Simon Duquennoy

The Web of Things: Interconnecting Devices with High Usability and Performance

In this paper, we show that Web protocols and technologies are good candidates to design the Internet of Things. This approach allows anyone to access embedded devices through a Web application, via a standard Web browser. This Web of Things requires to embed Web servers in hardware-constrained devices. We first analyze the traffics embedded Web servers have to handle. Starting from this analysis, we propose a new way to design embedded Web servers, using a dedicated TCP/IP stack and numerous cross-layer off-line pre-calculation (where information are shared between IP, TCP, HTTP and the Web application). We finally present a prototype -- named Smews -- as a proof of concept of our proposals. It has been embedded in tiny devices (smart cards, sensors and other embedded devices), with a requirement of only 200~bytes of RAM and 7~kilo-bytes of code. We show that it is significantly faster than other state of the art solutions. We made Smews source code publically available under an open-source license.

Consistency and scalability in event notification for embedded Web applications

A new way to interact with small devices consists in embedding tiny Web servers, allowing the devices to serve fully-fledged Web applications. When the device needs to keep its users up-to-date of its internal state, the Web application has to use an event publication solution. Several works have recently been conducted in order to evaluate the trade-offs of various Web-based event notification solutions. In this paper, we propose to evaluate the feasibility of event notification in embedded Web applications. We conduct a large set of experiments in order to compare various push and pull based approaches for embedded systems. We show that a push-based approach can be very efficient in most situations, both in terms of client consistency and of scalability.

Serving embedded content via web applications: model, design and experimentation

Embedded systems such as smart cards or sensors are now widespread, but are often closed systems, only accessed via dedicated terminals. A new trend consists in embedding Web servers in small devices, making both access and application development easier. In this paper, we propose a TCP performance model in the context of embedded Web servers, and we introduce a taxonomy of the contents possibly served by Web applications. The main idea of this paper is to adapt the communication stack behavior to application contents properties. We propose a strategies set fitting with each type of content. The model allows to evaluate the benefits of our strategies in terms of time and memory charge. By implementing a real use case on a smart card, we measure the benefits of our proposals and validate our model. Our prototype, called Smews, makes a gap with state of the art solutions both in terms of performance and memory charge.

Massively parallel processing on a chip

MppSoC is a SIMD architecture composed of a grid of processors andmemories connected by a X-Net neighbourhood network and a general purpose global router. MppSoC is an evolution of the famous massively parallel systems proposed at the end of the eighties. We claim that today such a machine may be integrated in a single chip. On one side, new design methodologies such as IP reuse and, on the other side, thepossible high level of integration on a chip let us envisage sucha revival. Some improvements of the system architecture are possible because of the high degree of integration: The mppSoC processing elements sharemost of their design with the control processor, the integrated network allows to exchange data between PEs, but also between thecontrol processor and the PE memories, and even to connect the external devices to the system. This paper presents the mppSoC architecture, a cycle-accurate bit-accurate SystemC simulator of this architecture, and a prototype of implementation on FPGA. A complete tool chain and the execution ofsome applications on the simulator and the FPGA implementation validate the modeling choices and show the effectiveness of this design.

Efficient Web Requests Scheduling Considering Resources Sharing

Requests scheduling in Web servers is a hot research topic. Many works aim at providing optimal algorithms according to various metrics. Most of these works are based on classical scheduling metrics, considering jobs completion times, but ignoring intermediate states. We claim that this choice conduces to the design of algorithm that do not efficiently share the system resources. Indeed, Web servers have some properties that make them different than the system considered in usual scheduling theory. The classical round-robin policy, used in most production Web servers, has intrinsic qualities: it shares equally the system resources and avoids any job starvation. We introduce a novel parameterizable algorithm proposing a compromise between the benefits of the round-robin and the policies that provide the best performances. Then, we discuss the appropriate choice of the parameter depending in the requirements and the context of the Web server.