The Internet has led to the creation of a digital society, where (almost) everything is connected and is accessible from anywhere. However, despite their widespread adoption, traditional IP networks are complex and very hard to manage. It is both difficult to configure the network according to predefined policies, and to reconfigure it to respond to faults, load, and changes. To make matters even more difficult, current networks are also vertically integrated: the control and data planes are bundled together. Software-defined networking (SDN) is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network. The separation of concerns, introduced between the definition of network policies, their implementation in switching hardware, and the forwarding of traffic, is key to the desired flexibility: by breaking the network control problem into tractable pieces, SDN makes it easier to create and introduce new abstractions in networking, simplifying network management and facilitating network evolution. In this paper, we present a comprehensive survey on SDN. We start by introducing the motivation for SDN, explain its main concepts and how it differs from traditional networking, its roots, and the standardization activities regarding this novel paradigm. Next, we present the key building blocks of an SDN infrastructure using a bottom-up, layered approach. We provide an in-depth analysis of the hardware infrastructure, southbound and northbound application programming interfaces (APIs), network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications. We also look at cross-layer problems such as debugging and troubleshooting. In an effort to anticipate the future evolution of this new paradigm, we discuss the main ongoing research efforts and challenges of SDN. In particular, we address the design of switches and control platforms—with a focus on aspects such as resiliency, scalability, performance, security, and dependability—as well as new opportunities for carrier transport networks and cloud providers. Last but not least, we analyze the position of SDN as a key enabler of a software-defined environment.

https://publications.uni.lu/bitstream/10993/20596/1/survey_on_SDN.pdf

Software-Defined Networking: A Comprehensive Survey

Together with an explosive growth of the mobile applications and emerging of cloud computing concept, mobile cloud computing (MCC) has been introduced to be a potential technology for mobile services. MCC integrates the cloud computing into the mobile environment and overcomes obstacles related to the performance (e.g., battery life, storage, and bandwidth), environment (e.g., heterogeneity, scalability, and availability), and security (e.g., reliability and privacy) discussed in mobile computing. This paper gives a survey of MCC, which helps general readers have an overview of the MCC including the definition, architecture, and applications. The issues, existing solutions, and approaches are presented. In addition, the future research directions of MCC are discussed. Copyright © 2011 John Wiley & Sons, Ltd.

A survey of mobile cloud computing: architecture, applications, and approaches

Matrix Factorization Techniques for Recommender Systems

/pdf/a-break-in-the-clouds-towards-a-cloud-definition-svovsw1r5a.pdf

A Break in the Clouds: Towards a Cloud Definition

Software-Defined Networking (SDN) is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network. The separation of concerns introduced between the definition of network policies, their implementation in switching hardware, and the forwarding of traffic, is key to the desired flexibility: by breaking the network control problem into tractable pieces, SDN makes it easier to create and introduce new abstractions in networking, simplifying network management and facilitating network evolution. In this paper we present a comprehensive survey on SDN. We start by introducing the motivation for SDN, explain its main concepts and how it differs from traditional networking, its roots, and the standardization activities regarding this novel paradigm. Next, we present the key building blocks of an SDN infrastructure using a bottom-up, layered approach. We provide an in-depth analysis of the hardware infrastructure, southbound and northbound APIs, network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications. We also look at cross-layer problems such as debugging and troubleshooting. In an effort to anticipate the future evolution of this new paradigm, we discuss the main ongoing research efforts and challenges of SDN. In particular, we address the design of switches and control platforms -- with a focus on aspects such as resiliency, scalability, performance, security and dependability -- as well as new opportunities for carrier transport networks and cloud providers. Last but not least, we analyze the position of SDN as a key enabler of a software-defined environment.

In this paper we describe modifications to a natural language grocery retrieval system, introduced in our earlier work. We also compare our system against an off-the-shelf retrieval tool, and show that our system is significantly better for top-ranked retrieval results.

/pdf/natural-language-retrieval-of-grocery-products-17zbj8z8f3.pdf

Natural language retrieval of grocery products

In the near future, mobile devices are expected to have a storage capacity comparable to today’s desktop machines. As the amount of infomation grows, conventional search tools become less effective. To meet these challenges, we turn to desktop search. This paper presents Dessy, aDESktop Search directorY system for mobile and desktop computers alike. It allows a user to find files by their content, metadata, and context information, provides an interface for locating files for both users and applications, and allows finding files with just their metadata available. Dessy supports separate synchronization of file metadata and data. Dessy is unique among desktop search software in that it clearly separates extraction, exchange, and querying of search metadata. In particular, metadata extraction may be performed on one device and querying on another, with only search metadata being exchanged between the devices. Dessy emphasizes extensibility: adding new indexed file types, metadata fields, and index storage methods is easy. Finding files is done with virtual directories, which are views into the user’s files, browseable by regular file managers.

/pdf/dessy-towards-flexible-mobile-desktop-search-tduzdniaun.pdf

Dessy: Towards Flexible Mobile Desktop Search.

With the explosive growth of communication technologies, modern mobile phones become more powerful than ever. Unfortunately, the battery lifetime of mobile phones is still limited, and energy awareness is a priority of designing applications on mobile phones. To demonstrate the energy awareness on mobile phones, we propose a new approach for full-text keyword searches to retrieve content matching input keywords. The proposed approach generalizes the two solutions that answer the keyword searches either (i) locally by mobile phones themselves or (ii) remotely by power servers when the keywords are offloaded to such servers. Instead, for low energy, we propose to split the keywords in a search into two subsets, such that one subset is processed by the mobile phone and another by the remote server. Our preliminary experiment results indicate the hybrid approach can save the most energy for the keyword searches than the local and remote approaches. In our example tests, energy of the hybrid approach saves 75% and 47% of energy when compared to local execution and complete offloading approaches, respectively.

/pdf/energy-aware-keyword-search-on-mobile-phones-5aeuq1f7c5.pdf

Energy-aware keyword search on mobile phones

BeTelGeuse is an extensible data collection platform for mobile devices, which also automatically infers higher level context from sensor data. In this article, the authors introduce BeTelGeuse's architecture and current features, and evaluate its impact on mobile phone performance.

/pdf/a-platform-for-gathering-and-processing-situational-data-4cki1fvhem.pdf

a Platform for Gathering and Processing Situational Data

Differential privacy allows quantifying privacy loss resulting from accessing sensitive personal data. Repeated accesses to underlying data incur increasing loss. Releasing data as privacy-preserving synthetic data would avoid this limitation, but would leave open the problem of designing what kind of synthetic data. We propose formulating the problem of private data release through probabilistic modelling. This approach transforms the problem of designing the synthetic data into choosing a model for the data, allowing also including prior knowledge, which improves the quality of the synthetic data. We demonstrate empirically, in an epidemiological study, that statistical discoveries can be reliably reproduced from the synthetic data. We expect the method to have broad use in creating high-quality anonymized data twins of key data sets for research.

Eemil Lagerspetz

Papers

Natural language retrieval of grocery products

Dessy: Towards Flexible Mobile Desktop Search.

Energy-aware keyword search on mobile phones

a Platform for Gathering and Processing Situational Data

Privacy-preserving data sharing via probabilistic modelling