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VShard — horizontal scaling in Tarantool

Reading time14 min
Views2.5K


Hi, my name is Vladislav, and I am a member of the Tarantool development team. Tarantool is a DBMS and an application server all in one. Today I am going to tell the story of how we implemented horizontal scaling in Tarantool by means of the VShard module.

Some basic knowledge first.

There are two types of scaling: horizontal and vertical. And there are two types of horizontal scaling: replication and sharding. Replication ensures computational scaling whereas sharding is used for data scaling.

Sharding is also subdivided into two types: range-based sharding and hash-based sharding.

Range-based sharding implies that some shard key is computed for each cluster record. The shard keys are projected onto a straight line that is separated into ranges and allocated to different physical nodes.

Hash-based sharding is less complicated: a hash function is calculated for each record in a cluster; records with the same hash function are allocated to the same physical node.

I will focus on horizontal scaling using hash-based sharding.
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Digital Forensics Tips&Tricks: How to Find Active VPN Connection in the Memory Dump

Reading time2 min
Views9K
Sometimes you can meet a case when a cyber-attacker uses VPN to establish a reliable channel between C2 server and infected IT-infrastructure. And, as Threat Intelligence experts say, attackers often use native Windows VPN connection tools and Windows .pbk (phonebook) files. Lets find out how we can detect it using a memory dump.

What is .pbk file and how does it look inside? It's just a text file with a lot of different parameters using when VPN connection is establishing.

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How to vendor a git into another git

Reading time4 min
Views4.1K

Discovering git vendor extension.


Cross-post from my medium blog: https://medium.com/opsops/git-vendor-295db4bcec3a


I would like to introduce the proper way to handle vendoring of git repositories.


What is is ‘vendoring’?


Vendoring is a way to integrate other’s work into your own. It’s the opposite of ‘linking’ against third-party library. Instead of having that library as a dependency, application uses this library as a part of own source code and keep that code ‘inside’ itself.


Normally, vendoring is done by language tooling: bundler, cargo, pip, etc. But sometimes you need to vendor something not covered by any existing toolset, or something multi-language, that it’s impossible to find the ‘core’ language tool for that.


The solution for this situation is vendoring on a git level. You have your own git repository (I call it ‘destination repo’), and you want to incorporate some other repository (I call it ‘source repo’) as a directory into your (destination repo).


The things you expect from a well-designed vendoring system (regardless of Git it is or not):


  • Visibility. You want to know that some code is vendored, means it wasn’t written by committer.
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We're in UltraHD Morty! How to watch any movie in 4K

Reading time3 min
Views14K
You’ve probably heard about Yandex’s DeepHD technology they once used to improve the quality of old Soviet cartoons. Unfortunately, it’s not public yet, and we, regular programmers, don’t have the dedication to write our own solution. But I personally really wanted to watch Rick and Morty on my 2880x1880 Retina display. And I was deeply disappointed, as even 1080p video (the highest available for this series) looks really blurry on a Retina display! Don’t get me wrong, 1080p is often good enough, but Retina is designed in such a way that an animation with its pronounced outlines in 1080p looks awfully blurry, like 480p on a FullHD monitor.

I decided I want to see Rick and Morty in 4K, even though I can’t write neural networks. And, amazingly, I found a solution. You don’t even need to write any code: all you need is around 100GB of free space and a bit of patience. The result is a sharp 4K image that looks better than any interpolation.


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Microsoft Q# Coding Contest – Winter 2019

Reading time3 min
Views1.8K

Microsoft’s Quantum team is excited to announce the Q# Coding Contest – Winter 2019! In this contest you can put your quantum programming skills to the test, solving quantum computing tasks in Q#. Winners will receive a Microsoft Quantum T-shirt!


Quantum computing is a radically different computing paradigm compared to classical computing. Indeed, it is so different that some tasks that are believed to be classically intractable (such as factoring integers or simulating physical systems) can be performed efficiently on a quantum computer. In 2017 Microsoft introduced the Quantum Development Kit which includes the Q# programming language. Q# can be used with Visual Studio, Visual Studio Code or the command line, on Windows, macOS, and Linux.


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How to prevent targeted cyber attacks? 10 best network sandboxes

Reading time10 min
Views3.2K


Targeted attacks are the most dangerous among the multitude of modern cyber threats. They are also known as ATP (an abbreviation which stands for Advanced Persistent Threat). Those are not viruses that can accidentally get into the computer due to user's carelessness. Neither it is an attempt to replace the address of a popular site in order to cheat billing information from credulous users. Targeted cyber attacks are prepared and thought out carefully and pose a particular threat.
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The ever-lasting strife of static vs dynamic typing – TypeScript won’t help

Reading time6 min
Views5K


When my friend and I were of school age and aspiring to become software developers, we daydreamed of designing some cool stuff together – like a game or a mega-useful app.

I chose to learn C++ and C#, he picked JavaScript. We finished school, graduated from our universities, served in the army and started our jobs. We had a pretty busy time in industrial software engineering, with lots of different jobs and positions, and after it all started to wear on us, we recalled where it all had begun.

Having finally got together as mature developers, we decided to work on our own project – a 2D video game. Since my friend’s domain was front-end and I was a full-stack developer, our immediate choice of development platform was an Internet browser. As I was only used to working with TypeScript when designing front-end, we thought, ok, no problem, after all, TS is just JavaScript at scale. Let’s use it and things will go smoothly. If I only knew how wrong I was! When we started discussing the project, we ran into an extensive chasm of misunderstanding between us.
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[SAP] SAPUI5 for dummies: A complete step-by-step exercise

Reading time2 min
Views4.6K

Yesterday I’ve blogged about the content I’m creating for new developers that have arrived at our Techedge office in Lucca.


Teaching is something I started to love, is the natural consequence of the fact that I love to learn and love to share my knowledge. And I think that it’s important that new students or young developers have some curated content to start with, maybe with also some tip&tricks that senior has learned during their journey.


The idea behind this exercise is to cover every topic a SAPUI5 developer should know and understand.


The exercise will be available on my GitHub project openui5-exercise.

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In-Memory Showdown: Redis vs. Tarantool

Reading time13 min
Views5.9K
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In this article, I am going to look at Redis versus Tarantool. At a first glance, they are quite alike — in-memory, NoSQL, key value. But we are going to look deeper. My goal is to find meaningful similarities and differences, I am not going to claim that one is better than the other.

There are three main parts to my story:

  • We’ll find out what is an in-memory database, or IMDB. When and how are they better than disk solutions?
  • Then, we’ll consider their architecture. What about their efficiency, reliability, and scaling?
  • Then, we’ll delve into technical details. Data types, iterators, indexes, transactions, programming languages, replication, and connectors.

Feel free to scroll down to the most interesting part or even the summary comparison table at the very bottom and the article.
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Multiple violations of policies in RMS open letter

Reading time7 min
Views3.9K

Author: Chris Punches (@cmpunches, Silo group). License: "Please feel free to share unmodified".

The following text is an unmodified copy of now removed issue #2250 on rms-open-letter.github.io repository. The text claims multiple violations of different policies, codes of conduct and other documents in creation, content and support of the "Open letter to remove Richard M. Stallman from all leadership positions". The issue has not been addressed.

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Toxic Comments Detection in Russian

Reading time17 min
Views8.2K

Currently, social network sites tend to be one of the major communication platforms in both offline and online space. Freedom of expression of various points of view, including toxic, aggressive, and abusive comments, might have a long-term negative impact on people’s opinions and social cohesion. As a consequence, the ability to automatically identify and moderate toxic content on the Internet to eliminate the negative consequences is one of the necessary tasks for modern society. This paper aims at the automatic detection of toxic comments in the Russian language. As a source of data, we utilized anonymously published Kaggle dataset and additionally validated its annotation quality. To build a classification model, we performed fine-tuning of two versions of Multilingual Universal Sentence Encoder, Bidirectional Encoder Representations from Transformers, and ruBERT. Finetuned ruBERT achieved F1 = 92.20%, demonstrating the best classification score. We made trained models and code samples publicly available to the research community.
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Windows Native Applications and Acronis Active Restore

Reading time9 min
Views1.9K
We continue telling you about our cooperation with Innopolis University guys to develop Active Restore technology. It will allow users to start working as soon as possible after a failure. Today, we will talk about Native Windows applications, including details on their development and launch. Under the cut, you will find some information about our project, and a hands-on guide on developing native apps.

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Vue.js Is Good, But Is It Better Than Angular or React?

Reading time3 min
Views6.3K
Vue.js is a JavaScript library for building web interfaces. Combining with some other tools It also becomes a “framework”. Now, from our last blog, you already know that Vue.js is one of the top JavaScript frameworks and it is replacing Angular and React in many cases. This brings in the topic of this blog ‘Vue.js is good, but is it better than Angular or React?


In case you’ve never heard or used Vue.js before, you are probably thinking: Come on! yet another JavaScript framework! We get it. However, Vue.js is not new in the custom software development domain. It was first released in 2013 and now it has 130549 stars on Github and downloaded a number of times this year.

How to Write a Smart Contract with Python on Ontology? Part 1: the Blockchain & Block API

Reading time5 min
Views3.1K
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This is an official tutorial published earlier on Ontology Medium blog
Excited to publish it for Habr readers. Feel free to ask any related questions and suggest a better format for tutorial materials

Foreword


In this article, we will begin to introduce the smart contract API of Ontology. The Ontology’s smart contract API is divided into 7 modules:


In this article, we will introduce the Blockchain & Block API, which is the most basic part of the Ontology smart contract system. The Blockchain API supports basic blockchain query operations, such as obtaining the current block height, whereas the Block API supports basic block query operations, such as querying the number of transactions for a given block.

Let’s get started!

First, create a new contract in SmartX and then follow the instructions below.

1. How to Use Blockchain API


References to smart contract functions are identical to Python’s references. Developers can introduce the appropriate functions as needed. For example, the following statement introduces GetHeight, the function to get the current block height, and GetHeader, the function to get the block header.
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An Easy Way to Make Money on Bug Bounty

Reading time5 min
Views5.2K

Рисунок 2


Surely you've heard the expression «bug hunting» many times. I dare to assume, you won't mind earning one or two hundred (or even thousand) dollars by finding a potential vulnerability in someone's program. In this article, I'll tell you about a trick that will help analyzing open source projects in order to find such vulnerabilities.
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Saving Routing State to the Disk in a Cross-Platform .NET Core GUI App with ReactiveUI and Avalonia

Reading time17 min
Views8.4K

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User interfaces of modern enterprise applications are quite complex. You, as a developer, often need to implement in-app navigation, validate user input, show or hide screens based on user preferences. For better UX, your app should be capable of saving state to the disk when the app is suspending and of restoring state when the app is resuming.


ReactiveUI provides facilities allowing you to persist application state by serializing the view model tree when the app is shutting down or suspending. Suspension events vary per platform. ReactiveUI uses the Exit event for WPF, ActivityPaused for Xamarin.Android, DidEnterBackground for Xamarin.iOS, OnLaunched for UWP.


In this tutorial we are going to build a sample application which demonstrates the use of the ReactiveUI Suspension feature with Avalonia — a cross-platform .NET Core XAML-based GUI framework. You are expected to be familiar with the MVVM pattern and with reactive extensions before reading this note. Steps described in the tutorial should work if you are using Windows 10 or Ubuntu 18 and have .NET Core SDK installed. Let's get started! Source code of the app described in this tutorial is available on GitHub.

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How to shoot yourself in the foot in C and C++. Haiku OS Cookbook

Reading time20 min
Views3K
The story of how the PVS-Studio static analyzer and the Haiku OS code met goes back to the year 2015. It was an exciting experiment and useful experience for teams of both projects. Why the experiment? At that moment, we didn't have the analyzer for Linux and we wouldn't have it for another year and a half. Anyway, efforts of enthusiasts from our team have been rewarded: we got acquainted with Haiku developers and increased the code quality, widened our error base with rare bugs made by developers and refined the analyzer. Now you can check the Haiku code for errors easily and quickly.
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PHP microservices framework — Swoft 2.0.3 published

Reading time4 min
Views3.9K

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What is Swoft?


Swoft is a PHP microservices coroutine framework based on the Swoole extension. Like Go, Swoft has a built-in coroutine web server and a common coroutine client and is resident in memory, independent of traditional PHP-FPM. There are similar Go language operations, similar to the Spring Cloud framework flexible annotations, powerful global dependency injection container, comprehensive service governance, flexible and powerful AOP, standard PSR specification implementation and so on.


Through three years of accumulation and direction exploration, Swoft has made Swoft the Spring Cloud in the PHP world, which is the best choice for PHP's high-performance framework and microservices management.


Elegant service governance


Swoft officially recommends that developers use service mesh patterns, such as the Istio/Envoy framework, to separate business and service governance, but Swoft also provides a set of microservices components for small and medium-sized businesses to quickly build microservices.

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