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Caching Failure
In computer programming, negative cache is a cache that also stores "negative" responses, i.e. failures. This means that a program remembers the result indicating a failure even after the cause has been corrected. Usually negative cache is a design choice, but it can also be a software bug. Examples Consider a web browser which attempts to load a page while the network is unavailable. The browser will receive an error code indicating the problem, and may display this error message to the user in place of the requested page. However, it is incorrect for the browser to place the error message in the page cache, as this would lead it to display the error again when the user tries to load the same page - even after the network is back up. The error message must not be cached under the page's URL; until the browser is able to successfully load the page, whenever the user tries to load the page, the browser must make a new attempt. A frustrating aspect of negative caches is that the us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Programming
Computer programming or coding is the composition of sequences of instructions, called computer program, programs, that computers can follow to perform tasks. It involves designing and implementing algorithms, step-by-step specifications of procedures, by writing source code, code in one or more programming languages. Programmers typically use high-level programming languages that are more easily intelligible to humans than machine code, which is directly executed by the central processing unit. Proficient programming usually requires expertise in several different subjects, including knowledge of the Domain (software engineering), application domain, details of programming languages and generic code library (computing), libraries, specialized algorithms, and Logic#Formal logic, formal logic. Auxiliary tasks accompanying and related to programming include Requirements analysis, analyzing requirements, Software testing, testing, debugging (investigating and fixing problems), imple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cache (computing)
In computing, a cache ( ) is a hardware or software component that stores data so that future requests for that data can be served faster; the data stored in a cache might be the result of an earlier computation or a copy of data stored elsewhere. A cache hit occurs when the requested data can be found in a cache, while a cache miss occurs when it cannot. Cache hits are served by reading data from the cache, which is faster than recomputing a result or reading from a slower data store; thus, the more requests that can be served from the cache, the faster the system performs. To be cost-effective, caches must be relatively small. Nevertheless, caches are effective in many areas of computing because typical Application software, computer applications access data with a high degree of locality of reference. Such access patterns exhibit temporal locality, where data is requested that has been recently requested, and spatial locality, where data is requested that is stored near dat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Bug
A software bug is a design defect ( bug) in computer software. A computer program with many or serious bugs may be described as ''buggy''. The effects of a software bug range from minor (such as a misspelled word in the user interface) to severe (such as frequent crashing). In 2002, a study commissioned by the US Department of Commerce's National Institute of Standards and Technology concluded that "software bugs, or errors, are so prevalent and so detrimental that they cost the US economy an estimated $59 billion annually, or about 0.6 percent of the gross domestic product". Since the 1950s, some computer systems have been designed to detect or auto-correct various software errors during operations. History Terminology ''Mistake metamorphism'' (from Greek ''meta'' = "change", ''morph'' = "form") refers to the evolution of a defect in the final stage of software deployment. Transformation of a ''mistake'' committed by an analyst in the early stages of the softw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Web Browser
A web browser, often shortened to browser, is an application for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen. Browsers can also display content stored locally on the user's device. Browsers are used on a range of devices, including desktops, laptops, tablets, smartphones, smartwatches and consoles. As of 2024, the most used browsers worldwide are Google Chrome (~66% market share), Safari (~16%), Edge (~6%), Firefox (~3%), Samsung Internet (~2%), and Opera (~2%). As of 2023, an estimated 5.4 billion people had used a browser. Function The purpose of a web browser is to fetch content and display it on the user's device. This process begins when the user inputs a Uniform Resource Locator (URL), such as ''https://en.wikipedia.org/'', into the browser's address bar. Virtually all URLs on the Web start with either ''http:'' or ''h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uniform Resource Locator
A uniform resource locator (URL), colloquially known as an address on the World Wide Web, Web, is a reference to a web resource, resource that specifies its location on a computer network and a mechanism for retrieving it. A URL is a specific type of Uniform Resource Identifier (URI), although many people use the two terms interchangeably. URLs occur most commonly to reference web pages (Hypertext Transfer Protocol, HTTP/HTTPS) but are also used for file transfer (File Transfer Protocol, FTP), email (mailto), database access (Java Database Connectivity, JDBC), and many other applications. Most web browsers display the URL of a web page above the page in an address bar. A typical URL could have the form http://www.example.com/index.html, which indicates a protocol (http), a hostname (www.example.com), and a file name (index.html). History Uniform Resource Locators were defined in in 1994 by Tim Berners-Lee, the inventor of the World Wide Web, and the URI working group of the In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Troubleshooting
Troubleshooting is a form of problem solving, often applied to repair failed products or processes on a machine or a system. It is a logical, systematic search for the source of a problem in order to solve it, and make the product or process operational again. Troubleshooting is needed to identify the symptoms. Determining the most likely cause is a process of elimination—eliminating potential causes of a problem. Finally, troubleshooting requires confirmation that the solution restores the product or process to its working state. A strategy is an organized set of activities expressing a plausible way of achieving a goal. Strategies should not be viewed as algorithms, inflexibly followed to solutions. Problem solvers behave opportunistically, adjusting activities within a strategy and changing strategies and tactics in response to information and ideas. Diagnostics In general, troubleshooting is the identification or diagnosis of "trouble" in the management flow of a sys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Domain Name System
The Domain Name System (DNS) is a hierarchical and distributed name service that provides a naming system for computers, services, and other resources on the Internet or other Internet Protocol (IP) networks. It associates various information with ''domain names'' (identification (information), identification String (computer science), strings) assigned to each of the associated entities. Most prominently, it translates readily memorized domain names to the numerical IP addresses needed for locating and identifying computer services and devices with the underlying network protocols. The Domain Name System has been an essential component of the functionality of the Internet since 1985. The Domain Name System delegates the responsibility of assigning domain names and mapping those names to Internet resources by designating authoritative name servers for each domain. Network administrators may delegate authority over subdomains of their allocated name space to other name servers. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anti-pattern
An anti-pattern in software engineering, project management, and business processes is a common response to a recurring problem that is usually ineffective and risks being highly counterproductive. The term, coined in 1995 by computer programmer Andrew Koenig (programmer), Andrew Koenig, was inspired by the book ''Design Patterns'' (which highlights a number of design patterns in software development that its authors considered to be highly reliable and effective) and first published in his article in the ''Journal of Object-Oriented Programming''. A further paper in 1996 presented by Michael Ackroyd at the Object World West Conference also documented anti-patterns. It was, however, the 1998 book ''AntiPatterns'' that both popularized the idea and extended its scope beyond the field of software design to include software architecture and project management. Other authors have extended it further since to encompass environmental, organizational, and cultural anti-patterns. Definiti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perl Design Patterns Book
''Perl Design Patterns Book'' is an online textbook about Perl style and design and analysis. The contents are licensed under GNU Free Documentation License. External links Perl Design Patterns(archived) (wiki) Perl Design Patterns Bookin Savannah A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) biome and ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach th ... Books about Perl {{computer-book-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Bugs
A software bug is a design defect ( bug) in computer software. A computer program with many or serious bugs may be described as ''buggy''. The effects of a software bug range from minor (such as a misspelled word in the user interface) to severe (such as frequent crashing). In 2002, a study commissioned by the US Department of Commerce's National Institute of Standards and Technology concluded that "software bugs, or errors, are so prevalent and so detrimental that they cost the US economy an estimated $59 billion annually, or about 0.6 percent of the gross domestic product". Since the 1950s, some computer systems have been designed to detect or auto-correct various software errors during operations. History Terminology ''Mistake metamorphism'' (from Greek ''meta'' = "change", ''morph'' = "form") refers to the evolution of a defect in the final stage of software deployment. Transformation of a ''mistake'' committed by an analyst in the early stages of the softwa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Anomalies
Software consists of computer programs that instruct the execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital computers in the mid-20th century. Early programs were written in the machine language specific to the hardware. The introduction of high-level programming languages in 1958 allowed for more human-readable instructions, making software development easier and more portable across different computer architectures. Software in a programming language is run through a compiler or interpreter to execute on the architecture's hardware. Over time, software has become complex, owing to developments in networking, operating systems, and databases. Software can generally be categorized into two main types: # operating systems, which manage hardware resources and provide services for applications # application software, which performs specific tasks for users The rise of cloud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
