Model comparison Unique id？

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Hello, awesome developer. How does sp model comparison know that the modified data is the same component?
By what do they determine that this component is one? Do you put the two models together and determine by points, lines and surfaces?
Or does sp have the same stream as long as the model is the same will have the same id?
Can you tell me what value in the database determines that two components in different versions have the same id

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Where I marked above, this component is modified, do they have the same id data?

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Great question @feitiandacao and welcome to Speckle Community.

I’ll start with a truism:

  • Any two objects that are 100% identical will be understood by Speckle to be a single Element:
    • same data AND
    • same geometry

The opposite position makes sense in this regard. If any property is different, either data or geometry, then the two objects will be considered as different.

To bring that back to your question, how would two different objects be determined by Speckle to be one object that is changed.

When sending to Speckle, many softwares have internal IDs separate from the ones they may display to the user to track exactly this issue; in conversion, Speckle adds this internal property to the Speckle objects as applicationId. For this reason if you send an element from Rhino to Speckle, receive in Blender and then send again, it may end up with a completely new applicationId

In this case our diffing tools will consider the original Element deleted and replaced and not changed.

If the Speckle Viewer team has an even cleverer logic id love for them to add details. @alex ?

You can see for yourself if you are code savvy: https://github.com/specklesystems/speckle-server/blob/ffb96eaf5593aa7943a4d60449cce4fd9aceb8a9/packages/viewer/src/modules/Differ.ts

Id love to know more what you are thinking in this regard @feitiandacao and feel free to introduce yourself if you want: Introduce yourself 🙆

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This means that applicationId is just an application or it is a string of ids similar to mobile phone device codes. This applicationId does not have unique parameter identifiers as objects. Speckle’s Differ is also doing a rough comparison of data via this app id(device id)?
My question:
1.applicationId does not have unique reference value?
2.Speckle’s Differ is only compared to an approximate data by subscript?
Thanks for your answer great developer

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how would two different objects be determined by Speckle to beone object that is changed.
How does Speckle determine if two objects are different and are they defined as modified, by any specific attribute or id
Thanks for your
I mainly do back-end java development

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The applicationId schema/format varies hugely by application but is always a rendered as a string property. They can only be guaranteed as unique inside the host application (at the time of creation)

There is no universal standard in AEC software as it sounds it maybe in devices you mention.

Also, Grasshopper has no application ID for the objects it creates, but graph authors can create their own nomenclature for use cases such as diff tracking.

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Thanks for your answer, which solved my big confusion, sp is a great product!
Do you have any plans to convert it to a front end separation version when you do the later development iteration, haha haha maybe I am doing the java side and I want to see a fun project that I can run, and now sp is data processing into the library (pgsql) that feels great.
It is expected that sp can make data processing based on http interface form.

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Unsure what you mean by separate version?

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Front-end vue
Backend java or go or… …
Data processing The bim design software data is analyzed through http interface on the server side, and then the data is stored in the database