  Nowadays, e-government has emerged as a government policy to improve the
quality and efficiency of public administrations. By exploiting the potential
of new information and communication technologies, government agencies are
providing a wide spectrum of online services. These services are composed of
several web services that comply with well defined processes. One of the big
challenges is the need to optimize the composition of the elementary web
services. In this paper, we present a solution for optimizing the computation
effort in web service composition. Our method is based on Graph Theory. We
model the semantic relationship between the involved web services through a
directed graph. Then, we compute all shortest paths using for the first time,
an extended version of the Floyd-Warshall algorithm.
