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Add note explaining that NoticeResponse messages can

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arrive even while idle.
This commit is contained in:
Tom Lane 1998-10-04 22:48:42 +00:00
parent 22da903a48
commit 4fe24467f4
1 changed files with 14 additions and 4 deletions
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18
doc/src/sgml/protocol.sgml
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@ -4,7 +4,7 @@
<FirstName>Phil</FirstName> <FirstName>Phil</FirstName>
<Surname>Thompson</Surname> <Surname>Thompson</Surname>
</Author> </Author>
<Date>1998-07-13</Date> <Date>1998-08-08</Date>
</DocInfo> </DocInfo>
<Title>Frontend/Backend Protocol</Title> <Title>Frontend/Backend Protocol</Title>
@ -389,9 +389,19 @@ The possible response messages from the backend are:
<Para> <Para>
A frontend must be prepared to accept ErrorResponse and NoticeResponse A frontend must be prepared to accept ErrorResponse and NoticeResponse
messages whenever it is expecting any other type of message. Also, messages whenever it is expecting any other type of message.
if it issues any listen(l) commands then it must be prepared to accept
NotificationResponse messages at any time; see below. <Para>
Actually, it is possible for NoticeResponse to arrive even when the frontend
is not expecting any kind of message, that is, the backend is nominally idle.
(In particular, the backend can be commanded to terminate by its postmaster.
In that case it will send a NoticeResponse before closing the connection.)
It is recommended that the frontend check for such asynchronous notices just
before issuing any new command.
<Para>
Also, if the frontend issues any listen(l) commands then it must be prepared
to accept NotificationResponse messages at any time; see below.
<Sect2> <Sect2>