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Re: gEDA-user: Functional blocks and PCB format changes

At 11:49 AM 9/4/2010, you wrote:

On Sat, Sep 04, 2010 at 01:16:01AM -0400, Rick Collins wrote:
>
> Don't hold back, tell us how you really feel!
>
> The spec is large because it addresses a wide range of design
> aspects, which is one of the great reasons for using it, one file
> for the entire design, schematic, layout, mechanical, etc, even
> board lay up.  So the compatibility issue is moot because any one
> app only needs to deal with the portion that applies to it.  Just
> don't muck with the other parts.
>
> The "heavy" issue is a red herring (are you planning on hosting this
> on a cell phone maybe?)  No PCB file format is going to be easy for
> humans to read.  Bandwidth?  Back to the MCU in the cell phone I
> guess.  "Ugly", now there is a great technical argument.
>
> But I suppose it is better to re-invent the wheel.  There is no
> reason to try to foster any sort of compatibility in file formats
> between all the different CAD tools.  There are always conversion
> programs to be written, no?
>

This is not an emotional argument, but a technical one, and the
choice is not between XML and reinventing the wheel. (Sadly, my
Lisp suggestion has been shot down - by better arguments than
popularity, I might add. ;) There are other formats to consider,
and yes, inventing one might be an option.

How do you know PCB won't ever run on cell phones, or over a
slow network link, or on an embedded device or network PC or
overtaxed virtual machine? How do you know we won't one day
need to work with 1000-layer boards when suddenly it /does/
matter how heavy the file format is?
So are you suggesting that we should, at this time, plan for running PCB on a cell phone? Do you want to design PCB to work on overtaxed virtual machines, if so, I expect there will be a lot more important things to optimize than the file format which only impacts the performance when reading or saving the file. If we need to work with 1000 layer boards, I expect we would have computers which would be not at all burdened by XML file formats.
I'm trying to be realistic about the requirements. I think that the 2x or 3x factor of file size of using something like XML would be lost in the noise. The advantages of working with an industry standard file format could be very large. Of course as you or someone pointed out, IPC-2511B is not a well established format. But to my knowledge it is the only one that spans most if not all aspects of circuit board manufacturing. It seems like a great idea to work with something this useful and I am pretty sure that concerns with using it can be ironed out. 



Unless you want feature-parity with other CAD programs, it
is impossible to have file-format-parity. So no matter what,
conversion programs will have to be written. Creating similar
file formats won't help anything, other than to limit our own
format, and potentially cause problems if PCB and another CAD
program are able to open (and corrupt) each other's files.
I don't agree that a common file format has to be restrictive. If the file format is flexible enough, the program won't be limited. Everything doesn't have to be included from the start. I don't know if IPC-2511B is flexible enough for PCB and future ideas for PCB, but using XML I expect it can be expanded easily. I don't think anyone here has really looked hard at it. It may well be extensible. I don't know. But I would like to at least consider it and not toss it away without giving it a chance.
Rick 


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