This article describes the tendency of transition to "cloud computing" in the development of simulation tools. It is proposed to use the Java language in the development of simulation "cloud" services. The short description of Java class library for developing of simulation models in the "cloud" services implementations is provided. An example of simulation of M/M/1 type queuing system realization in the form of the Java applet was shown. Analytical calculation of model and results in the GPSS language were presented for a verification of the simulation results.