## 3 Use Case Scenario  
Consider the following scenario: [PERSON] is a stock broker. While he is on his way to his office he wants to receive the latest news regarding stock markets from abroad on his smartphone. Finally, arriving at his office, he switches to his office desktop PC and continues watching stock market news. [PERSON]'s smartphone, as well as the desktop PC, run a sophisticated application automatically selecting the best from a list of available information sources based on [PERSON]'s content preferences and technical capabilities. This basic task of the application can be accomplished in different ways, so the application designer may have envisioned several possible service chains with different workflows. **Detailed Example**: Another Monday morning and [PERSON] has to go to work. He switches on his Android smartphone application which offers several settings of how to react to different events, e.g., network change or low battery event. Starting the application at home he receives the latest stock market news and due to the high battery load of his smartphone and the available WLAN he retrieves them via a video stream. Since watching videos require a lot of energy his smartphone's battery load gets lower and lower. While riding the train the battery load reaches 20%. The application automatically switches into audio mode to save battery capacity. Arriving at the train station only 10% of the battery load is left and [PERSON] retrieves the latest news via instant messaging. Finally, [PERSON] arrives at his office, starts his Desktop PC and runs the application there. Now the content is streamed in high definition resolution as a picture in picture stream combining several information providers. Instead of building complex multimedia applications (like a monolithic Video-on-Demand based information system), providers need the flexibility to dynamically adapt to a variety of content requests and support a plethora of (mobile) client devices. Service providers need to acquire the content from several content providers that will provide the content and its description in a high-quality format suitable for different adaptation steps, like scaling or re-encoding. Then the content has to be adapted to the end user needs and the respective device's technical profile. Though the basic workflows are generally well-understood and can be used in the form of templates, the digital item adaptation (DIA) can usually be performed in several ways. To dynamically realize a best possible instantiation user preferences, transcoding hints, and technical capabilities (e.g., given by MPEG-7/21) have to be considered. This complex optimization problem of workflow selection has already been addressed in recent literature; see [36] or [1]. Moreover, to allow for optimizing the necessary adaptations of the content on its path through the network, as well as being able to flexibly choose and instantiate workflows, recent work proposes that the actual adaptation should be done in a service-oriented way (see for instance [37]). The respective techniques strongly differ from the one-size-fits-all that is still prevalent in most multimedia delivery scenarios. Providers have to use service components (like formalized by Web service standards) and compose them into the final workflow. Since most users have similar requirements and network providers are in tight control of their networks, providers will directly provide at least some services such that compatibility and interoperability considerations will not play a big role for simple adaptations. However, by integratingservices from other providers added value can also be generated to cater for smaller user groups with special needs (like translation or subtitling services). In the case of integrating third party providers' services, interoperability is an important issue, so we also address this topic in our multimedia service composition framework [9]. Moreover, the space- and time-dependent nature of media streams poses hard constraints on current service provisioning frameworks.