ComponentInstance Guid question

[oajfh]

Hi,

Quick question : Which characters are NOT part of a ComponentInstance Guid ? It seems these specific guids are not the same as the longer guids one can find elsewhere, and the only thing the API says is 'a unique 22 character ID', or something along those lines.

I'm sending ComponentInstance data from SketchUp, and the quick dirty way I'm sending it so far is by creating a string from data. I don't want the guid to mess up my delimiters, so I'd like to make sure it's ok.

So far, the guids I've looked at were exclusively composed of alphabetical, numeric, '$' and '_' characters. I didn't see others, but...

Does anyone know ? For the moment I'm going to assume there's no whitespace...

[tt_su]

The GUID is Base64. Are you actually seeing dollar and underscore characters?

[sdmitch]

@tt_su said:

The GUID is Base64. Are you actually seeing dollar and underscore characters?

Apparently so in SU2014. Here is an example from a model of mine.

@unknownuser said:

3b1aPlRYjAAwO_o5_Y_sH8
1ek_9uHFbBkBOk60A4CUTj
2E9I543eD0KhmvF07odLJe
1FxdB0eHL9$O3G2kzcXhyB
2vY$wnUdb3PAiz$HWZGRRK
372Br$S2v6DeJBakA$Nfg3
2cAoJTfx1FPv1WkW5OmBeX
0N5ukFAF96AAR_zp1QMCjB
20fVk5NOj3DREBJ$kXpy$f

[oajfh]

Yes, these are the kind of Guids I get, but I'm using SketchUp 2015. I've only bothered trying with ComponentInstances though. Any particular reason why they seem non-standard Guids ? And are the dollars and underscores the only non alphanumeric symbols ?

[tt_su]

It appear that Base64 character set will depend on implementation. I'm not exactly sure which ones we generate, but I'm asking for more details.

@oajfh said:

Any particular reason why they seem non-standard Guids ?

Which standard are you referring to?

[TIG]

I expect he means something like this:
1bbf21fa-6616-49a3-aa12-713a5e20370d
A GUID generator will make them...
https://www.guidgenerator.com/online-guid-generator.aspx
http://www.guidgen.com/
https://msdn.microsoft.com/en-us/library/kw069h38.aspx
They are all but sure to be unique...

[tt_su]

GUIDs doesn't have a standard for formatting though.

Looking into the GUIDs we return it they are based on the IFC specification which describe compressed GUIDs for file-based exchange: http://www.buildingsmart-tech.org/implementation/get-started/ifc-guid

Having said that - the API doesn't actually have a contract to which characters it return. It would be safest to not depend on specific delimiter characters and instead use something like JSON or XML to carry the data.

[oajfh]

Thanks a lot for the details !

I believe that's my original question answered.

What exactly do you mean by "the API doesn't actually have a contract to which characters it return" though ? It isn't guaranteed to generate GUIDs containing only those characters from your base ?

[tt_su]

The API currently call the underlying existing GUID implementation - just pass through the call. I wouldn't expect it to change, should the underlying GUID implementation change for whatever reason, then the characters might be different. Say if the IFC specs changed for instance.

[inteloide]

Hello there !

I take benefit of this post to say that I have an example of one file with 2 components instances from 2 different definitions but with the same GUID.

So of course GUID is not unique.

My question : is the EntityID unique, but really unique within the same model ?

I mean, it may be a random number but the random number is checked to be sure that it's really unique.

Best regards.
Inteloide

[Dan Rathbun]

They are supposed to be unique. If you can, can you send Thomas (tt_su) the file by PM so he can take a look ?

[thomthom]

EntityID are unique for the model - but entities will be assigned a new ID each time you open it. They are not persistent. There will not be two entities with the same entityID in a model.

ComponentDefinition GUIDs change as you modify the definition.

ComponentInstance GUIDs persist - even if you edit the instance/definition.