Developers Club geek daily blog

Use of JMeter for the organization of a distributed load

2 years, 10 months ago

Author: Roman Denisenko, senior test engineer of DataArt.


Quite often when testing performance there is a task to load too high-performance system capable without problems to digest a huge number of simultaneous requests. Or the situation when the experimental system very sensitively treats a loading source is possible, balancing with the computational capabilities depending on a geographical arrangement of clients.

For generation of such loading of opportunities of one test machine becomes already insufficiently. And then there is a classical question — as it is possible to reproduce similar loading with a minimum of costs and a maximum of result.

Fortunately, the most part of the modern software used for load testing allows to use the additional removed agents necessary for emulation of a distributed load. Within this article I would like to consider the possibility of creation of a load cluster on an example, I think, one of the most widespread programs used by testers — great and awful Apache JMeter'a.

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Opinions: Swift became Open Source

2 years, 10 months ago

This month there was this revolution for developers on platforms of Apple. On December 3 the new version of an object-oriented language from Apple — Swift was published. What is especially surprising, Swift let out with the open license Apache 2.0 license with a Runtime Library Exception. All of you correctly understood, it is a powerful programming language from Apple moreover and open source. That it means to developers, We asked Igor Litvinenko, Senior Mobile Developer in DataArt.

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Development of plug-ins for Atlassian JIRA

2 years, 11 months ago

All of us in IT faced bug tracking systems — with so-called bug trackers, with issue-trackers. One of popular products such — Atlassian JIRA.

Actually, Atlassian JIRA is more, than just bug tracking system. JIRA can be used quite widely — including for project management. It is possible to tell that JIRA is a system for tracking of the status of tasks. Tasks can be different: it is requirements gathering, testing, directly development etc. I saw even attempts to place on JIRA of accountants — and that supposedly we will have an agile-accounts department!

On the official website JIRA it is described as follows:
JIRA is the tracker for teams planning and building great products. Thousands of teams choose JIRA to capture and organize issues, assign work, and follow team activity. At your desk or on the go with the new mobile interface, JIRA helps your team get the job done. Generally, the main idea of JIRA that it allows to plan work.

In this article I will tell about how to develop additions to this program. However, there can be a question — and why to develop additions for JIRA. Therefore let's consider what additions happen.

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Lean UX — trifles for successful projects

2 years, 11 months ago

Author: Anastasia Rezhepp, head of DataArt design studio.

In this article I will a little tell about methodology of Lean of UX design and I will give several technician and the exercises showing how to apply it.

Often we have the following problem: to us the client with a startup comes: it has a certain general idea, and specific he can tell nothing since he does not know precisely what functions he would like to add to a product and what to clean. Our purpose — to help it with it to understand. And with it we can be helped by the UX design Lean method.

That "lean" means

The word "lean" is translated into Russian as "lean", "thin", "fast". If to translate this term more in a special way, then — "economical", "economical", "minimalistic". For example, there is already a term "economical production" — transfer of English "lean production". Economical production means permanent elimination of all types of losses — it is reached, including, the maximum orientation to the consumer. The same is right also for approach of economical (lean) UX design.

Principles of economical UX design

When we follow a method of lean UX design, there are several moments to which it is worth paying attention:
  • We understand target audience and its problems.
  • We create MVP (Minimum Viable Product — minimum viable product).
  • We work with short iterations.
  • We constantly test innovations on users and if something not so, we are quickly rolled away.
  • We work with command: UX designers, designers, developers and testers work together and constantly exchange opinions and tasks.

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Use of the MVVM (Model-View-ViewModel) template in Android

2 years, 11 months ago

Author: Anton Valyukh, Senior Mobile Developer.

In this article we will talk about the theory and practice of use of very convenient template of design of MVVM (Model-View-ViewModel) when developing Android-applications.

MVP — Model-View-Presenter

For a start — there is a little theory. Everything began with the fact that many thought how to adapt the MVC (Model-View-Controller) template for an applications writing with a user interface. And in 2006 in work of "GUI Architectures" of Martine Fowler in detail considered a template which received afterwards the name "MVP" ("Model-View-Presenter").

So, MVP — the design template derivative of MVC developed generally for creation of the user interface. MVP is used for simplification of automatic modular testing and improvement of separation of logic and display.

In this template there are three elements:
  1. View.
  2. Presenter.
  3. Model (model).

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How to count time for testing

2 years, 11 months ago

… Or, in other words, how to count time for testing so that all believed? Actually at us it is normal — two purposes. The first — to consider time so that not to be mistaken and correctly to distribute resources — most likely, first to make it well all the same it will not turn out. The second purpose is more real: to count time for testing so that to prove to someone that you need still people in command, to explain why you are not in time etc. Strangely enough, after time 50 you will make the second, and the first will turn out!

Let's look now how to consider time for testing, on specific examples.

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Use of the AJAX processor of WordPress

2 years, 12 months ago

WordPress, being one of the most popular CMS in the world, it is supplied with detailed documentation, to be exact, even two. In this connection you should not perceive this text as the description of certain "best practices" at all and precisely nobody forces to follow described blindly. Article — just prompt reply to a question "as?!" (the following paragraph) and the detailed description of everything that needs to be known to force WordPress to answer AJAX requests (all other article).


Traditionally AJAX requests require two things: a script on the server (bekend) which will respond to the requests, and a script on the client (frontend) who will make these requests. WordPress allows to delegate functions on the appeal to special URL according to which there is a processor of requests.

So, it works, "WordPress-way", here so:

  1. On a bekenda by means of function admin_url we receive the link on the processor of AJAX requests and we transfer it to a frontend to one of methods. To this link we will make our requests.
  2. On a bekenda Hook with function for processing of a certain action is registered. Let's call this action, for example, of get_posts.
  3. Front-end makes requests to URL-at from point 1, transferring an action name. For example, ?action=get_posts.
    On a bek-enda if on an action Hook is registered, the function set by us is executed.

Here and so it is simple. Now is more detailed.

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Why it is impossible to let programmers on servers or Why devopsa did not die out yet though spoke about it much

3 years ago

Hi, Habr!

Today we have unusual material. We will not publish the tutorial or to consider new frameworks, and we will just pledge the word to the colleague to whom is what to tell.

The opinion of the author can not reflect a position of the company and other colleagues.

Get acquainted — Alexander Yefimov, Configuration manager/DevOps

I have an acquaintance who, being the first-class system administrator, dreams to become a programmer. According to him, wants to create, but not to use not really good software which is already existing …. In something I understand it: "pure" creativity — is unconditional, abruptly. But let's understand as as really happens.

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GDG DevFest Voronezh 2015: the photo and video report from action

3 years ago

Hi, Habr! As we also promised, we post a photo and the video report from last ivent. The Voronezh GDG carry on tradition and the fourth year in a row DevFest carry out to discuss the most important and actual in Google world. This year conference was visited by more than 500 participants that it is almost twice more, than in the past. And as organizers, as usual, DataArt and VGU acted.

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It is clear and just about WEB COMPONENTS and Polymer

3 years ago

Who I am

I am Alexander Kasheverov. By training — the master of radiophysics. By profession — the web developer, I work in the DataArt company since 2011, since 2009 I am fond of IT and web technologies.

About what article, shortly

Let's consider that it web components and polymer. Let's a little reflect on development of a web. Let's look at technical details, examples, support with browsers, testing. Shortly, it is clear, on business. With pictures.


The web constantly develops. Technologies were thought up and implemented, proceeding from the requirements actual at the time of creation. It was impossible to make ten years ago what we implement now, and it is difficult to provide that will be in 10 years.

Business demands creation of large and difficult program web products with rich functionality, beauty, high performance. Such solutions are nontrivial in itself, so also specificity of web technologies is imposed. Often, to reduce complexity of a product, it is separated into a set of simpler parts. Such component approach reduces chaos, improves structure, intelligibility, increases efficiency of team work.

For reduction of a headache it is good if in a context a web:

  • CSS was not crossed.
  • Areas of visibility of JS were not crossed.
  • HTML was clear and readable, any excess elements.

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