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Re: preemptive or preemtive ?

From: Henrik Frystyk Nielsen <frystyk@w3.org>
Date: Tue, 16 Jan 1996 13:35:04 -0500
Message-Id: <9601161835.AA26055@www20>
To: Jiang Tao <jiangt@ceci.mit.edu>
Cc: W3C Lib <www-lib@w3.org>
Jiang Tao writes:

> Who can tell me should it be preemptive or preemtive? And
> what is the EXACT meaning?

Alex Lian has told me that its preemptive with a "p".

The difference between preemptime and non-preemtive requests is whether you 
use non-blocking sockets or not. When you register a protocol, for example 
HTTP, you say what the default behavior should be. This is mostly a question 
of how the protocol module is implemented as in order to support non-blocking 
sockets you need to be able to keep state of where you are. This is described 
in the User's guide at

	http://www.w3.org/pub/WWW/Library/User/Using/Methods.html

You can override the default behavior pr request by setting a specific flag 
for not blocking sockets. This can be done by using the methods which is also 
described in the user's guide:

	http://www.w3.org/pub/WWW/Library/User/Using/Request.html

Preemtive or Non-preemtive Access

A access scheme is defined with a default for using either preemtive (blocking 
I/O) or non-premitve (non-blocking I/O). This is
basically a result of the implementation of the protocol module itself. 
However, if non-blocking I/O is the default then some times it
is nice to be able to set the mode to blocking instead. For example when 
loading the first document (the home page) then blocking
can be used instead of non-blocking. 

	extern void HTRequest_setPreemtive (HTRequest *request, BOOL mode);
	extern BOOL HTRequest_preemtive (HTRequest *request);

-- 

Henrik Frystyk Nielsen, <frystyk@w3.org>
World-Wide Web Consortium, MIT/LCS NE43-356
545 Technology Square, Cambridge MA 02139, USA
Received on Tuesday, 16 January 1996 13:35:31 GMT

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