wcf - Web service must be accessible from internet but firewall blocks incoming request -

so here situation:

• we need client app able make requests throught internet wcf web service.
• we have total control of both service , client implementation, major problem don't control router service not visible internet. (and router configuration can't change , doesn't allow request internet)
• we don't want use vpn client or ipsec tunnel.

the service knows clients, idea had initiate socket connections service clients, , client call service using callback methods.

it not seem common way of communication, maybe more common think. wondering if had such kind of constraint, , if solution consider work.

i fear run accross several issues in long term if wrong way proceed, because foundation of our platform need sure not over-complicate future development nor reduce system capabilities.

we several tests opinion on ? or bad idea ? see @ first glance go wrong approach ? there important things should aware of ?

for example service capabilities / wcf features limited approach ? multiusers / performance / transport security / authentication / etc.

may correct answer "you not need that".

if need periodically export or import data, consider swapping client , server in architecture, i.e. application in customer network (client) periodically connects service located in internet (server).

the reason otherwise need in near-realtime updates. in case can separate notification mechanism data exchange. example, use rss notify client start information exchange server.