Computer Cluster

Computer cluster is a set of loosely or tightly connected computers which works together and can be viewed as a single system.

They all are connected together with LAN , each computer working as a node.
Due to availability of high speed networks and low cost microprocessors it became possible to design such a system.Clusters are usually deployed to improve performance and availability over that of a single computer, while typically being much more cost-effective than single computers of comparable speed or availability.
The activities of the computing nodes are planned by "clustering middleware", a software layer that sits atop the nodes and allows the users to treat the cluster as by and large one cohesive computing unit.

Alike from peer to peer approach where computers are connected projects only a distributed approach but this clustering system just project a centralized approach.

Round Robin Algorithm

The Operating system can process a job in many ways , based on time , priority or first come first serve . But instead of all these we can go to another scheduling algorithm known as Round Robin Algorithm.

In this case

• Each process is provided a fix time to execute called quantum.
• Once a process is executed for given time period. Process is preempted and other process executes for given time period.
• Context switching is used to save states of preempted processes.

Scripting Language

A language written in terms of script???
what does it mean??


This is an interpreting language rather than compiling, which executes the code line by line.
Sometimes it is termed as very high level programming language, because each time we are working on high level of abstraction.

These are generally domain specific language.

UNIX Philosophy

The term given by Ken Thompson , became popular to promote a common user to develop the program on its-own.The Unix philosophy emphasizes building short, simple, clear, modular, and extendable code that can be easily maintained and repurposed by developers other than its creators.

Unix is simple. It just takes a genius to understand its simplicity." –
Dennis Ritchie

Web crawler

A Web crawler is a computer program that browses the World Wide Web in a methodical, automated manner or in an orderly fashion.

• Yahoo! Slurp is the name of the Yahoo Search crawler.
• Bingbot is the name of Microsoft's Bing webcrawler. It replaced Msnbot.
• FAST Crawler is a distributed crawler, used by Fast Search & Transfer, and a general description of its architecture is available
• Googlebot  is described in some detail, but the reference is only about an early version of its architecture, which was based in C++ and Python. The crawler was integrated with the indexing process, because text parsing was done for full-text indexing and also for URL extraction. There is a URL server that sends lists of URLs to be fetched by several crawling processes. During parsing, the URLs found were passed to a URL server that checked if the URL have been previously seen. If not, the URL was added to the queue of the URL server.

Open-source crawlers

• Aspseek is a crawler, indexer and a search engine written in C++ and licensed under the GPL
• DataparkSearch is a crawler and search engine released under the GNU General Public License.

Search engine optimization

 

Search engine optimization (SEO) is the process of improving the visibility of a website or a web page in a search engine's "natural," or un-paid ("organic" or "algorithmic"), search results. In general, the earlier (or higher ranked on the search results page), and more frequently a site appears in the search results list, the more visitors it will receive from the search engine's users. SEO may target different kinds of search, including image search, local search, video search, academic search,news search and industry-specific vertical search engines.
As an Internet marketing strategy, SEO considers how search engines work, what people search for, the actual search terms or keywords typed into search engines and which search engines are preferred by their targeted audience. Optimizing a website may involve editing its content and HTML and associated coding to both increase its relevance to specific keywords and to remove barriers to the indexing activities of search engines. Promoting a site to increase the number of backlinks, or inbound links, is another SEO tactic.
The acronym "SEOs" can refer to "search engine optimizers," a term adopted by an industry of consultants who carry out optimization projects on behalf of clients, and by employees who perform SEO services in-house. Search engine optimizers may offer SEO as a stand-alone service or as a part of a broader marketing campaign. Because effective SEO may require changes to the HTML source code of a site and site content, SEO tactics may be incorporated into website development and design. The term "search engine friendly" may be used to describe website designs, menus, content management systems, images, videos, shopping carts, and other elements that have been optimized for the purpose of search engine exposure.
The effectiveness of SEO may be measured by the position of a web site on a Search Engine Results Page (SERP) when searching for a certain keyword, or by web analytics Key Performance Indexes (KPIs).

 

LESS (stylesheet language)

 

LESS is a dynamic stylesheet language designed by Alexis Sellier. It is influenced by Sass and has influenced the newer "SCSS" syntax of Sass, which adapted its CSS-like block formatting syntax.
LESS is open-source. Its first version was written in Ruby, however in the later versions, use of Ruby has been deprecated and replaced by JavaScript. The indented syntax of Less is a nested metalanguage, as valid CSS is valid Less code with the same semantics.
LESS provides the following mechanisms: variables, nesting, mixins, operators and functions.LESS can run on the client-side (Internet Explorer 6+, WebKit, Firefox) and server-side, with Node.js or Rhino (JavaScript engine).

LESS