XML Descriptor Based Approach for Real Time Data Messaging

This paper was presented at the Ninth IEEE International Symposium on
Object and Component-Oriented Real-Time Distributed Computing. It
presents an overview of the Real Time Markup Language (RTML). RTML
is a XML profile which provides the syntactic representation for
describing the semantics of real time data for exchange over
distributed networked real time systems. We demonstrate a method which
uses descriptor based approach to describe the real time semantics in
distributed real time systems using XML. We have chosen XML Schema for
a number of advantages. In order to create a consistent schema that
contains the correct semantics offer by conceptual design model, we
have used the OO conceptual model transformation approach proposed by
L. Feng, et al., "Schemata Transformation of Object-Oriented Conceptual
Models to XML." As discussed in this paper, very often the individual
real time systems do not have knowledge of the application from each
other. So attempting to set up collaboration for data exchange will
be a major challenge and especially when it is dealing with multiple
heterogeneous sources. We introduce a descriptor based approach for
describing the resources using three types of descriptors namely
Concept Descriptor for illustrating the details of the features from
a real times systems; a Category Descriptor for organizing the logical
structure of Concept Descriptors whose share common similarities; and
Relationship Descriptor which describe the structure of a collection of
Concept Descriptors and Relationship Descriptors which illustrate the
semantics, syntax and organization of such a structure. We believe that
this work will be one of the first steps towards defining an approach
using XML to describe real time resources. By providing such a XML
profile, it establishes a knowledge based for organizations to exchange
data using XML messaging... RTML is a XML descriptor based profile.
Elements in RTML can be classified into three corresponding descriptor
types: Descriptor (D), DescriptorMapper (DM) or DescriptorCategory. The
use of descriptors allows multi level abstraction. Ds and DMs are
further defined into corresponding spectrums Apart from OMG SPT, RTML
has also adopted the specification developed by ISO and ITU-T document
number X.641 Recommendation (ISO/IEC IS 13236). This specification
provides a standard approach to describe QoS for different purposes,
and how can QoS be described from different levels or viewpoints and
precision. Along with the ISO/IEC specification, we have also adopt
QoS Profile. The meta-model in QoS Profile provides a lightweight
modeling component for conceptual design customization.The above
standards have provided fundamental constructs for conceptual model
transformation into RTML constraints. This design time construct can
be complemented by realizing additional details to enrich the
description to the design elements defined in those specifications.
RTML provides a reference model for the realization of abstract details.