Draft XP Terminology Section
Last Modified: $Date: 2000/11/15 21:21:09 $
- Latest revision
- http://www.w3.org/2000/xp/Group/xp-terms
- This revision
- http://www.w3.org/2000/xp/Group/xp-terms-01
- Previous revisions
- n/a
- Editors:
- Henrik Frystyk Nielsen, Microsoft, <frystyk@microsoft.com>
This document specifies a DRAFT set of proposed terms. It is not an output
of the XML Protocol WG but rather a proposal for consideration.
This document is a request for comments on a proposed set of terms defined
for use by the XP WG. It is not a result of discussion of the XML Protocol WG
and is not an official W3C Technical Report. It is to be considered work in
progress and does not imply endorsement by the W3C membership or by the XML
Protocol WG.
Please send comments to the public <xml-dist-app@w3.org> mailing list (Archives).
- 7 Terminology
- 7.1 General Protocol Concepts
- 7.2 Data Encapsulation Concepts
- 7.3 Message Sender and Receiver Concepts
- 7.4 Data Representation Concepts
For a description of fundamental Web concepts including resources and
resource manifestations, see the "Web Characterization Terminology
& Definitions Sheet" W3C Working Draft. For many useful terms, see
also the Proposed
Telecom Glossary 2000.
The XML Protocol is a framework which can accommodate an
open-ended set of XML Protocol modules carrying a large
variety of functions and services. Typical functions and services carried by
XML Protocol modules can range from generic mechanisms for handling security,
caching, routing, and eventing to specific functions like submitting a
purchase order.
While the XML Protocol itself is intended to be as simple and lightweight
as possible, XML Protocol modules can be designed and composed to perform
arbitrarily complex operations allowing the core protocol to remain
simple.
The XML Protocol itself can be layered on top of a variety of transfer or
application protocols that can help facilitate the transfer of XP Messages. Typical examples of protocols that XML Protocol
might be layered on top of are HTTP and TCP. The exact rules and conventions
for how to layer the XML Protocol on top of another protocol is defined by an
XML Protocol Binding.
Note: Component oriented implementation models may take advantage of
the layering model illustrated above to provide a component oriented interface
to components driving specific XP
modules. However, this is strictly an implementation choice for
which XML Protocol has nothing to say.
- application
- See the proposed
Telecom Glossary 2000's definition of the term application.
- protocol
- See the proposed
Telecom Glossary 2000's definition of the term protocol.
- XML Protocol (XP)
- The formal set of conventions governing the format and processing rules of an XP message
and basic control of interaction among applications generating and accepting XP
messages for the purpose of exchanging information along an XP message path.
- XP module
- A syntactic construct or structure used to delimit data that logically
constitutes a single computational unit as seen by the XP processor. Services carried by XP modules can range
from generic mechanisms for handling security, caching, routing, and
eventing to specific functions like submitting a purchase order. XP
Modules can be composed within an XP message to
provide the overall desired functionality of the message.
- XP binding
- The formal set of rules for carrying an XP message within or on top of
another protocol for the purpose of transmission. Typical XP bindings
include carrying an XP message within an HTTP message, or on top of
TCP.
The XML Protocol data encapsulation model describes how data defined by XP modules can be carried within an XP
message which is the fundamental unit of communication in the XML Protocol. The following diagram illustrates how an XP
message is composed.
An XP message is composed of an XP
envelope which contains an XP header and an XP body each of which can each contain zero, one or more XP modules. While an XP envelope by
itself provides a minimum set of services, XP modules can
provide an open-ended set of functions and services that can be composed
within an XP message.
- XP message
- The basic unit of communication within the XML
Protocol.
- XP processor
- An XP Processor is an application that can process
an XP message according to the formal set of
conventions defined by the XML Protocol and generate
an XP fault if the conventions are not followed.
Insufficient or wrong data carried in an XP module
can cause an XP processor to generate a fault (see also XP receiver and XP sender)
- XP envelope
- The outermost syntactical construct or structure of an XP message defined by XML Protocol
within which all other syntactical elements of the message are
enclosed.
- XP header
A collection or zero, or more XP modules which
may be intended for any XP receiver within the XP
message path.
- XP body
- A collection or zero, or more XP modules intended
for the ultimate XP receiver within the XP message path.
- XP fault
- A special XP module which contains fault
information generated by an XP processor.
The XML Protocol message path model is defined in terms of XP senders and XP receivers who can
generate and accept XP messages respectively. Behind each
XP receiver is an XP processor that
processes the message according to the rules of the XML Protocol.
A important part of the XML Protocol message path model is the concept of
XP intermediaries. Intermediaries contain both an XP receivers and an XP sender which
allows them to forward a message on behalf of the previous sender.
Note: Especially in some b2b interactions, more complicated message
path models are required to encapsulate the semantics of multi-party
interactions like for example "fan-out" or "fan-in" models. Such models can be
built using the basic XP message path model provided that
the semantics of message "split" and "merge" are provided by higher layer
semantics.
- XP sender
- An application that can generate an XP message and perform an XP
binding to a specific protocol for the purpose of transmitting the
message.
- XP receiver
- An application that can accept an incoming XP message transmitted using some XP
binding, extract the message from the XP binding
and pass the message to an XP processor.
- XP application
- An application that is either an XP sender, an XP receiver, or
both
- XP message path
- The set of XP senders and XP
receivers that a single XP message passes on its
way from the initial XP sender, through zero or more
XP intermediaries, and to the ultimate XP receiver.
- initial XP sender
- The XP sender that originates an XP message as the starting point of an XP message path.
- XP intermediary
- An application that can act as both an XP sender
and an XP receiver with the purpose of forwarding an
XP message along an XP message
path.
- ultimate XP receiver
- The XP receiver that the initial
sender specifies as the final destination of the XP
message within an XP message path. An XP message may not reach the ultimate recipient because
of an XP fault generated by an XP
processor along the XP message path.
- XP data model
- A set of abstract constructs that can be used to describe common data
types and link relationships in data defined by XP
modules.
- XP data encoding
- The syntactic representation of data described by the XP data model within one or more XP modules in an XP message.
- binary data
- Data which is represented using a non-XML based, non-human readable
syntax
@(#) $Id: xp-terms-01.html,v 1.7 2000/11/15 21:21:09 frystyk Exp $