Can't set a large size file as a process variable!

Camunda 7 Topics Discussion & Questions
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1

Hello world!
I am new to Camunda !
I am trying to create a user task variable that will enable the user to download a zip file.
I’ve created a service task to problematically fetch the file and attach it to the process as a variable process.
Below the piece of code I am using :

String FilePath= "C:/mydisk/myfolder/myfile.zip";
String fileValue ="myfile.zip";
FileValue typedFileValue = Variables
				  .fileValue(fileValue)
				  .file(new File(FilePath))
				  .mimeType("application/zip")
				  .encoding("UTF-8")
				  .create();
execution.setVariable("downloadZipVariable", typedFileValue);

Then, I am calling the process variable downloadZipVariable in a form in this way :

	<a cam-file-download=downloadZipVariable></a>

When I’ve tested the code below with a zip file of 4xx Ko, the code works perfectly.
However, when I used a zip file of 70Mo, Camunda craches :frowning: I get this error :

camundaError
camundaError636×507 103 KB

Is there something I should add to my code and/or to my camunda conf to enable large size file download ?

I am running the community distribution of Camunda-bpm-tomcat-7.9.0 in a Windows 10 OS.

I would appreciate your help !
Thanks :slight_smile:

2

Hi Hel,

It’s likely that the Camunda transaction times out. In general, process variables are not suited to store large files and you are going to observe rather bad performance down the road. I recommend to store such data in a separate storage and only reference it from your process instance.

Best regards,
Thorben

3

Hi Thorben,
Thank you for your prompt reply.
I come to the following external storage solution :
I’ve created a public directory in Apache web server where I store the myFile.zip and reference the file location in camunda process variable.
I’ve created a user form which contains a download link. The link uses the file location stored in camunda process variable.
Here is the piece of code I am using for the user form :

	<br /> <a download> Click here to download content </a>
	<script cam-script type="text/form-script">
	var variableManager = camForm.variableManager;

	camForm.on('form-loaded', function() {
      // this callback is executed *before* the variables are loaded from the server.
      // if we declare a variable here, its value will be fetched as well
      variableManager.fetchVariable('downloadZipVariablePath');
    });

	camForm.on('variables-fetched', function() {
      // value has been fetched from the backend
      var value = variableManager.variableValue('downloadZipVariablePath');
      // write the variable value to the form field
	 console.log(value);
	$("a").attr("href", value)
    });
  </script>

I am currently working on finding a workaround to do the opposite operation : uploading large file in a user form without loading it as a process variable. Work in progress…
Best regards,
Hanane

4