Is Alibre file format "open"?

[moyesboy]

Is Alibre file format "open"?

I read something from Greg (CEO) about how the CAD industry suffers because the file formats are encryprted and closed.

Is the alibre file format published?
I think the alibre step format might be available for all to see?

What I mean is, is the way Alibre interfaces with ACIS published so that it is a simple task for another cad system to be written to open the Alibre files and drawings?
Most CAD companies keep this infomation to themselves, and even make it deliberately difficult.
If the Alibre file format is open, and the use of ADX is widespread then perhaps other cad systems will be pressured to write import routines that allow them to open alibre files including the creating history and links to drawings etc (all that is in the Alibre step).

So is that good or bad for Alibre?
Good I think. I don't think Alibre has much to loose. More small places can use Alibre and exchange info with the other systems.

Would there be an incentive for other cad vendors to make that import reversible?
I think not because then its easier to switch from the expensive system to the lower cost Alibre - and we see already that they try to retain their customers by locking them in!

 

[swertel]

There are two different aspects to what you are describing.

In terms of being open, Alibre uses STEP as it's native file type. BUT, Step only contains geometry information, not the steps to create it. In other words, the feature tree is not part of the step standard and therefore import/export will not contain those features. The result is a dumb solid.

Parasolid is becoming the de facto modeling kernel. That's why you see more and more CAD systems being able to open competitor files... find where the parasolid data is in the filestream and extract it. Closing or encrypting the file means taking that parasolid data and breaking it up or hiding it within the stream.

Since all CAD can import/export step, they can import/export Alibre files without Alibre having to export into another format (limit the translations to one import instead of two - export and import).

 

[MilesH]

As Alibre have submitted their parametric extension to the STEP format to ISO, I guess they consider this "open" as well. They are proposing this as a possible "intelligent solid" exchange format. so I doubt if they'd object to another CAD system providing import for it

 

[MilesH]

Here's a link to the Press Release:
http://www.alibre.com/news/pr/pr20020814.asp

 

[MilesH]

Also, scroll down to "Letters to the Editor" here:
http://www.upfrontezine.com/2005/upf-415.htm

 

[moyesboy]

milesH
I read Ralph Grabowski regularly. Doubt if an expansion into Norway is that important to Alibre though...

Swertel
I <think> that parasolid transmit format (_xt) does not contain the creation history. If you have a SWX file and export parasolid then import it to solidedge (or back into solidworks) then you get no creation history.

An alibre step does include the feature history (and also possibly one 2D detail drawing but if you include that it seems to confuse the import to SWX at least!). Its just when solidworks or ANother opens the alibre step that chunk of information is ignorred and you get only the dumb solid.
However a step 213/214 export from Alibre does not include the creation history - import that back in and you get dumb solid.

The process consists of the modelling kernel plus a set of instructions to the modelling kernel. The way those instructions work is unique and proprietry to the cad vendor and for most it is kept secret. It is highly significant if alibre published their file format (the way it instructs ACIS)completely.

I don't agree that parasolid is becoming a defacto std. Only if you consider that the packages that use it (SW, SE etc) are becoming dominant. Inventor is not about to switch to parasolid, neither is pro/E so probably PTC and Autodesk would disagree with your statement about parasolid! Where a package is not based on parasolid the export option in that format may be a very expensive add on.

I guess the fact that Alibre have submitted their extension to step may or might not mean the format is published. But we are talking only of the alibre step that you exported from Alibre - not the usual format of AD_PRT. So thats a bit like autocads dxf compared to dwg isn't it?
If another vendor wrote an import for Alibre step to read and translate the creation history you would still need to do the export op with an Alibre installation. It wouldn't read the AD_PRT, ASM, DRA directly. A working Alibre would still be needed in the loop.

By the way Scott, do you have a double in the ADX forum? I think it may be possible for someone else to reuse an identity from here in there as there seem to be some unexpected comments from "swertel"!

 

[swertel]

Moyesboy,

I'm not referring to the .x_t or .x_b format. I'm actually referring to a SE .prt, .asm, .pwd, .psm and SW .sldprt, .sldasm.
The file stream is the binary string XXX101010001110101011010YYYYY...

The first few characters are typically the metadata or the Windows file table information. I don't know the technical term for it. From there, the application writes out its file data. In the above example, the binary digits would be the parasolid data and the YYYYY the creation history. Since the parasolid data is right at the beginning of the file stream, it is easier for competitors to extract that data from the native file and not from a .x_t or .stp translation.

But, if the file stream were like XXX100100YYY0100101YYYY, it is much harder to find the parasolid data (or ACIS or Granite or whatever) and recreate even a dumb solid.

I can't read schema, so I don't know what Alibre's says, but if it defines not only where the kernel information should reside, but also creation history, it may be possible to import featured solids through step.

(Yes, I took a slightly less professional tone on the xpress forum. I got really annoyed by so few people loudly expressing their hatred for something they haven't even seen yet. "I want something for nothing that you are willfully giving me, but it better be exactly what I want or else!" You could make a Seinfeld episode out of people like that.)

 

[MilesH]

Re:

I guess the fact that Alibre have submitted their extension to step may or might not mean the format is published. But we are talking only of the alibre step that you exported from Alibre - not the usual format of AD_PRT. So thats a bit like autocads dxf compared to dwg isn't it?
If another vendor wrote an import for Alibre step to read and translate the creation history you would still need to do the export op with an Alibre installation. It wouldn't read the AD_PRT, ASM, DRA directly. A working Alibre would still be needed in the loop.

It's all covered in the Press Release.........

It's interesting that a similar debate over open formats and access to data is taking place in the Digital Photography world.

Also interesting, in this context, is Evan Yares letter in the latest eZine.