Move export to HTTP

[aicam]

This PR is part of the effort to move download functionality from front end to backend.

New endpoint: /export/result

Previously, ResultExportService was called from WorkflowWebsocketResource, with this PR, it is now called from a new endpoint defined in ResultExportResource. To unify export to dataset and export to local (download), we need to have an endpoint to remove front end from the process. Currently front end fetch all the result and then send them to the user but the goal is to use this new endpoint to stream result directly from backend to user.

Current behavior

The new endpoint only provides export to dataset currently. In code, it supports multiple formats but in front end, we only allow two formats: CSV and Arrow (for binary files). This limitation is based on the previous implementation and might be revised.

Future work

There are four main TODOs left in this PR:

• Use rowIndex and columnIndex in frontend because already available in backend
• Request multiple operators result in one HTTP request
• Adjust endpoint to return the file itself if the export destination is local
• Adjust endpoint to return a zip file if the export destination is local and multiple operators are selected

2025-01-18.10-34-04.mp4

[bobbai00]

Left some comments.

I have one question: how about the downloading to the local? Is the download done in the frontend by concatenating pages?

[aicam]

Left some comments.

I have one question: how about the downloading to the local? Is the download done in the frontend by concatenating pages?

Download to local is currently disabled (although its logic is still on frontend), however, professor asked me to make small contributions at a time. So in this PR, I just moved export to HTTP.

[bobbai00]

Left some comments.

Make sure you keep the PR description updated.

[bobbai00]

LGTM! Left a minor