XML QoS Specification Language for Enhancing Communication Services Ernesto Exposito 12 , Mathieu Gineste 13 , Romain Peyrichou 12 , Patrick Sénac 12 , Michel Diaz 2 and Serge Fdida 3 1 ENSICA, DMI 1 Place Emile Blouin 31056, Toulouse Cedex, France 2 LAAS/CNRS, 7 avenue du Colonel Roche, 31077 Toulouse cedex 04. France 3 LIP6, 8 rue du Capitaine Scott, 75015 Paris. France {Ernesto.Exposito , Mathieu.Gineste , Romain.Peyrichou , Patrick.Senac}@ensica.fr Michel.Diaz@laas.fr Serge.Fdida@lip6.fr Abstract This paper introduces a global XML-based QoS specification language, called XQoS and an associated architecture. The design of this language is driven by the need of a global QoS description language, able to supply a complete description of applications QoS needs that can be easily mapped towards transport, network and system QoS oriented services. Moreover we propose a communication architecture that provides an efficient support to multimedia application of which the QoS needs are explicitly or implicitly expressed from the XQoS approach. This architecture allows a dynamic mapping to be done between the applicative QoS needs and the various available underlying services. An experiment illustrates how XQoS can be used for creating dynamically a protocol architecture that satisfies audio and video on demand applications QoS requirements. 1.0 Introduction In the last few years, multimedia applications have been evolving and taking an important role in the multi-domain information exchange on the Internet. However, most of these applications have been implemented over a best effort network service not suited for the quality of services (QoS) requirements related to order, reliability, bandwidth, time and synchronization constraints. Moreover, TCP and UDP standard transport protocols offer only an everything-or-nothing service in terms of order and reliability. Consequently, adding the standard transport protocols (.i.e. TCP and UDP) to the best effort network service, does not permit to take completely into account the QoS required by new applications. Although the QoS parameters required by the multimedia applications are well known and some form of guaranteed QoS is available at transport and network layers, there is no standard QoS specification enabling to deploy the underlying mechanisms in accordance with the application QoS needs. Actually, there is no standard QoS-oriented architecture including the