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We study a two-hop cache-aided network, where a layer of relay nodes connects a server and a set of end users, i.e., a combination network. We consider the case where both the relay nodes and the end users have caching capabilities. We provide upper and lower bounds which are applicable to any combination network, noting that previous work had focused on models where the relays do not have caches...
Distributed key-value store-based caching solutions are being increasingly used to accelerate Big Data applications on modern HPC clusters. This has necessitated incorporating fault-tolerance capabilities into high-performance key-value stores such as Memcached that are otherwise volatile in nature. In-memory replication is being used as the primary mechanism to ensure resilient data operations. However,...
Cloud storage services, such as Dropbox, iCloud Drive, Google Drive, and Microsoft OneDrive, have greatly facilitated users’ synchronizing files across heterogeneous devices. Among them, Dropbox-like services are particularly beneficial owing to the delta sync functionality that strives towards greater network-level efficiency. However, when delta sync trades computation overhead for network-traffic...
Deployed in various distributed storage systems, erasure coding has demonstrated its advantages of low storage overhead and high failure tolerance. Typically in an erasure-coded distributed storage system, systematic maximum distance seperable (MDS) codes are chosen since the optimal storage overhead can be achieved and meanwhile data can be read directly without decoding operations. However, data...
Compared to traditional head-mounted displays (HMD) which are mostly for industrial usage, the more compact and affordable HMDs for mass-market have claimed to be an emerging impact in the gaming industry. Such kind of HMDs, which are represented by Oculus Rift, HTC Vive and Playstation VR, have proved to be a more accessible solution for game players to experience VR gaming. However, the popularity...
Many large-scale distributed storage systems deploy erasure coding to protect data from frequent server failures for cost reason. In most of these systems, newly inserted data is first replicated across different storage servers and then migrated to erasure coded. Although this offline encoding manner can improve data access before data is erasure coded for some storage systems, it helps little and...
Adaptive bitrate (ABR) streaming is the de facto solution in online video services to cope with heterogeneous devices and varying network connections. However, this solution is computation intensive, demanding a large number of servers for encoding videos. Moreover, due to the time-varying nature of video generation, intelligent strategies are required in order to determine the right amount of resources...
Distributed storage systems are known to be susceptible to long tails in response time. It has been shown that in modern online applications such as Bing, Facebook, and Amazon, the long tail of latency is of particular concern, with 99.9th percentile response times being orders of magnitude worse than the mean. As erasure codes emerge as a popular technique in distributed storage to achieve high data...
Modern communication and computation systems consist of large networks of unreliable nodes. Yet, it is well known that such systems can provide aggregate reliability via information redundancy, duplicating paths, or replicating computations. While redundancy may increase the load on a system, it can also lead to major performance improvements through the judicious management of additional system resources...
The hybrid architecture of content distribution network (CDN) and peer to peer (P2P) is promising in providing online streaming media services. It's convenient and low in cost to study the design space of hybrid streaming systems via simulation. In this paper, we designed a discrete-event simulator for hybrid CDN-P2P VoD systems. The simulator supports multiple switching strategies, different video...
Although network coding has shown the potential to revolutionize networking and storage, its deployment has faced a number of challenges. Usual proposals involve two approaches. First, deploying a new protocol (e.g., Multipath Coded TCP), or retrofitting another one (e.g., TCP/NC) to deliver benefits to any application in a computer. However, incorporating new protocols to the Internet is a challenging...
HTTP Adaptive Streaming (HAS) is a widely used video streaming technology that suffers from a degradation of user's Quality of Experience (QoE) and network's Quality of Service (QoS) when many HAS players are sharing the same bottleneck link and competing for bandwidth. The two major factors of this degradation are: the large OFF period of HAS, which causes false bandwidth estimations, and the TCP...
To execute cloud computing tasks over a data center hosting hundreds of thousands of server nodes, it is natural to distribute computations across the nodes to take advantage of parallel processing. However, as we allocate more computing resources and further distribute the computations, a large amount of intermediate data must be moved between consecutive computation stages among the nodes, causing...
Road Side Units (RSUs)-based data communication (V2I) is an increasingly popular technique in vehicular networks to alleviate the frequent vehicle-to-vehicle (V2V) communication problem. On-demand broadcasting is a scalable approach for supporting large clients with dynamic demands. However, the performance of the traditional on-demand broadcast can be improved significantly with the incorporation...
The delivery and display of 360-degree videos on Head-Mounted Displays (HMDs) presents many technical challenges. 360-degree videos are ultra high resolution spherical videos, which contain an omnidirectional view of the scene. However only a portion of this scene is displayed on the HMD. Moreover, HMD need to respond in 10 ms to head movements, which prevents the server to send only the displayed...
Multiview applications endow final users with the possibility to freely navigate within 3D scenes with minimum-delay. High-quality rendering of the scene is enabled by transmitting multiple high-quality camera views, which can be used to synthesize additional virtual views to offer a smooth navigation in the scene. When network resources are limited, the set of camera views needs to be properly selected...
We propose a method and algorithm for lossless compression of tabular data – including, for example, machine learning datasets, server logs and genomic datasets. Superior compression ratios are achieved by exploiting dependencies between the fields (or "features") in the dataset. The algorithm compresses the records w.r.t. a probabilistic graphical model – specifically an optimized forest,...
Peer code review locates common coding rule violations and simple logical errors in the early phases of software development, and thus reduces overall cost. However, in GitHub, identifying an appropriate code reviewer for a pull request is a non-trivial task given that reliable information for reviewer identification is often not readily available. In this paper, we propose a code reviewer recommendation...
Internet has witnessed its paramount function transition from host-to-host communication to content dissemination. Named Data Networking (NDN) and Content-Centric Networking (CCN) emerge as a clean slate network architecture to embrace this shift. Pending Interest Table (PIT) in NDN/CCN keeps track of the Interest packets that are received but yet un-responded, which brings NDN/CCN significant features,...
Exception handling is a technique that addresses exceptional conditions in applications, allowing the normal flow of execution to continue in the event of an exception and/or to report on such events. Although exception handling techniques, features and bad coding practices have been discussed both in developer communities and in the literature, there is a marked lack of empirical evidence on how...
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