In this paper we deal with the study of the actual convenience of using the agent programming paradigm for accessing distributed service. We try to point out the benefits of such a communication paradigm, by providing an analytical study of its basic features in comparison with client-server approach and remote evaluation. The results that we have obtained show how agents must not always be considered the only solution to any communication issue, since in several cases their use might even reveal a drawback. In this paper we present several models of non-Markovian Petri nets, which have been solved through the WebSPN tool, and we provide a close comparison between the agents technique, the client-server and the remote evaluation. We also focus our attention on providing some practical remarks, which can help the developer during the design, in order to select the communication paradigm which best suits to the features of the application that has to be developed.