Computer software has to be "loaded" into the computer's storage (such as a hard drive, memory, or RAM). Once the software is loaded, the computer is able to execute the software. Computers operate by executing the computer program. This involves passing instructions from the application software, through the system software, to the hardware which ultimately receives the instruction as machine code. Each instruction causes the computer to carry out an operation -- moving data, carrying out a computation, or altering the control flow of instructions.Data movement is typically from one place in memory to another. Sometimes it involves moving data between memory and registers which enable high-speed data access in the CPU. Moving data, especially large amounts of it, can be costly. So, this is sometimes avoided by using "pointers" to data instead. Computations include simple operations such as incrementing the value of a variable data element. More complex computations may involve many operations and data elements together.
Instructions may be performed sequentially, conditionally, or iteratively. Sequential instructions are those operations that are performed one after another. Conditional instructions are performed such that different sets of instructions execute depending on the value(s) of some data. In some languages this is known as an "if" statement. Iterative instructions are performed repetitively and may depend on some data value. This is sometimes called a "loop." Often, one instruction may "call" another set of instructions that are defined in some other program or module. When more than one computer processor is used, instructions may be executed simultaneously.
A simple example of the way software operates is what happens when a user selects an entry such as "Copy" from a menu. In this case, a conditional instruction is executed to copy text from data in a 'document' area residing in memory, perhaps to an intermediate storage area known as a 'clipboard' data area. If a different menu entry such as "Paste" is chosen, the software may execute the instructions to copy the text from the clipboard data area to a specific location in the same or another document in memory.
Depending on the application, even the example above could become complicated. The field of software engineering endeavors to manage the complexity of how software operates. This is especially true for software that operates in the context of a large or powerful computer system.
Currently, almost the only limitations on the use of computer software in applications is the ingenuity of the designer/programmer. Consequently, large areas of activities (such as playing grand master level chess) formerly assumed to be incapable of software simulation are now routinely programmed. The only area that has so far proved reasonably secure from software simulation is the realm of human art especially, pleasing music and literature.
Application software
Application software is a subclass of computer software that employs the capabilities of a computer directly and thoroughly to a task that the user wishes to perform. This should be contrasted with system software which is involved in integrating a computer's various capabilities, but typically does not directly apply them in the performance of tasks that benefit the user. In this context the term application refers to both the application software and its implementation.
A simple, if imperfect analogy in the world of hardware would be the relationship of an electric light as an example of an application to an electric power generation plant as an example of a system. The power plant merely generates electricity, not itself of any real use until harnessed to an application like the electric light that performs a service that the user desires.
The exact delineation between the operating system and application software is not precise, however, and is occasionally subject to controversy. For example, one of the key questions in the United States v. Microsoft antitrust trial was whether Microsoft's Internet Explorer web browser was part of its Windows operating system or a separable piece of application software. As another example, the GNU/Linux naming controversy is, in part, due to disagreement about the relationship between the Linux kernel and the Linux operating system.
Typical examples of software applications are word processors, spreadsheets, and media players.
Multiple applications bundled together as a package are sometimes referred to as an application suite. Microsoft Office and OpenOffice.org, which bundle together a word processor, a spreadsheet, and several other discrete applications, are typical examples. The separate applications in a suite usually have a user interface that has some commonality making it easier for the user to learn and use each application. And often they may have some capability to interact with each other in ways beneficial to the user. For example, a spreadsheet might be able to be embedded in a word processor document even though it had been created in the separate spreadsheet application.
User-written software tailors systems to meet the user's specific needs. User-written software include spreadsheet templates, word processor macros, scientific simulations, graphics and animation scripts. Even email filters are a kind of user software. Users create this software themselves and often overlook how important it is.
In some types of embedded systems, the application software and the operating system software may be indistinguishable to the user, as in the case of software used to control a VCR, DVD player or Microwave Oven.
Software Developmentr Process
The Capability Maturity Model (CMM) is one of the leading models. Independent assessments grade organizations on how well they follow their defined processes, not on the quality of those processes or the software produced. CMM is gradually replaced by CMMI. ISO 9000 describes standards for formally organizing processes with documentation.
ISO 15504, also known as Software Process Improvement Capability Determination (SPICE), is a "framework for the assessment of software processes". This standard is aimed at setting out a clear model for process comparison. SPICE is used much like CMM and CMMI. It models processes to manage, control, guide and monitor software development. This model is then used to measure what a development organization or project team actually does during software development. This information is analyzed to identify weaknesses and drive improvement. It also identifies strengths that can be continued or integrated into common practice for that organization or team.
Six Sigma is a methodology to manage process variations that uses data and statistical analysis to measure and improve a company's operational performance. It works by identifying and eliminating defects in manufacturing and service-related processes. The maximum permissible defects is 3.4 per one million opportunities. However, Six Sigma is manufacturing-oriented and needs further research on its relevance to software development.
Often the first step in attempting to design a new piece of software, whether it be an addition to an existing software, a new application, a new subsystem or a whole new system, is, what is generally referred to as "Domain Analysis". Assuming that the developers (including the analysts) are not sufficiently knowledgeable in the subject area of the new software, the first task is to investigate the so-called "domain" of the software. The more knowledgeable they are about the domain already, the less the work required.
Another objective of this work is to make the analysts who will later try to elicit and gather the requirements from the area experts or professionals, speak with them in the domain's own terminology and to better understand what is being said by these people. Otherwise they will not be taken seriously. So, this phase is an important prelude to extracting and gathering the requirements. The following quote captures the kind of situation an analyst who hasn't done his homework well may face in speaking with a professional from the domain-I know you believe you understood what you think I said, but I am not sure you realize what you heard is not what I meant.
Software Elements Analysis The most important task in creating a software product is extracting the requirements. Customers typically know what they want, but not what software should do, while incomplete, ambiguous or contradictory requirements are recognized by skilled and experienced software engineers. Frequently demonstrating live code may help reduce the risk that the requirements are incorrect.
Specification Specification is the task of precisely describing the software to be written, possibly in a rigorous way. In practice, most successful specifications are written to understand and fine-tune applications that were already well-developed, although safety-critical software systems are often carefully specified prior to application development. Specifications are most important for external interfaces that must remain stable.
Programming language
A prominent purpose of programming languages is to provide instructions to a computer. As such, programming languages differ from most other forms of human expression in that they require a greater degree of precision and completeness. When using a natural language to communicate with other people, human authors and speakers can be ambiguous and make small errors, and still expect their intent to be understood. However, computers do exactly what they are told to do, and cannot understand the code the programmer "intended" to write. The combination of the language definition, the program, and the program's inputs must fully specify the external behavior that occurs when the program is executed.
Many languages have been designed from scratch, altered to meet new needs, combined with other languages, and eventually fallen into disuse. Although there have been attempts to design one "universal" computer language that serves all purposes, all of them have failed to be accepted in this role.[7] The need for diverse computer languages arises from the diversity of contexts in which languages are used:
Programs range from tiny scripts written by individual hobbyists to huge systems written by hundreds of programmers.
Programmers range in expertise from novices who need simplicity above all else, to experts who may be comfortable with considerable complexity.
Programs must balance speed, size, and simplicity on systems ranging from microcontrollers to supercomputers.
Programs may be written once and not change for generations, or they may undergo nearly constant modification.
Finally, programmers may simply differ in their tastes: they may be accustomed to discussing problems and expressing them in a particular language.
One common trend in the development of programming languages has been to add more ability to solve problems using a higher level of abstraction. The earliest programming languages were tied very closely to the underlying hardware of the computer. As new programming languages have developed, features have been added that let programmers express ideas that are more removed from simple translation into underlying hardware instructions. Because programmers are less tied to the needs of the computer, their programs can do more computing with less effort from the programmer. This lets them write more programs in the same amount of time.
Natural language processors have been proposed as a way to eliminate the need for a specialized language for programming. However, this goal remains distant and its benefits are open to debate. Edsger Dijkstra took the position that the use of a formal language is essential to prevent the introduction of meaningless constructs, and dismissed natural language programming as "foolish.Alan Perlis was similarly dismissive of the idea.
A language is typed if operations defined for one data type cannot be performed on values of another data type. For example, "this text between the quotes" is a string. In most programming languages, dividing a number by a string has no meaning. Most modern programming languages will therefore reject any program attempting to perform such an operation. In some languages, the meaningless operation will be detected when the program is compiled ("static" type checking), and rejected by the compiler, while in others, it will be detected when the program is run ("dynamic" type checking), resulting in a runtime exception.A special case of typed languages are the single-type languages. These are often scripting or markup languages, such as Rexx or SGML, and have only one data type most commonly character strings which are used for both symbolic and numeric data.
In contrast, an untyped language, such as most assembly languages, allows any operation to be performed on any data, which are generally considered to be sequences of bits of various lengths. High-level languages which are untyped include BCPL and some varieties of Forth.
In practice, while few languages are considered typed from the point of view of type theory (verifying or rejecting all operations), most modern languages offer a degree of typing. Many production languages provide means to bypass or subvert the type system
Free software
Free software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions only to ensure that further recipients can also do these things. To make these acts possible, the human readable form of the program (called the source code) must be made available and the software must be accompanied by a software licence saying that the copyright holder permits these acts (a free software licence). Software can also be free software by putting the source code in the public domain.Alternative terms for free software have been coined in an attempt to make the use of "free" less ambiguous. The most common is "open-source software", which has since evolved to refer to a subtly different sense of freedom. Free software is also known as "software libre", "free, libre and open-source software" ("FLOSS"), and "free/open-source software" ("FOSS").
Free software and "freeware" should not be confused. Freeware is software made available free of charge. Everyone is free to sell copies of free software, to use it commercially, and to charge for distribution and modifications. Because anyone who has a copy may distribute the software at no cost, the software generally is available at no cost. Free software business models are usually based on adding value such as support, training, customisation, integration, or certification. At the same time, some business models which work with non-free software are not compatible with free software, such as those that depend on a user having no choice but to pay for a license in order to lawfully use a software product.The free software movement was launched in 1983 to make these freedoms available to every computer user. Software that does not provide these freedoms is referred to as proprietary software or non-free software.
Free software is a huge international effort, producing software used by individuals, large organisations, and governmental administrations.
Free software has a very high market penetration in server-side Internet applications such as the Apache web server, MySQL database, and PHP scripting language. Completely free computing environments are available as large packages of basic system software such as the many GNU/Linux distributions and the FreeBSD OS. Free software developers have also created free versions of almost all commonly used desktop applications such as web browsers, office productivity suites, and multimedia players. It is important to note, however, that in many categories, free software for individual workstation or home users has only a fraction of the market share of their proprietary competitors. Most free software is distributed online without charge, or off-line at the marginal cost of distribution, but this is not required, and people may sell copies for any price.
The economic advantages of the free software model have been recognised by large corporations such as IBM, Red Hat, and Sun Microsystems. Many companies whose core business is not in the IT sector choose free software for their Internet information and sales sites, due to the lower initial capital investment and ability to freely customize the application packages. Also, some non-software industries are beginning to use techniques similar to those used in free software development for their research and development: scientists, for example, are looking towards more open development processes, and hardware such as microchips are beginning to be developed with specifications released under copyleft licenses (see the OpenCores project, for instance). Creative Commons and the free culture movement have also been largely influenced by the free software movement.
Free software played a part in the development of the Internet, the World Wide Web and the infrastructure of dot-com companies[citation needed]. Free software allows users to cooperate in enhancing and refining the programs they use; free software is a pure public good rather than a private good.
Companies that contribute to free software can increase commercial innovation amidst the void of patent cross licensing lawsuits. (See mpeg2 patent holders)
Under the free software business model, free software vendors may charge a fee for distribution and offer pay support and software customization services. Proprietary software uses a different business model, where a customer of the proprietary software pays a fee for a license to use the software. This license may grant the customer the ability to configure some or no parts of the software themselves. Often some level of support is included in the purchase of proprietary software, but additional support services (especially for enterprise applications) are usually available for an additional fee. Some proprietary software vendors will also customize software for a fee.
Free software is generally available at little to no cost and can result in permanently lower costs compared to proprietary software. With free software, businesses can fit software to their specific needs by changing the software themselves or by hiring programmers to modify it for them. Free software often has no warranty, and more importantly, generally does not assign legal liability to anyone. However, warranties are permitted between any two parties upon the condition of the software and its usage. Such an agreement is made separately from the free software license.
There is debate over the security of free software in comparison to proprietary software, with a major issue being security through obscurity. A popular quantitative test in computer security is using relative counting of known unpatched security flaws. Generally, users of this method advise avoiding products which lack fixes for known security flaws, at least until a fix is available. Some claim that method counts more vulnerabilities for the free software, since their source code is accessible and their community is more forthcoming about what problems exist.
Business software-MIS
Business software is generally any software program that helps a business increase productivity or measure their productivity. The term covers a large variation of uses within the business environment, and can be categorized by using a small, medium and large matrix:
The small business market generally consists of home accounting software, and office suites such as Microsoft Office and OpenOffice.org.
The medium size, or SME, has a broader range of software applications, ranging from accounting, groupware, customer relationship management, human resources software, loan origination software, shopping cart software, field service software, and other productivity enhancing applications.
The last segment covers enterprise level software applications, such as those in the fields of enterprise resource planning, enterprise content management (ECM), business process management and product lifecycle management. These applications are extensive in scope, and often come with modules that either add native functions, or incorporate the functionality of third-party software programs.
Now, technologies that have previously only existed in peer-to-peer software applications, like Kazaa and Napster, are starting to feature within business applications. JXTA is an open source platform that enables the creation of machine and language neutral applications. Peer based applications will be especially useful for aggregating the information at the edge of the network that currently resides in the neurons of the users themselves.
Management Information Systems (MIS) is a general name for the academic discipline covering
the application of people, technologies, and procedures collectively called information systems
to solve business problems. MIS are distinct from regular information systems in that they are used
to analyze other information systems applied in operational activities in the organization.
Academically, the term is commonly used to refer to the group of information management methods
tied to the automation or support of human decision making, e.g. Decision Support Systems,
Expert systems, and Executive information systems.