ActiveX To ADSTAR Distributed Storage Management (Technology Terms)

ActiveX

ActiveX is the name Microsoft has given to a set of "strategic" object-oriented programming technologies and tools. The main technology is the Component Object Model (COM). Used in a network with a directory and additional support, COM becomes the Distributed Component Object Model (DCOM). The main thing that you create when writing a program to run in the ActiveX environment is a component, a self-sufficient program that can be run anywhere in your ActiveX network (currently a network consisting of Windows and Macintosh systems). This component is known as an ActiveX control. ActiveX is Microsoft’s answer to the Java technology from Sun Microsystems. An ActiveX control is roughly equivalent to a Java applet.

If you have a Windows operating system on your personal computer, you may notice a number of Windows files with the "OCX" file name suffix. OCX stands for "Object Linking and Embedding control.” Object Linking and Embedding (OLE) was Microsoft’s program technology for supporting compound documents such as the Windows desktop. The Component Object Model now takes in OLE as part of a larger concept. Microsoft now uses the term "ActiveX control” instead of "OCX" for the component object.

One of the main advantages of a component is that it can be re-used by many applications (referred to as component containers). A COM component object (ActiveX control) can be created using one of several languages or development tools, including C++ and Visual Basic, or PowerBuilder, or with scripting tools such as VBScript.


Currently, ActiveX controls run in Windows 95/98/NT/ 2000 and in Macintosh. Microsoft plans to support ActiveX controls for UNIX.

ActiveX control

An ActiveX control is a component program object that can be re-used by many application programs within a computer or among computers in a network. The technology for creating ActiveX controls is part of Microsoft’s overall ActiveX set of technologies, chief of which is the Component Object Model (COM). ActiveX controls can be downloaded as small programs or animations for Web pages, but they can also be used for any commonly needed task by an application program in the latest Windows and Macintosh environments. In general, ActiveX controls replace the earlier OCX (Object Linking and Embedding custom controls). An ActiveX control is roughly equivalent in concept and implementation to the Java applet. An ActiveX control can be created in any programming language that recognizes Microsoft’s Component Object Model. The distributed support for COM is called the Distributed Component Object Model (DCOM). In implementation, an ActiveX control is a dynamic link library (DLL) module. An ActiveX control runs in what is known as a container, an application program that uses the Component Object Model program interfaces. This reuseable component approach to application development reduces development time and improves program capability and quality. Windows application development programs such as PowerBuilder and Microsoft Access take advantage of ActiveX controls.

Visual Basic and C++ are commonly used to write ActiveX controls.

ActiveX Data Objects

ActiveX Data Objects (ADO) is an application program interface from Microsoft that lets programmers writing Windows applications get access to a relational or nonrelational database from both Microsoft and other database providers. For example, if you wanted to write a program that would provide users of your Web site with data from an IBM DB2 database or an Oracle database, you could include ADO program statements in an HTML file that you then identified as an Active Server Page. When a user requested the page from the Web site, the page sent back could include appropriate data from a database, obtained using ADO code.

Like Microsoft’s other system interfaces, ADO is an object-oriented programming interface. It is also part of an overall data access strategy from Microsoft called Universal Data Access. Microsoft says that rather than try to build a universal database as IBM and Oracle have suggested, why not provide universal access to various kinds of existing and future databases? In order for this to work, Microsoft and other database companies provide a "bridge" program between the database and Microsoft’s OLE DB, the low-level interface to databases. OLE DB is the underlying system service that a programmer using ADO is actually using. A feature of ADO, Remote Data Service, supports "data-aware” ActiveX controls in Web pages and efficient client-side caches. As part of ActiveX, ADO is also part of Microsoft’s overall Component Object Model (COM), its component-oriented framework for putting programs together.

ADO evolved from an earlier Microsoft data interface, Remote Data Objects (RDO). RDO works with Microsoft’s ODBC to access relational databases, but not nonrelational databases such as IBM’s ISAM and VSAM.

ACTS

ACTS (Automatic Coin Telephone System) is a public coin-operated telephone service that completes a variety of phone calls, times the calls, and collects payment without the aid of an operator.

Ada

Ada (pronounced AY-duh) is a programming language somewhat similar to Pascal that was selected in a competition and made a U.S. Defense Department standard. (It is named for Augusta Ada Byron, Countess of Lovelace [1815-1852], who helped Charles Babbage conceive how programs might run in his mechanical Analytical Engine.

She is often considered the first computer programmer.) Ada was originally intended for real-time embedded systems programming.

By its supporters, Ada is described as a programming language that avoids error-prone notation, is relatively quick to implement, encourages reuse and team coordination, and is relatively easy for other programmers to read. The most recent version, Ada 95, is apparently a significant improvement over earlier versions. Among the sophisticated, according to The New Hacker’s Dictionary, Ada has a reputation as a committee-written language, with poor exception-handling and interprocess communication features. It’s not clear that "hackers" still feel this way. The Ada home page says: "The original Ada design was the winner of a language design competition; the winning team was headed by Jean Ichbiah (Ichbiah’s language was called "Green"). The 1995 revision of Ada (Ada 95) was developed by a small team led by Tucker Taft. In both cases, the design underwent a public comment period where the designers responded to public comments.”

Ada 95 can be used with object-oriented programming design methodology and source code can be compiled into Java classes by the Ada 95 compiler. These classes can be run as Java applets or applications on a Java virtual machine.

First standardized by ANSI in 1983 and ISO in 1987, the latest standard is ANSI/ISO/IEC-8652:1995 Ada 95.

adapter

An adapter is a physical device that allows one hardware or electronic interface to be adapted (accommodated without loss of function) to another hardware or electronic interface. In a computer, an adapter is often built into a card that can be inserted into a slot on the computer’s motherboard. The card adapts information that is exchanged between the computer’s microprocessor and the devices that the card supports.

ADAT

The ADAT (a registered trademark of Alesis) is an eight-track digital tape recorder that caught the recording industry by storm when it was first released in the early 1990s. Today, with over 100,000 ADATs in use in recording facilities around the world, it is the most widely used professional digital recording system. The ADAT was the first product in the category now known as modular digital multitracks (MDMs).

The ADAT system allows up to 16 ADAT units to be used in synchronization, enabling the user to build a very cost-effective multi-track recording environment. The transportability and modularity of the system makes it ideal for mobile recording and wherever space is limited. Digital transfer between ADATs in a system uses a optical fiber digital communication standard pioneered by Alesis which has become known as Lightpipe. The Lightpipe digital interface has been adopted by other manufacturers as a means of transferring digital data from other types of audio devices, such as mixers, synthesizers, and effect processors.

The ADAT uses the S-VHS % inch tape format. This tape is similar in design to the tape used in consumer VCRs.

add-in

Add-in is a term used, especially by Microsoft, for a software utility or other program that can be added to a primary program. The Microsoft Style Guide says that Microsoft Bookshelf is an add-in for Word and that Analysis Toolpak is an add-in for Microsoft Excel. According to the Style Guide, add-in should not be confused with add-on, a term for a hardware expansion unit. (However, some add-on manufacturers do call them "add-ins.")

A similar term is plug-in, a term originated by Netscape for application programs that can be activated within a Netscape Web browser window.

add-on

An add-on is either a hardware unit that can be added to a computer to increase its capabilities or a program utility that enhances a primary program. Less frequently, some manufacturers and software developers use the term add-in. Examples of add-ons for a computer include cards for sound, graphics acceleration, modem capability, and memory. Software add-ons are common for games, word processors, and accounting programs.

The Microsoft Style Guide suggests using add-ons for hardware only and add-ins for software utilities. Industrywide, however, this guideline does not seem to be widely followed.

A similar term is plug-in, a term originated by Netscape for application programs that can be activated within a Netscape Web browser window.

address

People use this word several ways. You can ask someone for the address of their server, or for their home page on the Web, or where to send e-mail. So an "address" can mean the unique location of either (1) an Internet server, (2) a specific file (for example, a Web page), or (3) an e-mail user. It is also used to specify the location of data within computer storage.

1) An Internet address or IP address is a unique computer (host) location on the Internet (expressed either as a unique string of numbers or as its associated domain name). Example of an IP address expressed in dot notation: 205.245.172.72

Example of the domain name version: whatis.com For more information, see IP address.

2) A file (or home page) address is expressed as the defining directory path to the file on a particular server. (A Web page address is also called a Uniform Resource Locator, or URL.)

3) An e-mail address is the location of an e-mail user (expressed by the user’s e-mail name followed by an "at" sign followed by the user’s server domain name.)

4) In a computer, a storage address is the beginning location of a sequence of data that is stored on some electronic storage medium.

Address Resolution Protocol

Address Resolution Protocol (ARP) is a protocol for mapping an Internet Protocol address (IP address) to a physical machine address that is recognized in the local network. For example, in IP Version 4, the most common level of IP in use today, an address is 32 bits long. In an Ethernet local area network, however, addresses for attached devices are 48 bits long. (The physical machine address is also known as a Media Access Control or MAC address.) A table, usually called the ARP cache, is used to maintain a correlation between each MAC address and its corresponding IP address. ARP provides the protocol rules for making this correlation and providing address conversion in both directions.

How ARP Works

When an incoming packet destined for a host machine on a particular local area network arrives at a gateway, the gateway asks the ARP program to find a physical host or MAC address that matches the IP address. The ARP program looks in the ARP cache and, if it finds the address, provides it so that the packet can be converted to the right packet length and format and sent to the machine. If no entry is found for the IP address, ARP broadcasts a request packet in a special format to all the machines on the LAN to see if one machine knows that it has that IP address associated with it. A machine that recognizes the IP address as its own returns a reply so indicating. ARP updates the ARP cache for future reference and then sends the packet to the MAC address that replied.

Since protocol details differ for each type of local area network, there are separate ARP Requests for Comments (RFC) for Ethernet, ATM, Fiber Distributed-Data Interface, HIPPI, and other protocols.

There is a Reverse ARP (RARP) for host machines that don’t know their IP address. RARP enables them to request their IP address from the gateway’s ARP cache.

ad-hoc network

An ad-hoc (or ”spontaneous”) network is a local area network or other small network, especially one with wireless or temporary plug-in connections, in which some of the network devices are part of the network only for the duration of a communications session or, in the case of mobile or portable devices, while in some close proximity to the rest of the network. In Latin, ad hoc literally means ”for this,” further meaning ”for this purpose only,” and thus usually temporary. The term has been applied to future office or home networks in which new devices can be quickly added, using, for example, the proposed Bluetooth technology in which devices communicate with the computer and perhaps other devices using wireless transmission.

One vendor offers an ad-hoc network technology that allows people to come to a conference room and, using infrared transmission or radio frequency (RF) wireless signals, join their notebook computers with other conferees to a local network with shared data and printing resources. Each user has a unique network address that is immediately recognized as part of the network. The technology would also include remote users and hybrid wireless/wire connections.

Jini is an approach to instant recognition of new devices in a network that would seem to make it easier to have an ad-hoc network.

admittance

Admittance (symbolized Y) is an expression of the ease with which alternating current (AC) flows through a complex circuit or system. Admittance is a vector quantity comprised of two independent scalar phenomena: conductance and susceptance.

Conductance, denoted G, is a measure of the ease with which charge carriers can pass through a component or substance. The more easily the charge carriers move in response to a given applied electric potential, the higher the conductance, which is expressed in positive real-number siemens. Conductance is observed with AC and also with direct current (DC).

Susceptance, denoted B, is an expression of the readiness with which an electronic component, circuit, or system releases stored energy as the current and voltage fluctuate. Susceptance is expressed in imaginary number siemens. It is observed for AC, but not for DC. When AC passes through a component that contains susceptance, energy might be stored and released in the form of a magnetic field, in which case the susceptance is inductive (denoted —jBL), or energy might be stored and released in the form of an electric field, in which case the susceptance is capacitive (denoted +jBC). Admittance is the vector sum of conductance and susceptance. Susceptance is conventionally multiplied by the positive square root of —1, the unit imaginary number called symbolized by j, to express Y as a complex quantity G—jBL (when the net susceptance is inductive) or G + jBC (when the net susceptance is capacitive). In parallel circuits, conductance and susceptance add together independently to yield the composite admittance. In series circuits, conductance and susceptance combine in a more complicated manner. In these situations, it is easier to convert conductance to resistance, susceptance to reactance, and then calculate the composite impedance.

Also see conductance, reactance, resistance, impedance, ohm, siemens, henry, and farad.

ADPCM

ADPCM (adaptive differential pulse-code modulation) is a technique for converting sound or analog information to binary information (a string of 0′s and 1′s) by taking frequent samples of the sound and expressing the value of the sampled sound modulation in binary terms. ADPCM is used to send sound on fiber-optic long-distance lines as well as to store sound along with text, images, and code on a CD-ROM.

ADSI

ADSI (Analog Display Services Interface) is the standard protocol for enabling alternate voice and data services, such as a visual display at the phone, over the analog telephone network. Developed by Bellcore in 1993, ADSI is now built into devices such as special telephones with small display screens, cable TV set-top box, personal digital assistants (PDAs), pagers, and personal computers with telephone applications.

A popular application enabled by ADSI is Call Waiting Deluxe, an application that displays the name and number of an incoming call while you are on the phone. If you have an ADSI screen phone, several options are displayed on your screen including switching to the new call, forwarding the new call to your voice mail, putting the new caller on hold, playing a recorded message, or dropping the current call and switching to the new call. Other ADSI applications include:

• Visual voice mail, the display of telephone voice mail menu options and a list of your voice mail messages

• Visual directory, a service that allows you to locate the telephone number of an individual or business and, possibly at extra charge, to download the address of that individual to your screen phone

• E-mail browsing, allowing you to send and receive e-mail messages via an ADSI-enabled device.

• Schedule-based services, faxing abilities, notification of incoming e-mail messages, home banking, ticket purchasing, and access to train and plane schedules

ADSL

ADSL (Asymmetric Digital Subscriber Line) is a technology for transmitting digital information at a high bandwidth on existing phone lines to homes and businesses. Unlike regular dialup phone service, ADSL provides continously available, ”always on” connection. ADSL is asymmetric in that it uses most of the channel to transmit downstream to the user and only a small part to receive information from the user. ADSL simultaneously accommodates analog (voice) information on the same line. ADSL is generally offered at downstream data rates from 512 Kbps to about 6 Mbps. A form of ADSL, known as Universal ADSL or G.lite, has been approved as a standard by the ITU-TS.

ADSL was specifically designed to exploit the one-way nature of most multimedia communication in which large amounts of information flow toward the user and only a small amount of interactive control information is returned. Several experiments with ADSL to real users began in 1996. In 1998, wide-scale installations began in several parts of the U.S. In 2000 and beyond, ADSL and other forms of DSL are expected to become generally available in urban areas. With ADSL (and other forms of DSL), telephone companies are competing with cable companies and their cable modem services.

ADSTAR Distributed Storage Management

ADSTAR Distributed Storage Management (ADSM) is a collective term for IBM’s family of high-end software that helps a customer manage the storage devices (such as mainframe storage, PC disk drives, and Zip drives) that are scattered around the company.

ADSM helps medium and large companies automatically back up the business information in all of the storage devices throughout the enterprise. ADSM software works with a variety of database formats, including those made by IBM competitors.

The basic premise behind ADSM is to allow customers to view and manage storage as a single comprehensive endeavor. The idea is to let customers back up on an enterprise level, instead of having to save all the data residing in all the PCs, networks and other machines throughout a company at each individual location.

IBM is no longer actively selling ADSM software. Instead, IBM and its Tivoli subsidiary are selling Tivoli Storage Manager software as the ADSM successor.

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