Jobs & Progress bar for XWiki Exports

Development
#1

Hi,

I’d like to brainstorm about how we’d implement introducing progress bar for exports. Exports can take a long time depending on the export type and what is exported (exporting a full wiki to HTML for example can take quite long).

These are my current ideas/notes.

Principle:

  • Progress bars/jobs require client and server code
  • The server code perform the code to export and notify the Job Progress Manager about the status
  • The client code displays the progress bar, calls the server code and updates the progress bar

So my idea ATM would be to do the following:

  • Modify the existing export.vm by introducing a query string param to display progress.
  • Once the user clicks the “Export” button in the export modal we render this export template (by using the export action as we currently do)
  • We introduce a new export script service (and a new Export component) in charge of performing the export, in a new xwiki-platform-export module. The export.vm uses this script service to trigger the export.
  • Once the export is finished, the export.vm displays a link to the export in the UI and the user just have to click on it to get the result.

WDYT?

Thanks

#2

Note that we don’t need to refactor existing exports immediately since we’d introduce a query string parameter to indicate if the export should be sync or async.

#3

Exporter:

@Role
public interface Exporter
{
    void export(List<EntityReference> entitiesToExport, Map<String, Object> parameters, OutputStream output);
}

Another option is to introduce a ExportRequest interface or class instead of entitiesToExport and parameters.

WDYT?

#4

Note that this is not perfect since it means storing the result locally in a temporary location on the server in order to serve it. It’s not great since in the case when the export is fast, it’s less efficient than just returning the streamed data.

Now for fully streamed exports, they can just not use progress bars :slight_smile:

#5

So that would mean a new export extension would propose an action link with that query string parameter: something like /export/MyPage/?async=true? So that ExportAction knows it should renders immediately export.vm with the progress bar, or that it should only return the exported document?

#6

yes

#7

Related to that topic I created back then a ticket for having a cache of exported document, sounds like it would solve that issue too: https://jira.xwiki.org/browse/XWIKI-16764

#8

Note that having a progress would actually solve an issue we have now in that we don’t have a proper reporting of errors during export.