Integration of heterogeneous devices and communication models via the cloud in the constrained internet of things

As the Internet of Things continues to expand in the coming years, the need for services that span multiple IoT application domains will continue to increase in order to realize the efficiency gains promised by the IoT. Today, however, service developers looking to add value on top of existing IoT systems are faced with very heterogeneous devices and systems. These systems implement a wide variety of network connectivity options, protocols (proprietary or standards-based), and communication methods all of which are unknown to a service developer that is new to the IoT. Even within one IoT standard, a device typically has multiple options for communicating with others. In order to alleviate service developers from these concerns, this paper presents a cloud-based platform for integrating heterogeneous constrained IoT devices and communication models into services. Our evaluation shows that the impact of our approach on the operation of constrained devices is minimal while providing a tangible benefit in service integration of low-resource IoT devices. A proof of concept demonstrates the latter by means of a control and management dashboard for constrained devices that was implemented on top of the presented platform. The results of our work enable service developers to more easily implement and deploy services that span a wide variety of IoT application domains

Expedited Data Transfers for Serverless Clouds

Serverless computing has emerged as a popular cloud deployment paradigm. In serverless, the developers implement their application as a set of chained functions that form a workflow in which functions invoke each other. The cloud providers are responsible for automatically scaling the number of instances for each function on demand and forwarding the requests in a workflow to the appropriate function instance. Problematically, today's serverless clouds lack efficient support for cross-function data transfers in a workflow, preventing the efficient execution of data-intensive serverless applications. In production clouds, functions transmit intermediate, i.e., ephemeral, data to other functions either as part of invocation HTTP requests (i.e., inline) or via third-party services, such as AWS S3 storage or AWS ElastiCache in-memory cache. The former approach is restricted to small transfer sizes, while the latter supports arbitrary transfers but suffers from performance and cost overheads. This work introduces Expedited Data Transfers (XDT), an API-preserving high-performance data communication method for serverless that enables direct function-to-function transfers. With XDT, a trusted component of the sender function buffers the payload in its memory and sends a secure reference to the receiver, which is picked by the load balancer and autoscaler based on the current load. Using the reference, the receiver instance pulls the transmitted data directly from the sender's memory. XDT is natively compatible with existing autoscaling infrastructure, preserves function invocation semantics, is secure, and avoids the cost and performance overheads of using an intermediate service for data transfers. We prototype our system in vHive/Knative deployed on a cluster of AWS EC2 nodes, showing that XDT improves latency, bandwidth, and cost over AWS S3 and ElasticCache.Comment: latest versio

From Static and Dynamic Websites to Static Site Generators

Dünaamilised sisuhaldustarkvara paketid, näiteks WordPress, on kasutusel peaaegu pooltel maailma aktiivsetest veebilehtedest. Paljudel neist lehtedest on peamiselt eelloodud sisu – näiteks blogiartiklid, uudised ja isiklikud või ettevõtete veebilehed. Sellise iseloomuga veebilehtede esitamine läbi igakordse dünaamilise genereerimise ei lisa mingit väärtust võrreldes sellega, kui lehed oleksid eelgenereeritud ehk staatilised.\n\rKäesolevas töös on analüüsitud staatiliste ja dünaamiliste veebilehtede põhimõttelisi erinevusi. On leitud, et staatilised lehed omavad sisulisi eeliseid dünaamiliste ees – näiteks turvalisus ja kiirus – kuid dünaamiliste veebilehtede eelised seisnevad peamiselt küpsemate tööriistade olemasolus.\n\rTöös on võrreldud kolme populaarseimat staatilise veebilehe generaatorit – Jekyll’i, Hexo’t ja Hugo’t. On leitud, et Hexo sobib hästi blogimiseks, kuid Jekyll ja Hugo ka universaalsete veebilehtede loomiseks. Hugo’t tasub eelistada suurte veebilehtede puhul tänu selle oluliselt suuremale genereerimiskiirusele, kuid peab arvestama selle keerulisema laiendatavusega. \n\rStaatiliste veebilehtede ökosüsteemi on põgusalt tutvustatud ning toodud välja vahendeid lehtede majutamiseks, graafilisi kasutajaliideseid jmt. On pakutud ideid, mida tasuks staatiliste veebilehtede tööriistades edasi arendada.Dynamic Content Management Systems like WordPress are used on almost half of the world’s active websites. As many of these sites are content-driven, like blogs, news sites, personal, company and organisation websites, rendering them dynamically does not offer any value compared to if they were static. \n\rParadigmatic differences between static and dynamic websites are analysed and the bene-fits of each described. It is found that for static-by-nature websites, static approach has core benefits such as security and end-user performance, as benefits of dynamic platforms come mainly from the more mature toolset.\n\rFeatures and usability of three popular Static Site Generators – Jekyll, Hexo and Hugo are analysed. It is found that Jekyll and Hugo are more suitable for universal websites, as Hexo is oriented for blogging. Hugo should be preferred for a large website, as its site generation speed is significantly faster than Jekyll’s. However, the extensibility of Hugo is more complicated. \n\rAdditional tools in the growing static websites ecosystem are pointed out. Some ways of combining these to create a complete toolset are given and ideas for future development proposed

The Means Structure of Information Resources Processing in Electronic Content Commerce Systems

Some of principal problems of electronic content commerce and functional services of content processing are analyzed in the article. Proposed method gives an opportunity to form resources processing tools for electronic commerce systems so as implement subsystems for content formation, management and support

Map Services Management

About 20 years ago, Google and other companies introduced the tiled maps, and nowadays, it is possible to produce similar work using open data and open source software. Web Map Service and Tile Map Service are a set of open standards to provide ways for users to access and visualize maps by interacting with geospacial data, over the internet. Most of the solutions to provide maps, make use of geospacial databases like PostgreSQL/PostGIS or MBTiles/PMTiles. Dedicated servers follows the standards specified by organizations such as Open Geospatial Consortium. The main goal of this work is to create a centralized and scalable solution that publish basemaps for a predefined set of geographic regions. These basemaps are displayed as part of a desktop or mobile applications with internet access. In order to fulfill this purpose, the best approach is, for each geographic region, to generate a MBTile database using raw data extract of the OpenStreetMap packed by Geofabrik. The raw data are also combined with a second data source, Natural Earth, to complete the map information at smaller scales. The final result goes through a process of cartographic generalization to be able to access only the relevant geospatial data at a given map scale or zoom level. The data are published as vector tiles, using a tile server, and for legacy applications there’s also the possibility to display the basemaps as raster tiles. Another available option is to use PMTiles files, which are similar to MBTiles but cloud optimized and suitable for serverless solutions. In the interest of ensuring good performance and stability, it is possible to keep everything together behind a reverse proxy, using as an example a Nginx server. Taking advantage of HTTP range requests functionality, also available in Nginx, it is possible to consider the serverless option of PMTiles and the standard tile server under the same umbrella. Finally, two points were considered and explored as opportunities for improvement, however not fully implemented. The first is the ability to cache vector/raster tiles requests, and the second is the ability to deploy the solution supported by a Content Delivery Network.Google e outros serviços introduziram o tiled maps há cerca de 20 anos. Atualmente, é possível produzir trabalhos semelhantes usando dados e software de código abertos. Web Map Service e Tile Map Service são um conjunto de protocolos padrão abertos que fornecem aos utilizadores uma forma de acederem e visualizarem mapas interagindo com dados geoespaciais, através da Internet. A maioria das soluções que fornecem mapas fazem uso de bases de dados geoespaciais PostgreSQL/PostGIS ou MBTiles/PMTiles. Os servi dores são dedicados conforme normas padrão especificadas por instituições como a Open Geospatial Consortium. O principal objetivo deste trabalho é criar uma solução centralizada e escalável que publique mapas de base para um conjunto predefinido de regiões geográficas. Estes mapas de base devem ser mostrados numa aplicação desktop ou mobile com acesso à internet. De forma a atingir este propósito, a melhor abordagem é, para cada região geográfica, gerar uma base de dados MBTile, usando extratos de dados em bruto do OpenStreetMap disponibilizados pela Geofabrik. Os dados em bruto são também combinados com uma segunda fonte de dados, o Natural Earth, para completar a informação do mapa nas escalas menores. O resultado final passa por um processo de generalização cartográfica de forma a disponibilizar os dados geoespaciais relevantes para uma determinada escala ou um determinado nível de zoom do mapa. Os dados são publicados como vector tiles, usando um tile server, e para aplicações legacy também existe a possibilidade de disponibilizar os mapas em formato raster. Existe uma outra opção que consiste na utilização de ficheiros PMTile, que são ficheiros similares aos MBTiles mas otimizados para a cloud e disponibilizados num princípio serverless. De forma a garantir um bom desempenho e estabilidade, é possível agregar toda a solução atrás de uma reverse proxy usando por exemplo um servidor Nginx. Tirando partido da funcionalidade HTTP range requests, disponível também no Nginx, torna-se possível servir PMTiles (serverless) e Tile servers sob a mesma infraestrutura. Por fim, mais dois pontos foram considerados e explorados como oportunidades de melhoria, mas não foram totalmente implementados. O primeiro é a capacidade de armazenar em cache pedidos de Tiles vector/raster e o segundo é a capacidade de disponibilizar a solução apoiada num Content Delivery Network

Content Distribution in P2P Systems

The report provides a literature review of the state-of-the-art for content distribution. The report's contributions are of threefold. First, it gives more insight into traditional Content Distribution Networks (CDN), their requirements and open issues. Second, it discusses Peer-to-Peer (P2P) systems as a cheap and scalable alternative for CDN and extracts their design challenges. Finally, it evaluates the existing P2P systems dedicated for content distribution according to the identied requirements and challenges