How to change IDs in XMI data files from integers to UUIDs

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XMI data files, by default, have a format for references to other objects as "//@anyObject.x" where x is an integer. My original data is on RDF format so the object ID is stored in the rdf:about attribute and the references are stored in the rdf:resource attributes.
This far I have figured out that the class "org.eclipse.emf.ecore.xmi.impl.XMLResourceImpl" has a method "useUUIDs()" that returns a hardcoded "false" so I assume I need to change it to "true". I have read that the object IDs will then be stored in the xmi:id attribute and the references will be stored as href attributes. So I will then put my rdf:abouts in the xmi:id and the rdf:resources in the href. Will EMF extend the Ecore information model for all classes with an ID attribute for UUIDs? I already have such an attribute so how do I tell the loader and saver to use it for the xmi:id? The loader will have to translate all the hrefs to internal object references and the saver will have to look up the referenced object and use their xmi:id (wherever it is stored) to put them in a href. From some of my findings EMF is said to generate to UUIDs, as I already have them I don't want this. Last but not least I need to override useUUIDs() to deliver "true". But what about all the classes that call useUUIDs() in XMLResourceImpl, do I have to override them as well to refert to my new class?
I am new to looking into the EMF details at this level so this is tricky for me and I would appreciate some help. / Lars-Ola

[merks]

That's a lot of questions. You can look at other subclasses such as org.eclipse.emf.ecore.xmi.impl.XMIResourceImpl.useIDs(), org.eclipse.emf.ecore.xmi.impl.XMLHelperImpl and its subclasses. You'll really need to study the existing classes in detail to see where the different types of processing happens for both load and save. It's often best to do the studying by setting breakpoints and seeing how it all actually functions while loading and saving a single instance.

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Yes, I will have to debug trace the code while performing the functions I want to study. I am not a skilld Java developer so a bit of threshold here.
I also started to use Claude. It told me to not use XMLResourceImpl and gave two options 1) use its factory XMLResourceFactoryImpl which reduce the number of changes to just a few or 2) change the settings in the plugin.xml which doesn't need Java code changes at all. So I will first try option 2) but the plugin is regenerated when the app code is generated I assume so I have to remember to update the plugin . Fun stuff, hope it works :-)
Thanks for responding / Lars-Ola

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No, I have to create a custom version of XMLResourceFactoryImpl and register it in plugin.xml.

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So I need to override XMIResourceImpl and update the useUUIDs() method (inherited from XMLResourceImpl) and the XMIResourceFactoryImpl to return my new version of XMIResourceImpl. Then register my new version of XMIResourceFactoryImpl in plugin.xml of do it programatically.
Why cant there be a configuration setting in some configuration file for this? It is awkward having to do this code change and I expect using UUIDs instead of integer numbers as object IDs is a common need. Integer IDs is old school Fortan style but it is fast, maybe the reason for keeping it.
Best regards / Lars-Ola

[merks]

It already returns true as the default behavior for XMI.

org.eclipse.emf/plugins/org.eclipse.emf.ecore.xmi/src/org/eclipse/emf/ecore/xmi/impl/XMIResourceImpl.java

Line 92 in 95f7c31

return true;

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Hi Ed Yes, the method XMIResourceImpl.useIDs() returns true. As I understand it, XMLResourceImpl.useUUIDs() must return true if I want to use UUIDs instead of integer numbers in the XMI files. XMIResourceImpl doesn’t have useUUIDs() and XMLResourceImpl.useUUIDs() returns false. So I have the change useUUIDs() to return true, use it to override XMLResourceImpl.useUUIDs() in a new class MyXMIResourceImpl, create a new factory MyXMIResourceFactoryImpl for it and finally register the new factory in the plugin.xml. If you see an issue with this please let me know. Thanks for looking into to this / Lars-Ola Från: Ed Merks ***@***.***> Skickat: den 28 mars 2026 12:14 Till: eclipse-emf/org.eclipse.emf ***@***.***> Kopia: Lars-Ola Osterlund ***@***.***>; Author ***@***.***> Ämne: Re: [eclipse-emf/org.eclipse.emf] How to change IDs in XMI data files from integers to UUIDs (Discussion #104) It already returns true as the default behavior for XMI. https://github.com/eclipse-emf/org.eclipse.emf/blob/95f7c311a6a3e821e1d593886dea7e4d342fc70c/plugins/org.eclipse.emf.ecore.xmi/src/org/eclipse/emf/ecore/xmi/impl/XMIResourceImpl.java#L92 — Reply to this email directly, view it on GitHub <#104?email_source=notifications&email_token=AN4NIQ3K3AP5VNUO32L7YTT4S6XV7A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNRTGU2TGNBTUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVRTG633UMVZF6Y3MNFRWW#discussioncomment-16355343> , or unsubscribe <https://github.com/notifications/unsubscribe-auth/AN4NIQ73MGNV2OC3VIBOOJT4S6XV7AVCNFSM6AAAAACXCICHKKVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTMMZVGUZTIMY> . You are receiving this because you authored the thread. <https://github.com/notifications/beacon/AN4NIQYEVRX5MFHR4WBA4A34S6XV7BFCNFSM6AAAAACXCICHKKWGG33NNVSW45C7OR4XAZNRIRUXGY3VONZWS33OINXW23LFNZ2KUY3PNVWWK3TUL5UWJTQA7GIA7JTSMVQXG33OUZQXK5DIN5ZA.gif> Message ID: ***@***.*** ***@***.***> >

[merks]

I'm answering with my iPhone with bad internet while on vacation. From what you describe, you have quite some specialization to do in a framework that is quite complex.

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Oh, sorry to disturb your vacation. Yes, I realize I will have to update the EMF platform and rebuild it, a huge topic on its own. I will investigate it a bit but maybe it is better if you could this for me. Have a nice holiday / Lars-Ola Från: Ed Merks ***@***.***> Skickat: den 28 mars 2026 15:48 Till: eclipse-emf/org.eclipse.emf ***@***.***> Kopia: Lars-Ola Osterlund ***@***.***>; Author ***@***.***> Ämne: Re: [eclipse-emf/org.eclipse.emf] How to change IDs in XMI data files from integers to UUIDs (Discussion #104) I'm answering with my iPhone with bad internet while on vacation. From what you describe, you have quite some specialization to do in a framework that is quite complex. — Reply to this email directly, view it on GitHub <#104?email_source=notifications&email_token=AN4NIQ363UHFQZRHCOA2G4T4S7Q3BA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNRTGU3TAMJRUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVRTG633UMVZF6Y3MNFRWW#discussioncomment-16357011> , or unsubscribe <https://github.com/notifications/unsubscribe-auth/AN4NIQ4L43QS6JV7KCTGOQD4S7Q3BAVCNFSM6AAAAACXCICHKKVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTMMZVG4YDCMI> . You are receiving this because you authored the thread. <https://github.com/notifications/beacon/AN4NIQ7RXBRTK45ZE2Q5YYL4S7Q3BBFCNFSM6AAAAACXCICHKKWGG33NNVSW45C7OR4XAZNRIRUXGY3VONZWS33OINXW23LFNZ2KUY3PNVWWK3TUL5UWJTQA7GLJHJTSMVQXG33OUZQXK5DIN5ZA.gif> Message ID: ***@***.*** ***@***.***> >

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I used the bowling tutotial to understand how the xmi load and save works. With help from Claude Code i figured it out. The useUUID() method need not be changed. I just needed to add xmi:id attributes with UUIDs in the xmi data files and updated the Ecore correspondingly.
Then I updated the href references with the UUIDs and it worked! I have not found any documentation for this but Claude knew! Maybe the bowling tutorial could be updated with a section describing this?
But a snag is that the id attribute flagged as an ID is not visible in the editor as the value sits in a map object. Maybe the GUI could be updated to look in the map object?