M.Sc. Tianyin Xu
Position:
Research Assistant
Phone:
+49 551 39-172057
Office:
3.111
Email:
Homepage
I am a full-time research assistant of Computer Networks Group , University of Goettingen . My supervisor is Prof. Dr. Xiaoming Fu .
I received my B.S. and M.E. degrees in Computer Science from Nanjing University , China. My Master's advisor is Prof. Sanglu Lu , Prof. Baoliu Ye, and Prof. Wenzhong Li .
In 2007, I was selected for graduate study exempted from the graduate
school entrance exam at Nanjing University. In 2010, I was awarded a
highly selective fellowship (LiSUM scholarship) from the Chinese
National Commitee for Education for graduate exchanging in Europe, and
studied at University of Goettingen.
My
current research interests are in networking and distributed systems,
in particular, online social networking, multimedia communications,
overlay/peer-to-peer networking, service-oriented computing.
See my always out-of-date Curriculum Vitae (CV) .
Research Projects
Publications
Disclaimer :
These papers are made available as a means to ensure timely dissemination of scholarly and technical work
on a non-commercial basis. Copyright and all rights therein are maintained by the authors or by other copyright holders,
notwithstanding that they have offered their works here electronically. It is understood that all persons copying
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2012
Cost Optimization for Online Social Networks on Geo-Distributed Clouds ,
Lei Jiao , Jun Li , Tianyin Xu and Xiaoming Fu , the 20th IEEE International Conference on Network Protocols (ICNP 2012), Austin, Texas, USA,
November 2012.
Read abstract
Geo-distributed IaaS (Infrastructure-as-a-Service) clouds provide an intriguing platform to deploy Online Social Network (OSN) services. To leverage the potential of clouds, a major task of OSN providers is optimizing the monetary cost spent on cloud resource utilization while providing satisfactory Quality of Service (QoS) to OSN users. We thus study the problem of cost optimization for the dynamic OSN on multiple geo-distributed clouds over consecutive time periods, with its QoS meeting the pre-defined requirement. We model the QoS as well as the cost of an OSN, formulate the problem, and design a solution named cosplay. Our experiments with a large-scale Twitter trace show that, while always ensuring the QoS as required, cosplay can achieve superior one-time cost reduction compared with the state of the art, and can also reduce the accumulative cost significantly when continuously evaluated over 48 months with dynamics comparable to real-world OSNs.
jiao_icnp12.pdf [465.1 kB]
CloudGPS: A Scalable and ISP-Friendly Server Selection Scheme in Cloud Computing Environments ,
Cong Ding , Yang Chen , Tianyin Xu , Xiaoming Fu , IEEE/ACM International Workshop on Quality of Service (IWQoS 2012), Coimbra, Portugal,
IEEE, June 2012.
Read abstract
In order to minimize user perceived latency while
ensuring high data availability, cloud applications desire to select
servers from one of the multiple data centers (i.e., server clusters)
in different geographical locations, which are able to provide desired
services with low latency and low cost. This paper presents
CloudGPS, a new server selection scheme of the cloud computing
environment that achieves high scalability and ISP-friendliness.
CloudGPS proposes a configurable global performance function
that allows Internet service providers (ISPs) and cloud service
providers (CSPs) to leverage the cost in terms of inter-domain
transit traffic and the quality of service in terms of network
latency. CloudGPS bounds the overall burden to be linear with
the number of end users. Moreover, compared with traditional
approaches, CloudGPS significantly reduces network distance
measurement cost (i.e., from O(N) to O(1) for each end user in
an application using N data centers). Furthermore, CloudGPS
achieves ISP-friendliness by significantly decreasing inter-domain
transit traffic.
CloudGPS_IWQoS12.pdf [357.9 kB]
2011
Scaling Microblogging Services with Divergent Traffic Demands ,
Tianyin Xu , Yang Chen , Lei Jiao , Ben Y. Zhao, Pan Hui, Xiaoming Fu , ACM/IFIP/USENIX 12th International Middleware Conference (Middleware 2011), Lisboa, Portugal, Lecture Notes in Computer Science 7049, pages 20-40,
Springer Verlag, December 2011.
Read abstract
Today’s microblogging services such as Twitter have long outgrown their initial designs as SMS-based social networks. Instead, a massive and steadily-growing user population of more than 100 million is using Twitter for everything from capturing the mood of the country to detecting earthquakes and Internet service failures. It is unsurprising that the traditional centralized client-server architecture has not scaled with user demand, leading to server overload and significant loss of availability.
In this paper, we argue that the divergence in usage models of microblogging services can best be addressed using complementary mechanisms, one that provides reliable messages between friends, and another that delivers events from popular celebrities and media outlets to their millions of followers. We present Cuckoo, a new microblogging system that offloads processing and bandwidth costs away from a small centralized server base while ensuring reliable message delivery. We use a 20-day Twitter availability measurement to guide our design, and trace-driven emulation of 30,000 Twitter users to evaluate our Cuckoo prototype. Compared to a centralized approach, Cuckoo achieves 30-50% server bandwidth savings and 50-60% CPU load reduction, all while guaranteeing reliable message delivery.
cuckoo.pdf [2593.3 kB]
Latency-Aware Data Partitioning for Geo-Replicated Online Social Networks ,
Lei Jiao , Tianyin Xu , Jun Li , Xiaoming Fu , ACM/IFIP/USENIX 12th International Middleware Conference (Middleware 2011), Poster session, Lisboa, Portugal,
December 2011.
Read abstract
No abstract is associated with this entry. Please download the two-page poster directly. Thanks.
TAMER.pdf [156.4 kB]
Understanding Graph Sampling Algorithms for Social Network Analysis ,
Tianyi Wang, Yang Chen , Zengbin Zhang, Tianyin Xu , Long Jin, Pan Hui, Beixing Deng, Xing Li, The 3rd ICDCS Workshop on Simplifying Complex Networks for Practitioners (SIMPLEX'11),
Minneapolis, MN, USA, June 2011.
Read abstract
Being able to keep the graph scale small while capturing the properties of the original social graph, graph sampling provides an efficient, yet inexpensive solution for social network analysis. The challenge is how to create a small, but representative sample out of the massive social graph with millions or even billions of nodes. Several sampling algorithms have been proposed in previous studies, but there lacks fair evaluation and comparison among them. In this paper, we analyze the state-ofart graph sampling algorithms and evaluate their performance on some widely recognized graph properties on directed graphs using large-scale social network datasets. We evaluate not only the commonly used node degree distribution, but also clustering coefficient, which quantifies how well connected are the neighbors of a node in a graph. Through the comparison we have found that none of the algorithms is able to obtain satisfied sampling results in both of these properties, and the performance of each algorithm differs much in different kinds of datasets.
simplex11.pdf [167.5 kB]
An Approximate Truthfulness Motivated Spectrum Auction for Dynamic Spectrum Access ,
Qinhui Wang, Baoliu Ye, Tianyin Xu , Sanglu Lu, IEEE Wireless Communications and Networking Conference (WCNC 2011),
Quintana-Roo, Mexico, March 2011.
Read abstract
Secondary Spectrum Auction (SSA) has been proposed as an effective approach to design spectrum sharing mechanism for dynamic spectrum access. However, due to the location-constrained spectrum interference among users, it is a great challenge to provide truthful auction with maximized spectrum utilization. Most previous SSA designs either fail in addressing truthfulness or cause loss on spectrum utilization. In this paper, we focus on providing truthful SSA with maximized spectrum utilization. In order to minimize the computational overhead involved in addressing location-constrained interference, we leverage the truthfulness by introducing approximate truthfulness. Moreover, we define a general spectrum auction model using linear programming. Based on this model, we further propose ETEX, a sealed-bid auction mechanism with approximate truthfulness. Theoretical analysis confirms that ETEX is able to achieve truthfulness in expectation with polynomial complexity. Extensive experimental results show that ETEX outperforms most popular truthful spectrum auctions in terms of social welfare, spectrum utilization and user satisfaction.
ETEX_final.pdf [393.7 kB]
Cuckoo: Scaling Microblogging Services with Divergent Traffic Demands ,
Tianyin Xu , Yang Chen , Lei Jiao , Ben Y. Zhao, Pan Hui, Xiaoming Fu , Technical Report No. IFI-TB-2011-01, Institute of Computer Science, University of Goettingen, Goettingen, Germany, ISSN 1611-1044,
January 2011.
Read abstract
Today's microblogging services such as Twitter have long outgrown their initial designs as SMS-based social networks. Instead, a massive and steadily-growing user population of more than 100 million is using Twitter for everything from capturing the mood of the country to detecting earthquakes and Internet service failures. It is unsurprising then, that the traditional centralized client-server architecture has not scaled with user demand, leading to server overload and significant loss of availability.
In this paper, we argue that the divergence in usage models of microblogging services can best be addressed using complementary mechanisms, one that provides reliable messages between friends, and another that delivers events from popular celebrities and media outlets to their millions of followers. We present Cuckoo, a new microblogging system that offloads processing and bandwidth costs away from a small centralized server base while ensuring reliable message delivery. We use a 20-day Twitter availability measurement to guide our design, and trace-driven emulation of 30,000 Twitter users to evaluate our Cuckoo prototype. Compared to a centralized approach, Cuckoo achieves 30-50% server bandwidth savings and 50-60% CPU load reduction, all while guaranteeing reliable message delivery.
Technical Report.pdf [4259.3 kB]
2010
Twittering by Cuckoo -- Decentralized and Socio-Aware Online Microblogging Services ,
Tianyin Xu , Yang Chen , Xiaoming Fu , Pan Hui, ACM SIGCOMM Computer Communication Review, Volume 40, Issue 4, Pages 473-474,
ACM, October 2010.
Read abstract
Online microblogging services, as exemplified by Twitter, have become immensely popular during the latest years. However, current microblogging systems severely suffer from performance bottlenecks and malicious attacks due to the centralized architecture. Thus, centralized microblogging systems may threaten the scalability, reliability as well as availability of the offered services, not to mention
the high operational and maintenance cost.
This demo presents a decentralized, socio-aware microblogging system named Cuckoo. The key aspects of Cuckoo’s design is to take advantage of the inherent social relations while leveraging peer-to-peer (P2P) techniques in order to provide scalable, reliable microblogging services. The demo will show these aspects of Cuckoo and provide insights on the performance gain that decentralization and socioawareness can bring for microblogging systems.
Cuckoo_sigcomm10.pdf [257.5 kB]
Improving Prediction Accuracy of Matrix Factorization Based Network Coordinate Systems ,
Yang Chen , Peng Sun, Xiaoming Fu , and Tianyin Xu , IEEE ICCCN 2010 Track on Multimedia and Peer-to-Peer Networking (MP2P),
IEEE, August 2010.
Read abstract
Network Coordinate (NC) systems provide a lightweight and useful way for scalable Internet distance prediction while serving as an important component in many Peer-to-Peer applications. Most of the existing NC systems utilize the Euclidean distance model, which is largely impaired by the persistent occurrence of Triangle Inequality Violation (TIV) in the Internet. Recently, matrix factorization (MF) based NC systems, which can completely remove the TIV constraint, provide an alternative approach towards better prediction accuracy. Phoenix, an NC system based on the MF model, well explores the advantage of the MF model and becomes the most accurate NC system so far. However, through experimental study, we find that the prediction accuracy of Phoenix for short links is significantly worse compared with the overall prediction accuracy. Based on the observation, we propose a new NC system, named Pancake, aiming at reducing the high prediction error for short links. By introducing a two-level architecture, Pancake achieves much higher prediction accuracy than other selected existing NC systems. Through extensive experiments, we demonstrate that Pancake reduces the 90th percentile relative error by up to 25.37% from Phoenix. Moreover, Pancake converges very fast and is robust to different dimension values. For further insights, we study the performance of Pancake using a dynamic data set in addition to the widely used aggregate data sets. With varying RTTs over time, Pancake outperforms other NC systems consistently.
Pancake_ICCCN10.pdf [269.1 kB]
APEX: A Personalization Framework to Improve Quality of Experience for DVD-like Functions in P2P VoD Applications ,
Tianyin Xu , Baoliu Ye, Qinhui Wang, Wenzhong Li , Sanglu Lu, Xiaoming Fu , the 18th IEEE International Workshop on Quality of Service (IWQoS 2010), Beijing, China,
IEEE, June 2010.
Read abstract
The requirement for supporting DVD-like functions raises new challenges to the design of P2P VoD systems. The uncertainty of frequent user DVD-like interactivity makes it difficult to ensure user perceived Quality of Experience (QoE) for real-time streaming services over distributed self-organized P2P overlay networks. Most existing solutions are based on the unreasonable assumption that all the users in P2P VoD systems have the same preference. Few attention has been paid to personalization, which accommodates the differences between users. In this paper, we present a video model which characterizes the personalization information for users' contents and preferences. Based on this model, we develop APEX, a practical personalization framework for P2P VoD applications. APEX makes the personalization practical by using a hybrid architecture which leverages the offline pattern mining on the server side and online collaborative filtering on the peer side. Furthermore, APEX helps peers to personalize navigation, prefetching and membership management, aiming at improving QoE for DVD-like functions by reducing the response latency and optimizing content sharing. Both theoretical analysis and comprehensive simulations show that APEX outperforms most existing schemes in terms of accumulated hit ratio, response latency, and searching efficiency.
PDF [392.2 kB]
Towards Decentralized, Socio-Aware Online Microblogging Services and Data Measurement ,
Tianyin Xu , Yang Chen , Jin Zhao , and Xiaoming Fu , In Proc. ACM MobiSys 2010 HotPlanet Workshop,
ACM, June 2010.
Read abstract
Online microblogging services, as exemplified by Twitter and Yammer, have become immensely popular during the latest three years. Twitter, the most successful microblogging service, has attracted more than 41.7 million users as of July 2009 and is still growing fast. However,
current microblogging systems severely suffer from performance bottlenecks and central points of failure due to their centralized architecture. Thus, centralized microblogging systems may threaten the scalability, reliability, as well as availability of the offered services, not to mention the extremely high operational and maintenance cost.
However, it is not trivial to decentralize microblogging services in a peer-to-peer fashion. The challenges first derive from the heterogeneity of the inherent online social network (OSN) features. The non-reciprocation feature of microblogging services also increases the heterogeneity. Moreover, different from traditional approaches used in centralized server based systems, an efficient, robust and scalable approach for data collection and dissemination in such distributed heterogeneous environments is desirable.
In this paper, we present a decentralized, socio-aware microblogging system named Cuckoo. The design takes advantages of the inherent social relationships while leverages P2P techniques towards scalable, reliable microblogging services. Besides, Cuckoo provides a flexible interface for data collection while circumventing unnecessary traffic on the server. We discuss the benefits that our system may bring for both service providers and end users. We also discuss the technical aspects to be considered and report our work in progress.
Cuckoo_Hotplanet10.pdf [223.9 kB]
A Personalization Framework to Improve Quality of Experience for DVD-like Functions in P2P VoD Applications ,
Tianyin Xu , Baoliu Ye, Qinhui Wang, Wenzhong Li , Sanglu Lu, Xiaoming Fu , Technical Report No. IFI-TB-2010-03, Institute of Computer Science, University of Goettingen, Goettingen, Germany,
ISSN 1611-1044, May 2010.
Read abstract
The requirement for supporting DVD-like functions raises new challenges to the design of P2P VoD systems. The
uncertainty of frequent user DVD-like interactivity makes it difficult to ensure user perceived Quality of Experience
(QoE) for real-time streaming services over distributed self-organized P2P overlay networks. Most existing solutions
are based on the unreasonable assumption that all the users in P2P VoD systems have the same preference. Few
attention has been paid to personalization, which accommodates the differences between users. In this paper, we
present a video model which characterizes the personalization information for users’ contents and preferences. Based
on this model, we develop APEX, a practical personalization framework for P2P VoD applications. APEX makes
the personalization practical by using a hybrid architecture which leverages the offline pattern mining on the server
side and online collaborative filtering on the peer side. Furthermore, APEX helps peers to personalize navigation,
prefetching and membership management, aiming at improving QoE for DVD-like functions by reducing response
latency and optimizing content sharing. Both theoretical analysis and comprehensive simulations show that APEX
outperforms most existing schemes in terms of accumulated hit ratio, response latency, and searching efficiency.
PDF [506.9 kB]
