## 1 Introduction
Web services are the basic technology in service-based architectures to implement service-orientation. However, the current Web service specification does not support continuous data such as handled in the multimedia domain. [PERSON] _et al._[6] shows an approach overcoming this limitation by introducing a communication policy that is used in addition to the Web Services Description Language (WSDL) description of a service enabling the implementation of applications with no standard communication requirements, e.g., data streaming. In addition, [PERSON] _et al._[7] introduces an extension of the Web service specification, _i.e._ Flex-SwA, allowing the transport of continuous data over Web services enabling, e.g., streaming. Furthermore, Web services are developed for machine-to-machine communication in the area of business transactions and, therefore, not optimized for real-time applications. Nevertheless, instead of building monolithic systems, the flexible composition of services into suitable workflows for media handling is an important goal for system integration and reusability of components. First approaches were discussed in the multimedia community as a brave new topic on ACM MM 2004 [8]. Indeed, the handling of multimedia content serving a plethora of client devices in a personalized fashion puts great demands on the selection of suitable services and the adaptation of media content [9]. For every delivery process a specific workflow has to be created containing multiple multimedia services. Every individual multimedia service fulfills a specific task (e.g., adaptation) respecting the user's preferences, content semantics and terminal capabilities. **Example** Imagine a user who wants to get a video streamed to a personal digital assistant (PDA) over the Universal Mobile Telecommunications System (UMTS) network. Since, the user has limited free data volume and the PDA imposes some strict technical constraints, e.g., display size and resolution, bandwidth would be wasted if the video is streamed in a resolution higher than the best  
Figure 1: Technology Overview. possible display resolution. Thus, it is reasonable to adapt the video content during delivery to the PDA by creating a specific service chain including a scaling service. On the other hand, a user with a multimedia PC has entirely different technical constraints. A PC has much more processing power than a PDA and usually a high definition monitor. A re-scaling of the media stream may not be needed, but users might want the video with specific subtitles. In that case it is necessary to add the desired subtitles to the media content by integrating a subtitle service into the workflow. All workflows have to be planned and their execution closely monitored to fulfill the Quality of Service (QoS) restrictions necessary for real time multimedia applications. This includes, among other issues, the seamless replacements of failing services, or exchanging services on-the-fly reflecting the alteration of the underlying networks parameters. This is especially important in mobile environments where handovers between networks can drastically change the requirements. Moreover, the creation and instantiation of such a service chain needs to solve a multi-objective optimization problem considering all possible services (as discussed in [10]), the currently available content and the author's, user's and client device's, constraints on the adaptation. The actual workflow creation, service discovery and monitoring in our architecture is not the focus of this paper, but can be found in [11]. In the course of this paper we focus on the service chain instantiation to demonstrate our approach's practicality. We will adapt the Web service approach for the area of multimedia applications and create multimedia services that are subsequently composed to form flexible workflows. Our experiments show that personalization of media streams is possible under real-time constraints in a service-oriented way.