FR: send() to support multipart for attachments

[ebruchez]

The send action must support sending attachments alongside the main payload.

[avernet]

This is even more annoying for those who are not saving through our persistence API, and have to do so, just so they can then retrieve attachments, since Form Runner's send() currently isn't able to also send attachments.

+1 from community

[ebruchez]

In addition to sending via multipart, we could also send attachments with separate PUTs or POSTs, as we now support for the PDF. There is a process parameter which allows relating multiple PUTs or POSTs. Something like:

send(content = 'attachments', ...)

Optionally, but only if that makes sense, we could also take a parameter to specify which attachment(s) we would like to send:

send(content = 'attachments', attachments = 'my-file my-pictures', ...)

[avernet]

+1 from community

[ebruchez]

+1 from customer

[ebruchez]

+1 from customer

[avernet]

+1 from customer

[avernet]

+1 from customer

[ebruchez]

+1 from customer

What would it take? We already have code (putWithAttachments()) that:

1. Finds attachment references in the XML data.
2. Updates references to these attachments
3. Reads those attachments
4. Writes those attachments and the updated XML data

We "just" need to do the same but instead we need to prepare a multipart body and send it. HttpClient's MultipartEntityBuilder is probably what we should use.

[ebruchez]

Right now, send uses fr-send-submission, and creates the content with:

ref="
    let $params := xxf:split(instance('fr-send-submission-params')/@content)
    return
        if ($params = ('pdf', 'pdf-url', 'tiff', 'tiff-url')) then
           xxf:instance('fr-urls-instance')/*[name() = instance('fr-send-submission-params')/@binary-content-key]
        else if ($params = 'metadata') then
           metadata:createFormMetadataDocument()
        else
           grid-migration:dataMaybeMigratedFromEdge(
               fr:app-name(),
               fr:form-name(),
               xxf:instance('fr-form-instance')/root(),
               xxf:instance('fr-form-metadata')/root(),
               instance('fr-send-submission-params')/@data-format-version,
               instance('fr-send-submission-params')/@prune-metadata = 'true'
           )"

In order to send binary content, we use the application/octet-stream serialization, and point the ref to a URL. We would need to do the following:

• create the binary body and save it to a temporary file
• then point to the temporary path with the submission
• OR bypass the submission, which we should do at some point anyway

[ebruchez]

See also what XForms says.

We could do this at the XForms submission level, but there is the difficulty of identifying attachments, for which we have reliable support outside of XForms submission, in Form Runner.

So for now I suggest we do this at the Form Runner level.

[ebruchez]

Made some progress on this. I am still wondering, however, about doing this in Form Runner vs. XForms. I started doing the former. One drawback is that for plain xml we also support annotating the data and pruning it, and this is not going to happen automatically if we create the multipart request "by hand" before passing that to xf:submission.

Solutions:

1. support these feature (at least pruning) but call the code from Form Runner
2. do this at the XForms level, but somehow pass a "multipart handler" from Form Runner to XForms, as at that level how to identify Form Runner attachments and their metadata is not known

[ebruchez]

• minimal implementation
• relevance handling, etc.
• consider using tokens for content, for example content = "xml attachments"
  • then we can add support for more tokens this, for example pdf, etc.
• check pdf-url: was broken? if so fix/restore
• update filename for pdf, etc.
• tests
• doc

[ebruchez]

Documented

[ebruchez]

Not sure what kind of automated test we can run for this given the deep integration with the Form Runner code. Could we run a send action upon form load and retrieve the result?