Name | Value |
---|---|
NAME | SWP |
SEND | D SEND^XMLSWP |
RECEIVE | D REC^XMLSWP0 |
OPEN | K XMLD S:$G(XM)["D" XMLD=1 I $D(^%ZOSF("OS")),^%ZOSF("OS")["VAX" U IO:PACK |
CLOSE | K XMLD |
DESCRIPTION | This is a sliding window protocol using a logitudinal parity check checksum. than the 3BSCP protocol. Like 3BSCP protocol, SWP (Sliding Window Protocol) tries to take advantage of response time over the network by sending lines without waiting for acknowledgements. SWP will increase the number of lines that it will send without acknowledgement to a maximum if the connection seems successful and will reduce the number of lines in a 'window' to as few as 1 if there seems to be a lot of errors. Each line has its own checksum. Each line is acknowledged. Under ideal circumstances, it is therefore more resource intensive than 3BSCP. However, when errors occur, SWP only resends lines It is comparable in speed to the 3BSCP protocol, but is a bit slower and that were not acknowledged (1 for each error), while 3BSCP must resend an entire block (100 the 1st error, 50 lines the 2nd...). 3BSCP also quits when a maximum number of errors is sensed, while SWP does not quit unless it senses that the virtual connection has been terminated. 'SWP' CAN NOT BE USED WITH VERSIONS OF MAILMAN PRIOR TO 3.17a !!! more likely to succeed. Speed reported is based on actual lines sent. Characters (lines) resent because of errors are not included in the total as they are in the 3BSCP protocol. Error recovery is much better. Short of the virtual connection almost totally disintegrating, messages sent with this protocol will be transmitted. While the 3BSCP protocol must resend an entire block when it gets an error, this protocol sends only lines that were not acknowledged. It is therefore faster under non-ideal circumstances |