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File name:	UDP_STX.TXT			Revision date:	1999.10.15
Created by:	Ulf Ronald Andersson		Creation date:	1999.09.22
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This file describes the current development state of the UDP module for
STinG, as it has progressed since Peter 'disappeared' in mid-January 1999.
Recently he has confirmed that he wants me to handle the administration of
the future STinG development and has passed on all the sources to me.

The copyright to updated versions remains property of Peter Rottengatter,
and the release form remains FREEWARE, as originally defined by him.

Updates will be described below, in reverse chronological order.
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UDP.STX 1.45:		Beta release:	1999.10.15
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This version has been changed to use the message E_LOCKED, rather than the
message E_DEFERRED, to tell callers that they can not be serviced at once,
and should instead call again later. This change was for STiK compatibility,
and code E_DEFERRED is abolished, as it duplicated the purpose of E_LOCKED.

This version has also been improved so as to allow safe and efficient use of
a connection from multiple threads/forks/APPs/ACCs, in all TOS variants.

Such usage may however lead to E_LOCKED return for cases where the caller
is executing in supervisor mode, while other threads (etc) already have
an access to the same connection in progress.  Programmers should be aware
of this, and note that such a message does not mean the function can not be
performed, but only that it will have to be done later, when other threads
are not locking the access.
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UDP.STX 1.44:		Beta release:	1999.10.11
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This version has a new function, UDP_info, to be used similarily to the
TCP_info function, except that some things obviously don't apply to UDP
connections.

Because the UDP_info function does not exist in older kernels, this UDP
module requires STinG kernel 1.21 or newer.  NB: Older kernels may BOMB.
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UDP.STX 1.43:		Beta release:	1999.09.22    Public:	1999.09.26
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This version contains some major updates relative to earlier versions.

All the Supexec calls have been removed from the UDP API functions, which
should make servers of all kinds more reliable, especially under singleTOS.
Now the only TOS function ever called by API functions is _appl_yield, as
is required for proper multitasking (NB: this is true even in singleTOS).

UDP CNbyte_count never returned E_LISTEN for passive connections.  This is
fixed by making a passive UDP connection return E_LISTEN until it has
received some incoming packet.  This ceases as soon as it does receive any
incoming packet, even if that packet has no data at all.  From then on the
value returned will be the number of data bytes received (0 if none) unless
a network error occurs, in which case that error code will be passed as is
normal for STinG API functions.  This should make consistent server design
easier, as it allows TCP and UDP functions to be 'watched' by similar means.

Note however, that in reality there is no such thing as a UDP connection
and consequently there is no such thing as a 'passive' UDP connection.

The concept is undefined, but for the purpose of our STinG usage I have
followed the tradition that a UDP opened for an unspecified remote host
IP shall be considered to be passive, and return E_LISTEN for CNbyte_count
calls, until some packet has been received.  Connections with specified
remote host will continue to function like previously, returning E_NODATA
until packets arrive.

Several of the TCP patches I have made over the last year also apply to
the UDP module, and these have now been merged in as well.
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End of file:	UDP_STX.TXT
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