 developers in creating composed services. The paper presents a case study that investigates how this environment can be used in a Telecom setting. Synthy [10] demonstrates the composition of a workforce management application enabled over a Telecom network, where core functionalities like Location are exposed as semantically annotated Web services and orchestrated using AI planning techniques. The Meteor-S [11] framework looks at a number of aspects related to the composition of Web services, including capture of semantic requirements of the process and choosing components under given constraints. Zeng et al. [12] propose a method for choosing component services during Web service composition based on a generic QoS model (based on price, duration, reliability, etc.) and established linear programming techniques. As noted earlier, we focus on SewNet in this chapter as it provides a broader model than pure Web services to cover different protocols. SewNet's T-Rec proxy model is rich enough to apply many of these techniques. For example, each proxy can be annotated with QoS guarantees regarding its reliability, response time, and SO on, using which developers can estimate the QoS parameters of their composed services according to [13]. Tools for Mashup Applications: One of the most commonly used terms for Web 2.0 applications is a mashup-an application that combines content from more than one source into an integrated experience. Content is picked up from multiple servers (data sources) using technologies like Ajax and REST, and Service Delivery Platforms composed (or rendered) at the same UI, typically a browser. There are several tools that aid in the creation of such mashup UIs. Examples are QEDWiki [14], Yahoo Pipes [15], Aqualogic [16], and PrestoStudio [17]. These tools cater to a class of application developers who prefer "drag-and-drop" operations to create their own mashups. It is worth noting that most of these tools are not Telecom specific and can benefit by incorporating SewNet's proxies. Web21C [5] fr