Node synchronization or trigerring


Does anyone know how to synchronize nods or trigger them so for example one nod lets say X will be waiting for node Y to complete its tasks, and then run and complete his own?



If you start KNIME in expert mode you can "Show Flow Variable Ports" on nodes via their context menu. This gives you two red "Mickey Mouse ears". If you connect your two nodes via these red ports the second node will not start before the first node has finished.

Thanks, but actually it does not work as I have expected, I would like to use script by external tool , and then open the file created by this script.

Instead when the node (external tool) ends, it passes control to the next node (what is good) but file reader acts to quickly and needs to be run once more time so it can load file correctly. Otherwise it is sending me an error that it cant find  the file.



That is odd. If a node has finished, it is really finished and it should have written the file completely. And then the File Reader should also find it. Are you writing to a network drive?

No, I had to add perl script to wait 1 second, otherwise next node is just loading the file not generated yet - and we have an error.

Is there perhaps any way to add variables to workflow, so I would be able to pass values from nodes into another nodes?


I mean something like user interaction - asking user to do thins , choose file, etc, of course it can be done via external tool - but just in case I would like to use knime.

Yes, as soon as you have enabled the so-called expert mode, you will get a whole bunch of Flow Support & Control nodes (see resp. category after restart) allowing to extract and inject flow variables in a KNIME workflow.

Nice, thanks, will try this out!