In recent years the need to fast access resources, distributed almost everywhere on the planet, found in Web services a suitable solution for rapid and low cost creation and composition of distributed applications. The benefits of this paradigm soon became clear also to the members of the GIS community who saw in this technology an effective way to rapidly share data between distributed and heterogeneous sources and to achieve spatial interoperability. Nevertheless, despite sharing the same philosophy, geospatial services standards and traditional Web services standards are quite different. In fact, although both types of services adopt XML as the underlying language to encode messages, metadata, schema and interfaces, the other core technologies are quite different and this aspect is crucial when trying to use another of the basic characteristics that make Web services such a widespread and adopted solution: the services composition. While this functionality is of interest to both W3C and the geographic community and a quite wide amount of work has been done towards the possibility of combining traditional Web services and geographic services, literature presents solutions where a standardized approach is not yet completely guaranteed, when different services are used in a composite application. This chapter will cover the issues mentioned above and highlight efforts made to try to overcome the corresponding challenges. In particular, it will also refer to a specific side effect of the service composition, related to the management of the large and flexible amount of data returned by a geographic service, which can cause bottlenecks when performance considerations are not taken into account in the design phase.
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