We measured the result after sending and receiving 1000 messages which were composed with 20 bytes from a client to another client at an intervals of 0.1 s. The CPU usage of RMS server module was measured about 5 %, the database’s was about 40 % and the mosquito’s was about 26 % like in Table 6 when 100 clients send messages concurrently. The CPU usage of MySQL was higher than others. It showed database system used the highest CPU usage to store messages and the performance will be better if the database system is optimized (Figs. 10, 11).