[Gambas-user] Strings and Network input ...

[Daniel Campos]

Hi:

I don't know why changing anything... when you read from a socket you
don't know when the other part will send the complete message, so the
programmer has to care about this, discard incomplete messages and so
on, that's life: you're not reading data from your own safe hard disk,
the communication may fail in any moment, and any programmer should
care about that or things will become wrong in its program.

The programs which just block until they receive a complete message,
use to just hang forever if something fails, like the old Netscape
Navigator for Linux: without threading it waited for DNS query
sometimes forever providing a distressing interface.

Anyway you can use the Peek() method in the _read event to read the
data without extracting it from the socket buffer, that is, without
creating any Gambas String buffer if you don't want to, until you find
a Chr(0), Chr(13) or whatever using Instr() for example, It's not so
difficult.

Daniel


2007/5/9, Benoit Minisini <gambas at ...1...>:
> On mercredi 9 mai 2007, nando wrote:
> > Actually, the complexity increase isn't really too much more.
> >
> > 1) have a public var for the receive buffer (string)
> > 2) use _read for the socket to continuously append to that string
> > 3) use INSTR to look for \n\r.  IF it finds it, remove the string and use
> > it. -Fernando
> >
> >
>
> Yes, LINE INPUT is only safe when you use file streams. When you
> use "character" streams, i.e. sockets or process output, you cannot read as
> much data as you want.
>
> In that case, LINE INPUT takes the end of the buffer as an end of line, so you
> cannot know if you really read a full line, or just a part of it because the
> buffer is void - if the socket didn't receive the data yet, for example.
>
> A solution could be having blocking input/output, but then your LINE INPUT may
> wait for the data until a timeout occurs (for a socket) or forever (for a
> void pipe). And this can lead to other problems.
>
> So at the moment, I don't know how to make the situation better. If someone
> has some idea about the semantic of LINE INPUT and other stream functions, he
> is welcome!
>
> Regards,
>
> --
> Benoit Minisini
>
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