[viatra-dev] Last minute updates to the incremental API

[Ujhelyi Zoltán <ujhelyiz@xxxxxxxxxx>]

Hi all,

yesterday we had a long discussion with Ákos about the incremental transformation API of VIATRA, and found two missing features that might be very useful for various cases. As both issues seemed easy to implement, I came up with quick solutions - however, as the freeze date is very close, I’d like to have somebody having a look at these changes before something trivially wrong goes into the code base.

1. Currently it is not possible to instantiate an incremental transformation rule, where some pattern parameters are bound to concrete values. This can be very helpful in cases where this could reduce the number of activations greatly. This feature is only missing on the VIATRA level; in EVM the required functionality is already present.

I have opened bug https://bugs.eclipse.org/bugs/show_bug.cgi?id=468828 for this issue, and have a corresponding Gerrit change available in https://git.eclipse.org/r/48974 

2. It would be also useful to instantiate event driven transformations that runs only on transactions. The EVM-level support is also available by the use of specific SchedulerFactories, but the VIATRA API did not allow to specify such elements on the interface.

I have opened bug https://bugs.eclipse.org/bugs/show_bug.cgi?id=468829 for this issue, and have a corresponding Gerrit change available in https://git.eclipse.org/r/49023

——
Sadly, both issues required some cleanup on the incremental transformation code, that caused some minor changes in the API. The transformations I have checked out either required no changes (maybe a rebuild was necessary, but thats all), or some very trivial updates. 

Considering the freeze for the project is close, I would like to have some review of these changes before I merge them into master.

Thanks,
Zoli
-- Zoltán Ujhelyi
https://www.inf.mit.bme.hu/en/members/ujhelyiz

Fault Tolerant Systems Research Group
Budapest University of Technology and Economics