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Self-reference in viatra [message #1758263]

Sun, 26 March 2017 04:17

Eclipse User

Hi,
In the past days, i tried to use viatra to copy the TTC model, but when i copy elements of Switch and Segment, it is hard to implement the self-reference 'connectsTo' with vql and xtend. Could you offer me any advice? Or could you show me an example?
The attachment is the meta-model of TTC, you can refer to is.
Hope for your reply and thanks in advance!

Attachment: TTC Meta-model.PNG
(Size: 56.33KB, Downloaded 200 times)

Re: Self-reference in viatra [message #1758343 is a reply to message #1758263]

Mon, 27 March 2017 16:20

Eclipse User

Hi,

I don't really understand what are you trying to achieve here. In general, self-references can be easily extended in VQL using two variables, like `Switch.connectsTo(a,b);` or even `Switch.connectsTo(a,a);` depending on what you want to achieve. If you provide a more precise use case, I would be better equipped to suggest a use.

However, if you only want to copy the model (or a subtree of it), you could also have a look at the EcoreUtil#copy static method provided by EMF.

Best regards,
Zoltán

Re: Self-reference in viatra [message #1758731 is a reply to message #1758343]

Sat, 01 April 2017 03:40

Eclipse User

Hi,
Thanks for your advice and sorry for my late reply !
The purpose of mine is to check whether VIATRA can finish this task and what about the performance is, not just copy the model. and fortunately i have finished the copy task. But i found the consumed time of 1st transformation is about 25 minutes(Maybe it is unacceptable for me) and the 2nd transformation is less 1 second(It's excellent), the model element is 1,565,000 and in my test i referred to the tutorial on http://static.incquerylabs.com/projects/viatra/viatra-docs/ViatraDocs.html with the event-driven mode .

Re: Self-reference in viatra [message #1758733 is a reply to message #1758731]

Sat, 01 April 2017 07:38

Eclipse User

Hi,

without seeing any detailed performance measurement results, I am only guessing, but I believe, the indexing required for one of the queries should be the culprit.

I'd do the following steps here:

1. Ensure the pattern editor provides no warnings, especially cartesian product warnings. The ones detected can increase initialization time and memory consumption greatly.
2. Look at our query optimization guide [1] and review your patterns.
3. Execute the query performance suite [2] and find out which query seems expensive. If the result is unclear, and you can share the problematic pattern(s), we can try to help figuring out what goes wrong.

Best regards,
Zoltán

[1] https://wiki.eclipse.org/VIATRA/Query/FAQ#Optimizing_queries_and_transformations
[2] https://wiki.eclipse.org/VIATRA/Query/UserDocumentation/SDK/QueryHotspotTesting

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