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Applying a ChangeDescription to a different model [message #526581]

Mon, 12 April 2010 11:01

Scott Dybiec

Messages: 148
Registered: July 2009

Senior Member

I have written some code that captures changes to an EMF Resource
(capture-side) and applies those changes to a remote replica copy
(apply-side).

Since the ChangeDescription captured by a ChangeRecorder contains URI
references to the original capture-side model, the easiest thing to do
seemed to be to replace these URIs using a ResourceSet's URI Converter.

Here's the code I used:

// Convert the proxy hrefs in the ChangeDescription to point to the
replica file
URIConverter converter = new ExtensibleURIConverterImpl() {

URI replacementURI = resource.getURI();

@Override
public URI normalize(URI uri) {
if (uri.fileExtension().equals("rml")) {
return replacementURI;
} else {
return super.normalize(uri);
}
}
};

// Put the change description and model in the same ResourceSet, then
apply the changes
ResourceSet resourceSet = getResourceSet(); // This ResourceSet already
contains the model to apply changes to
resourceSet.setURIConverter(converter);
resourceSet.getResources().add(changeDescription.eResource() );
changeDescription.apply();

It works, is there a better way to attack this problem?

$cott

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Re: Applying a ChangeDescription to a different model [message #526637 is a reply to message #526581]

Mon, 12 April 2010 13:27

Ed Merks

Messages: 33142
Registered: July 2009

Senior Member

Scott,

Comments below.

Scott Dybiec wrote:
> I have written some code that captures changes to an EMF Resource
> (capture-side) and applies those changes to a remote replica copy
> (apply-side).
>
> Since the ChangeDescription captured by a ChangeRecorder contains URI
> references to the original capture-side model, the easiest thing to do
> seemed to be to replace these URIs using a ResourceSet's URI Converter.
>
> Here's the code I used:
>
> // Convert the proxy hrefs in the ChangeDescription to point to the
> replica file
> URIConverter converter = new ExtensibleURIConverterImpl() {
>
> URI replacementURI = resource.getURI();
>
> @Override
> public URI normalize(URI uri) {
> if (uri.fileExtension().equals("rml")) {
> return replacementURI;
> } else {
> return super.normalize(uri);
> }
> }
> };
Could you have don't this just with a URI mapping rather than
specializing the normalize method?
>
> // Put the change description and model in the same ResourceSet, then
> apply the changes
> ResourceSet resourceSet = getResourceSet(); // This ResourceSet
> already contains the model to apply changes to
> resourceSet.setURIConverter(converter);
> resourceSet.getResources().add(changeDescription.eResource() );
> changeDescription.apply();
>
> It works, is there a better way to attack this problem?
If you can get away with URI mappings, that would be nicer.
>
> $cott

Ed Merks
Professional Support: https://www.macromodeling.com/

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Re: Applying a ChangeDescription to a different model [message #526663 is a reply to message #526637]

Mon, 12 April 2010 14:05

Maximilian Koegel

Messages: 253
Registered: July 2009

Senior Member

Scott,

I have (successfully) tried what you did with a URI mapping. It works
quite OK until you have multiple Change Descriptions from different
nodes that might be contradicting and incoming at the same time. Then
you would essentially need to scan the change descriptions for conflicts
before applying them to the remote replica and potentially you would
need to merge them. If you will never run in such a situation, I guess
your approach could work just fine. Otherwise I would recommend you to
use CDO (EMF) or EMFStore (emfstore.org) to share your models among
multiple nodes.

Cheers,
Maximilian

> Comments below.
>
> Scott Dybiec wrote:
>> I have written some code that captures changes to an EMF Resource
>> (capture-side) and applies those changes to a remote replica copy
>> (apply-side).
>>
>> Since the ChangeDescription captured by a ChangeRecorder contains URI
>> references to the original capture-side model, the easiest thing to do
>> seemed to be to replace these URIs using a ResourceSet's URI Converter.
>>
>> Here's the code I used:
>>
>> // Convert the proxy hrefs in the ChangeDescription to point to the
>> replica file
>> URIConverter converter = new ExtensibleURIConverterImpl() {
>>
>> URI replacementURI = resource.getURI();
>>
>> @Override
>> public URI normalize(URI uri) {
>> if (uri.fileExtension().equals("rml")) {
>> return replacementURI;
>> } else {
>> return super.normalize(uri);
>> }
>> }
>> };
> Could you have don't this just with a URI mapping rather than
> specializing the normalize method?
>>
>> // Put the change description and model in the same ResourceSet, then
>> apply the changes
>> ResourceSet resourceSet = getResourceSet(); // This ResourceSet
>> already contains the model to apply changes to
>> resourceSet.setURIConverter(converter);
>> resourceSet.getResources().add(changeDescription.eResource() );
>> changeDescription.apply();
>>
>> It works, is there a better way to attack this problem?
> If you can get away with URI mappings, that would be nicer.
>>
>> $cott

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Re: Applying a ChangeDescription to a different model [message #531868 is a reply to message #526581]

Thu, 06 May 2010 12:32

Csaba Koncz

Messages: 49
Registered: July 2009

Member

Scott Dybiec wrote on Mon, 12 April 2010 07:01

I have written some code that captures changes to an EMF Resource
(capture-side) and applies those changes to a remote replica copy
(apply-side).

$cott

I would like to do the same thing, but I can not. The ChangeDescription created by ChangeRecorder contains the old state of the model, so I can only use it to undo the changes. What I need is to keep two model instances in sync. Is there a dedicated change model and recorder for this?
Thank you,
Csaba

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Re: Applying a ChangeDescription to a different model [message #531886 is a reply to message #531868]

Thu, 06 May 2010 13:13

Cyril Jaquier

Messages: 80
Registered: July 2009

Member

Hi,

> I would like to do the same thing, but I can not. The ChangeDescription
> created by ChangeRecorder contains the old state of the model, so I can
> only use it to undo the changes. What I need is to keep two model
> instances in sync. Is there a dedicated change model and recorder for this?

No, there is nothing dedicated to this. You can applyAndReverse the
ChangeDescription, serialize it and apply it again. You can then apply
the serialized ChangeDescription to your second model.

Regards,
Cyril

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Re: Applying a ChangeDescription to a different model [message #531899 is a reply to message #531886]

Thu, 06 May 2010 13:50

Csaba Koncz

Messages: 49
Registered: July 2009

Member

Hi Cyril,

Thank you for the tip. It is a smart trick, but I am concerned of the performance issues it might have. At both endpoints I have a number of change listeners and unless I disable them somehow, will have a lot of unnecessary view and domain model changes.

Currently I am using Epatch for propagating the changes. Epatch is nice but it has two features that are not really needed for me:
1. is a two way-patch. For me it means it carries unnecessary information (I am applying it only in one direction)
2. I can not apply the patch directly to the target model. Epatch only creates a patched copy of the target that needs then Matched/Diffed/Merged with the original in order to get the changes to their destination.

So despite of my concerns the ChangeDescription trick might be more effective than what I currently have.

Thank you again!
Csaba

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Re: Applying a ChangeDescription to a different model [message #531957 is a reply to message #531868]

Thu, 06 May 2010 15:07

Ed Merks

Messages: 33142
Registered: July 2009

Senior Member

Csaba,

Using applyAndReverse you can achieve the inverted set of changes and of
course you can do it again to get back to the final state.
Alternatively you could copy the model and the change description
(EcoreUtil.copyAll) and then invert that copy.

Csaba Koncz wrote:
> Scott Dybiec wrote on Mon, 12 April 2010 07:01
>> I have written some code that captures changes to an EMF Resource
>> (capture-side) and applies those changes to a remote replica copy
>> (apply-side).
>>
>> $cott
>
>
> I would like to do the same thing, but I can not. The
> ChangeDescription created by ChangeRecorder contains the old state of
> the model, so I can only use it to undo the changes. What I need is to
> keep two model instances in sync. Is there a dedicated change model
> and recorder for this?
> Thank you,
> Csaba

Ed Merks
Professional Support: https://www.macromodeling.com/

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