Anyone know average HL7 clinical message response times?

[ClarkJason]

Hi,

I'm designing a interface for sending and receiving  HL7 messages.

My question is.... Would anyone be able to share their experience on how long it could take to get a message response back from a hospital HL7 server. (Particularly when requesting patient demographics) - seconds / minutes / Hours?

My dilemma is do I design my application to make the user wait for the message to come back.

(Sorry if this is a little off topic, it’s still kinda programming related? – I searched the web for HL7 forums but got stuck so again if anyone knows of any please let me know )

cheers, Jason