3 Definitions
3.1 Introduction
For the purposes of this part of ISO/IEC 14772, the definitions in this
clause apply. Terms that are formatted in fixed width font represent
terms from the table definitions in 6. Services
reference. Other terms are formatted in the normal font.
Table 3.1 defines the contents of this clause
3.2 browser
There may be two forms of browser discussed: a web browser and a VRML browser.
A browser is a computer program that interprets files accessed, presents
their content to a user on a display device, and allows the user to interact
with them. See VRML Browser and
Web Browser. When used as an unqualified
word the VRML Browser meaning shall be implied.
3.3 buffered
Indicator to say whether this service request is effected by 6.3.12
Update control
3.4 display device
A graphics device on which VRML worlds may
be rendered.
3.5 errors
Error conditions that can be generated as part of a service invocation.
Errors are fatal for the service request issuing the error. No return value
shall be generated if an error is generated. Errors are synchronous with
the request.
3.6 event
There are two forms of events: VRML events that are defined in ISO/IEC
14772-1 3.23 Event.and information that is passed from the VRML browser
to the external environment. In this part, an event is a message
sent from either a node or the browser itself to the external application.
Events signal external stimuli, changes to field values, and interactions
between nodes. An event consists of at least a timestamp and a field value.
3.7 event cascade
A sequence of events initiated by a script
or sensor event and propagated from node to
node along one or more routes.
All events in an event cascade are considered to have occurred simultaneously.
See ISO/IEC
14772-1 4.10.3, Execution model, for details.
3.8 eventIn
A logical receptor attached to a node which
receives events. (See 2.VRML)
3.9 eventOut
A logical output terminal attached to a node
from which events are sent. The eventOut also
stores the event most recently sent. (See 2.VRML)
3.10 events
Asynchronous events that are generated to listeners that have registered
interest in this particular object (browser or field) resulting in notification
to the listener of the event. The listener may not be the same as the caller
that generated the event condition. For example, consider two applications
registered as browser listeners. One invokes the loadURL service but both
will receive shutdown and initialize events. The required event types are
defined in 4.5 Events.
3.11 execution model
The rules governing how events are processed
by browsers and scripts. (See 2.VRML)
3.12 exposed field
A field that is capable of receiving events
via an eventIn to change its value(s), and
generating events via an eventOut when its
value(s) change. (See 2.VRML)
3.13 external
External means anything that exists outside of the VRML browser environment.
This may take the form of an container application that holds a VRML browser,
or a client/server style environment where the VRML browser forms the client
and the application is a server located on a remote machine.
3.14 field
A property or attribute of a node. Each node
type has a fixed set of fields. Fields may contain various kinds
of data and one or many values. Each field has a default value. (See
2.VRML)
3.15 field name
The identifier of a field. Field names are
unique within the scope of the node. (See
2.VRML)
3.16 file
A collection of related data. A file may be stored on physical media or
may exist as a data stream or as data within a computer program.
(See 2.VRML)
3.17 HTML
HyperText Markup Language. See 2.[HTML].
3.18 IETF
Internet Engineering Task Force. The organization which develops Internet
standards. See
http://www.ietf.org/overview.html.
3.19 image
A two-dimensional (2D) rectangular array of pixel values. Pixel values
may have from one to four
components. See ISO/IEC
14772-1 5.5 SFImage, for details.
3.20 Internet
The world-wide named network
of computers which communicate with each other using a common set of communication
protocols known as TCP/IP. See IETF. The World
Wide Web is implemented on the Internet.
3.21 ISO
International Organization for Standardization. See http://www.iso.ch/infoe/intro.html.
3.22 JTC 1
ISO/IEC Joint Technical Committee 1. See http://www.iso.ch/meme/JTC1.html.
3.23 node
The fundamental component of a scene graph
in ISO/IEC 14772-1. Nodes are abstractions of various real-world objects
and concepts. Examples include spheres, lights, and material descriptions.
Nodes contain fields and events.
Messages may be sent between nodes along routes.
3.24 node type
A characteristic of each node that describes,
in general, its particular semantics. For example, Box, Group, Sound, and
SpotLight are node types. See ISO/IEC
14772-1 4.6, Node semantics, and ISO/IEC
14772-1 6, Node reference, for details.
3.25 parameters
The list of values that are required in order to complete a service request.
These values may take any form as required by the particular language binding.
3.26 returns
Immediate, synchronous values that are passed back to the external application
upon completion of a service request. The request is blocked until these
values are sent, if specified.
3.27 RURL
Relative Uniform Resource Locator. See 2.[RURL].
3.28 scene graph
An ordered collection of grouping nodes and other nodes. Grouping nodes
(such as LOD, Switch, and Transform nodes) may have children nodes. See
ISO/IEC
14772-1 4.2.3 Scene graph, and ISO/IEC
14772-1 4.4.2 Scene graph hierarchy, for details.
3.29 script
A set of procedural functions normally executed as part of an event
cascade (see ISO/IEC
14772-1 6.40 Script). A script function may also be executed asynchronously
(see ISO/IEC
14772-1 4.12.6 Asynchronous scripts).
3.30 scripting
The process of creating or referring to a script.
3.31 scripting language
A system of syntactical and semantic constructs used to define and automate
procedures and processes on a computer. Typically, scripting languages
are interpreted and executed sequentially on a statement-by-statement basis
whereas programming languages are generally compiled prior to execution.
3.32 service
What this specification defines as the method of interfacing between external
applications and the browser. The interface is broken down into a collection
of functional areas defined in terms of parameters,
returns, errors,
events and whether the capabilities are
buffered.
3.33 URL
Uniform Resource Locator. See 2.[URL].
3.34 URN
Universal Resource Name. See ISO/IEC
14772-1, E.[URN].
3.35 user
A person or agent who uses and interacts with VRML
files by means of a browser.
3.36 VRML browser
A computer program that interprets VRML files,
presents their content to a user on a display
device, and allows the user to interact with worlds
defined by VRML files by means of a user interface. (See 2.VRML)
3.37 VRML file
A set of VRML nodes and statements as defined in this part of ISO/IEC 14772.
This set of VRML nodes and statements may be in the form of a file, a data
stream, or an in-line sequence of VRML information as defined by a particular
VRML encoding. (See 2.VRML)
3.38 Web Browser
A computer program that is used to interpret and display files that have
been retrieved over the Internet. Typically, this involves using the HTTP
transfer protocol and HTML documents, but may include other types of data.
3.39 world
A collection of one or more VRML files and
other multimedia content that, when interpreted by a VRML
browser, presents an interactive experience to the user
consistent with the author's
intent.
3.40 World Wide Web
The collection of documents, data, and content typically encoded in HTML
pages and accessible via the Internet using
the HTTP protocol.
http://www.vrml.org/Specifications/VRML97/part2/glossary.html