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README.md

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+PV Access to PV Access protocol gateway (aka. proxy)
+
+
+Theory of Operation
+
+The GW maintains a Channel Cache, which is a dictionary of client side channels
+(shared_ptr<epics::pvAccess::Channel> instances)
+in the NEVER_CONNECTED or CONNECTED states.
+
+Each entry also has an activity flag and reference count.
+
+The activity flag is set each time the server side receives a search request for a PV.
+
+The reference count is incremented for each active server side channel.
+
+Periodically the cache is iterated and any client channels with !activity and count==0 are dropped.
+In addition the activity flag is unconditionally cleared.
+
+
+Name search handling
+
+The server side listens for name search requests.
+When a request is received the channel cache is searched.
+If no entry exists, then one is created and no further action is taken.
+If an entry exists, but the client channel is not connected, then it's activiy flag is set and no further action is taken.
+If a connected entry exists, then an affirmative response is sent to the requester.
+
+
+When a channel create request is received, the channel cache is checked.
+If no connected entry exists, then the request is failed.
+
+
+Structure associations
+
+ServerChannelProvider 1->1 ChannelCache  (composed)
+
+ChannelCache 1->N ChannelCacheEntry  (map<shared_ptr<E> >)
+ChannelCache :: cacheLock
+
+ChannelCacheEntry 1->1 ChannelCache (C*)
+ChannelCacheEntry 1->1 Channel (PVA Client) (shared_ptr<C>)
+
+Channel (PVA Client) 1->1 CRequester (shared_ptr<R>)
+Channel :: lock
+
+CRequester 1->1 ChannelCacheEntry (weak_ptr<E>)
+
+ChannelCacheEntry 1->N GWChannel  (std<C*>)
+
+GWChannel 1->1 ChannelCacheEntry  (shared_ptr<E>)
+
+
+
+ServerChannelRequesterImpl::channelStateChange() - placeholder, needs implementation