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Re: Filters: 6 vs 7 Arguments

On Tuesday, June 24, 2003, at 09:55 PM, Mike Sweet wrote:

You can't depend on the your filter always reading from stdin or
always reading from a file; if you make an assumption about where
your print data comes from, you'll almost certainly run into an
issue with one or more of your users.

Alright, so I did some more poking around and the logic seems to boil down to three points:
* The first filter in the chain may get input either as a file or on the standard input stream.
* All consecutive filters will always receive their data on standard in.
* The backend will always receive data on standard in, unless the job is printed as "raw" (i.e. no filters invoked), in which case it could be either a file or stdin.

Which leads to a follow-up question: Is it guaranteed that the filters and the backend will all be launched at the same time? This seems like a requirement for connecting up all the streams; and debug logging indicates that this is indeed the case.

Specifically, I want to know for sure that my custom backend will always be launched at roughly the same time as the first filter; even if it's a huge job that might take minutes to make it through the filter chain.

Thanks,
Tobias Peciva
Pharos Systems
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 >Re: Filters: 6 vs 7 Arguments (From: Mike Sweet <email@hidden>)



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