Easysoft ODBC-ODBC Bridge

How does the OOB client handle refused connections?

Article:
00627
Last Reviewed:
28th October 2008
Revision:
2

The OOB client will retry connection attempts if the server operating system returns ECONREFUSED (connection refused). The reason for this is that on some platforms (notably NT workstation) the listen backlog can only be set to a low level so if there is a sudden rush of connections the operating system may turn some down before the OOB Server sees them. When ECONREFUSED is received by the client it waits connection_attempt * 0.1 seconds before trying again up to a maximum of NetConnectRetryCount times.

Here is an example where NetConnectRetryCount is 5 (the default) and the server always refuses the connection:

connect attempt 1 - refused by server
wait 0.1 seconds
connect attempt 2 - refused by server
wait 0.1*2 seconds
.
.
.
connect attempt 5 - refused by server
client gets error diagnostic:

08001:1:4:[Easysoft ODBC (Client)]
Client unable to establish connection
HY000:2:4:[Easysoft ODBC (Client)]
Connection refused, connect(), after 5 attempts

and here is an example where the first few attempts are refused due to the listen backlog queue being full but by the third attempt the backlog is cleared and the connection accepted:

connect attempt 1 - refused by server
wait 0.1 seconds
connect attempt 2 - refused by server
wait 0.1 * 2 seconds
connect attempt 3
connection accepted by server operating system

The NetConnectRetryCount is 5 by default but it may be modified in the OOB Settings off the DSN dialogue (Windows) or in the {Settings} section of your odbc.ini file. e.g.

{Settings}
NetConnectRetryCount = 3

Please note NetConnectRetryCount is a global setting for all DSNs.

Applies To

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