Backward/forward compatibility (vs. deprecation) of nodes

Preamble: I'm aware of the "deprecation" mechanisms for nodes. My problem is more in the opposite direction, or a special sub case:

(1) I've a Plugin v1.0 with various nodes

(2) I'm developing Plugin v2.0 which will become much better. One of the existing nodes gets an additional setting in the configuration, let's call it “[ ] Append column with value XYZ“. But the existing behaviour of the node does not change, it is 100 % backwards compatible to v1.0 (so, I see no reason to @Deprecate it, instead I simply add to the existing implementation)

Now the issue:

(3) User A creates a workflow using v2.0 of the nodes, and checks above mentioned option “[ ] Append column with value XYZ“

(4) User B opens this workflow, but he’s still using v1.0 of the nodes. Upon resetting and re-executing the node with the option added in v2.0, the resulting column will not contain the additional column and downstream nodes will fail.

Until today, I expected that opening a workflow which was created using a newer version of some nodes than currently installed would trigger a warning message. Upon my tests, this does not seem to be the case? So user B will probably not be aware that there's a v2.0 available.

(a) Just to clarify: KNIME performs no checking and warning about the node versions upon opening a workflow? Or am I missing something?

(b) Code wise, I would really like to avoid having to deprecate and adding a new copy of a node every time there are additive changes which do not break existing functionality. (the mentioned node in the scenario above is actually an abstract superclass, so I would have to deprecate the entire inheritants).

(c) Are there any general best practices for such a case?


Hi Philipp,

That's a perfectly correct summary of the status quo. KNIME guarantees backward compatibility but no forward compatibility (which is what you are describing here).

KNIME currently warns the user when he opens a workflow of a "future" KNIME version but only if the workflow format has changed (like the framework saves the connection table differently or the data format has changed). It does not warn if the format remains the same. Note, it's the format of the core, not a format of the individual node implementation. 

We are going to change that for the next release -- we'll also add a warning that you may loose some configuration when you save a workflow that was created by a future version.


Great. Thanks Bernd for confirming this!

Best, Philipp