Access Controls An access control system

[edit] Contemporary status

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[edit] Contemporary status

As of 2007, centralized computing is now coming back into fashion - to a certain extent. Thin clients have been used for many years by businesses to reduce total cost of ownership, while web applications are becoming more popular because they can potentially be used on many types of computing device without any need for software installation. Already, however, there are signs that the pendulum is swinging back again, away from pure centralization, as thin client devices become more like diskless workstations due to increased computing power, and web applications start to do more processing on the client side, with technologies such as AJAX and rich clients.

In addition, mainframes are still being used for some mission-critical applications, such as payroll, or for processing day-to-day account transactions in banks. These mainframes will typically be accessed either using terminal emulators (real terminal devices are not used much any more) or via modern front-ends such as web applications - or (in the case of automated access) protocols such as web services protocols.

Hybrid client model

Some organisations use a hybrid client model partway between centralized computing and conventional desktop computing, in which some applications (such as web browsers) are run locally, while other applications (such as critical business systems) are run on the terminal server. One way to implement this is simply by running remote desktop software on a standard desktop computer.

Check Digit

A check digit is a form of redundancy check used for error detection, the decimal equivalent of a binary checksum. It consists of a single digit computed from the other digits in the message.

With a check digit, one can detect simple errors in the input of a series of digits, such as a single mistyped digit, or the permutation of two successive digits

The final digit of a Universal Product Code is a check digit computed as follows:[1]

  1. Add the digits (up to but not including the check digit) in the odd-numbered positions (first, third, fifth, etc.) together and multiply by three.

  2. Add the digits (up to but not including the check digit) in the even-numbered positions (second, fourth, sixth, etc.) to the result.

  3. If the last digit of the result is 0, then the check digit is 0.

  4. The check digit will be the smallest number required to round the Sum up to the nearest multiple of 10.

For instance, the UPC-A barcode for a box of tissues is "036000241457". The last digit is the check digit "7", and if the other numbers are correct then the check digit calculation must produce 7.

  1. We add the odd number digits: 0+6+0+2+1+5 = 14

  2. Multiply the result by 3: 14 × 3 = 42

  3. We add the even number digits: 3+0+0+4+4 = 11

  4. We add the two results together: 42 + 11 = 53

  5. 60 (the next highest multiple of 10) modulo 53 is 7. Therefore, 7 is the check digit.[2]

[edit] ISBN 10

The final character of a ten digit International Standard Book Number is a check digit computed so that multiplying each digit by its position in the number (counting from the right) and taking the sum of these products modulo 11 is 0. The last digit (which is multiplied by 1) is the check digit, chosen to make the sum correct. It may need to have the value 10, which is represented as the letter X. For example, take the ISBN 0-201-53082-1. The sum of products is 0×10 + 2×9 + 0×8 + 1×7 + 5×6 + 3×5 + 0×4 + 8×3 + 2×2 + 1×1 = 99 ≡ 0 modulo 11. So the ISBN is valid.

While this may seem more complicated than the first scheme, it can be validated very simply by adding all the products together then dividing by 11. The sum can be computed without any multiplications by initializing two variables, t and sum, to 0 and repeatedly performing t = t + digit; sum = sum + t; (which can be expressed in C as sum += t += digit;). If the final sum is a multiple of 11, then the ISBN is valid.

Chief Security Officer (CSO)

A chief security officer (CSO) is a corporation's top executive who is responsible for security. The CSO serves as the business leader responsible for the development, implementation and management of the organization’s corporate security vision, strategy and programs. They direct staff in identifying, developing, implementing and maintaining security processes across the organization to reduce risks, respond to incidents, and limit exposure to liability in all areas of financial, physical, and personal risk; establish appropriate standards and risk controls associated with intellectual property; and direct the establishment and implementation of policies and procedures related to data security. Those primarily responsible for information security may have the title of Chief Information Security Officer (CISO) to differentiate the positions.


Client-server computing or networking is a distributed application architecture that partitions tasks or work loads between service providers (servers) and service requesters, called clients.[1] Often clients and servers operate over a computer network on separate hardware. A server machine is a high-performance host that is running one or more server programs which share its resources with clients. A client does not share any of its resources, but requests a server's content or service function. Clients therefore initiate communication sessions with servers which await (listen to) incoming requests Client-server describes the relationship between two computer programs in which one program, the client program, makes a service request to another, the server program. Standard networked functions such as email exchange, web access and database access, are based on the client-server model. For example, a web browser is a client program at the user computer that may access information at any web server in the world. To check your bank account from your computer, a web browser client program in your computer forwards your request to a web server program at the bank. That program may in turn forward the request to its own database client program that sends a request to a database server at another bank computer to retrieve your account balance. The balance is returned to the bank database client, which in turn serves it back to the web browser client in your personal computer, which displays the information for you.

The client-server model has become one of the central ideas of network computing. Many business applications being written today use the client-server model. So do the Internet's main application protocols, such as HTTP, SMTP, Telnet, DNS. In marketing, the term has been used to distinguish distributed computing by smaller dispersed computers from the "monolithic" centralized computing of mainframe computers. But this distinction has largely disappeared as mainframes and their applications have also turned to the client-server model and become part of network computing.

Each instance of the client software can send data requests to one or more connected servers. In turn, the servers can accept these requests, process them, and return the requested information to the client. Although this concept can be applied for a variety of reasons to many different kinds of applications, the architecture remains fundamentally the same.

The most basic type of client-server architecture employs only two types of hosts: clients and servers. This type of architecture is sometimes referred to as two-tier. It allows devices to share files and resources. The two tier architecture means that the client acts as one tier and application in combination with server acts as another tier.

Cold Site

A cold site is the most inexpensive type of backup site for an organization to operate. It does not include backed up copies of data and information from the original location of the organization, nor does it include hardware already set up. The lack of hardware contributes to the minimal startup costs of the cold site, but requires additional time following the disaster to have the operation running at a capacity close to that prior to the disaster.

Computer Operator

A role within IT, computer operators oversee the running of computer systems, ensuring that the machines are running and physically secured. The traditional role of a computer operator was to work with mainframes which required a great deal of management day-to-day. Computer operator positions are distinct from system administrators in that they only require a 2-year college Associate's degree (similar to nuclear power plant operators and car mechanics), and are paid significantly less than system administrators, and traditionally used operating systems other than UNIX before the 1990s with far more rudimentary operations than a complex UNIX system. The computer operator works in a computer room (now days known as "data centers"). The employment of operators has greatly decreased due to modern technology making the more traditional roles obsolete. Most of the duties that operations staff undertake is taught on-the-job as the variety of roles is unique to the systems they help manage.

Logging events is also amongst the operators role, listing each backup that is run or things such as machine malfunctions. Operators assist System administrators and programmers in testing and debugging of new systems and programs prior to them becoming production environments.

As modern day computing has led to a ger proliferation of personal computers, the role of the operator has changed to include these within their duties. Similar roles such as managing the backup systems, cycling tapes or other media, filling and maintaining printers, indeed anything that is monotonous or in need of legwork for the system or network administrators s handled by the operation staff.

The shifting and changing of duties for the operators has resulted due to the speed of change from older mainframe systems to newer self-managing systems but overall the operator fills in as a lower level system administrator.

Computer Programmer

A programmer is someone who writes computer software. The term computer programmer can refer to a specialist in one area of computer programming or to a generalist who writes code for many kinds of software. One who practices or professes a formal approach to programming may also be known as a programmer analyst. A programmer's primary computer language (Lisp, Java, Delphi, C++, etc.) is often prefixed to the above titles, and those who work in a web environment often prefix their titles with web. The term programmer can be used to refer to a software developer, software engineer, computer scientist, or software analyst. However, members of these professions typically possess other software engineering skills, beyond programming; for this reason, the term programmer is sometimes considered an insulting or derogatory oversimplification of these other professions. This has sparked much debate amongst developers, analysts, computer scientists, programmers, and outsiders who continue to be puzzled at the subtle differences in these occupations.[1][2][3][4][5]

Those proficient in computer programming skills may become famous, though this regard is normally limited to software engineering circles. Ada Lovelace is popularly credited as history's first programmer. She was the first to express an algorithm intended for implementation on a computer, Charles Babbage's analytical engine, in October 1842.[6] Her work never ran, though that of Konrad Zuse did in 1941. The ENIAC programming team, consisting of Kay McNulty, Betty Jennings, Betty Snyder, Marlyn Wescoff, Fran Bilas and Ruth Lichterman were the first working programmers.[7][8]

Computer programmers write, test, debug, and maintain the detailed instructions, called computer programs, that computers must follow to perform their functions. Programmers also conceive, design, and test logical structures for solving problems by computer. Many technical innovations in programming — advanced computing technologies and sophisticated new languages and programming tools — have redefined the role of a programmer and elevated much of the programming work done today. Job titles and descriptions may vary, depending on the organization.

Programmers work in many settings, including corporate information technology departments, big software companies, and small service firms. Many professional programmers also work for consulting companies at client' sites as contractors. Licensing is not typically required to work as a programmer, although professional certifications are commonly held by programmers. Programming is widely considered a profession (although some authorities disagree on the grounds that only careers with legal licensing requirements count as a profession).

Programmers' work varies widely depending on the type of business they are writing programs for. For example, the instructions involved in updating financial records are very different from those required to duplicate conditions on an aircraft for pilots training in a flight simulator. Although simple programs can be written in a few hours, programs that use complex mathematical formulas whose solutions can only be approximated or that draw data from many existing systems may require more than a year of work. In most cases, several programmers work together as a team under a senior programmer’s supervision.

Programmers write programs according to the specifications determined primarily by more senior programmers and by systems analysts. After the design process is complete, it is the job of the programmer to convert that design into a logical series of instructions that the computer can follow. The programmer codes these instructions in one of many programming languages. Different programming languages are used depending on the purpose of the program. COBOL, for example, is commonly used for business applications which are run on mainframe and midrange computers, whereas Fortran is used in science and engineering. C++ is widely used for both scientific and business applications. Java, C# and PHP are popular programming languages for Web and business applications. Programmers generally know more than one programming language and, because many languages are similar, they often can learn new languages relatively easily. In practice, programmers often are referred to by the language they know, e.g. as Java programmers, or by the type of function they perform or environment in which they work: for example, database programmers, mainframe programmers, or Web developers.

When making changes to the source code that programs are made up of, programmers need to make other programmers aware of the task that the routine is to perform. They do this by inserting comments in the source code so that others can understand the program more easily. To save work, programmers often use libraries of basic code that can be modified or customized for a specific application. This approach yields more reliable and consistent programs and increases programmers' productivity by eliminating some routine steps.

[edit] Testing and debugging

Programmers test a program by running it and looking for bugs. As they are identified, the programmer usually makes the appropriate corrections, then rechecks the program until an acceptably low level and severity of bugs remain. This process is called testing and debugging. These are important parts of every programmer's job. Programmers may continue to fix these problems throughout the life of a program. Updating, repairing, modifying, and expanding existing programs sometimes called maintenance programmer. Programmers may contribute to user guides and online help, or they may work with technical writers to do such work.

Certain scenarios or execution paths may be difficult to test, in which case the programmer may elect to test by inspection which involves a human inspecting the code on the relevant execution path, perhaps hand executing the code. Test by inspection is also sometimes used as a euphemism for inadequate testing. It may be difficult to properly assess whether the term is being used euphemistically.

Customer Relationship Management (CRM)

Customer relationship management (CRM) are methods that companies use to interact with customers. The methods include employee training and special purpose CRM software. There is an emphasis on handling incoming customer phone calls and email, although the information collected by CRM software may also be used for promotion, and surveys such as those polling customer satisfaction.

Initiatives often fail because implementation was limited to software installation, without providing the context, support and understanding for employees to learn.[1] Tools for customer relationship management should be implemented "only after a well-devised strategy and operational plan are put in place".[2]

Other problems occur[3] when failing to think of sales as the output of a process that itself needs to be studied and taken into account when planning automation[4].

From the outside, customers interacting with a company perceive the business as a single entity, despite often interacting with a number of employees in different roles and departments. CRM is a combination of policies, processes, and strategies implemented by an organization to unify its customer interactions and provide a means to track customer information. It involves the use of technology in attracting new and profitable customers, while forming tighter bonds with existing ones.

CRM includes many aspects which relate directly to one another:

  • Front office operations — Direct interaction with customers, e.g. face to face meetings, phone calls, e-mail, online services etc.

  • Back office operations — Operations that ultimately affect the activities of the front office (e.g., billing, maintenance, planning, marketing, advertising, finance, manufacturing, etc.)

  • Business relationships — Interaction with other companies and partners, such as suppliers/vendors and retail outlets/distributors, industry networks (lobbying groups, trade associations). This external network supports front and back office activities.

  • Analysis — Key CRM data can be analyzed in order to plan target-marketing campaigns, conceive business strategies, and judge the success of CRM activities (e.g., market share, number and types of customers, revenue, profitability).

Proponents of CRM software claim that it doesn't only allow more effective ways of managing customer relationships, but also more customer-centric ways of doing business[5]. Executives often cite the need for the proper tools as a barrier to delivering the experience their customers expect. A 2009 study of over 860 corporate executives revealed only 39% believe that their employees have tools and authority to solve customer problems.[6]

The term data means groups of information that represent the qualitative or quantitative attributes of a variable or set of variables. Data (plural of "datum", which is seldom used) are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which information and knowledge are derived.


A database is an integrated collection of logically related records or files consolidated into a common pool that provides data for one or more multiple uses.

One way of classifying databases involves the type of content, for example: bibliographic, full-text, numeric, image. Other classification methods start from examining database models or database architectures: see below.

The data in a database is organized according to a database model. As of 2009[update] the relational model occurs most commonly. Other models such as the hierarchical model and the network model use a more explicit representation of relationships.

On-line Transaction Processing systems (OLTP) often use a "row-oriented" or an "object-oriented" datastore architecture, whereas data-warehouse and other retrieval-focused applications like Google's BigTable, or bibliographic database (library catalogue) systems may use a Column-oriented DBMS architecture.

Document-Oriented, XML, knowledgebases, as well as frame databases and RDF-stores (also known as triple-stores), may also use a combination of these architectures in their implementation.

Not all databases have or need a database schema ("schema-less databases").

Over many years[update] general-purpose database systems have dominated the database industry. These offer a wide range of functions, applicable to many, if not most circumstances in modern data processing. These have been enhanced with extensible datatypes (pioneered in the PostgreSQL project) to allow development of a very wide range of applications.

There are also other types of databases which cannot be classified as relational databases. Most notable is the object database management system, which stores language objects natively without using a separate data definition language and without translating into a separate storage schema. Unlike relational systems, these object databases store the relationship between complex data types as part of their storage model in a way that does not require runtime calculation of related data using relational algebra execution algorithms.

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