OASIS - Organization for Structured Information Standards:
See Organization for Structured Information Standards.
In object-oriented programming (OOP), objects are the things you think about first in designing a program and they are also the units of code that are eventually derived from the process. In between, each object is made into a generic class of object and even more generic classes are defined so that objects can share models and reuse the class definitions in their code. Each object is an instance of a particular class or subclass with the class's own methods or procedures and data variables. An object is what actually runs in the computer.
Source code and object code refer to the "before" and "after" versions of a computer program that is compiled (see compiler) before it is ready to run in a computer. The source code consists of the programming statements that are created by a programmer with a text editor or a visual programming tool and then saved in a file. For example, a programmer using the C language types in a desired sequence of C language statements using a text editor and then saves them as a named file. This file is said to contain the source code. It is now ready to be compiled with a C compiler and the resulting output, the compiled file, is often referred to as object code. The object code file contains a sequence of instructions that the processor can understand but that is difficult for a human to read or modify. For this reason and because even debugged programs often need some later enhancement, the source code is the most permanent form of the program.
When you purchase or receive operating system or application software, it is usually in the form of compiled object code and the source code is not included. Proprietary software vendors usually don't want you to try to improve their code since this may created additional service costs for them. Lately, there is a movement to develop software (Linux is an example) that is open to further improvement by anyone who wants to improve it, and here the source code is provided.
The Synchronous Optical Network (SONET) includes a set of signal rate multiples for transmitting digital signals on optical fiber. The base rate (OC-1) is 51.84 Mbps. Certain multiples of the base rate are provided as shown in the following table. Asynchronous transfer mode (ATM) makes use of some of the Optical Carrier levels. Optical Carrier Level Data Rates:
OC-1 51.84 Mbps
OC-3 155.52 Mbps
OC-12 622.08 Mbps
OC-24 1.244 Gbps
OC-48 2.488 Gbps
OC-192 10 Gbps
OC-256 13.271 Gbps
OC-768 40 Gbps
OC-768 is currently the fastest synchronous optical network (SONET) standard rate for data transmission on optical fiber as part of the broadband ISDN (BISDN). OC stands for optical carrier and the number affixed is the multiple of the base rate bandwidth of 51.85 Mbps. OC-768 supports rates of 40 gigabits per second (Gbps) on a fiber optic carrier, a rate that translates to the equivalent of seven CD-ROM's worth of data in one second. Developed to meet ever-growing demands for bandwidth, OC-768 uses dense wavelength division multiplexing (DWDM) to carry multiple channels of data on a single optic fiber. New DWDM systems are now in development to run at at 10 trillion bits per second (10 Tbps) per fiber. This translates into the theoretical capability of one fiber to support, simultaneously, an active Internet connection to every household in the U.S. Enkido was the first company to offer OC-768 service, which they currently provide for a number of clients including Deutsche Telecom.
Ockham's Razor (also spelled Occam's razor, pronounced AHK-uhmz RAY-zuhr) is the idea that, in trying to understand something, getting unnecessary information out of the way is the fastest way to the truth or to the best explanation. William of Ockham (1285-1349), English theologian and philosopher, spent his life developing a philosophy that reconciled religious belief with demonstratable, generally experienced truth, mainly by separating the two. Where earlier philosophers attempted to justify God's existence with rational proof, Ockham declared religious belief to be incapable of such proof and a matter of faith. He rejected the notions preserved from Classical times of the independent existence of qualities such as truth, hardness, and durability and said these ideas had value only as descriptions of particular objects and were really characteristics of human cognition. Ockham was noted for his insistence on paying close attention to language as a tool for thinking and on observation as a tool for testing reality. His thinking and writing is considered to have laid the groundwork for modern scientific inquiry. Ockham's insistence on the use of parsimony (we might call it minimalism) in thought resulted in some later writer's invention of the term, Ockham's razor. Among his statements (translated from his Latin) are: "Plurality is not to be assumed without necessity" and "What can be done with fewer [assumptions] is done in vain with more." One consequence of this methodology is the idea that the simplest or most obvious explanation of several competing ones is the one that should be preferred until it is proven wrong.
ODBC - Open Database Connectivity:
See Open Database Connectivity.
Ohm's Law is the mathematical relationship among electric current, resistance, and voltage. The principle is named after the German scientist Georg Simon Ohm.
In direct-current (DC) circuits, Ohm's Law is simple and linear. Suppose a resistance having a value of R ohms carries a current of I amperes. Then the voltage across the resistor is equal to the product IR. There are two corollaries. If a DC power source providing E volts is placed across a resistance of R ohms, then the current through the resistance is equal to E/R amperes. Also, in a DC circuit, if E volts appear across a component that carries I amperes, then the resistance of that component is equal to E/I ohms.
Mathematically, Ohm's Law for DC circuits can be stated as three equations:
E = IR
I = E/R
R = E/I
When making calculations, compatible units must be used. If the units are other than ohms (for resistance), amperes (for current), and volts (for voltage), then unit conversions should be made before calculations are done. For example, kilohms should be converted to ohms, and microamperes should be converted to amperes.
OLAP - Online Analytical Processing:
See Online Analytical Processing.
Online Analytical Processing - OLAP:
OLAP (online analytical processing) is computer processing that enables a user to easily and selectively extract and view data from different points-of-view. For example, a user can request that data be analyzed to display a spreadsheet showing all of a company's beach ball products sold in Florida in the month of July, compare revenue figures with those for the same products in September, and then see a comparison of other product sales in Florida in the same time period. To facilitate this kind of analysis, OLAP data is stored in a multidimensional database. Whereas a relational database can be thought of as two-dimensional, a multidimensional database considers each data attribute (such as product, geographic sales region, and time period) as a separate "dimension." OLAP software can locate the intersection of dimensions (all products sold in the Eastern region above a certain price during a certain time period) and display them. Attributes such as time periods can be broken down into subattributes.
OLAP can be used for data mining or the discovery of previously undiscerned relationships between data items. An OLAP database does not need to be as large as a data warehouse, since not all transactional data is needed for trend analysis. Using Open Database Connectivity (ODBC), data can be imported from existing relational databases to create a multidimensional database for OLAP.
Two leading OLAP products are Hyperion Solution's Essbase and Oracle's Express Server. OLAP products are typically designed for multiple-user environments, with the cost of the software based on the number of users.
An open relay (sometimes called an insecure relay or a third-party relay) is an SMTP e-mail server that allows third-party relay of e-mail messages. By processing mail that is neither for nor from a local user, an open relay makes it possible for an unscrupulous sender to route large volumes of spam. In effect, the owner of the server -- who is typically unaware of the problem -- donates network and computer resources to the sender's purpose. In addition to the financial costs incurred when a spammer hijacks a server, an organization may also suffer system crashes, equipment damage, and loss of business.
In the past, open relays were used intentionally to facilitate mail relay between the separate closed e-mail systems (such as UUCP or FidoNet) served by the Internet. However, the Internet has expanded enormously since then, and the potential for abuse has expanded accordingly. Open relays are sometimes used legitimately: they are frequently used to support mobile users connecting to a corporate network through an ISP or to support multiple domains within an organization, and are sometimes used for debugging connectivity or to circumvent a known routing problem. However, other mechanisms can be used to route an authorized user around a closed relay.
The Mail Abuse Prevention System (MAPS) is one of several organizations that seeks to control the problem of open relays, though educating the public about the danger, and through publishing a blacklist of organizations whose mail hosts allow third-party relays (a similar organization, ORBS, is now defunct). The relay feature is a part of all SMTP-based servers, which means that most modern e-mail servers, if unprotected, are vulnerable. According to MAPS, because spammers use automated tools to search the Internet for vulnerable servers, an open relay will eventually be found and used. To avoid allowing spammers free access to their resources -- and to help stem the Internet's flow of spam -- MAPS urges administrators to turn off the relay option on their servers.
1) In general, open source refers to any program whose source code is made available for use or modification as users or other developers see fit. (Historically, the makers of proprietary software have generally not made source code available.) Open source software is usually developed as a public collaboration and made freely available.
2) Open Source is a certification mark owned by the Open Source Initiative (OSI). Developers of software that is intended to be freely shared and possibly improved and redistributed by others can use the Open Source trademark if their distribution terms conform to the OSI's Open Source Definition. To summarize, the Definition model of distribution terms require that:
a) The software being distributed must be redistributed to anyone else without any restriction
b) The source code must be made available (so that the receiving party will be able to improve or modify it)
c) The license can require improved versions of the software to carry a different name or version from the original software
The idea is very similar to the copyleft concept of the Free Software Foundation. Open Source is the result of a long-time movement toward software that is developed and improved by a group of volunteers cooperating together on a network. Many parts of the UNIX operating system were developed this way, including today's most popular version, Linux. Linux uses applications from the GNU project, which was guided by Richard Stallman and the Free Software Foundation. The Open Source Definition, spearheaded by Eric Raymond (editor of The New Hacker's Dictionary), is an effort to provide a branded model or guideline for this kind of software distribution and redistribution. The OSI considers the existing software distribution licenses used by GNU, BSD (a widely-distributed version of UNIX), X Window System, and Artistic to be conformant with the Open Source Definition.
Prior to its acquisition by AOL, Netscape, in an effort to stay viable in its browser competition with Microsoft, made its browser source code (codenamed Mozilla) freely available, encouraging hacker to improve it. Possible enhancements will presumably be incorporated into future versions. The open source movement has gained momentum as commercial enterprises have begun to consider Linux as an open alternative to Windows operating systems.
Organization for Structured Information Standards - OASIS:
Organization for Structured Information Standards (OASIS) is a nonprofit, international consortium whose goal is to promote the adoption of product-independent standards for information formats such as Standard Generalized Markup Language (SGML), Extensible Markup Language (XML), and Hypertext Markup Language (HTML). Currently, OASIS (formerly known as SGML Open) is working to bring together competitors and industry standards groups with conflicting perspectives to discuss using XML as a common Web language that can be shared across applications and platforms.
OASIS sponsors XML.org , a non-profit XML Web portal. The goal of OASIS is not to create structured information standards for XML, but to provide a forum for discussion, to promote the adoption of interoperability standards, and to recommend ways members can provide better interoperability for their users. OASIS has worked with the United Nations to sponsor ebXML, a global initiative for electronic business data exchange. EbXML, whose goal is to make it easier for companies of all sizes and locations to conduct business on the Internet, is currently focusing on the specific needs of business-to-business (B2B) and Internet security as it relates to XML.
Open Database Connectivity - ODBC
Open Database Connectivity (ODBC) is an open standard application programming interface (API) for accessing a database. By using ODBC statements in a program, you can access files in a number of different databases, including Access, dBase, DB2, Excel, and Text. In addition to the ODBC software, a separate module or driver is needed for each database to be accessed. The main proponent and supplier of ODBC programming support is Microsoft.
ODBC is based on and closely aligned with The Open Group standard Structured Query Language (SQL) Call-Level Interface. It allows programs to use SQL requests that will access databases without having to know the proprietary interfaces to the databases. ODBC handles the SQL request and converts it into a request the individual database system understands.
ODBC was created by the SQL Access Group and first released in September, 1992. Although Microsoft Windows was the first to provide an ODBC product, versions now exist for UNIX, OS/2, and Macintosh platforms as well.
In the newer distributed object architecture called Common Object Request Broker Architecture (CORBA), the Persistent Object Service (POS) is a superset of both the Call-Level Interface and ODBC. When writing programs in the Java language and using the Java Database Connectivity (JDBC) application program interface, you can use a product that includes a JDBC-ODBC "bridge" program to reach ODBC-accessible databases.
Operating System - OS:
An operating system (sometimes abbreviated as "OS") is the program that, after being initially loaded into the computer by a boot program, manages all the other programs in a computer. The other programs are called applications or application programs. The application programs make use of the operating system by making requests for services through a defined application program interface (API). In addition, users can interact directly with the operating system through a user interface such as a command language or a graphical user interface (GUI).
An operating system performs these services for applications:
* In a multitasking operating system where multiple programs can be running at the same time, the operating system determines which applications should run in what order and how much time should be allowed for each application before giving another application a turn.
* It manages the sharing of internal memory among multiple applications.
* It handles input and output to and from attached hardware devices, such as hard disks, printers, and dial-up ports.
* It sends messages to each application or interactive user (or to a system operator) about the status of operation and any errors that may have occurred.
* It can offload the management of what are called batch jobs (for example, printing) so that the initiating application is freed from this work.
* On computers that can provide parallel processing, an operating system can manage how to divide the program so that it runs on more than one processor at a time.
All major computer platforms (hardware and software) require and sometimes include an operating system. Linux, Windows 2000, VMS, OS/400, AIX, and z/OS are all examples of operating systems.
Optical fiber (or "fiber optic") refers to the medium and the technology associated with the transmission of information as light pulses along a glass or plastic wire or fiber. Optical fiber carries much more information than conventional copper wire and is in general not subject to electromagnetic interference and the need to retransmit signals. Most telephone company long-distance lines are now of optical fiber.
Transmission on optical fiber wire requires repeater at distance intervals. The glass fiber requires more protection within an outer cable than copper. For these reasons and because the installation of any new wiring is labor-intensive, few communities yet have optical fiber wires or cables from the phone company's branch office to local customers (known as local loop).
Single mode fiber fiber is used for longer distances; multimode fiber fiber is used for shorter distances. A single strand of single mode fiber can be less than 4 microns in diameter. Also see Fiber Optics.
OS - Operating System:
See Operating System.
OS/390 is the IBM operating system most commonly installed on its S/390 line of mainframe server. It is an evolved and newly renamed version of MVS (Multiple Virtual Storage), IBM's long-time, robust mainframe operating system. By whatever name, MVS has been said to be the operating system that keeps the world going. The payroll, accounts receivable, transaction processing, database management, and other programs critical to the world's largest businesses are usually run on an MVS system. Although MVS tends to be associated with a monolithic, centrally-controlled information system, IBM has in recent years repositioned it as a "large server" in a network-oriented distributed environment that would tend to use a 3-tier application model.
Since MVS represents a certain epoch and culture in the history of computing and since many older MVS systems still operate, the term "MVS" will probably continue to be used for some time. Since OS/390 also comes with UNIX user and programming interfaces built in, it can be used as both an MVS system and a UNIX system at the same time. OS/390 (and earlier MVS) systems run older applications developed using Common Business Oriented Language and, for transaction programs, Customer Information Control System. Older application programs written in PL/I and Formula Translation are still running. Older applications use the Virtual Storage Access Method access method for file management and Virtual Telecommunications Access Method for telecommunication with users. The most common program environment today uses the C and C++ languages. DB2 is IBM's primary . Java applications can be developed and run under OS/390's UNIX environment.
For additional information about major components of OS/390, see MVS. Other IBM operating systems for their larger computers include or have included: the Transaction Processing Facility (TPF), used in some major airline reservation systems, and virtual machine, an operating system designed to serve many interactive users at the same time.