Thanks Dario,

But I need the answers for the following questions:

1 - Is there any way to increase the (max frequency update)/item/second to more than 3?
2 - What is the max message size that can be sent?
3 - for the purpose of BW, which is better: sending small message to equivalent item [ # items = 400]... OR.... combining all messages in one big message and send it to common item [common item for 400 items].

4 - for BW calculation purpose: each client has one connection (one session), it has subscribed for 100 items, each item has 3 updates per second as you mentioned, if each message size is 50 bytes, then BW required is:

100 * 3 * 50 * 8/1000 = 120 kbits/second, Am I right???

if we combine those 100 items in 1 item, the max message size is 5000 bytes, then new BW is:
1 * 3 * 5000 * 8/1000 = 120 kbits/second, same as above?

so if the above is true, I need to know what is the effect of large message size?

Thanks for your kind help and usual support.