Online Computer Terms Dictionary - H

hierarchical database

<database> A kind of database management system that links records together like a family tree such that each record type has only one owner, e.g. an order is owned by only one customer. Hierarchical structures were widely used in the first mainframe database management systems. However, due to their restrictions, they often cannot be used to relate structures that exist in the real world.

Hierarchical Data Format

<file format, data> (HDF) A library and multi-object file format for the transfer of graphical and numerical data between computeres. The freely available HDF distribution consists of the library, command line utilities, test suite source, Java interface, and the Java-based HDF Viewer (JHV).

HDF supports several different data models, including multidimensional arrays, raster images, and tables. Each defines a specific aggregate data type and provides an API for reading, writing, and organising the data and metadata. New data models can be added by the HDF developers or users.

HDF is self-describing, allowing an application to interpret the structure and contents of a file without any outside information.

One HDF file can hold a mixture of related objects which can be accessed as a group or as individual objects. Users can create their own grouping structures called "vgroups".

HDF files can be shared across most common platforms, including many workstations and high performance computers. An HDF file created on one computer can be read on a different system without modification.

Home.

(2001-07-02)

hierarchical file system

<file system> A file system in which the files are organised into a hierarchy. The nodes of the hierarchy are called directories while the leaves are the files themselves.

See also root directory. Compare flat file system.

(1996-11-21)

Hierarchical Music Specification Language

<language, music> (HMSL) A programming language for experimental music composition and performance. It is a set of object-oriented extensions to Forth. (Its near-total unintelligibility to people unfamiliar with Forth has led some to expand "HMSL" as "Her Majesty's Secret Language".)

Phil Burk (who also later developed pForth), Larry Polansky, and David Rosenboom started developing HMSL in 1980 while working at the Mills College Center for Contemporary Music. As of June 1998, development is ongoing.

http://www.softsynth.com/hmsl/.

(1998-09-07)

hierarchical navigation

<World-Wide Web> On a web page, any type of menu whose hierarchical structure matches that of the site to which the page belongs. A hierarchical navigation menu allows the user to jump ("navigate") directly to a section of the site several levels below the top. The menu may present only a fixed number of levels rather than the whole structure.

(2003-10-01)

hierarchical routing

The complex problem of routing on large networks can be simplified by breaking a network into a hierarchy of smaller networks, where each level is responsible for its own routing. The Internet has, basically, three levels: the backbones, the mid-levels, and the stub networks. The backbones know how to route between the mid-levels, the mid-levels know how to route between the sites, and each site (being an autonomous system) knows how to route internally. See also Exterior Gateway Protocol, Interior Gateway Protocol, transit network.