# From Service Composition to Mashup Editor: A Multiperspective Taxonomy
## 6 Discussion and Conclusions  
We presented in this paper a literature review of Web service composition and end-user oriented composition environments (Mashup editors). In this regard, we discussed the concepts of service, SOA, Web services composition, and its key concepts. We classified the different approaches to service composition either from system or end-user perspectives. In particular, we pointed out the concepts of SOC and composition of services, which were originally developed for enterprise application integration, and have recently evolved for end-users usage, typically Web users. These end-users are characterized by limited technical and programming skills, but are nevertheless producing Web content. In fact, in the Web 2.0 context, one of the interesting properties of end-users is their ability to produce or participate in producing content. Web 2.0 has brought a set of different technologies dedicated to end-users (even in an enterprise context), so it has become very easy for such users to publish or annotate resources (user-generated content (UGC)). Furthermore, these end-users are trying new relationships based on interests to the generated content, and stay in touch with their social relatives through online social networks and collaborative environments. Consequently, the composition of services should currently be driven by end-user needs, as it is encouraged by online environments of sharing and social interactions through the Internet. Mashup editors have emerged as an answer to this evolution in order to overcome the technical complexity that the end-users are facing and to ease the composition process for them. In fact, through this Mashup concept, existing works have provided (i) abstraction features such as visual workflow language, (ii) community features such as rating and tagging, and (iii) service selection facilities such as text-based search. Even if these features are absolutely necessary, we hardly believe that they are sufficient. In particular, during the composition process itself, and as we have pointed out previously, existing features do not currently provide any direct support to end-users. In fact, the users have to manually select and connect all services in order to compose them according to specific requirements and the composition logic. This phase of the composition represents a relatively painful phase of the process due to the lack of support. Regarding the evolution of the Web from Web 1.0 to Web 4.0, Web 1.0 was about connecting to the Internet and retrieving information, Web 2.0 was the advent of social media and user-generated content, Web 3.0 was the advent of the semantic Web, where computers generate and think about new information instead of humans, and Web 4.0 is the Internet of Things, or, as we call it, the intelligently connected Web. The objective was to propose a comprehensive and consistent classification framework by conducting a thorough analysis of the different Web service composition approaches and providing a clear and detailed explanation of the proposed classification framework. However, as in most classification approaches, our taxonomy was limited because it was intended for the end-user perspective of Web service composition, and hence did not cover many other classification criteria, such as QoS, expressiveness, scalability, security, and interoperability. Different emerging approaches promote the continuous assistance of the end-user when they are composing services. This concept is sometimes presented as a service dynamic recommendation [105], where, in a Mashup environment, such a feature is called _Mashup completion_[106]. In other interesting recent studies [107; 108; 109], new environments for Web service composition (such as on mobile devices) have been explored. While Web 2.0 was a central motivation of this work since we considered service composition as user-generated content (UGC), it is interesting to keep in perspective the evolution of the Web from Web 1.0 to Web 4.0.