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The Question is:
I have written a TCPIP client/server app. The server is a standalone app
implemented using $QIO. The client is a shareable image and is implemeted
using IPC for portability. I want the server to detect loss of communication
with a client when the network
cable to the client is disconnected. How can I implement this? As I see it,
periodic roundtrip application level messages from the server will force the
caller of the client image to accommodate a loop containing a select(). And I
do not want the caller t
o have to deal with that. If also the client image was implemented using $QIO
then queing a read with an AST which calls the read would be a solution. I do
not either want to change any TCPIP configuration which will affect other
processes on the system.
If I remember correctly then detection of this condition is default behavior of
DECnet task-to-task communication and delivered via a mailbox.
Thank you very much.
The Answer is :
Assuming TCP (rather than UDP), you will eventually detect connection
failures when a message cannot be successfully transfered. You can
simply wait for this to happen (and should check for and trap this
condition in any event), though the OpenVMS Wizard would also utilize
asynchronous application-level ping-like messages to probe inactive
connections.
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