On Wed, 13 Dec 2000, Chris Lattner wrote:
> Which is exactly why it doesn't work well for many applications. The
> problem is this: how do you get from a byte stream to a structured data
> stream? There are many answers:
>
> 1. Keep your data structures so simple, that it's obvious. Not a good
> choice. :)
> 2. Defined interfaces to the bytestream for every interface that you
> define.
> 3. Define a standard for inflating/deflating "things" into
> bytestreams. Oh wait, that's what corba does. :)
OK, now I'm completely confused.
* which complex data structures do you want to export from the kernel
in non-opaque way?
* which of those structures are guaranteed to remain unchanged?
* if you have userland-to-userland RPC in mind - why put anything
marshalling-related into the kernel?
> The 9P way of doing things is not fundementally new, they just applied the
> idea that "everything is a file" more broadly. What annoys me is that it
> is not immediately obvious how to "demarshall" the data that comes out of
> /dev/mouse for example. Combine that with the problem that /dev/mouse
> might change format in the future (okay stupid example, but you get the
> idea) to use floating point coordinates, and things certainly get hairy.
HUH? OK, suppose it had happened. Do you really expect that you will not
need to change your applications? I mean, if you expected a bunch of
ints and received a bunch of doubles... You either need to decide on
rounding (and it's a non-obvious question) or you need to change quite a
bit of code in your program. It goes way past the demarshalling, no
matter whether you use CORBA, 9P or printf/scanf.
OK, suppose you have a CORBA-based system and mouse drivers' API had been
changed - they really want to return floating point coordinates. How will
CORBA help you? Aside of making your programs scream aloud, that is.
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