The most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.
For large systems, the operating system has even greater responsibilities and powers. It is like a traffic cop -- it makes sure that different programs and users running at the same time do not interfere with each other. The operating system is also responsible for security, ensuring that unauthorized users do not access the system.
Operating systems can be classified as follows: # multi-user : Allows two or more users to run programs at the same time. Some operating systems permit hundreds or even thousands of concurrent users. # multiprocessing : Supports running a program on more than one CPU. # multitasking : Allows more than one program to run concurrently. # multithreading : Allows different parts of a single program to run concurrently. # real time: Responds to input instantly. General-purpose operating systems, such as DOS and UNIX, are not real-time.
Operating systems provide a software platform on top of which other programs, called application programs, can run. The application programs must be written to run on top of a particular operating system. Your choice of operating system, therefore, determines to a great extent the applications you can run. For PCs, the most popular operating systems are DOS, OS/2, and Windows, but others are available, such as Linux.
As a user, you normally interact with the operating system through a set of commands. For example, the DOS operating system contains commands such as COPY and RENAME for copying files and changing the names of files, respectively. The commands are accepted and executed by a part of the operating system called the command processor or command line interpreter. Graphical user interfaces allow you to enter commands by pointing and clicking at objects that appear on the screen.
An operating system (commonly abbreviated to either OS or O/S) is an interface between hardware and user. An OS is responsible for the management and coordination of activities and the sharing of the resources of the computer. The operating system acts as a host for computing applications run on the machine. As a host, one of the purposes of an operating system is to handle the details of the operation of the hardware. This relieves application programs from having to manage these details and makes it easier to write applications. Almost all computers (including handheld computers, desktop computers, supercomputers, video game consoles) as well as some robots, domestic appliances (dishwashers, washing machines), and portable media players use an operating system of some type.[1] Some of the oldest models may however use an embedded operating system, that may be contained on a compact disk or other data storage device.
Operating systems offer a number of services to application programs and users. Applications access these services through application programming interfaces (APIs) or system calls. By invoking these interfaces, the application can request a service from the operating system, pass parameters, and receive the results of the operation. Users may also interact with the operating system with some kind of software user interface (UI) like typing commands by using command line interface (CLI) or using a graphical user interface (GUI, commonly pronounced “gooey”). For hand-held and desktop computers, the user interface is generally considered part of the operating system. On large multi-user systems like Unix and Unix-like systems, the user interface is generally implemented as an application program that runs outside the operating system. (Whether the user interface should be included as part of the operating system is a point of contention.)
Types of Operating Systems Within the broad family of operating systems, there are generally four types, categorized based on the types of computers they control and the sort of applications they support. The categories are:
* Real-time operating system (RTOS) - Real-time operating systems are used to control machinery, scientific instruments and industrial systems. An RTOS typically has very little user- interface capability, and no end-user utilities, since the system will be a "sealed box" when delivered for use. A very important part of an RTOS is managing the resources of the computer so that a particular operation executes in precisely the same amount of time, every time it occurs. In a complex machine, having a part move more quickly just because system resources are available may be just as catastrophic as having it not move at all because the system is busy.
* Single-user, single task - As the name implies, this operating system is designed to manage the computer so that one user can effectively do one thing at a time. The Palm OS for Palm handheld computers is a good example of a modern single-user, single-task operating system.
* Single-user, multi-tasking - This is the type of operating system most people use on their desktop and laptop computers today. Microsoft's Windows and Apple's MacOS platforms are both examples of operating systems that will let a single user have several programs in operation at the same time. For example, it's entirely possible for a Windows user to be writing a note in a word processor while downloading a file from the Internet while printing the text of an e-mail message.
* Multi-user - A multi-user operating system allows many different users to take advantage of the computer's resources simultaneously. The operating system must make sure that the requirements of the various users are balanced, and that each of the programs they are using has sufficient and separate resources so that a problem with one user doesn't affect the entire community of users. Unix, VMS and mainframe operating systems, such as MVS, are examples of multi-user operating systems.
Photo courtesy Apple Mac OS X Panther screen shot
It's important to differentiate between multi-user operating systems and single-user operating systems that support networking. Windows 2000 and Novell Netware can each support hundreds or thousands of networked users, but the operating systems themselves aren't true multi-user operating systems. The system administrator is the only "user" for Windows 2000 or Netware. The network support and all of the remote user logins the network enables are, in the overall plan of the operating system, a program being run by the administrative user.
When you turn on the power to a computer, the first program that runs is usually a set of instructions kept in the computer's read-only memory (ROM). This code examines the system hardware to make sure everything is functioning properly. This power-on self test (POST) checks the CPU, memory, and basic input-output systems (BIOS) for errors and stores the result in a special memory location. Once the POST has successfully completed, the software loaded in ROM (sometimes called the BIOS or firmware) will begin to activate the computer's disk drives. In most modern computers, when the computer activates the hard disk drive, it finds the first piece of the operating system: the bootstrap loader.
The bootstrap loader is a small program that has a single function: It loads the operating system into memory and allows it to begin operation. In the most basic form, the bootstrap loader sets up the small driver programs that interface with and control the various hardware subsystems of the computer. It sets up the divisions of memory that hold the operating system, user information and applications. It establishes the data structures that will hold the myriad signals, flags and semaphores that are used to communicate within and between the subsystems and applications of the computer. Then it turns control of the computer over to the operating system.
The operating system's tasks, in the most general sense, fall into six categories:
* Processor management * Memory management * Device management * Storage management * Application interface * User interface
A single process can have multiple threads that share global data and address space with other threads running in the same process, and therefore can operate on the same data set easily. Processes do not share address space and a different mechanism must be used if they are to share data.
If we consider running a word processing program to be a process, then the auto-save and spell check features that occur in the background are different threads of that process which are all operating on the same data set (your document). process
In computing, a process is an instance of a computer program that is being sequentially executed[1] by a computer system that has the ability to run several computer programs concurrently.
Thread
A single process may contain several executable programs (threads) that work together as a coherent whole. One thread might, for example, handle error signals, another might send a message about the error to the user, while a third thread is executing the actual task of the...
NETWORK ------
Introduction
The network allows computers to communicate with each other and share resources and information. The Advanced Research Projects Agency (ARPA) designed "Advanced Research Projects Agency Network" (ARPANET) for the United States Department of Defense. It was the first computer network in the world in late 1960s and early 1970s.[1] [edit] Network classification
The following list presents categories used for classifying networks.
[edit] Connection method
Computer networks can also be classified according to the hardware and software technology that is used to interconnect the individual devices in the network, such as Optical fiber, Ethernet, Wireless LAN, HomePNA, Power line communication or G.hn. Ethernet uses physical wiring to connect devices. Frequently deployed devices include hubs, switches, bridges and/or routers.
Wireless LAN technology is designed to connect devices without wiring. These devices use radio waves or infrared signals as a transmission medium.
ITU-T G.hn technology uses existing home wiring (coaxial cable, phone lines and power lines) to create a high-speed (up to 1 Gigabit/s) local area network.
Wired Technologies
Twisted-Pair Wire - This is the most widely used medium for telecommunication. Twisted-pair wires are ordinary telephone wires which consist of two insulated copper wires twisted into pairs and are used for both voice and data transmission. The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction. The transmission speed range from 2 million bits per second to 100 million bits per second.
Coaxial Cable – These cables are widely used for cable television systems, office buildings, and other worksites for local area networks. The cables consist of copper or aluminum wire wrapped with insulating layer typically of a flexible material with a high dielectric constant, all of which are surrounded by a conductive layer. The layers of insulation help minimize interference and distortion. Transmission speed range from 200 million to more than 500 million bits per second.
Fiber Optics – These cables consist of one or more thin filaments of glass fiber wrapped in a protective layer. It transmits light which can travel over long distance and higher bandwidths. Fiber-optic cables are not affected by electromagnetic radiation. Transmission speed could go up to as high as trillions of bits per second. The speed of fiber optics is hundreds of times faster than coaxial cables and thousands of times faster than twisted-pair wire.
Wireless Technologies
Terrestrial Microwave – Terrestrial microwaves use Earth-based transmitter and receiver. The equipment look similar to satellite dishes. Terrestrial microwaves use low-gigahertz range, which limits all communications to line-of-sight. Path between relay stations spaced approx. 30 miles apart. Microwave antennas are usually placed on top of buildings, towers, hills, and mountain peaks.
Communications Satellites – The satellites use microwave radio as their telecommunications medium which are not deflected by the Earth's atmosphere. The satellites are stationed in space, typically 22,000 miles above the equator. These Earth-orbiting systems are capable of receiving and relaying voice, data, and TV signals.
Cellular and PCS Systems – Use several radio communications technologies. The systems are divided to different geographic area. Each area has low-power transmitter or radio relay antenna device to relay calls from one area to the next area.
Wireless LANs – Wireless local area network use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology. Wireless LANS use spread spectrum technology to enable communication between multiple devices in a limited area. Example of open-standard wireless radio-wave technology is IEEE 802.11b.
Bluetooth – A short range wireless technology. Operate at approx. 1Mbps with range from 10 to 100 meters. Bluetooth is an open wireless protocol for data exchange over short distances.
The Wireless Web – The wireless web refers to the use of the World Wide Web through equipments like cellular phones, pagers, PDAs, and other portable communications devices. The wireless web service offers anytime/anywhere connection.
[edit] Scale
Networks are often classified as Local Area Network (LAN), Wide Area Network (WAN), Metropolitan Area Network (MAN), Personal Area Network (PAN), Virtual Private Network (VPN), Campus Area Network (CAN), Storage Area Network (SAN), etc. depending on their scale, scope and purpose. Usage, trust levels and access rights often differ between these types of network - for example, LANs tend to be designed for internal use by an organization's internal systems and employees in individual physical locations (such as a building), while WANs may connect physically separate parts of an organization to each other and may include connections to third parties.
[edit] Functional relationship (network architecture)
Computer networks may be classified according to the functional relationships which exist among the elements of the network, e.g., Active Networking, Client-server and Peer-to-peer (workgroup) architecture.
[edit] Network topology
Computer networks may be classified according to the network topology upon which the network is based, such as bus network, star network, ring network, mesh network, star-bus network, tree or hierarchical topology network. Network topology signifies the way in which devices in the network see their logical relations to one another. The use of the term "logical" here is significant. That is, network topology is independent of the "physical" layout of the network. Even if networked computers are physically placed in a linear arrangement, if they are connected via a hub, the network has a Star topology, rather than a bus topology. In this regard the visual and operational characteristics of a network are distinct; the logical network topology is not necessarily the same as the physical layout. Networks may be classified based on the method of data used to convey the data, these include digital and analog networks. [edit] Types of networks
Below is a list of the most common types of computer networks in order of scale.
[edit] Personal area network
A personal area network (PAN) is a computer network used for communication among computer devices close to one person. Some examples of devices that are used in a PAN are printers, fax machines, telephones, PDAs and scanners. The reach of a PAN is typically about 20-30 feet (approximately 6-9 meters), but this is expected to increase with technology improvements.
[edit] Local area network
A local area network (LAN) is a computer network covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport. Current wired LANs are most likely to be based on Ethernet technology, although new standards like ITU-T G.hn also provide a way to create a wired LAN using existing home wires (coaxial cables, phone lines and power lines)[2].
For example, a library may have a wired or wireless LAN for users to interconnect local devices (e.g., printers and servers) and to connect to the internet. On a wired LAN, PCs in the library are typically connected by category 5 (Cat5) cable, running the IEEE 802.3 protocol through a system of interconnected devices and eventually connect to the Internet. The cables to the servers are typically on Cat 5e enhanced cable, which will support IEEE 802.3 at 1 Gbit/s. A wireless LAN may exist using a different IEEE protocol, 802.11b, 802.11g or possibly 802.11n. The staff computers (bright green in the figure) can get to the color printer, checkout records, and the academic network and the Internet. All user computers can get to the Internet and the card catalog. Each workgroup can get to its local printer. Note that the printers are not accessible from outside their workgroup. Typical library network, in a branching tree topology and controlled access to resources
All interconnected devices must understand the network layer (layer 3), because they are handling multiple subnets (the different colors). Those inside the library, which have only 10/100 Mbit/s Ethernet connections to the user device and a Gigabit Ethernet connection to the central router, could be called "layer 3 switches" because they only have Ethernet interfaces and must understand IP. It would be more correct to call them access routers, where the router at the top is a distribution router that connects to the Internet and academic networks' customer access routers.
The defining characteristics of LANs, in contrast to WANs (wide area networks), include their higher data transfer rates, smaller geographic range, and lack of a need for leased telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating the standardization of 40 and 100 Gbit/s.[3]
[edit] Campus area network
A campus area network (CAN) is a computer network made up of an interconnection of local area networks (LANs) within a limited geographical area. It can be considered one form of a metropolitan area network, specific to an academic setting. In the case of a university campus-based campus area network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls. A campus area network is larger than a local area network but smaller than a wide area network (WAN) (in some cases).
The main aim of a campus area network is to facilitate students accessing internet and university resources. This is a network that connects two or more LANs but that is limited to a specific and contiguous geographical area such as a college campus, industrial complex, office building, or a military base. A CAN may be considered a type of MAN (metropolitan area network), but is generally limited to a smaller area than a typical MAN. This term is most often used to discuss the implementation of networks for a contiguous area. This should not be confused with a Controller Area Network. A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a LAN will span a group of nearby buildings.
[edit] Metropolitan area network
A metropolitan area network (MAN) is a network that connects two or more local area networks or campus area networks together but does not extend beyond the boundaries of the immediate town/city. Routers, switches and hubs are connected to create a metropolitan area network.
[edit] Wide area network
A wide area network (WAN) is a computer network that covers a broad area (i.e. any network whose communications links cross metropolitan, regional, or national boundaries [1]). Less formally, a WAN is a network that uses routers and public communications links Contrast with personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs), which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively. The largest and most well-known example of a WAN is the Internet. A WAN is a data communications network that covers a relatively broad geographic area (i.e. one city to another and one country to another country) and that often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer.
[edit] Global area network
A global area networks (GAN) (see also IEEE 802.20) specification is in development by several groups, and there is no common definition. In general, however, a GAN is a model for supporting mobile communications across an arbitrary number of wireless LANs, satellite coverage areas, etc. The key challenge in mobile communications is "handing off" the user communications from one local coverage area to the next. In IEEE Project 802, this involves a succession of terrestrial WIRELESS local area networks (WLAN).[4]
[edit] Virtual private network
A virtual private network (VPN) is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network (e.g., the Internet) instead of by physical wires. The data link layer protocols of the virtual network are said to be tunneled through the larger network when this is the case. One common application is secure communications through the public Internet, but a VPN need not have explicit security features, such as authentication or content encryption. VPNs, for example, can be used to separate the traffic of different user communities over an underlying network with strong security features. A VPN may have best-effort performance, or may have a defined service level agreement (SLA) between the VPN customer and the VPN service provider. Generally, a VPN has a topology more complex than point-to-point.
A VPN allows computer users to appear to be editing from an IP address location other than the one which connects the actual computer to the Internet.
[edit] Internetwork
An Internetwork is the connection of two or more distinct computer networks or network segments via a common routing technology. The result is called an internetwork (often shortened to internet). Two or more networks or network segments connected using devices that operate at layer 3 (the 'network' layer) of the OSI Basic Reference Model, such as a router. Any interconnection among or between public, private, commercial, industrial, or governmental networks may also be defined as an internetwork.
In modern practice, interconnected networks use the Internet Protocol. There are at least three variants of internetworks, depending on who administers and who participates in them:
* Intranet * Extranet * Internet
Intranets and extranets may or may not have connections to the Internet. If connected to the Internet, the intranet or extranet is normally protected from being accessed from the Internet without proper authorization. The Internet is not considered to be a part of the intranet or extranet, although it may serve as a portal for access to portions of an extranet.
[edit] Intranet
An intranet is a set of networks, using the Internet Protocol and IP-based tools such as web browsers and file transfer applications, that is under the control of a single administrative entity. That administrative entity closes the intranet to all but specific, authorized users. Most commonly, an intranet is the internal network of an organization. A large intranet will typically have at least one web server to provide users with organizational information.
[edit] Extranet
An extranet is a network or internetwork that is limited in scope to a single organization or entity but which also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities (e.g., a company's customers may be given access to some part of its intranet creating in this way an extranet, while at the same time the customers may not be considered 'trusted' from a security standpoint). Technically, an extranet may also be categorized as a CAN, MAN, WAN, or other type of network, although, by definition, an extranet cannot consist of a single LAN; it must have at least one connection with an external network.
[edit] Internet
The Internet consists of a worldwide interconnection of governmental, academic, public, and private networks based upon the networking technologies of the Internet Protocol Suite. It is the successor of the Advanced Research Projects Agency Network (ARPANET) developed by DARPA of the U.S. Department of Defense. The Internet is also the communications backbone underlying the World Wide Web (WWW). The 'Internet' is most commonly spelled with a capital 'I' as a proper noun, for historical reasons and to distinguish it from other generic internetworks.
Participants in the Internet use a diverse array of methods of several hundred documented, and often standardized, protocols compatible with the Internet Protocol Suite and an addressing system (IP Addresses) administered by the Internet Assigned Numbers Authority and address registries. Service providers and large enterprises exchange information about the reachability of their address spaces through the Border Gateway Protocol (BGP), forming a redundant worldwide mesh of transmission paths.
[edit] Basic hardware components
All networks are made up of basic hardware building blocks to interconnect network nodes, such as Network Interface Cards (NICs), Bridges, Hubs, Switches, and Routers. In addition, some method of connecting these building blocks is required, usually in the form of galvanic cable (most commonly Category 5 cable). Less common are microwave links (as in IEEE 802.12) or optical cable ("optical fiber"). An ethernet card may also be required.
[edit] Network interface cards
A network card, network adapter, or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network. It provides physical access to a networking medium and often provides a low-level addressing system through the use of MAC addresses.
[edit] Repeaters
A repeater is an electronic device that receives a signal and retransmits it at a higher power level, or to the other side of an obstruction, so that the signal can cover longer distances without degradation. In most twisted pair Ethernet configurations, repeaters are required for cable which runs longer than 100 meters.
[edit] Hubs
A network hub contains multiple ports. When a packet arrives at one port, it is copied unmodified to all ports of the hub for transmission. The destination address in the frame is not changed to a broadcast address.[5]
[edit] Bridges
A network bridge connects multiple network segments at the data link layer (layer 2) of the OSI model. Bridges do not promiscuously copy traffic to all ports, as hubs do, but learn which MAC addresses are reachable through specific ports. Once the bridge associates a port and an address, it will send traffic for that address only to that port. Bridges do send broadcasts to all ports except the one on which the broadcast was received.
Bridges learn the association of ports and addresses by examining the source address of frames that it sees on various ports. Once a frame arrives through a port, its source address is stored and the bridge assumes that MAC address is associated with that port. The first time that a previously unknown destination address is seen, the bridge will forward the frame to all ports other than the one on which the frame arrived.
Bridges come in three basic types: 1. Local bridges: Directly connect local area networks (LANs) 2. Remote bridges: Can be used to create a wide area network (WAN) link between LANs. Remote bridges, where the connecting link is slower than the end networks, largely have been replaced by routers. 3. Wireless bridges: Can be used to join LANs or connect remote stations to LANs.
[edit] Switches
A network switch is a device that forwards and filters OSI layer 2 datagrams (chunk of data communication) between ports (connected cables) based on the MAC addresses in the packets. [6] This is distinct from a hub in that it only forwards the packets to the ports involved in the communications rather than all ports connected. Strictly speaking, a switch is not capable of routing traffic based on IP address (OSI Layer 3) which is necessary for communicating between network segments or within a large or complex LAN. Some switches are capable of routing based on IP addresses but are still called switches as a marketing term. A switch normally has numerous ports, with the intention being that most or all of the network is connected directly to the switch, or another switch that is in turn connected to a switch.[7]
Switch is a marketing term that encompasses routers and bridges, as well as devices that may distribute traffic on load or by application content (e.g., a Web URL identifier). Switches may operate at one or more OSI model layers, including physical, data link, network, or transport (i.e., end-to-end). A device that operates simultaneously at more than one of these layers is called a multilayer switch.
Overemphasizing the ill-defined term "switch" often leads to confusion when first trying to understand networking. Many experienced network designers and operators recommend starting with the logic of devices dealing with only one protocol level, not all of which are covered by OSI. Multilayer device selection is an advanced topic that may lead to selecting particular implementations, but multilayer switching is simply not a real-world design concept.
[edit] Routers
A router is a networking device that forwards packets between networks using information in protocol headers and forwarding tables to determine the best next router for each packet. Routers work at the Network Layer of the OSI model and the Internet Layer of TCP/IP.
ISO OSI Reference Model
A set of protocols is open if:
* protocol details are publicly available * changes are managed by an organization whose membership and transactions are open to the public
A system that implements open protocols is called an open system.
International Organization for Standards (ISO) prescribes a standard to connect open systems
* open system interconnect (OSI)
Figure 6: The (OSI) Seven Layer Model Physical Layer
Specification of voltage levels, cables, connectors, timing of bots, electrical access and maintenance of circuit (i.e. corresponds to the basic hardware).
Data Link Layer
Transforms basic physical services to enable the transmission of units of data called frames. Frames carry data between two points on the same type of physical network, and maybe relayed if the network is extended. They normally contain low level addressing information and some error checking. This layer may be involved in arbitrating access to the physical network. The Data Link layer detects, and possibly corrects errors in the physical layer
Network
Controls routing of data by providing an address domain, and in consequence the routing of messages. This addressing is separate from the hardware which implements the network connections. i.e. specifies how addresses are assigned and how packets are forwarded from one end of the network to another.
Transport
Provides an interface for the upper layers to communications facilities. The presence of this layer obscures the underlying network hardware and topology from the applications. A very complex set of protocols are required for this layer!
Session
The protocols for this layer specify how to establish a communication session with a remote System (e.g., How to login to a remote timesharing computer). Specifications for security details such as authentication using passwords are described in this layer.
Presentation
Layer 6 protocols specify how to represent data. Such protocols are needed because different brands of computer use different internal representation for integer and characters. Thus layer 6 protocols are needed to translate from the representation on one computer to the representation on another.
Application Layer
This is where the application using the network resides. Common network applications include remote login, file transfer, e-mail, and web page browsing.
DATABASE ------A database is an integrated collection of logically related records or files which consolidates records into a common pool of data records that provides data for many applications. A database is a collection of information that is organized so that it can easily be accessed, managed, and updated.
In one view, databases can be classified according to types of content: bibliographic, full-text, numeric, and images. The data in a database is organized according to a database model. The model that is most commonly used today is the relational model. Other models such as the hierarchical model and the network model use a more explicit representation of relationships. database is a collection of information that is organized so that it can easily be accessed, managed, and updated. In one view, databases can be classified according to types of content: bibliographic, full-text, numeric, and images.
Ask your database questions at ITKnowledgeExchange.com
In computing, databases are sometimes classified according to their organizational approach. The most prevalent approach is the relational database, a tabular database in which data is defined so that it can be reorganized and accessed in a number of different ways. A distributed database is one that can be dispersed or replicated among different points in a network. An object-oriented programming database is one that is congruent with the data defined in object classes and subclasses.
a "minicomputer" is a powerful computer that can support many users at once. A "mainframe" is a large, high-powered computer that can perform billions of calculations from multiple sources at one time. Finally, a "supercomputer" is a machine that can process billions of instructions a second and is used to calculate extremely complex calculations. A programmable machine. The two principal characteristics of a computer are: • It responds to a specific set of instructions in a well-defined manner. It can execute a prerecorded list of instructions (a program). Modern computers are electronic and digital. The actual machinery -- wires, transistors, and circuits -- is called hardware; the instructions and data are called software. All general-purpose computers require the following hardware components: • memory : Enables a computer to store, at least temporarily, data and programs. • mass storage device : Allows a computer to permanently retain large amounts of data. Common mass storage devices include disk drives and tape drives. • input device : Usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a computer. • output device : A display screen, printer, or other device that lets you see what the computer has accomplished. • central processing unit (CPU): The heart of the computer, this is the component that actually executes instructions. In addition to these components, many others make it possible for the basic components to work together efficiently. For example, every computer requires a bus that transmits data from one part of the computer to another. Computers can be generally classified by size and power as follows, though there is considerable overlap: • personal computer : A small, single-user computer based on a microprocessor. In addition to the microprocessor, a personal computer has a keyboard for entering data, a monitor for displaying information, and a storage device for saving data. • workstation : A powerful, single-user computer. A workstation is like a personal computer, but it has a more powerful microprocessor and a higher- quality monitor. • minicomputer : A multi-user computer capable of supporting from 10 to hundreds of users simultaneously. • mainframe : A powerful multi-user computer capable of supporting many hundreds or thousands of users simultaneously. • supercomputer : An extremely fast computer that can perform hundreds of millions of instructions per second.
JAVA
Before you can develop an application written in the Java programming language, you will need the Java Platform Standard Edition (Java SE) development kit. It has the necessary Java Virtual Machine1 (JVM), core Application Programming Interfaces (API)s, and the compiler you'll need for most and perhaps all of your development. Note: Mac users should go to Apple's Mac OS X Java Runtime Environment. Then return for Java programming information and tutorials. If you are used to working in an Integrated Development Environment (IDE) or want to learn, you can download Java SE with the NetBeans IDE. For some projects, you'll want additional bundles. Some of the more popular downloads are listed below. If you're not certain what you need, start with Java SE. You'll discover other tools as you become familiar with the Java platform. Java SE : This kit is necessary for developing all applications, except those designed for consumer devices (See the Micro Edition). Java SE comes bundled with the compiler, a runtime environment, and core API. Java Platform Enterprise Edition (Java EE) : This packages includes an application server, web server, J2EE APIs, support for Enterprise JavaBeans, Java Servlets API, and JavaServer Pages (JSP) technology. Use J2EE with the Java SE. Java Platform Micro Edition (Java ME) : If you are interested in developing programs for Palm Pilots, screen phones, and other consumer devices, this kit provides tools for compiling, deployment and device configuration, and APIs that are specialized for each type of device. JavaFX Script Technology is a highly productive scripting language that enables content developers to create rich media and content for deployment on Java environments. The development kits above include the APIs necessary to whatever type of applications you develop in the Java programming language. The APIs and compiler are explained briefly below. Java APIs are libraries of compiled code let you add ready-made and customizable functionality to your programs to save coding time. Java programs are executed within a program called the JVM. Rather than running directly on the native operating system, the program is interpreted by the JVM for the native operating system. This is key to making your programs portable from one platform to another. In other words, you can develop your programs on a Solaris, Linux, Macintosh, or Windows, then run it on another server or platform. Once you have the development kits you need, you are ready to begin writing code in the Java programming language. Programs are written in three basic flavors: applets, applications, and servlets/JSP pages. Applets run in the JVM built into a web browser; applications run in the JVM installed on a computer system; and servlets/JSP run in the JVM installed on a web server. While applets and applications usually have some kind of user interface coupled to backend functionality, servlets provide backend functionality only. The user interface for a servlet is usually an HTML form in a browser that invokes the servlet, but any applet or application that opens a hypertext transfer protocol (HTTP) request can call a servlet. JSP, on the other hand, combines the servlet and HTML into a single component. Instead of using an HTML page with a separate servlet, you use an HTML page with regular HTML tags in combination with scriptlets, short bits of code. The entire page is then processed into a servlet when it's accessed or submitted and the results return to the same HTML page that contains the code. You can also program using a simple text editor, and compile and run from the command line. Many text editors now come with the ability to run and compile Java files, but you may need to tell the program where javac.exe and java.exe reside on your computer. Use the Windows Find command, if you are unsure where these files were installed. Once, your IDE or text editor is set up, you can begin programming. Next, copy and paste the following programs, and invoke the compiler and interpreter either at the command line or within the IDE you're using. The following three examples use the javac and java commands and illustrate how to compile and run an application, applet, and servlet. When compiling and running from the command line, be sure to cd into the directory where you saved your .java file. Application Compile the ExampleProgram.java application with the javac command and run it with the java command. //A Very Simple Example class ExampleProgram {
public static void main(String[] args){
System.out.println("I'm a Simple Program"); } } Compile and then run with the following commands: javac ExampleProgram.java java ExampleProgram Applet Copy the SimpleApplet.java applet code, and compile with the javac command: import java.applet.Applet; import java.awt.Graphics; import java.awt.Color; public class SimpleApplet extends Applet{
String text = "I'm a simple applet";
public void init() { text = "I'm a simple applet"; setBackground(Color.cyan); }
public void start() { System.out.println("starting..."); }
public void stop() { System.out.println("stopping..."); }
public void destroy() { System.out.println("preparing to unload..."); }
public void paint(Graphics g){ System.out.println("Paint"); g.setColor(Color.blue); g.drawRect(0, 0, getSize().width -1, getSize().height -1); g.setColor(Color.red); g.drawString(text, 15, 25); } }
Compile: javac SimpleApplet.java You can run the applet in appletviewer (a Java platform tool for running applets independently of the browser) or in the browser. Either way you need an HTML file for the applet. Here is the HTML file:
To run the applet in the browser, you load the HTML file. To run the applet in appletviewer with an HTML file named simple.html, type this in an MS-DOS window on Windows, or in a terminal window on Solaris: appletviewer simple.html Servlet As mentioned above, to compile and run a servlet, you need to use either NetBeans or Sun Java Studio Creator. Then compile with the javac command. import java.io.*; import javax.servlet.*; import javax.servlet.http.*;
public class ExampServlet extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); out.println("
out.println("
Button Clicked
");String DATA = request.getParameter("DATA");
if(DATA != null){ out.println(DATA); } else { out.println("No text entered."); }
out.println("
Return to Form"); out.close(); } } To compile: javac ExampServlet.java Servlets can be called directly by typing their uniform resource locator (URL) into a browser's location window after you've started the server. Servlets can also be invoked from an HTML form by specifying their URL in the definition for a Submit button, for example. Servlets can be called by any program that can open an hypertext transfer protocol (HTTP) request.
JavaServer Pages, JDBC, RMI, JDK--Java technology names and acronyms can be confusing for newcomers and experienced developers. This article defines the most common Java terminology in easy-to-scan, alphabetical order, and provides links for more information and downloads. This list is not a complete list of Sun's products for the Java platform, and is subject to change and updates.. Java Definition More Information Terminology Abstract AWT is a package of classes for AWT Fundamentals Window creating components such as Toolkit (AWT) buttons, menus, and scrollbars for Package java.awt applets and standalone Description applications. AWT Forums
Applet An applet is a Java program that Building Applets runs within the web browser. Applets use a graphical user Trail: Writing Applets interface and may have text, Package java.applet images, buttons, scrollbars, and Class JApplet sound. HotSpot VM On platforms typically used for Performance client applications, the JDK comes Documentation for the with a VM implementation called Java HotSpot VM the Java HotSpot Client VM (client Java HotSpot VM FAQ VM). The client VM is tuned for reducing start-up time and memory footprint. It can be invoked by using the -client command-line option when launching an application. The JDK also comes with an implementation of the Java virtual machine called the Java HotSpot Server VM (server VM). The server VM is designed for maximum program execution speed. It can be invoked by using the -server command-line option when launching an application.
Java Advanced The JAI API provides a set of What is Java Advanced Imaging (JAI) object-oriented interfaces that Imaging? API support a simple, high-level programming model which lets Java Advanced Imaging you manipulate images easily, and API FAQ JAI broadens the reach of the Java Java Advanced Imaging platform to allow sophisticated, API Collateral high performance image processing functionality to be incorporated into Java applets and applications. Java API The Java Application Download Java 2 Programming Interface (API) is Platform Standard prewritten code, organized into Edition 5.0 packages of similar topics. For instance, the Applet and AWT API Documentation packages include classes for Online Training and creating fonts, menus, and buttons. Tutorials The full Java API is included in the Technical Articles Java 2 Standard Edition download. Building an Application
Java API for JAXP enables applications to parse Java API for XML XML validate and transform XML Processing Tutorial Processing documents. The latest release is (JAXP) JAXP 1.3, which is part of J2SE JAXP - FAQ 5.0. An implementation that works The J2EE 1.4 Tutorial for earlier versions of J2SE is also available. Java JAAS is a set of APIs that enable Java Authentication and Authentication services to authenticate and Authorization Service and enforce access controls upon users. (JAAS)in Java 2, Authorization It implements a Java technology Standard Edition (J2SE) Services version of the standard Pluggable 1.4 (JAAS) Authentication Module (PAM) framework, and supports user- Overview based authorization. Java The Java Communications API can Java Communications Communicatio be used to write platform- API FAQ ns API independent communications applications for technologies such Java Communications API Users Guide as voice mail, fax, and smart cards. Java Communications Downloads
Java JCE is a set of packages that Java Communications Cryptography provides a framework and API FAQ Extension implementations for encryption, (JCE) key generation and key agreement, Java Cryptography and Message Authentication Code Extension (JCE) (MAC) algorithms. Support for How to Implement a encryption includes symmetric, Provider for the Java asymmetric, block, and stream Cryptography ciphers. The software also supports Extension 1.2.2 secure streams and sealed objects. Java JFC are a set of GUI components JFC/Swing Foundation and other services simplifying the Classes (JFC) development and deployment of Java Foundation desktop and Internet/Intranet Classes FAQ applications. The JFC are a Technical Articles superset that contains AWT. JFC Project Swing Forum extends AWT by adding many components and services. JFC Accessibility Forum consists of Swing, Java 2D, AWT, Accessibility, and the Drag-and- Drop APIs. Java Media JMF enables audio, video and JMF 2.1.1 - Supported FrameWork other time-based media to be Formats (JMF) added to applications and applets built on Java technology. This Java Media FrameWork optional package, which can FAQ capture, playback, stream, and transcode multiple media formats, extends the Java platform for multimedia developers by providing a powerful toolkit to develop scalable, cross-platform technology. Java Native JNI is the native programming Trail: Java Native Interface (JNI) interface for Java that is part of the Interface JDK. The JNI allows Java code to operate with applications and Chapter 5: JNI libraries written in other languages, Technology such as C, C++, and assembly. Java Native Interface Recommended only for advanced Specification programmers. Java 2 The J2EE platform provides a Java 2 Platform, Platform, component-based approach to the Enterprise Edition Enterprise design, development, assembly, Edition (J2EE) and deployment of enterprise J2EE Tutorial applications. The J2EE platform Downloads gives you a multitiered distributed Java BluePrints application model, the ability to reuse components, a unified Enterprise security model, and flexible JavaBeans(EJB) transaction control. Technology Fundamentals Java Programming Forums
Java 2 J2ME is targeted for the consumer Java 2 Platform Micro Platform, and embedded market. The API Edition (J2ME) Micro Edition specifications are based on J2SE, Technology (J2ME) but modified to meet the unique requirements of each product. Wireless Developer J2ME makes it possible to write Java Wireless Java applications for cell phones, Technology Discussions smart cards, pagers, and other consumer devices. Java 2 J2SE includes the essential Java 2 Platform, Platform, compiler, tools, runtimes, and APIs Standard Edition (J2SE) Standard for writing, deploying, and running Edition (J2SE) applets and applications in the Java Online Documentation programming language. Introducing the Java Platform Getting Started
Java 3D API The Java 3D API provides a set of Java 3D API object-oriented interfaces that support a simple, high-level Java 3D 1.3.1 API programming model you can use to Features build, render, and control the behavior of 3D objects and visual environments. With the Java 3D API, you can incorporate high- quality, scalable, platform- independent 3D graphics into applications and applets based on Java technology. Java Virtual The JVM executes instructions that 1 The Java Virtual Machine a Java compiler generates. This Machine Specification (JVM) runtime environment, or JVM, is embedded in various products, Ergonomics in the 5.0 such as web browsers, servers, and Java Virtual Machine operating systems. Java Virtual Machine Forums
Java Web Start Using Java Web Start technology, Java Web Start FAQ standalone Java software applications can be deployed with Java Web Start a single click over the network. Architecture Java Web Start ensures the most Reference current version of the application Documentation will be deployed, as well as the correct version of the Java Runtime Environment (JRE). JavaBeans JavaBeans architecture provides a JavaBeans Technology way of designing reusable software components, that can be visually JavaBeans Technology: manipulated in builder tools. Unlocking The JavaBeans can be simple like BeanContext API buttons, or more complex like a JavaBeans Forums tool to access databases. JavaBeans FAQ
Javadoc Tool The Javadoc tool is used to See documentation generate API documentation in generated by the HTML format from doc comments Javadoc tool in source code. It can be downloaded only as part of the Javadoc Tool FAQ JDK download. How to Write Doc Comments for the Javadoc Tool
JavaHelp JavaHelp software is a full- JavaHelp System System featured, platform-independent, extensible help system that enables JavaHelp System User's you to incorporate online help in Guide applets, components, applications, operating systems, and devices. Authors can also use the JavaHelp software to deliver online documentation for the Web and corporate intranet. JavaServer JavaServer Faces technology JavaServer Faces Faces simplifies building user interfaces Technology Overview Technology for JavaServer applications. Developers of various skill levels JavaServer Faces FAQ can quickly build web applications Developing Web by assembling reusable UI Applications with components in a page, connecting JavaServer Faces these components to an application data source, and wiring client- Sun Java Studio Creator generated events to server-side event handlers. JavaServer Create dynamic web pages with JavaServer Pages Pages (JSP) JSP pages by embedding scriptlets Documentation (Java programming language code) with HTML. JSP pages process JavaServer Pages: A forms, perform calculations, or do Developer's Perspective anything else that can be written JavaServer Pages Book with the Java programming Excerpts language. To develop and test JSP JavaServer Pages pages, download NetBeans, or Sun Forums Java Studio Creator. Sun Java Studio Creator
JDBC JDBC is a Java API for executing JDBC Technology SQL statements. By using the JDBC API, you can access almost Lesson: Learn JDBC any data source, from relational Basics databases to spreadsheets to flat JDBC API Tutorial and files. J2SE includes the JDBC API. Reference, Third Edition JDBC Overview JDBC Forums
JDK JDK is the short-cut name for the Download JDK 5.0 set of Java development tools, consisting of the API classes, a Online Documentation Java compiler, and the Java virtual Introducing the Java machine interpreter, regardless of Platform which version. The JDK is used to Getting Started compile Java applications and applets. The most current version is the J2SE., the preferred term these days. If you use J2SE 1.2 and later to develop applications, you are using what's known as the Java 2 Platform. JINI The Jini network technology Jini Network enables any service--from Technology enterprise systems to kitchen appliances--to network smoothly Distributed Events in and simply. The Jini architecture Jini lets each service (device or Technology software) tell others how to talk to How to Attach a User it, without any administrator Interface to a Jini settings. Service Core Jini
Project Swing The javax.swing package of Java Foundation classes is used to create GUI Classes components for applets and applications. Project Swing classes Fundamentals of enable programmers to specify a JFC/Swing: Part I different look and feel for each Fundamentals of platform, or a uniform look across JFC/Swing: Part II all platforms. Swing is the project Creating GUI with code name for the lightweight GUI JFC/Swing components in Java Foundation Classes (JFC). Project Swing: Building a User Interface Project Swing Forums
RMI RMI lets Java applications Java Remote Invocation communicate across a network. (RMI) The communicating applications can be running on different Fundamentals of RMI computers on opposite sides of the Short Course planet. This higher-level and RMI-IIOP method-based approach to network Documentation communications allows access to a Lesson 8: Remote remote object as easily as a local Method Invocation object. Servlets A servlet is an extension to a server Java Servlet that enhances the server's Technology functionality. Servlets are most commonly used to process forms, The Java Servlet API handle redirects or authenticate White Paper user names and passwords, and Lesson 5: Writing create dynamic content. To Servlets develop and test servlets, Story of a Servlet: An download NetBeans, or Sun Java Instant Tutorial Studio Creator. Fundamentals of Java Servlets Java Servlet Technology Forum C is a programming language originally developed for developing the Unix operating system. It is a low-level and powerful language, but it lacks many modern and useful constructs. C++ is a newer language, based on C, that adds many more modern programming language features that make it easier to program than C.
Basically, C++ maintains all aspects of the C language, while providing new features to programmers that make it easier to write useful and sophisticated programs.
For example, C++ makes it easier to manage memory and adds several features to allow "object-oriented" programming and "generic" programming. Basically, it makes it easier for programmers to stop thinking about the nitty-gritty details of how the machine works and think about the problems they are trying to solve.
So, what is C++ used for? C++ is a powerful general-purpose programming language. It can be used to create small programs or large applications. It can be used to make CGI scripts or console-only DOS programs. C++ allows you to create programs to do almost anything you need to do. The creator of C++, Bjarne Stroustrup, has put together a partial list of applications written in C++.Your continued donations keep Wikipedia running! Oracle Database From Wikipedia, the free encyclopedia Jump to: navigation, search Oracle Database
Developer(s) Oracle Corporation Stable release 11g R2 / 2009-09-01; 2 months ago Written in C Operating Cross-platform system Available in Multiple languages Type RDBMS License Proprietary Website http://www.oracle.com/ The Oracle Database (commonly referred to as Oracle RDBMS or simply Oracle) is a relational database management system (RDBMS) produced and marketed by Oracle Corporation. As of 2009, Oracle remains a major presence in database computing.[1] Larry Ellison and his friends and former co-workers Bob Miner and Ed Oates started the consultancy Software Development Laboratories (SDL) in 1977. SDL developed the original version of the Oracle software. The name Oracle comes from the code-name of a CIA-funded project Ellison had worked on while previously employed by Ampex.[2]
Contents [hide] 1 Physical and logical structures o 1.1 Storage 1.1.1 Disk files 1.1.1.1 Data files 1.1.1.2 Control files o 1.2 Database schema o 1.3 Memory architecture 1.3.1 System Global Area 1.3.2 Library cache 1.3.3 Data dictionary cache 1.3.4 Program Global Area o 1.4 Process architectures 1.4.1 Oracle processes 1.4.2 User processes, connections and sessions o 1.5 Concurrency and locking o 1.6 Configuration 2 Internationalization 3 History o 3.1 Corporate/technical timeline o 3.2 Version numbering o 3.3 List of claimed firsts 4 Editions 5 Host platforms 6 Related software o 6.1 Database options o 6.2 Suites o 6.3 Database "features" o 6.4 Standalone tools o 6.5 Other databases marketed by Oracle Corporation 7 Using Oracle Database software o 7.1 Official support o 7.2 Database-related guidelines o 7.3 Oracle Certification Program o 7.4 User groups 8 Market position o 8.1 Competition o 8.2 Pricing 9 See also 10 References 11 Bibliography 12 External links
[edit] Physical and logical structures An Oracle database system — identified by an alphanumeric system identifier or SID[3] — comprises at least one instance of the application, along with data storage. An instance — identified persistently by an instantiation number (or activation id: SYS.V_$DATABASE.ACTIVATION#) — comprises a set of operating-system processes and memory-structures that interact with the storage. Typical processes include PMON (the process monitor) and SMON (the system monitor). Users of the Oracle databases refer to the server-side memory-structure as the SGA (System Global Area). The SGA typically holds cache information such as data-buffers, SQL commands, and user information. In addition to storage, the database consists of online redo logs (or logs), which hold transactional history. Processes can in turn archive the online redo logs into archive logs (offline redo logs), which provide the basis (if necessary) for data recovery and for some forms of data replication. If the Oracle database administrator has implemented Oracle RAC (Real Application Clusters), then multiple instances, usually on different servers, attach to a central storage array. This scenario offers advantages such as better performance, scalability and redundancy. However, support becomes more complex, and many sites do not use RAC. In version 10g, grid computing introduced shared resources where an instance can use (for example) CPU resources from another node (computer) in the grid. The Oracle DBMS can store and execute stored procedures and functions within itself. PL/SQL (Oracle Corporation's proprietary procedural extension to SQL), or the object- oriented language Java can invoke such code objects and/or provide the programming structures for writing them. [edit] Storage The Oracle RDBMS stores data logically in the form of tablespaces and physically in the form of data files. Tablespaces can contain various types of memory segments, such as Data Segments, Index Segments, etc. Segments in turn comprise one or more extents. Extents comprise groups of contiguous data blocks. Data blocks form the basic units of data storage. Oracle database management tracks its computer data storage with the help of information stored in the SYSTEM tablespace. The SYSTEM tablespace contains the data dictionary — and often (by default) indexes and clusters. A data dictionary consists of a special collection of tables that contains information about all user-objects in the database. Since version 8i, the Oracle RDBMS also supports "locally managed" tablespaces which can store space management information in bitmaps in their own headers rather than in the SYSTEM tablespace (as happens with the default "dictionary- managed" tablespaces).
[edit] Disk files This section requires expansion.
[edit] Data files At the physical level, datafiles comprise one or more data blocks, where the block size can vary between datafiles. Datafiles can occupy pre-allocated space in the file system of a computer server, utilize raw disk directly, or exist within ASM logical volumes.[4]
[edit] Control files One (or multiple multiplexed) control files (also known as "controlfiles") store overall system information and statuses.[5] [edit] Database schema Oracle database conventions refer to defined groups of object ownership (generally associated with a "username") as schemas. Most Oracle database installations traditionally came with a default schema called SCOTT. After the installation process has set up the sample tables, the user can log into the database with the username scott and the password tiger. The name of the SCOTT schema originated with Bruce Scott, one of the first employees at Oracle (then Software Development Laboratories), who had a cat named Tiger.[6] Oracle Corporation has de-emphasized the use of the SCOTT schema, as it uses few of the features of the more recent releases of Oracle. Most recent examples supplied by Oracle Corporation reference the default HR or OE schemas. Other default schemas[7] include: SYS (essential core database structures and utilities) SYSTEM (additional core database structures and utilities, and privileged account) OUTLN (utilized to store metadata for stored outlines for stable query-optimizer execution plans.[8] BI, IX, HR, OE, PM, and SH (expanded sample schemas[9] containing more data and structures than the older SCOTT schema). [edit] Memory architecture
[edit] System Global Area Main article: System Global Area Each Oracle instance uses a System Global Area or SGA — a shared-memory area — to store its data and control-information.[10] Each Oracle instance allocates itself an SGA when it starts and de-allocates it at shut- down time. The information in the SGA consists of the following elements, each of which has a fixed size, established at instance startup: the database buffer cache: this stores the most recently-used data blocks. These blocks can contain modified data not yet written to disk (sometimes known as "dirty blocks"), unmodified blocks, or blocks written to disk since modification (sometimes known as clean blocks). Because the buffer cache keeps blocks based on a most-recently-used algorithm, the most active buffers stay in memory to reduce I/O and to improve performance. the redo log buffer: this stores redo entries — a log of changes made to the database. The instance writes redo log buffers to the redo log as quickly and efficiently as possible. The redo log aids in instance recovery in the event of a system failure. the shared pool: this area of the SGA stores shared-memory structures such as shared SQL areas in the library cache and internal information in the data dictionary. An insufficient amount of memory allocated to the shared pool can cause performance degradation.
[edit] Library cache The library cache[11] stores shared SQL, caching the parse tree and the execution plan for every unique SQL statement. If multiple applications issue the same SQL statement, each application can access the shared SQL area. This reduces the amount of memory needed and reduces the processing- time used for parsing and execution planning.
[edit] Data dictionary cache The data dictionary comprises a set of tables and views that map the structure of the database. Oracle databases store information here about the logical and physical structure of the database. The data dictionary contains information such as: user information, such as user privileges integrity constraints defined for tables in the database names and datatypes of all columns in database tables information on space allocated and used for schema objects The Oracle instance frequently accesses the data dictionary in order to parse SQL statements. The operation of Oracle depends on ready access to the data dictionary: performance bottlenecks in the data dictionary affect all Oracle users. Because of this, database administrators should make sure that the data dictionary cache[12] has sufficient capacity to cache this data. Without enough memory for the data-dictionary cache, users see a severe performance degradation. Allocating sufficient memory to the shared pool where the data dictionary cache resides precludes these particular performance problems.
[edit] Program Global Area The Program Global Area[13][14] or PGA memory-area of an Oracle instance contains data and control-information for Oracle's server-processes. The size and content of the PGA depends on the Oracle-server options installed. This area consists of the following components: stack-space: the memory that holds the session's variables, arrays, and so on. session-information: unless using the multithreaded server, the instance stores its session-information in the PGA. (In a multithreaded server, the session- information goes in the SGA.) private SQL-area: an area in the PGA which holds information such as bind- variables and runtime-buffers. sorting area: an area in the PGA which holds information on sorts, hash-joins, etc. [edit] Process architectures
[edit] Oracle processes The Oracle RDBMS typically relies on a group of processes running simultaneously in the background and interacting to monitor and expedite database operations. Typical operating groups might include some of the following individual processes — (shown along with their abbreviated nomenclature):[15] archiver processes (ARCn) checkpoint process (CKPT) *REQUIRED* coordinator-of-job-queues process (CJQn): dynamically spawns slave processes for job-queues database writer processes (DBWn) *REQUIRED* dispatcher processes (Dnnn): multiplex server-processes on behalf of users memory-manager process (MMAN): used for internal database tasks such as Automatic Shared Memory Management log-writer process (LGWR) *REQUIRED* log-write network-server (LNSn): transmits redo logs in Data Guard environments logical standby coordinator process (LSP0): controls Data Guard log-application media-recovery process (MRP): detached recovery-server process memory-monitor process (MMON): process for automatic problem-detection, self-tuning and statistics-gathering[16] memory-monitor light process (MMNL): gathers and stores Automatic Workload Repository (AWR) data mmon slaves (Mnnnn — M0000, M0001, etc): background slaves of the MMON process[17] process-monitor process (PMON) *REQUIRED* process-spawner (PSP0): spawns Oracle processes queue-monitor processes (QMNn) recoverer process (RECO) remote file-server process (RFS) shared server processes (Snnn): serve client-requests system monitor process (SMON) *REQUIRED*
[edit] User processes, connections and sessions Oracle Database terminology distinguishes different computer-science terms in describing how end-users interact with the database: user processes involve the invocation of application software[18] a connection refers to the pathway linking a user process to an Oracle instance[19] sessions consist of specific connections to an Oracle instance.[20] Each session within an instance has a session identifier or "SID"[21] (distinct from the system- identifier SID). [edit] Concurrency and locking Oracle databases control simultaneous access to data resources with locks (alternatively documented as "enqueues"[22] ). The databases also utilize "latches" -- low-level serialization mechanisms to protect shared data structures in the System Global Area.[23] [edit] Configuration Database administrators control many of the tunable variations in an Oracle instance by means of values in a parameter file.[24] This file in its ASCII default form ("pfile") normally has a name of the format init
[edit] History [edit] Corporate/technical timeline This article is in a list format that may be better presented using prose. You can help by converting this article to prose, if appropriate. Editing help is available. (September 2009) 1977: Larry Ellison and friends founded Software Development Laboratories. 1979: SDL changed its company-name to "Relational Software, Inc." (RSI) and introduced its product Oracle V2 as an early commercially-available relational database system. The version did not support transactions, but implemented the basic SQL functionality of queries and joins. (RSI never released a version 1 - instead calling the first version version 2 as a marketing gimmick.)[31] 1982: RSI in its turn changed its name, becoming known as "Oracle Corporation", [32] to align itself more closely with its flagship product. 1983: The company released Oracle version 3, which it had re-written using the C programming language and which supported COMMIT and ROLLBACK functionality for transactions. Version 3 extended platform support from the existing Digital VAX/VMS systems to include Unix environments.[32] 1984: Oracle Corporation released Oracle version 4, which supported read- consistency. 1985: Oracle Corporation released Oracle version 5, which supported the client- server model — a sign of networks becoming more widely available in the mid- 1980s. 1986: Oracle version 5.1 started supporting distributed queries. 1988: Oracle RDBMS version 6 came out with support for PL/SQL embedded within Oracle Forms v3 (version 6 could not store PL/SQL in the database proper), row-level locking and hot backups.[33] 1989: Oracle Corporation entered the application products market and developed its ERP product, (later to become part of the Oracle E-Business Suite), based on the Oracle relational database. 1990: the release of Oracle Applications release 8[32] 1992: Oracle version 7 appeared with support for referential integrity, stored procedures and triggers. 1997: Oracle Corporation released version 8, which supported object-oriented development and multimedia applications. 1999: The release of Oracle8i aimed to provide a database inter-operating better with the Internet (the i in the name stands for "Internet"). The Oracle 8i database incorporated a native Java virtual machine (Oracle JVM). 2000: Oracle E-Business Suite 11i pioneers integrated enterprise application software[32] 2001: Oracle9i went into release with 400 new features, including the ability to read and write XML documents. 9i also provided an option for Oracle RAC, or "Real Application Clusters", a computer-cluster database, as a replacement for the Oracle Parallel Server (OPS) option. 2003: Oracle Corporation released Oracle Database 10g. (The g stands for "grid"; emphasizing a marketing thrust of presenting 10g as "grid-computing ready".) 2005: Oracle Database 10.2.0.1 — also known as Oracle Database 10g Release 2 (10gR2) — appeared. 2006: Oracle Corporation announces Unbreakable Linux [32] 2007: Oracle Database 10g release 2 sets a new world record TPC-H 3000 GB benchmark result[34] 2007: Oracle Corporation released Oracle Database 11g for Linux and for Microsoft Windows. 2008: Oracle Corporation acquires BEA Systems. 2009: Oracle Corporation acquires Sun Microsystems. Note: as of October 2009 the acquisition awaits approval from the European Council[citation needed]. [edit] Version numbering Oracle products have historically followed their own release-numbering and naming conventions. With the Oracle RDBMS 10g release, Oracle Corporation started standardizing all current versions of its major products using the "10g" label, although some sources continued to refer to Oracle Applications Release 11i as Oracle 11i. Major database-related products and some of their versions include: Oracle Application Server 10g (also known as "Oracle AS 10g"): a middleware product; Oracle Applications Release 11i (aka Oracle e-Business Suite, Oracle Financials or Oracle 11i): a suite of business applications; Oracle Developer Suite 10g (9.0.4); Oracle JDeveloper 10g: a Java integrated development environment; Since version 5, Oracle's RDBMS release numbering has used the following codes: Oracle5 Oracle6 Oracle7: 7.0.16 — 7.3.4 Oracle8 Database: 8.0.3 — 8.0.6 Oracle8i Database Release 1: 8.1.5.0 — 8.1.5.1 Oracle8i Database Release 2: 8.1.6.0 — 8.1.6.3 Oracle8i Database Release 3: 8.1.7.0 — 8.1.7.4 Oracle9i Database Release 1: 9.0.1.0 — 9.0.1.5 (patchset as of December 2003) Oracle9i Database Release 2: 9.2.0.1 — 9.2.0.8 (patchset as of April 2007) Oracle Database 10g Release 1: 10.1.0.2 — 10.1.0.5 (patchset as of February 2006) Oracle Database 10g Release 2: 10.2.0.1 — 10.2.0.4 (patchset as of April 2008) Oracle Database 11g Release 1: 11.1.0.6 — 11.1.0.7 (patchset as of September 2008) Oracle Database 11g Release 2: 11.2.0.1 (released 2009-09-01) The version-numbering syntax within each release follows the pattern: major.maintenance.application-server.component-specific.platform-specific. For example, "10.2.0.1 for 64-bit Solaris" means: 10th major version of Oracle, maintenance level 2, Oracle Application Server (OracleAS) 0, level 1 for Solaris 64-bit. The Oracle Administrator's Guide offers further information on Oracle release numbers. Oracle Corporation provides a table[35] showing the latest patch-set releases by major release, operating-system, and hardware-architecture. [edit] List of claimed firsts This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (December 2007) Oracle Corporation claims to have provided: the first commercially-available SQL-based database (1979)[36] the first database to support symmetric multiprocessing (SMP) (1983) the first distributed database (1986) the first database product tested to comply with the ANSI SQL standard (1993)[36] the first 64-bit database (1995) the first database to incorporate a native JRE (1998) the first proprietary RDBMS to become available on Linux (1998)[37] the first database to support XML (1999) [edit] Editions Over and above the different versions of the Oracle database management software, Oracle Corporation subdivides its product into varying "editions" - apparently for marketing and license-tracking reasons. In approximate order of decreasing scale, we find: Enterprise Edition[38] (EE) includes more features than the 'Standard Edition', especially in the areas of performance and security. Oracle Corporation licenses this product on the basis of users or of processors, typically for servers running 4 or more CPUs. EE has no memory limits, and can utilize clustering using Oracle RAC software. Standard Edition[39] (SE) contains base database functionality. Oracle Corporation licenses this product on the basis of users or of processors, typically for servers running from one to four CPUs. If the number of CPUs exceeds 4 CPUs, the user must convert to an Enterprise license. SE has no memory limits, and can utilize clustering with Oracle RAC at no additional charge. Standard Edition One,[40] introduced with Oracle 10g, has some additional feature- restrictions. Oracle Corporation markets it for use on systems with one or two CPUs. It has no memory limitations. Express Edition[41] ('Oracle Database XE'), introduced in 2005, offers Oracle 10g free to distribute on Windows and Linux platforms. It has a footprint of only 150 MB and is restricted[by whom?] to the use of a single CPU, a maximum of 4 GB of user data. Although it can install on a server with any amount of memory, it uses a maximum of 1 GB.[42] Support for this version comes exclusively through on-line forums and not through Oracle support. Oracle Database Lite,[43] intended for running on mobile devices. The database located on the mobile device can synchronize with a server-based installation.
[edit] Host platforms Prior to releasing Oracle9i in 2001, Oracle Corporation ported its database product to a wide variety of platforms. More recently Oracle Corporation has consolidated on a smaller range of operating-system platforms. As of October 2006, Oracle Corporation supported the following operating systems and hardware platforms for Oracle Database 10g: Apple Mac OS X Server: PowerPC HP HP-UX: PA-RISC, Itanium HP Tru64 UNIX: Alpha HP OpenVMS: Alpha, Itanium IBM AIX5L: IBM POWER IBM z/OS: zSeries Linux : x86, x86-64, PowerPC, zSeries, Itanium Microsoft Windows: x86, x86-64, Itanium Sun Solaris: SPARC, x86, x86-64
[edit] Related software For links to some of Oracle Corporation's software which integrates with Oracle databases, see the Oracle Corporation category and the Oracle software category pages. [edit] Database options Oracle Corporation refers to some extensions to the core functionality of the Oracle database as "database options".[44] As of 2008 such options include: Active Data Guard (extends Oracle Data Guard physical standby functionality in 11g) Advanced Security (adds data encryption methods) Content database (provides a centralized repository for unstructured information) Database Vault (enforces extra security on data access) Data Mining (ODM) (mines for patterns in existing data) In-Memory Database Cache (utilizes TimesTen technology) Label Security (enforces row-level security) Management Packs (various) Oracle Answers (for ad-hoc analysis and reporting) Oracle OLAP (adds analytical processing) Oracle Programmer (provides programmatic access to Oracle databases via precompilers, interfaces and bindings)[45] Partitioning (granularizes tables and indexes for efficiency) Real Application Clusters (RAC) (coordinates multiple database servers, together accessing the same database) Oracle Real Application Testing (new at version 11g) — including Database Replay (for testing workloads) and SQL Performance Analyzer (SPA) (for preserving SQL efficiency in changing environments)[46] Records database (a records management application) Oracle Spatial (integrates relational data with geographic information systems (GIS)) Transparent Gateway for connecting to non-Oracle systems. Offers optimized solution, with more functionality and better performance than Oracle Generic Connectivity. Total Recall (optimizes long-term storage of historical data) Oracle Warehouse Builder (in various forms and sub-options) This list is incomplete; you can help by expanding it. In most cases, using these options entails extra licensing costs.[47] [edit] Suites In addition to its RDBMS, Oracle Corporation has released several related suites of tools and applications relating to implementations of Oracle databases. For example: Oracle Application Server , a J2EE-based application server, aids in developing and deploying applications which utilise Internet technologies and a browser. Oracle Collaboration Suite contains messaging, groupware and collaboration applications. Oracle Developer Suite contains software development tools, including JDeveloper. Oracle E-Business Suite collects together applications for enterprise resource planning (including Oracle Financials), customer relationship management and human resources management (Oracle HR). Oracle Enterprise Manager (OEM) used by database administrators (DBAs) to manage the DBMS, and recently in version 10g, a web-based rewrite of OEM called "Oracle Enterprise Manager Database Control". Oracle Corporation has dubbed the super-Enterprise-Manager used to manage a grid of multiple DBMS and Application Servers "Oracle Enterprise Manager Grid Control". Oracle Programmer/2000, a bundling of interfaces for 3GL programming languages, marketed with Oracle7 and Oracle8.[48][49] [edit] Database "features" Apart from the clearly-defined database options, Oracle databases may include many semi-autonomous software sub-systems, which Oracle Corporation sometimes refers to as "features" in a sense subtly different from the normal usage of the word.[50] Such "features" may include (for example): Active Session History (ASH), the collection of data for immediate monitoring of very recent database activity.[51] Automatic Workload Repository (AWR) , providing monitoring services to Oracle database installations from Oracle version 10. Prior to the release of Oracle version 10, the Statspack facility provided similar functionality. Clusterware Data Aggregation and Consolidation Data Guard for high availability Generic Connectivity for connecting to non-Oracle systems. Data Pump utilities, which aid in importing and exporting data and metadata between databases[52] Database Resource Manager (DRM), which controls the use of computing resources.[53] Fine-grained auditing (FGA) (in Oracle Enterprise Edition[54]) supplements standard security-auditing features[55] Flashback for selective data recovery and reconstruction[56] iSQL*Plus , a web-browser-based graphical user interface (GUI) for Oracle database data-manipulation (compare SQL*Plus) Oracle Data Access Components (ODAC), tools which consist of:[57] o Oracle Data Provider for .NET (ODP.NET)[58] o Oracle Developer Tools (ODT) for Visual Studio o Oracle Providers for ASP.NET o Oracle Database Extensions for .NET o Oracle Provider for OLE DB o Oracle Objects for OLE o Oracle Services for Microsoft Transaction Server Oracle-managed files (OMF) -- a feature allowing automated naming, creation and deletion of datafiles at the operating-system level. Recovery Manager (rman) for database backup, restoration and recovery SQL*Plus , a program that allows users to interact with Oracle database(s) via SQL and PL/SQL commands on a command-line. Compare iSQL*Plus. This list is incomplete; you can help by expanding it. [edit] Standalone tools Users can develop applications in Java and PL/SQL using tools such as Oracle JDeveloper, Oracle Forms, or Oracle Reports. Oracle Corporation has started[clarification needed] a drive toward 'wizard'-driven environments with a view to enabling non-programmers to produce simple data-driven applications. Oracle SQL Developer, a free graphical tool for database development, allows developers to browse database objects, run SQL statements and SQL scripts, and edit and debug PL/SQL statements. It incorporates standard and customized reporting. [edit] Other databases marketed by Oracle Corporation By acquiring other technology in the database field, Oracle Corporation has taken over: TimesTen , a memory-resident database that can cache transactions and synchronize data with a centralized Oracle database server. It functions as a real- time infrastructure software product intended for the management of low-latency, high-volume data, of events and of transactions. BerkeleyDB , a simple, high-performance, embedded database Oracle Rdb , a legacy relational database for the OpenVMS operating system MySQL a relational database purchased as part of its immediate previous owner, Sun Microsystems [edit] Using Oracle Database software Users of Oracle databases may access the online documentation, the Oracle Technology Network site, and the comp.databases.oracle Usenet discussion group. The Oracle Technet site offers downloads of full-featured evaluation software. Users can also check the Oracle FAQ site before posting questions to forums, mailing lists, etc. They can also log on to http://asktom.oracle.com/ to post questions to and get answers from Tom Kyte, a Vice-President of Oracle Corporation and the author of several Oracle books including Expert One-On-One Oracle (ISBN 1-59059-525-4). The Oracle RDBMS has had a reputation among novice users as difficult to install on Linux systems.[citation needed] Oracle Corporation has packaged recent versions for several popular Linux distributions in an attempt to minimize installation challenges beyond the level of technical expertise required to install a database server.[citation needed] [edit] Official support Users who have Oracle support contracts should turn to Oracle's MetaLink web site (password required). MetaLink provides users of Oracle Corporation products with a repository of reported problems, diagnostic scripts and solutions. It also integrates with the provision of support tools, patches and upgrades. The Remote Diagnostic Agent or RDA[59] can operate as a command-line diagnostic tool executing a script. The data captured provides an overview of the Oracle Database environment intended for diagnostic and trouble-shooting. Within RDA, the HCVE (Health Check Validation Engine)[60] can verify and isolate host system environmental issues that may affect the performance of Oracle software. [edit] Database-related guidelines Oracle Corporation also endorses certain practices and conventions as enhancing the use of its database products. These include: Oracle Maximum Availability Architecture (MAA) , guidelines on developing high-availability systems Optimal Flexible Architecture (OFA), blueprints for mapping Oracle-database objects to file-systems [edit] Oracle Certification Program Main article: Oracle Certification Program The Oracle Certification Program, a professional certification program, includes the administration of Oracle Databases as one of its main certification paths. It contains three levels: 1. Oracle Certified Associate (OCA) 2. Oracle Certified Professional (OCP) 3. Oracle Certified Master (OCM) [edit] User groups A variety of official (Oracle-sponsored)[61] and unofficial user groups has grown up of users and developers of Oracle databases. They include: Oracle Technology Network Independent Oracle Users Group Geographical/regional user groups Product-centric user groups Industry-centric user groups The Oak Table Network Usenet comp.databases.oracle groups
[edit] Market position [edit] Competition In the market for relational databases, Oracle Database competes against commercial products such as IBM's DB2 UDB and Microsoft SQL Server. Oracle and IBM tend to battle for the mid-range database market on UNIX and Linux platforms, while Microsoft dominates the mid-range database market on Microsoft Windows platforms. However, since they share many of the same customers, Oracle and IBM tend to support each other's products in many middleware and application categories (for example: WebSphere, PeopleSoft, and Siebel Systems CRM), and IBM's hardware divisions work closely with Oracle on performance-optimizing server-technologies (for example, Linux on zSeries). The two companies have a relationship perhaps best described as "coopetition". Niche commercial competitors include Teradata (in data warehousing and business intelligence), Software AG's ADABAS, Sybase, and IBM's Informix, among many others. Increasingly, the Oracle database products compete against open-source relational database systems, particularly PostgreSQL, Firebird, and MySQL. Oracle acquired Innobase, supplier of the InnoDB codebase to MySQL, in part to compete better in the open source market. Database products developed on the basis of the open-source model generally cost significantly less to acquire than Oracle systems. In 2007, competition with SAP AG occasioned litigation from Oracle Corporation.[62] [edit] Pricing Oracle Corporation offers term licensing for all Oracle products. It bases the list price for a term-license on a specific percentage of the perpetual license price.[63] Enterprise Edition As of March 2006, the database that costs the most per machine-processor among Oracle database editions. Standard Edition Cheaper: it can run on up to four processors but has fewer features than Enterprise Edition—it lacks proper parallelization,[64] etc; but remains quite suitable for running medium-sized applications. Standard ONE Sells even more cheaply, but remains limited to two CPUs. Standard Edition ONE sells on a per-seat basis with a five-user minimum. Oracle Corporation usually sells the licenses with an extra 22% cost for support and upgrades (access to MetaLink - Oracle Corporation's support site) which customers need to renew annually. Oracle Express Edition (Oracle XE) An addition to the Oracle database product family (beta version released in 2005, production version released in February 2006), offers a free version of the Oracle RDBMS, but one limited to 4 GB of user data and to 1 GB of RAM (SGA+PGA). XE will use no more than one CPU and lacks an internal JVM. XE runs only on Windows and on Linux, not on AIX, Solaris, HP-UX and the other operating systems available for other editions. As computers running Oracle often have eight or more processors, the software price can rise into the hundreds of thousands of dollars. The total cost of ownership often exceeds this, as large Oracle installations usually require experienced and trained database administrators to do the set-up properly. Because of the product's large installed base and available training courses, Oracle specialists in some areas have become a more abundant resource than those for more exotic databases. Oracle frequently provides special training offers for database-administrators. On Linux, Oracle's certified configurations include mostly commercial Linux distributions (Red Hat Enterprise Linux 3 and 4, SuSE SLES8 and 9, Asianux) which can cost in a range from a few hundred to a few thousand USD per year (depending on processor architecture and the support package purchased). The Oracle database system can also install and run on freely-available Linux distributions such as the Red Hat-based Centos,[65] or Debian-based systems.[66]
[edit] See also Wikibooks has a book on the topic of Oracle database List of relational database management systems List of object-relational database management systems Comparison of relational database management systems Comparison of object-relational database management systems Oracle Rdb for OpenVMS List of ERP software packages Run Book Automation
[edit] References 1. ^ IDC: Oracle Maintains Lead in Database Market 2. ^ Welcome to Larryland 3. ^ Bhakthavatsalam, Namrata (August 2008). "Glossary". Oracle Database Client Installation Guide 11g Release 1 (11.1) for AIX Based Systems Part Number B32077-03. Oracle. http://download.oracle.com/docs/cd/B28359_01/install.111/b32077/glossary.htm? type=popup#BABEBJAG. Retrieved 2008-11-17. "The SID automatically defaults to the database name portion of the global database name (sales in the example sales.us.example.com) until you reach eight characters or enter a period. You can accept or change the default value." 4. ^ Watkins, Bob (2007-01-30). "Look inside ASM disk groups with Oracle 10gR2's ASMCMD". techrepublic.com. ZDNet. http://articles.techrepublic.com.com/5100-10878_11-6154262.html. Retrieved 2009-07-30. "In 10g, Oracle introduced a new kind of storage for its database product. Automatic Storage Management (ASM) is a logical volume manager that takes physical disk partitions and manages their contents [...] Until ASM, there were only two choices: file system storage and raw disk storage." 5. ^ Nyffenegger, René. "Control files [Oracle]". René Nyffenegger's collection of things on the web. http://www.adp-gmbh.ch/ora/concepts/controlfiles.html. Retrieved 2009-07-30. "The control files of a database store the status of the physical structure of the database." 6. ^ Oracle FAQ 7. ^ Known schemas in Oracle 8. ^ Optimizer plan stability definition 9. ^ Oracle's sample schemas 10. ^ Oracle Architecture, System Global Area 11. ^ Oracle architecture, the library cache section 12. ^ Oracle Architecture, data dictionary cache 13. ^ Oracle architecture, Program Global Area section 14. ^ PGA Definition, Oracle Database Master Glossary 15. ^ Oracle Process architecture concepts 16. ^ http://my.safaribooksonline.com/9780072263053/new_background_processes_in_ 10 Niemiec, Richard (2007-06-25) "1.30. New Background Processes in 10g" Oracle Database 10g Performance Tuning: Tips & TechniquesOracle Pressp. 967ISBN 978-0-0722-6305-3 http://my.safaribooksonline.com/9780072263053/new_background_processes_in_ 10. Retrieved 2009-08-12 "MMON Memory Monitor process is associated with the Automatic Workload Repository new features used for automatic problem detection and self-tuning. MMON writes out the required statistics for AWR on a scheduled basis." 17. ^ http://my.safaribooksonline.com/9780072263053/new_background_processes_in_ 10 Niemiec, Richard (2007-06-25) "1.30. New Background Processes in 10g" Oracle Database 10g Performance Tuning: Tips & TechniquesOracle Pressp. 967ISBN 978-0-0722-6305-3 http://my.safaribooksonline.com/9780072263053/new_background_processes_in_ 10. Retrieved 2009-08-12 "M000 These are MMON background slave (m000) processes." 18. ^ Cyran, Michele; Paul Lane (2005). "Process Architecture". Oracle Database Concepts. Oracle Corporation. http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/process.htm#s thref1481. Retrieved 2008-08-13. "When a user runs an application program (such as a Pro*C program) or an Oracle tool (such as Enterprise Manager or SQL*Plus), Oracle creates a user process to run the user's application." 19. ^ Cyran, Michele; Paul Lane (2005). "Process Architecture". Oracle Database Concepts. Oracle Corporation. http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/process.htm#s thref1481. Retrieved 2008-08-13. "A connection is a communication pathway between a user process and an Oracle instance." 20. ^ Cyran, Michele; Paul Lane (2005). "Process Architecture". Oracle Database Concepts. Oracle Corporation. http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/process.htm#s thref1481. Retrieved 2008-08-13. "A session is a specific connection of a user to an Oracle instance through a user process" 21. ^ Morales, Tony (2008). "V$SESSION". Oracle Database Reference 11g Release 1(11.1). Oracle. http://download.oracle.com/docs/cd/B28359_01/server.111/b28320/dynviews_30 16.htm. Retrieved 2008-11-17. 22. ^ Chan, Immanuel (July 2008). "Glossary". Oracle Database Performance Tuning Guide 11g Release 1 (11.1). Oracle Corporation. http://download.oracle.com/docs/cd/B28359_01/server.111/b28274/glossary.htm? type=popup#sthref1649. Retrieved 2009-04-29. "enqueue[:] This is another term for a lock." 23. ^ "Oracle Database Master Glossary: 11g Release 1 (11.1)". Oracle Corporation. http://download.oracle.com/docs/cd/B28359_01/mix.111/b14388/gloss-l.htm. Retrieved 2009-04-24. "latch[:] A simple, low-level serialization mechanism to protect shared data structures in the System Global Area." 24. ^ Strohm, Richard; et al. (October 2008). "Parameter Files". Oracle Database Concepts 11g Release 1 (11.1). Oracle Corporation. http://download.oracle.com/docs/cd/B28359_01/server.111/b28318/intro.htm#sthr ef23. Retrieved 2009-07-14. "Parameter files contain a list of configuration parameters for that instance and database." 25. ^ Strohm, Richard; et al. (October 2008). "Initialization Parameter Files and Server Parameter Files". Oracle Database Concepts 11g Release 1 (11.1). Oracle Corporation. http://download.oracle.com/docs/cd/B28359_01/server.111/b28318/startup.htm#i9 633. Retrieved 2009-07-14. 26. ^ Morales, Tony; et al. (April 2009). "V$PARAMETER". Oracle Database Reference 11g Release 1 (11.1). Oracle Corporation. http://download.oracle.com/docs/cd/B28359_01/server.111/b28320/dynviews_2.h tm#insertedID85. Retrieved 2009-07-14. "V$PARAMETER displays information about the initialization parameters that are currently in effect for the session." 27. ^ Morales, Tony; et al. (April 2009). "V$SPPARAMETER". Oracle Database Reference 11g Release 1 (11.1). Oracle Corporation. http://download.oracle.com/docs/cd/B28359_01/server.111/b28320/dynviews_3.h tm#insertedID41. Retrieved 2009-07-14. "V$SPPARAMETER displays information about the contents of the server parameter file." 28. ^ "Locale Languages". http://download.oracle.com/docs/cd/B19306_01/server.102/b14225/applocaledata. htm#i634428. Retrieved 2008-02-26. 29. ^ "Error Message languagues". http://download.oracle.com/docs/cd/B19306_01/server.102/b14225/applocaledata. htm#i634673. Retrieved 2008-02-26. 30. ^ Shea, Cathy; et al. (September 2007). "Overview of Globalization Support". Oracle Database Globalization Support Guide 11g Release 1 (11.1). Oracle Corporation. http://download.oracle.com/docs/cd/B28359_01/server.111/b28298/ch1overview. htm#sthref8. Retrieved 2009-02-16. "In the past, Oracle referred to globalization support capabilities as National Language Support (NLS) features. NLS is actually a subset of globalization support. NLS is the ability to choose a national language and store data in a specific character set. Globalization support enables you to develop multilingual applications and software products that can be accessed and run from anywhere in the world simultaneously." 31. ^ As Larry Ellison said in an Oracle OpenWorld keynote presentation on 2007- 11-11: "Who'd buy a version 1.0 from four guys in California?" 32. ^ a b c d e http://www.oracle.com/oramag/profit/07-may/p27anniv_timeline.pdf 33. ^ Compare http://www.oracle.com/oramag/profit/07-may/p27anniv_timeline.pdf 34. ^ "Oracle Database 10g Sets New Record for TPC-H Three TB Benchmark". http://www.itmanagement.com/press-releases/oracle-tpc-h-record-060806/. Retrieved 2008-01-31. 35. ^ Oracle Database Patch Sets 36. ^ a b Greenwald, R., Stackowiak R., & Stern, J. (2001). Oracle Essentials: Oracle9i, Oracle8i & Oracle8 (2nd edition). Cambridge, MA: O'Reilly. 37. ^ http://www.oracle.com/technologies/open-source/docs/oracle-opensource- ds.pdf; but compare Informix's claim to priority: http://www.linuxjournal.com/article/3110, retrieved 2008-02-13 and that of Polyhedra 38. ^ Enterprise Edition 39. ^ Standard Edition 40. ^ Standard Edition One 41. ^ Express Edition 42. ^ FAQ on Express Edition 43. ^ "Oracle Database Lite 10g". oracle.com. Oracle Corporation. http://www.oracle.com/database/lite_edition.html. Retrieved 2009-06-23. "[...] for developing, deploying and managing applications for mobile and embedded environments." 44. ^ Oracle database options 45. ^ See download.oracle.com/docs/cd/B28359_01/license.111/b28287/options.htm#CIHB DGAD 46. ^ ""Real Application Testing Overview"". Oracle Corporation. August 2007. http://www.oracle.com/technology/products/manageability/database/pdf/wp07/ow p_real_application_testing_11g.pdf. Retrieved 2008-05-19. 47. ^ See "Term licenses" at http://oraclestore.oracle.com/ for various markets/countries. 48. ^ "Oracle Programmer/2000" (PDF). Oracle Corporation. http://www.alise.lv/ALISE/mrktinfo.nsf/6022a43db1063796c22566de00392130/4 20e0389f8672386c225645e00344ecb/$FILE/Oracle%20Programmer %202000%20data%20sheet%20Feb97.pdf. Retrieved 2009-02-25. "Oracle Programmer/2000 is a suite of programmatic interfaces that allows you to access and manipulate Oracle7 data and schemas. Programmer/2000 provides a rich set of interfaces and supports many programming languages, allowing the programmer to use the programming language and the programming paradigm of choice." 49. ^ "Other Ways of Working with Oracle". Oracle Corporation. http://download.oracle.com/docs/cd/A58617_01/server.804/a53717/ch1.htm#inde x0015. Retrieved 2009-02-25. "Programmer/2000[:] a set of 3GL programming language interfaces" 50. ^ For example, Oracle Data Guard counts officially as a "feature", but the command-stack within SQL*Plus, though a usability feature, does not appear in the list of "features" in http://download.oracle.com/docs/cd/B19306_01/license.102/b14199/editions.htm #CJACGHEB 51. ^ Alapati, Sam R. (2005) Expert Oracle database 10g administrationApressp. 845ISBN 9781590594513 http://books.google.co.nz/books? id=xxx0KAwY_ZMC&pg=PA845&lpg=PA845&dq=ASH+ +Active+Session+History&source=bl&ots=4DmmvFmU7v&sig=vpOt0kvOidJo- iSC-EJ_kRTyDAI&hl=en&ei=b- EZSo3qBISIkAXKoyk&sa=X&oi=book_result&ct=result&resnum=8#PPA845, M1. Retrieved 2009-05-25 "... ASH records very recent session activity (within the last five or ten minutes)." 52. ^ Overview of Oracle Data Pump 53. ^ Greenwald, Rick; Robert Stackowiak, Jonathan Stern (November 2007). Oracle Essentials: Oracle Database 11g. O'Reilly. p. 184. ISBN 978-0596514549. "The Database Resource Manager (DRM) was first introduced in Oracle8i [...] to place limits on the amount of computer resources that can be used [...]" 54. ^ "Feature Availability by Edition". Oracle Database Licensing Information 11g Release 1 (11.1) Part Number B28287-08. Oracle Corporation. May 2008. http://download.oracle.com/docs/cd/B28359_01/license.111/b28287/editions.htm #CJACGHEB. Retrieved 2008-08-19. 55. ^ Nanda, Arup. "Auditing Tells All". Oracle Database 10g: The Top 20 Features for DBAs. Oracle Corporation. http://www.oracle.com/technology/pub/articles/10gdba/week10_10gdba.html. Retrieved 2008-08-19. "...the standard audit (available in all versions) and the fine-grained audit (available in Oracle9i and up ..." 56. ^ http://www.oracle.com/technology/deploy/availability/htdocs/Flashback_Overvie w.htm 57. ^ "Oracle Product Accessibility Status: Database Server Enterprise Edition". Oracle Corporation. 2008-06-02. http://www.oracle.com/accessibility/templates/t1286.html. Retrieved 2009-04-14. 58. ^ "Oracle Data Provider for .NET". Oracle Corporation. http://www.oracle.com/technology/tech/windows/odpnet/index.html. Retrieved 2009-05-07. "The Oracle Data Provider for .NET (ODP.NET) features optimized ADO.NET data access to the Oracle database." 59. ^ http://www.oracle.com/global/tr/support/051006_ADVANCEDMETALINK_CUS TOMER.pdf page 10. Retrieved 2008-05-08. 60. ^ Rea, Stephen (2008-09-16). "Upgrading Oracle 9.2.0.6 to 10.2.0.3 on AIX 5.2". University of Arkansas. http://www.uaex.edu/srea/10gR2_upgrade.txt. Retrieved 2009-08-11. "Run the PreInstall checklist for Oracle 10.2.0 (Metalink Note 250262.1: RDA 4 - Health Check / Validation Engine Guide): The Health Check Validation Engine (HCVE) rule set for Oracle Database 10g R2 (10.2.0) PreInstall (AIX) is described in: https://metalink.oracle.com/metalink/plsql/docs/HCVE_A201DB10R2_aix.htm" 61. ^ See Oracle User Group 62. ^ About the case in Hungarian 63. ^ See the published price list. 64. ^ Oracle Database Licensing Information Database Editions 65. ^ Installation centos; official Oracle Wiki 66. ^ Installation on Debian-based systems; official Oracle Wiki
[edit] Bibliography Loney, Kevin (December 17, 2008), Oracle Database 11g The Complete Reference (1st ed.), McGraw-Hill, p. 1368, ISBN 0071598758, http://www.mhprofessional.com/product.php?isbn=0071598758, retrieved 2009- 09-05
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