Calling workflows which contain "File Download" nodes

#1

Hi KNIMERS,

Currently I am calling workflows locally or remotly which contains “File Donwload” nodes and I have to manage “Could not get output resource URL: Variable XXXXX does not denote an existing file:” errors, otherwise I cannot configure the “Call Workflow (Table Based)” or I got an error during the execution of the "Call Local/Remote Workflow (Row Based) " nodes.

So I would like to know if it there is an easy way to manage this issue because I have to create fake paths in order to avoid those errors.

For your information, I am using 3.7.1 version.

Is this issue is fixed in 4.0.2 ?

If not, will it be possible to have the possibility to not take in consideration those errors like in the “Testflow Configuration” node ?

Best Regards,
Joel

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#2

Hi @joel,

I’d strongly recommend to update to the latest Knime version 4.02 first to ensure you are not falling victim to a bug fixed already.

About your issue. How are you downloading the remote files? Can you upload a screenshot of the workflow that loads the files please? There can be fast differences how files are fetched via FTP, from Amazon S3 or via simple http receiver in Palladian (great extension btw!).

Cheers
Mike

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#3

Hi Mike,

I will try to use the latest version of KNIME to check if this issue has been fixed.

I think that there is a misunderstanding, my issue is related to the “File Download” output quickform node (now it is called File Download Widget in version 4.0.x) . In fact the issue is related to the node itself, which produces an error when you save the workflow because the path does not exist. This the case when you create temporary path during the job execution.

ERROR FileDownloadNodeModel Could not get output resource URL: Variable "output" does not denote an existing file: /tmp/workflow_name/random_string/XXXX.txt

When I try to call the workflow using the “call” nodes, they detect this error which is not really an error and then I cannot configure them or execute them. So I found a workaround which is to use an existing path and then override the value of the variable depending of some rest input parameters but it is not really convenient.

That’s why I was mentioning the “Testflow Configuration” node, which gives you the possibility to not take in consideration this error.

So I would like to know, if there is an easy way to call workflows which contain “File Download” nodes?

By the way, does someone know, why this node generates an error and not a warning like the CSV writer for instance ?

WARN CSV Writer Directory '/tmp/tmp/workflow_name/random_string' of output file does not exist

Regards,
Joel

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#4

Hi there @joel,

KNIME Server involved here, right?

Br,
Ivan

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#5

Hi Ivan

Yes it is.

Best Regards
joel

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#6

Hi @joel,

I was not able to reproduce this. Can you maybe share a simple workflow that reproduces the issue?

Best,
Marten

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#7

Hi @Marten_Pfannenschmidt

Please find in attachment 2 workflows identical except that one of them contains a file download node.

If I try to call the workflow “wk_receiving_call” using the “Call Workflow (Table Based)” node, I got an error (please see the screenshot below). So, I cannot configure it.

For your information the workflow, which calls those workflows, contains only 3 nodes: “Table Creator”, “KNIME Server Connection” and “Call Workflow (Table Based)”.

Best Regards,
Joel

wk_receiving_call (without file download).knwf (22.3 KB)
wk_receiving_call.knwf (26.6 KB)

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#8

Hi @joel,

thanks for providing the example. This indeed looks like a bug. I’ll let you know as soon as it is fixed.

Best,
Marten

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#9

Hi @Marten_Pfannenschmidt

Ok, I will wait for your feedback.

If it can help you to solve this issue, the node “Call Remote Workflow (Row Based)” is also impacted.
In fact this error is raised during the node execution in the console.

Regards
Joel

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