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3 Definitions

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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
 
 
Table 3.1 -- Table of Contents
3.1 Introduction  
3.2 browser 
3.3 buffered 
3.4 display device 
3.5 errors 
3.6 event 
3.7 event cascade 
3.8 eventIn 
3.9 eventOut 
3.10 events 
3.11 Execution Model 
3.12 ExposedField 
3.13 External  
3.14 field 
3.15 field name 
3.16 file 
3.17 HTML 
3.18 IETF 
3.19 image 
3.20 Internet 
3.21 ISO 
3.22 JTC1 
3.23 node 
3.24 node type 
3.25 parameters 
3.26 returns 
3.27 RURL 
3.28 scene graph 
3.29 Script 
3.30 Scripting 
3.32 Scripting Language 
3.33 service 
3.33 URL 
3.34 URN 
3.35 user 
3.36 VRML Browser 
3.37 VRML File 
3.38 Web Browser 
3.39 world 
3.40 World Wide Web
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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.

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