Saturday, August 29, 2015

Microsoft SQL Server_Buffer management,RAM ,checksum ,Buffer Manager, buffer cache,memory

SQL Server buffers pages in RAM to minimize disc I/O. Any 8 KB page can be buffered in-memory, and the set of all pages currently buffered is called the buffer cache. The amount of memory available to SQL Server decides how many pages will be cached in memory. The buffer cache is managed by the Buffer Manager. Either reading from or writing to any page copies it to the buffer cache. Subsequent reads or writes are redirected to the in-memory copy, rather than the on-disc version. The page is updated on the disc by the Buffer Manager only if the in-memory cache has not been referenced for some time. While writing pages back to disc, asynchronous I/O is used whereby the I/O operation is done in a background thread so that other operations do not have to wait for the I/O operation to complete. Each page is written along with its checksum when it is written. When reading the page back, its checksum is computed again and matched with the stored version to ensure the page has not been damaged or tampered with in the meantime.

Wednesday, August 26, 2015

Linux_Video input infrastructure,kernel-userspace,APIs , DVB API,userspace

Linux currently has two modern kernel-userspace APIs for handing video input devices: V4L2 API for video streams and radio, and DVB API for digital TV reception.
Due to the complexity and diversity of different devices, and due to the large amount of formats and standards handled by those APIs, this infrastructure needs to evolve to better fit other devices. Also, a good userspace device library is the key of the success for having userspace applications to be able to work with all formats supported by those devices.

Sunday, August 23, 2015

Microsoft SQL Server,relational database management system,Microsoft,database server,network ,workloads ,T-SQL,ANSI SQL

Microsoft SQL Server is a relational database management system developed by Microsoft. As a database server, it is a software product whose primary function is to store and retrieve data as requested by other software applications, be it those on the same computer or those running on another computer across a network (including the Internet). There are at least a dozen different editions of Microsoft SQL Server aimed at different audiences and for workloads ranging from small single-machine applications to large Internet-facing applications with many concurrent users. Its primary query languages are T-SQL and ANSI SQL.

Wednesday, August 19, 2015

Linux_User interface,CLI shells ,text-based user interfaces,userland,K Desktop Environment (KDE), GNOME, Cinnamon, Unity, LXDE, Pantheon and Xfce

The user interface, also known as the shell, is either a command-line interface (CLI), a graphical user interface (GUI), or through controls attached to the associated hardware, which is common for embedded systems. For desktop systems, the default mode is usually a graphical user interface, although the CLI is available through terminal emulator windows or on a separate virtual console.

CLI shells are the text-based user interfaces, which use text for both input and output. The dominant shell used in Linux is the GNU Bourne-Again Shell (bash), originally developed for the GNU project. Most low-level Linux components, including various parts of the userland, use the CLI exclusively. The CLI is particularly suited for automation of repetitive or delayed tasks, and provides very simple inter-process communication.

On desktop systems, the most popular user interfaces are the GUI shells, packaged together with extensive desktop environments, such as the K Desktop Environment (KDE), GNOME, Cinnamon, Unity, LXDE, Pantheon and Xfce, though a variety of additional user interfaces exist. Most popular user interfaces are based on the X Window System, often simply called "X". It provides network transparency and permits a graphical application running on one system to be displayed on another where a user may interact with the application; however, certain extensions of the X Window System are not capable of working over the network.Several popular X display servers exist, with the reference implementation, X.Org Server, being the most popular.

Different window managers exist for X11, including tiling, dynamic, stacking and compositing types. Simpler X window managers, such as FVWM, Enlightenment, and Window Maker, provide a minimalist functionality with respect to the desktop environments. A window manager provides a means to control the placement and appearance of individual application windows, and interacts with the X Window System. The desktop environments include window managers as part of their standard installations (Mutter for GNOME, KWin for KDE, Xfwm for xfce) although users may choose to use a different window manager if preferred.

Wayland is a display server protocol intended as a replacement for the aged X11 protocol; as of 2014, Wayland has not received wider adoption. Unlike X11, Wayland does not need an external window manager and compositing manager. Therefore, a Wayland compositor takes the role of the display server, window manager and compositing manager. Weston is the reference implementation of Wayland, while GNOME's Mutter and KDE's KWin are being ported to Wayland as standalone display servers instead of merely compositing window managers. Enlightenment has already been successfully ported to Wayland since version 19.

Sunday, August 16, 2015

Joomla_Extensions,components, modules, plugins, templates, and languages,boxes,login module,Joomla conversions

Joomla extensions extend the functionality of Joomla websites. Five types of extensions may be distinguished: components, modules, plugins, templates, and languages. Each of these extensions handles a specific function.

    Components are the largest and most complex extensions. Most components have two parts: a site part and an administrator part. Every time a Joomla page loads, one component is called to render the main page body. Components produce the major portion of a page because a component is driven by a menu item.

    Plugins are advanced extensions and are, in essence, event handlers. In the execution of any part of Joomla, a module or a component, an event may be triggered. When an event is triggered, plugins that are registered to handle that event execute. For example, a plugin could be used to block user-submitted articles and filter text. The line between plugins and components can sometimes be a little fuzzy. Sometimes large or advanced plugins are called components even though they don't actually render large portions of a page. An SEF URL extension might be created as a component, even though its functionality could be accomplished with just a plugin.

    Templates describe the main design of a Joomla website. While the CMS manages the website content, templates determine the style or look and feel and layout of a site.

    Modules render pages in Joomla. They are linked to Joomla components to display new content or images. Joomla modules look like boxes, such as the search or login module.However, they don?t require html in Joomla to work.

    Languages are very simple extensions that can either be used as a core part or as an extension. Language and font information can also be used for PDF or PSD to Joomla conversions.

Thursday, August 13, 2015

Linux ,POSIX,Unix,computer operating system,open-source software development,automation controls, televisions and video game consoles

Linux is a Unix-like and mostly POSIX-compliant computer operating system assembled under the model of free and open-source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released on 5 October 1991 by Linus Torvalds. The Free Software Foundation uses the name GNU/Linux to describe the operating system, which has led to some controversy.

Linux was originally developed as a free operating system for Intel x86?based personal computers, but has since been ported to more computer hardware platforms than any other operating system.It is the leading operating system on servers and other big iron systems such as mainframe computers and supercomputers, but is used on only around 1.5% of desktop computers.Linux also runs on embedded systems, which are devices whose operating system is typically built into the firmware and is highly tailored to the system; this includes mobile phones, tablet computers, network routers, facility automation controls, televisions and video game consoles. Android, the most widely used operating system for tablets and smartphones, is built on top of the Linux kernel.

The development of Linux is one of the most prominent examples of free and open-source software collaboration. The underlying source code may be used, modified, and distributed?commercially or non-commercially?by anyone under licenses such as the GNU General Public License. Typically, Linux is packaged in a form known as a Linux distribution, for both desktop and server use. Some popular mainstream Linux distributions include Debian, Ubuntu, Linux Mint, Fedora, openSUSE, Arch Linux, and the commercial Red Hat Enterprise Linux and SUSE Linux Enterprise Server. Linux distributions include the Linux kernel, supporting utilities and libraries and usually a large amount of application software to fulfill the distribution's intended use.

Distributions oriented toward desktop use typically include X11, a Wayland implementation or Mir as the windowing system, and an accompanying desktop environment such as GNOME or the KDE Software Compilation. Some of such distributions may include a less resource intensive desktop such as LXDE or Xfce, for use on older or less powerful computers. Distributions intended to run on servers may omit all graphical environments from the standard install, and instead include other software to set up and operate a solution stack such as LAMP. Because Linux is freely redistributable, anyone may create a distribution for any intended use.

Sunday, August 9, 2015

Joomla_Deployment,LAMP stack,control panels,Microsoft Web Platform Installer,PHP ,MySQL

Like many other web applications, Joomla may be run on a LAMP stack.

Many web hosts have control panels for automatic installation of Joomla. On Windows, Joomla can be installed using the Microsoft Web Platform Installer, which automatically detects and installs dependencies, such as PHP or MySQL.

Many web sites provide information on installing and maintaining Joomla sites.

Thursday, August 6, 2015

Joomla,content management system (CMS),open-source,web content, web application framework,page caching, RSS feeds, printable versions of pages, news flashes, blogs, polls, search

Joomla is a free and open-source content management system (CMS) for publishing web content. It is built on a model view controller web application framework that can be used independently of the CMS.

Joomla is written in PHP, uses object-oriented programming (OOP) techniques (since version 1.5) and software design patterns, stores data in a MySQL, MS SQL (since version 2.5), or PostgreSQL (since version 3.0) database, and includes features such as page caching, RSS feeds, printable versions of pages, news flashes, blogs, polls, search, and support for language internationalization.

As of February 2014, Joomla has been downloaded over 50 million times.Over 7,700 free and commercial extensions are available from the official Joomla! Extension Directory, and more are available from other sources.It is estimated to be the second most used content management system on the Internet after WordPress.

Monday, August 3, 2015

Interface, Java, JavaScript, DHTML, Flash, Silverlight,operating system, Ajax, PHP

Through Java, JavaScript, DHTML, Flash, Silverlight and other technologies, application-specific methods such as drawing on the screen, playing audio, and access to the keyboard and mouse are all possible. Many services have worked to combine all of these into a more familiar interface that adopts the appearance of an operating system. General purpose techniques such as drag and drop are also supported by these technologies. Web developers often use client-side scripting to add functionality, especially to create an interactive experience that does not require page reloading. Recently, technologies have been developed to coordinate client-side scripting with server-side technologies such as PHP. Ajax, a web development technique using a combination of various technologies, is an example of technology which creates a more interactive experience.