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July 31, 2015, 1:06 a.m.

Android

Android, read, write, file

Read and write operations to file are standard functionality of any applications that are logging the events, work with files, up to the transfer of data over the network. In this article, we consider methods of recording information in the files, and read from a file recorded line.

Project structure

Esthetic changes to the standard buttons or ListView will not be made in this lesson, since we work with what is hidden from the eyes of the user, namely, to work with files.

The entire structure of the project respectively is at this time only one class: MainActivity

Also, the project contains the following resource files:

  1. activity_main.xml
  2. strings.xml
  3. styles.xml - in the file does not have any changes relating to a project.
July 30, 2015, 7:49 a.m.

Data Transmission Technologies

виртуальный канал, дейтаграммная передача, коммутация каналов, коммутация пакетов, составной канал, элементарный канал

Circuit switching and packet - it's methods for solving the generalized problem of switching data in any network technology. Complex technical solutions of the generalized switching tasks in its entirety consists of the particular problems of data transmission networks.

By the special problems of data networks include:

  • define flows and appropriate routes;
  • fixation route configuration parameters, and tables of network devices;
  • recognition flows and data transfer between one device interface;
  • multiplexing / demultiplexing streams;
  • separation medium.
July 29, 2015, 8:47 a.m.

Fiber Optic Transmission Lines

fiber, волс, монтаж

Basic concepts and definitions

The most responsible operation in the process of construction of fiber-optic, predetermining the quality and range is the installation of optical fibers. Such a combination of fibers and installation cables are produced in the manufacturing process as well as during the construction and operation of cable lines.

Installation is divided into permanent (fiber welding) and temporary (plug connectors). Fiber optic connectors typically are valves designed for adjusting and fixing the fibers to be connected, as well as mechanical protection for the splice.

The main requirements for connectors are:

  • simple structure;
  • small transient loss;
  • resistance to external mechanical and climatic influences;
  • reliability;
  • In addition to the detachable connectors are required constancy of parameters during re-docking.

Insertion loss connection of optical fibers in a cable transmission path, are divided into external and internal.

External referred to the losses associated with the features of the connection method, including the preparation of the ends of optical fibers, and comprising lateral displacement of the core, diversity ends, the slope of the axes, the angle of the fiber end face, the Fresnel reflection.

I nternal losses are associated with the properties of the resulting optical fiber and, for example, variations in core diameter, numerical aperture, the refractive index profile, netsirkulyarnostyu core Concentricity core and cladding.

July 28, 2015, 7:56 a.m.

Fiber Optic Transmission Lines

fiber, волс, ВОК

Classification of fiber optic cables

Fiber-optic cables (FOC) - a cable products, containing a number of optical fibers and the reinforcing member enclosed in a common envelope, on top of which, depending on the operating conditions of the protective cover can be imposed.

Fiber-optic cables are classified by purpose and conditions of use, as shown in the figure below.

Since FOC less durable than electric cables, they must be protected from the harmful effects of the environment and human activities, which include mechanical stress (tension, bending, compression, torsion, shock, vibration); temperature changes; water penetration.

July 27, 2015, 7:32 a.m.

Data Transmission Technologies

Кампусные сети, корпоративная сеть, сеть отдела, сеть предприятия, сеть рабочей группы

Introduction

Corporate Network - a network whose primary purpose is to maintain the operation of a particular enterprise that owns this network. Corporate network users are the only employees of the company.

In contrast to the prodier networks, enterprise networks, in general, do not render services to third parties or users.

Local networks of end-users are included in the corporate network. The names of the structural units of the corporate network reflect not only the territory of coverage, but also the organizational structure of the enterprise. So, we decided to share a corporate network on a network of divisions and working groups, building a network, campus network backbone.

July 27, 2015, 7:21 a.m.

Data Transmission Technologies

Стандартизация, ЛВС, ШПД

Standardization and sources of standards

Universal argument about the benefits of standardization, which is valid for all industries, computer networks is of particular importance. The essence of the network - the connection of various equipment, and therefore there is a problem of compatibility of the most critical one. Without coordination by all producers generally accepted standards for the equipment and protocols progress in the "construction" of networks would be impossible. Therefore, all the development of the computer industry is ultimately reflected in the standards - any new technology only assumes a "legal" status, where its content is fixed in the relevant standard.

July 26, 2015, 2:12 p.m.

Android

Android, Toast

Give customization of all applications under OS Android !!!

With the slogan I want to tell today about customization pop-up message (Toast) in the Android OS. In any application that is designed and developed with great care, the question may arise about the customization of even such an element as a popup message. After the success of the application depends not only on ideas and utility, but also from the sale of the appearance of the parts, even the smallest and seemingly not very important.

Project structure

This lesson is to write an application that will display a customized pop-up message by pressing a button, which will not be subject of customization.

In the Project there are two classes:

  1. MainActivity
  2. MyListAdapter - which is responsible for the transmission of data in the form of a list item

Also, the project contains the following resource files:

  1. activity_main.xml
  2. toast_info.xml - pop-up message marking
  3. toast_border:xml - additional markup for background of pop-up message
  4. ic_info.png - Image Information icon, which will be used in the pop-up message
  5. string.xml - string constants file
July 21, 2015, 1:55 p.m.

Android

Android, ListView, ListAdapter

Customization ListView is common in developing applications for Android OS. ListView (List) allows you to display the same type of information in your application, for example, show the products with prices and features, if you develop applications for online sales. At the same time being in fact a routine operation, however, some questions for novice developers deliver a lot of inconvenience. Some of these inconveniences and questions will be discussed in this article.

Project structure

This lesson is proposed to establish a small list with the flags of countries, called the currencies of these countries, and the abbreviation of the country.

Total is used to create a list of four countries: Russia, South Africa, Singapore, Turkey. Flags of these countries are in the drawable folder. Also there is an xml file to create backgrounds ListViewi flags. For storing names and abbreviations used strings.xml file. Also, a separate xml file to create the ListView layout.

In the Project there are three classes:

  1. MainActivity
  2. MyListAdapter - which is responsible for the transmission of data in the form of a list item
  3. DataFlags - class that is designed to facilitate the transfer of data to the adapter ListView
July 20, 2015, 6:57 a.m.

Data Transmission Technologies

иерархическая звезда, кольцевая топология, топология ЛВС, полносвязная топология, ячеистая топология

Under the topology of the network refers to the configuration of the graph, whose vertices correspond to the end nodes of the network (such as computers) and communications equipment (eg, routers), and the edges of the physical or informational communication between nodes.

Full mesh

Full mesh

This topology requires communication nodes N N (N-1) / 2 duplex physical links. The advantage of this layout is that it connects each node to each. Thus, in the event of a node failure, there is no malfunction of other nodes in the network based on this topology.

But in practice, this type of topology is not applicable, because it is a very expensive option of building a network.

July 20, 2015, 6:38 a.m.

Data Transmission Technologies

network, transmission

Decomposition of the tasks of networking

Network architecture - a view of the network as a system of interrelated elements, each of which is assigned a specific private function.

In addition, each of the network elements solves a common problem. All common task is broken down into a number of small tasks that solve different network elements, ie one single task is decomposed. The interaction between all network elements through a formalized set of rules, called the protocol.

Decomposition of the task

Decomposition - splitting a complex task into several simple.

IT
March 25, 2019, 5:32 p.m.
Ilya The Engineer

Qt - Test 001. Signals and slots

  • Result:5points,
  • Rating points-10
G
March 25, 2019, 8:34 a.m.
GAG

C++ - Test 002. Constants

  • Result:41points,
  • Rating points-8
G
March 25, 2019, 8:25 a.m.
GAG

C++ - Test 001. The first program and data types

  • Result:66points,
  • Rating points-1
Last comments
March 26, 2019, 8:49 a.m.
Евгений Легоцкой

Да Да Да. Я тоже сейчас вспомнил, что проблема -R в том, что права и для файлов и для каталогов устанавливаются. А для веб-серверов нужно, чтобы права на каталоги были 755, а на файлы 64...
March 26, 2019, 8:47 a.m.
Ruslan Polupan

Был не прав....Почитал маны, флаг «выполнения» по-разному действует на файлы и каталоги.Правильно так chmod -R go=rX,u=rwX /path/to/target/dir
March 26, 2019, 8:35 a.m.
Евгений Легоцкой

По моему, только эта директория /path/to/target/dir и получит эти права, а все остальные вложенные остануться с тем, с чем были. UPD: Или я что-то жёстко путаю? ))) Надо переп...
March 26, 2019, 8:18 a.m.
Ruslan Polupan

А если так chmod -R 755 /path/to/target/dir
March 22, 2019, 12:32 p.m.
Евгений Легоцкой

Ну может бибилотеки не те положили? У вас сборка для MinGW, а либы для MSVC.
Now discuss on the forum
March 26, 2019, 12:07 p.m.
Евгений Легоцкой

Пожалуйста, не загружайте сейчас никакие изображения, это сейчас не работает. Вечером исправлю, остались ошибки на сервере после его переезда.
U
March 25, 2019, 12:43 p.m.
Unreal_man

Как сделать чтоб при клике на ячейку(ос андроид) ее сразу можно было редактировать?QGuiApplication::inputMethod()->show(); показывает клавиатуру, а вот что до этого прописать чтоб текст в ...
m
March 24, 2019, 10:36 a.m.
monevich

Отвечу на свой же вопрос, может кому то это пригодится. Да, можно в функции main использовать такую конструкцию. При запуске программы из Qt передаю свой аргумент в параметрах командной строк...
March 22, 2019, 12:29 p.m.
Дмитрий

Да, мьютекс добавил, но в том потоке, где сигнал вызывается.
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