, we show that a CDN with a larger number of deployment locations is likely to benefit more from end-user mapping than a CDN with a smaller number of deployments.

Cloud computing becomes a popular trend in recent years. In the meanwhile, content delivery network has been used for many years to distribute content all over the world. The relation between cloud computing and content delivery network is very interesting. In this paper, we proposed a cloud based content delivery network. This architecture integrates cloud infrastructure and content delivery network system together. It provides a low cost and elastic web serving cloud platform. Besides, it also provides easy way to manage data for web content developers, and accelerate the speed for users to access web sites. This system uses Hadoop Distributed File System as a cloud infrastructure service, and creates many data clusters around the world. Therefore, content providers could place content to closest node from end users. The result shows a high performance and flexible solution to build a personal content delivery network over cloud.

Content delivery networks (CDNs) deliver Web content to end-users from a large distributed platform of Web servers hosted in data centers belonging to thousands of Internet service providers (ISPs) around the world. The bandwidth cost incurred by a CDN is the sum of the amounts it pays each ISP for routing traffic from its servers located in that ISP out to end-users. A large enterprise may also contract with multiple ISPs to provide redundant Internet access for its origin infrastructure using technologies such as multihoming and mirroring, thereby incurring a significant bandwidth cost across multiple ISPs. This paper initiates the formal study of bandwidth cost minimization in the context of a large enterprise or a CDN, a problem area that is both algorithmically rich and practically very important. First, we model different types of contracts that are used in practice by ISPs to charge for bandwidth usage, including average, maximum, and 95th-percentile contracts. Then, we devise an optimal offline algorithm that routes traffic to achieve the minimum bandwidth cost, when the network contracts charge either on a maximum or on an average basis. Next, we devise a deterministic (resp., randomized) online algorithm that achieves cost that is within a factor of 2 (resp., e/(e - 1)) of the optimal offline cost for maximum and average contracts. In addition, we prove that our online algorithms achieve the best possible competitive ratios in both the deterministic and the randomized cases. An interesting theoretical contribution of this work is that we show intriguing connections between the online bandwidth optimization problem and the seemingly-unrelated but well-studied ski rental problem where similar optimal competitive ratios are known to hold. Finally, we consider extensions for contracts with a committed amount of spend (CIRs) and contracts that charge on a 95th-percentile basis

Content delivery networks (CDN) have been widely used to provide reduced delay and packet loss, fault tolerance, and improved scalability for Web content delivery. Additional benefits are provided for video streaming when one designs a streaming media CDN (SM-CDN) for either conventional single description (SD) or multiple description (MD) coding. Specifically, when precise network conditions and topology are known, simulations show that an MD-SM-CDN can provide 20 to 40% reduction in distortion over a conventional SD-SM-CDN, even when the underlying CDN is not designed with MD streaming in mind. This paper examines the performance of an MD-SM-CDN as a function of different network topologies and loss conditions, and compares it with a conventional SD-SM-CDN. This examination provides insight into an MD-SM-CDN's performance when knowledge of network topology and conditions is imprecise or uncertain. Our simulations indicate that an MD-SM-CDN can provide improved performance over a conventional SD-SM-CDN over a wide range of network topologies and loss conditions.

One of the main assets of service-orientation is composition, which consists of developing higher-level services by re-using well-known functionality provided by other services in a low-cost and rapid development process. However, considerable differences on structural, semantic and technical levels along with the growing number of available web services makes their discovery a significant challenging task. Therefore, services compatibility is an essential pre-requisite to service composition. Measuring the similarity of services is an important and valuable task to get useful information about their compatibility. Similarity measure can be considered as an optimisation step before composing services since it enables to reduce the search time by functionally classifying similar services. This paper presents a practical approach to measure the similarity of web services. Both semantic and syntactic descriptions are integrated through specific techniques for computing similarity measures between services. Formal concept analysis (FCA) is then used to classify web services into concept lattices, and therefore generate a hierarchy of classes of similar web services. Service clustering is used to narrow down the search space and to enable rapid semantic matching of a service request against a large size pool of services. Following this step, a composition engine takes as inputs the set of similar services and the specification of the required service, and generates the candidate composition plans that realise the goal. To determine the composition plan, the composition is reduced to a planning problem.

A content distribution network (CDN) is a system to improve the delivery of content to the end users on the Internet, in which popular content may be cached or replicated at a number of servers, placed closer to some client populations. The design of a CDN consists of defining which content should be replicated at each server, the number of servers, where they should be placed in the network, which server a client’s requests should be sent to, and how server responses should be routed to the clients. CDNs were originally designed for traditional web files. However, given the increase in streaming media content on the Internet, the development of efficient CDN design methods that take into account the special characteristics of media objects, is of great interest. These characteristics include sustained high bandwidth requirements and faster response time by multicast delivery. The main goal of this paper is to propose an algorithm for designing a streaming media CDN with the efficient byte hit ratio and fast response time. We propose the segment-based dynamic caching mechanism with the pheromone that is defined a kind of lifetime of each segment. We evaluate this algorithm in simulations using CDNsim.KeywordsCDNsegment based cachingpheromone

The advent of Cyber-Physical Systems (CPS) has brought a revolutionary change coined as a mixture of information, communication, computation, and control. With applications in smart grid, health monitoring, automatic avionics, distributed robotics, etc., CPS is currently an area of attention among the academia and industry. The advancement of mobile communications and embedded technology has made it possible to build large scale CPS consisting of the interconnection of mobile phones. These devices collect information about the surrounding environment at any time anywhere basis through real-time video capture. Video streaming has proven to be a massive industry that is growing rapidly playing an important role in everyday life. Customer-driven approach wanting best experience with quality has to be the core offering of contemporary scenario. Video streaming is categorized into Video-On-Demand Streaming (VoDS) and Live Video Streaming (LVS) showing the current state-of-art opportunities. Many diverse applications of video streaming are military video surveillance using drones, live sports match player face recognition, on-demand video characters recognition, movie summarization like identifying parts of the movie which are viewed many times by different users, movie and series recognition, motion detection, gesture recognition, image segmentation, etc. This paper introduces an approach to develop video analysis on VoD and LVS using cloud-based services and analyzes the impact of Quality of Experience (QoE), cost, and bandwidth on the cloud. To achieve the best user experience for video streaming and video analysis, Content Delivery Network (CDN) offers the best QoE at various analyzed locations using various cloud providers like Amazon Web Services (AWS) CloudFront, Google Cloud CDN, Azure CDN, Akamai CDN, etc.

The efficient delivery of Web content has been identified as a key issue of research for some time. Forward (or reverse) proxies, which are positioned along the request route from the users' browsers to the origin content servers, maintain a cache with copies of content from their origin servers. The strategic placement of proxies across the backbone ISP or the content delivery network can drastically improve the performance of the system (in terms of network bandwidth savings, origin server load, and user-request latency). The ultimate goal of this work is to develop a tool that decides on the position and the number of proxies required in order to achieve given performance improvements (expressed in terms of network bandwidth, origin server load, and user-latency). We believe such a tool will be very helpful to ISPs/CDNs, content providers and end-users, and is thus very much lacking.

The Web contains a lot of information but computers can't do very much with it. We have access to and a need for a lot of information (thanks to pervasive information devices such as mobile phones, PDAs, smart devices, TV, radio...) but we don't have time to find and make associations between information every time we want to. Given the need for quick, intuitive access to information, multimedia presentation is an effective form of communication - different media act as a better means to communicate dependant on the context, and synchronization (organisation of media in space and in time) can express non- verbally relationships between the content (e.g. linear presentation to represent a timeline of events). Appropriately delivering content in the form of synchronized multimedia is a complex task which needs to meet the requirements of the user, device, and actual context. This proves to be too complex to be fulfilled by manually authoring for all possibilities. This has lead to efforts in developing systems for (semi-)automatic multimedia generation. Knowledge representation techniques developed in earlier AI work are being applied to the World Wide Web. Through standards such as RDF and OWL, the so-called "Semantic Web" offers the potential of a large scale distributed knowledge repository built upon the existing Web infrastructure. This makes powerful amounts of knowledge available to Web-based applications as the basis for a new paradigm of Web-oriented services which are intelligent, dynamic, flexible and user-centred. Such services could find the information we need and present it to us in an effective manner. The current situation of Web content discovery and delivery displays significant disorder and inflexibility: natural language is problematically ambiguous and Web content is only adaptive to a limited extent. Using the Semantic Web, intelligent Web clients will be able to deliver the correct information every time by unambiguously understanding the meaning of queries and reasoning on them (through the knowledge available to them on the Web) to come to an answer. Likewise, Web resources will be described with metadata that supports their selection, adaptation and presentation to the needs of the client. Such a paradigm shift in Web-based systems (from content to knowledge-centred) requires a similar paradigm shift in system models, architectures, implementations and operations. This is equally the case for multimedia presentation systems. We propose a framework for a new type of multimedia presentation system in which the multimedia generation process is tightly integrated with the distributed knowledge of the Semantic Web. Unlike previous work in which knowledge is narrowly defined and used by the system, this approach is built with the scale and dynamics of the Web in mind. We name this framework SWeMPs - a Semantic Web-enabled Multimedia Presentation System. The key results of our research are the conceptual model for a multimedia presentation system and the generic rule base which interacts with that model (through querying, reasoning and deriving new knowledge) to realise individual multimedia generation tasks. These form the basis for an implementation of a multimedia presentation system which is fundamentally different from existing multimedia presentation systems in that it operates at the logical or conceptual level rather than the data or syntactic level. This reflects the reality that what users seek is information (knowledge about concepts) and effective communication of that information (respecting the relationships between concepts). It leverages the potential of the Semantic Web as a distributed, large scale, accessible repository of knowledge about the world of the user just as systems today use the Web as a repository of content. The implementation of this proposal serves as a 'proof of concept' and as a basis for the evaluation of the new approach through use cases.

To provide secure content delivery, Transport Layer Security (TLS) has become a de facto standard over a couple of decades. However, TLS has a long history of security weaknesses and drawbacks. Thus, the security of TLS has been enhanced by addressing security problems through continuous version upgrades. Meanwhile, to provide fast content delivery globally, websites (or origin web servers) need to deploy and administer many machines in globally distributed environments. They often delegate the management of machines to web hosting services or content delivery networks (CDNs), where the security configurations of distributed servers may vary spatially depending on the managing entities or locations. Based on these spatial differences in TLS security, we find that the security level of TLS connections (and their web services) can be lowered. After collecting the information of (web) domains that exhibit different TLS versions and cryptographic options depending on clients' locations, we show that it is possible to redirect TLS handshake messages to weak TLS servers, which both the origin server and the client may not be aware of. We investigate 7M domains with these spatial differences of security levels in the wild and conduct the analyses to better understand the root causes of this phenomenon. We also measure redirection delays at various locations in the world to see whether there are noticeable delays in redirections.

With Online Social Networking (OSN) services coming to prominence as a major platform for the popularization of Web content, recent research has focused on using information gleaned from these services to improve the performance of Content Distribution Networks (CDN). In this paper we find that contrary to popular belief, the simple cache replacement policy LRU outperforms methods based on OSN input. To establish this we propose an OSN-assisted caching strategy which we evaluate using a large Twitter dataset and through simulation. Our results show that vanilla LRU mostly outperforms the OSN-aided mechanisms. We study the reasons for this and find that if at any time there is a large enough percentage of highly popular content, which becomes popular within a short enough time span, CDN can do well by just following an LRU principle. While we do not claim generalizability to other workloads, or other caching architectures on the Internet, our results are important as they apply to the common use-case and show that simple algorithms do quite well.

Content Distribution Network (CDN) has been effective in accelerating the access and growth for web content such as web pages and streaming audio and video. However, the relatively static and bulky data CDNs are designed to serve makes them unsuitable to support latency-sensitive interactive streams such as network games or real-time conferencing. In this position paper, we describe the concepts for an Interaction Distribution Network (IDN), which supports small, interactive data streams in a scalable manner.An IDN shares certain concepts similar to a CDN in that end-user clients connect to the closest serving proxies for accessing and updating interaction data packets. However, the key differences lies in the bi-directional nature of the interaction streams, and that the data streams may belong to a certain “interaction group,” within which some additional processing on the data are possible. An IDN may support existing instant messenger (IM) services and Massively Multiplayer Online Games (MMOGs), while enabling new usage scenarios. We discuss the key challenges, potential solutions, and implications of IDNs in this paper.

By increasing popularity of SOC, using Web services in applications has increased too. SOC creates a loosely coupled environment in which the actual execution environment might differ significantly from the one with the presupposed conditions during application design. Therefore, although an appropriate Web service might have been selected, by passing time, the Web service may not be efficient enough or may not be applicable under specific conditions. For service-oriented systems to be flexible and self-adaptive, it is necessary to automatically select and use a similar service instead of the one which causes the above mentioned problems. Finding a similar service means specifying the proper services which fulfill the same requirements as those fulfilled by the problematic service. In most of the previous works, a number of the best services (k) are selected and ordered based on functional similarity. The user must select one of these services based on his/her preferences. One important metric in selecting a similar service is considering QoS properties and user preferences about QoS. Because of the importance of this issue, in the present paper, an architecture is proposed in which, in addition to functional similarity, QoS properties and user preferences are also considered in selecting a similar service.