Agile software development
Agile software development is an approach to software development under which requirements and solutions evolve through the collaborative effort of self-organizing and cross-functional teams and their customer/end user. It advocates adaptive planning, evolutionary development, early delivery, continual improvement, it encourages rapid and flexible response to change; the term agile was popularized, by the Manifesto for Agile Software Development. The values and principles expoused in this manifesto were derived from and underpin a broad range of software development frameworks, including Scrum and Kanban. There is significant anecdotal evidence that adopting agile practices and values improves the agility of software professionals and organizations. Iterative and incremental development methods can be traced back as early as 1957, with evolutionary project management and adaptive software development emerging in the early 1970s. During the 1990s, a number of lightweight software development methods evolved in reaction to the prevailing heavyweight methods that critics described as overly regulated and micro-managed.
These included: rapid application development, from 1991. Although these all originated before the publication of the Agile Manifesto, they are now collectively referred to as agile software development methods. At the same time, similar changes were underway in aerospace. In 2001, seventeen software developers met at a resort in Snowbird, Utah to discuss these lightweight development methods, including among others Kent Beck, Ward Cunningham, Dave Thomas, Jeff Sutherland, Ken Schwaber, Jim Highsmith, Alistair Cockburn, Robert C. Martin. Together they published the Manifesto for Agile Software Development. In 2005, a group headed by Cockburn and Highsmith wrote an addendum of project management principles, the PM Declaration of Interdependence, to guide software project management according to agile software development methods. In 2009, a group working with Martin wrote an extension of software development principles, the Software Craftsmanship Manifesto, to guide agile software development according to professional conduct and mastery.
In 2011, the Agile Alliance created the Guide to Agile Practices, an evolving open-source compendium of the working definitions of agile practices and elements, along with interpretations and experience guidelines from the worldwide community of agile practitioners. Based on their combined experience of developing software and helping others do that, the seventeen signatories to the manifesto proclaimed that they value: Individuals and Interactions over processes and tools Working Software over comprehensive documentation Customer Collaboration over contract negotiation Responding to Change over following a plan That is to say, the items on the left are valued more than the items on the right; as Scott Ambler elucidated: Tools and processes are important, but it is more important to have competent people working together effectively. Good documentation is useful in helping people to understand how the software is built and how to use it, but the main point of development is to create software, not documentation.
A contract is important but is no substitute for working with customers to discover what they need. A project plan is important, but it must not be too rigid to accommodate changes in technology or the environment, stakeholders' priorities, people's understanding of the problem and its solution; some of the authors formed the Agile Alliance, a non-profit organization that promotes software development according to the manifesto's values and principles. Introducing the manifesto on behalf of the Agile Alliance, Jim Highsmith said, The Agile movement is not anti-methodology, in fact many of us want to restore credibility to the word methodology. We want to restore a balance. We embrace modeling, but not in order to file some diagram in a dusty corporate repository. We embrace documentation, but not hundreds of pages of rarely-used tomes. We recognize the limits of planning in a turbulent environment; those who would brand proponents of XP or SCRUM or any of the other Agile Methodologies as "hackers" are ignorant of both the methodologies and the original definition of the term hacker.
The Manifesto for Agile Software Development is based on twelve principles: Customer satisfaction by early and continuous delivery of valuable software. Welcome changing requirements in late development. Deliver working software Close, daily cooperation between business people and developers Projects are built around motivated individuals, who should be trusted Face-to-face conversation is the best form of communication Working software is the primary measure of progress Sustainable development, able to maintain a constant pace Continuous attention to technical excellence and good design Simplicity—the art of maximizing the amount of work not done—is essential Best architectures and designs emerge from self-organizing teams Regularly, the team reflects on how to become more effective, adjusts accordingly Most agile development methods break product development work into small increments that minimize the amount of up-front planning and design. Iterations, or sprints, are short time frames that last from one to four weeks.
Each iteration involves a cross-functional team working in all functions: pl
Nokia Bell Labs is an industrial research and scientific development company owned by Finnish company Nokia. Its headquarters are located in New Jersey. Other laboratories are located around the world. Bell Labs has its origins in the complex past of the Bell System. In the late 19th century, the laboratory began as the Western Electric Engineering Department and was located at 463 West Street in New York City. In 1925, after years of conducting research and development under Western Electric, the Engineering Department was reformed into Bell Telephone Laboratories and under the shared ownership of American Telephone & Telegraph Company and Western Electric. Researchers working at Bell Labs are credited with the development of radio astronomy, the transistor, the laser, the photovoltaic cell, the charge-coupled device, information theory, the Unix operating system, the programming languages C, C++, S. Nine Nobel Prizes have been awarded for work completed at Bell Laboratories. In 1880, when the French government awarded Alexander Graham Bell the Volta Prize of 50,000 francs (approximately US$10,000 at that time for the invention of the telephone, he used the award to fund the Volta Laboratory in Washington, D.
C. in collaboration with Sumner Tainter and Bell's cousin Chichester Bell. The laboratory was variously known as the Volta Bureau, the Bell Carriage House, the Bell Laboratory and the Volta Laboratory, it focused on the analysis and transmission of sound. Bell used his considerable profits from the laboratory for further research and education to permit the " diffusion of knowledge relating to the deaf": resulting in the founding of the Volta Bureau, located at Bell's father's house at 1527 35th Street N. W. in Washington, D. C, its carriage house became their headquarters in 1889. In 1893, Bell constructed a new building close by at 1537 35th Street N. W. to house the lab. This building was declared a National Historic Landmark in 1972. After the invention of the telephone, Bell maintained a distant role with the Bell System as a whole, but continued to pursue his own personal research interests; the Bell Patent Association was formed by Alexander Graham Bell, Thomas Sanders, Gardiner Hubbard when filing the first patents for the telephone in 1876.
Bell Telephone Company, the first telephone company, was formed a year later. It became a part of the American Bell Telephone Company. American Telephone & Telegraph Company and its own subsidiary company, took control of American Bell and the Bell System by 1889. American Bell held a controlling interest in Western Electric whereas AT&T was doing research into the service providers. In 1884, the American Bell Telephone Company created the Mechanical Department from the Electrical and Patent Department formed a year earlier. In 1896, Western Electric bought property at 463 West Street to station their manufacturers and engineers, supplying AT&T with their product; this included everything from telephones, telephone exchange switches, transmission equipment. In 1925, Bell Laboratories was developed to better consolidate the research activities of the Bell System. Ownership was evenly split between Western Electric and AT&T. Throughout the next decade the AT&T Research and Development branch moved into West Street.
Bell Labs carried out consulting work for the Bell Telephone Company, U. S. government work, a few workers were assigned to basic research. The first president of research at Bell Labs was Frank B. Jewett who stayed there until 1940. By the early 1940s, Bell Labs engineers and scientists had begun to move to other locations away from the congestion and environmental distractions of New York City, in 1967 Bell Laboratories headquarters was relocated to Murray Hill, New Jersey. Among the Bell Laboratories locations in New Jersey were Holmdel, Crawford Hill, the Deal Test Site, Lincroft, Long Branch, Neptune, Piscataway, Red Bank and Whippany. Of these, Murray Hill and Crawford Hill remain in existence; the largest grouping of people in the company was in Illinois, at Naperville-Lisle, in the Chicago area, which had the largest concentration of employees prior to 2001. There were groups of employees in Indianapolis, Indiana. Since 2001, many of the former locations closed; the Holmdel site, a 1.9 million square foot structure set on 473 acres, was closed in 2007.
The mirrored-glass building was designed by Eero Saarinen. In August 2013, Somerset Development bought the building, intending to redevelop it into a mixed commercial and residential project. A 2012 article expressed doubt on the success of the newly named Bell Works site however several large tenants had announced plans to move in through 2016 and 2017 Bell Laboratories was, is, regarded by many as the premier research facility of its type, developing a wide range of revolutionary technologies, including radio astronomy, the transistor, the laser, information theory, the operating system Unix, the programming languages C and C++, solar cells, the CCD, floating-gate MOSFET, a whole host of optical and wired communications
International Standard Serial Number
An International Standard Serial Number is an eight-digit serial number used to uniquely identify a serial publication, such as a magazine. The ISSN is helpful in distinguishing between serials with the same title. ISSN are used in ordering, interlibrary loans, other practices in connection with serial literature; the ISSN system was first drafted as an International Organization for Standardization international standard in 1971 and published as ISO 3297 in 1975. ISO subcommittee TC 46/SC 9 is responsible for maintaining the standard; when a serial with the same content is published in more than one media type, a different ISSN is assigned to each media type. For example, many serials are published both in electronic media; the ISSN system refers to these types as electronic ISSN, respectively. Conversely, as defined in ISO 3297:2007, every serial in the ISSN system is assigned a linking ISSN the same as the ISSN assigned to the serial in its first published medium, which links together all ISSNs assigned to the serial in every medium.
The format of the ISSN is an eight digit code, divided by a hyphen into two four-digit numbers. As an integer number, it can be represented by the first seven digits; the last code digit, which may be 0-9 or an X, is a check digit. Formally, the general form of the ISSN code can be expressed as follows: NNNN-NNNC where N is in the set, a digit character, C is in; the ISSN of the journal Hearing Research, for example, is 0378-5955, where the final 5 is the check digit, C=5. To calculate the check digit, the following algorithm may be used: Calculate the sum of the first seven digits of the ISSN multiplied by its position in the number, counting from the right—that is, 8, 7, 6, 5, 4, 3, 2, respectively: 0 ⋅ 8 + 3 ⋅ 7 + 7 ⋅ 6 + 8 ⋅ 5 + 5 ⋅ 4 + 9 ⋅ 3 + 5 ⋅ 2 = 0 + 21 + 42 + 40 + 20 + 27 + 10 = 160 The modulus 11 of this sum is calculated. For calculations, an upper case X in the check digit position indicates a check digit of 10. To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by its position in the number, counting from the right.
The modulus 11 of the sum must be 0. There is an online ISSN checker. ISSN codes are assigned by a network of ISSN National Centres located at national libraries and coordinated by the ISSN International Centre based in Paris; the International Centre is an intergovernmental organization created in 1974 through an agreement between UNESCO and the French government. The International Centre maintains a database of all ISSNs assigned worldwide, the ISDS Register otherwise known as the ISSN Register. At the end of 2016, the ISSN Register contained records for 1,943,572 items. ISSN and ISBN codes are similar in concept. An ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an anonymous identifier associated with a serial title, containing no information as to the publisher or its location. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change. Since the ISSN applies to an entire serial a new identifier, the Serial Item and Contribution Identifier, was built on top of it to allow references to specific volumes, articles, or other identifiable components.
Separate ISSNs are needed for serials in different media. Thus, the print and electronic media versions of a serial need separate ISSNs. A CD-ROM version and a web version of a serial require different ISSNs since two different media are involved. However, the same ISSN can be used for different file formats of the same online serial; this "media-oriented identification" of serials made sense in the 1970s. In the 1990s and onward, with personal computers, better screens, the Web, it makes sense to consider only content, independent of media; this "content-oriented identification" of serials was a repressed demand during a decade, but no ISSN update or initiative occurred. A natural extension for ISSN, the unique-identification of the articles in the serials, was the main demand application. An alternative serials' contents model arrived with the indecs Content Model and its application, the digital object identifier, as ISSN-independent initiative, consolidated in the 2000s. Only in 2007, ISSN-L was defined in the
Computer programming is the process of designing and building an executable computer program for accomplishing a specific computing task. Programming involves tasks such as: analysis, generating algorithms, profiling algorithms' accuracy and resource consumption, the implementation of algorithms in a chosen programming language; the source code of a program is written in one or more languages that are intelligible to programmers, rather than machine code, directly executed by the central processing unit. The purpose of programming is to find a sequence of instructions that will automate the performance of a task on a computer for solving a given problem; the process of programming thus requires expertise in several different subjects, including knowledge of the application domain, specialized algorithms, formal logic. Tasks accompanying and related to programming include: testing, source code maintenance, implementation of build systems, management of derived artifacts, such as the machine code of computer programs.
These might be considered part of the programming process, but the term software development is used for this larger process with the term programming, implementation, or coding reserved for the actual writing of code. Software engineering combines engineering techniques with software development practices. Reverse engineering is the opposite process. A hacker is any skilled computer expert that uses their technical knowledge to overcome a problem, but it can mean a security hacker in common language. Programmable devices have existed at least as far back as 1206 AD, when the automata of Al-Jazari were programmable, via pegs and cams, to play various rhythms and drum patterns. However, the first computer program is dated to 1843, when mathematician Ada Lovelace published an algorithm to calculate a sequence of Bernoulli numbers, intended to be carried out by Charles Babbage's Analytical Engine. Women would continue to dominate the field of computer programming until the mid 1960s. In the 1880s Herman Hollerith invented the concept of storing data in machine-readable form.
A control panel added to his 1906 Type I Tabulator allowed it to be programmed for different jobs, by the late 1940s, unit record equipment such as the IBM 602 and IBM 604, were programmed by control panels in a similar way. However, with the concept of the stored-program computers introduced in 1949, both programs and data were stored and manipulated in the same way in computer memory. Machine code was the language of early programs, written in the instruction set of the particular machine in binary notation. Assembly languages were soon developed that let the programmer specify instruction in a text format, with abbreviations for each operation code and meaningful names for specifying addresses. However, because an assembly language is little more than a different notation for a machine language, any two machines with different instruction sets have different assembly languages. Kathleen Booth created one of the first Assembly languages in 1950 for various computers at Birkbeck College. High-level languages allow the programmer to write programs in terms that are syntactically richer, more capable of abstracting the code, making it targetable to varying machine instruction sets via compilation declarations and heuristics.
The first compiler for a programming language was developed by Grace Hopper. When Hopper went to work on UNIVAC in 1949, she brought the idea of using compilers with her. Compilers harness the power of computers to make programming easier by allowing programmers to specify calculations by entering a formula using infix notation for example. FORTRAN, the first used high-level language to have a functional implementation which permitted the abstraction of reusable blocks of code, came out in 1957. In 1951 Frances E. Holberton developed the first sort-merge generator which ran on the UNIVAC I. Another woman working at UNIVAC, Adele Mildred Koss, developed a program, a precursor to report generators. In USSR, Kateryna Yushchenko developed the Address programming language for the MESM in 1955; the idea for the creation of COBOL started in 1959 when Mary K. Hawes, who worked for Burroughs Corporation, set up a meeting to discuss creating a common business language, she invited six people, including Grace Hopper.
Hopper was involved in developing COBOL as a business language and creating "self-documenting" programming. Hopper's contribution to COBOL was based on her programming language, called FLOW-MATIC. In 1961, Jean E. Sammet developed FORMAC and published Programming Languages: History and Fundamentals which went on to be a standard work on programming languages. Programs were still entered using punched cards or paper tape. See computer programming in the punch card era. By the late 1960s, data storage devices and computer terminals became inexpensive enough that programs could be created by typing directly into the computers. Frances Holberton created a code to allow keyboard inputs while she worked at UNIVAC. Text editors were developed that allowed changes and corrections to be made much more than with punched cards. Sister Mary Kenneth Keller worked on developing the programming language, BASIC when she was a graduate student at Dartmouth in the 1960s. One of the first object-oriented programming languages, was developed by seven programmers, including Adele Goldberg, in the 1970s.
In 1985, Radia Perlman developed the Spannin