Flow Variables


Is there somewhere that I could find information on flow variables with a practical example?

I have read KNIME help but there was nothing there about flow variables!


Did you also checkout the wiki? :)


Yes. I have seen this article. that was the only thing I found about flow variables.

But the problem is I only learn things with examples and there is no example of using flow variables. Mabye I have to create an example by myself.

I think KNIME is a good data mining software but it's documentation is not complete and it doesn't provied enough examples.

Thanks a lot.


Have you seen the public KNIME server? (It [EXAMPLES (gues@publicserver.knime.org:47037)] is available from the KNIME Explorer, you only need to click on Login from from its context menu.) It has a category called 011_FlowVarsAndLoops, which contains some example workflows featuring the flow variables.

Cheers, gabor


Flow variables are tricky because it is hard to see how they flow with respect to the main logic flow of the workflow.

My first suggestion is to enable the KNIME Node Monitor (Either directly under View menu or View->Other and then select the Node Monitor)

This will show the value of every variable from node to node as you evaluate each node in turn.

Secondly, think of the red variable flow lines as something that flows the variable values from a node to another node. Once set, it will retain that value and "flow" with the logic flow for that branch.

Third, look at the configuration of each node, there is a flow variables panel that will usually let you set the value of one of the configuration settings in the main panel with the value of one of the variables.

Hopefully this will get you started.

If you have more specific questions about using flow variables, such as in Java snippets, etc. feel free to ask.


-- Scott

Thanks aborg. I didn't know about this examples.

Thanks Scott.