Integrates fetching citation counts online (Google Scholar, Semantic Scholar and OpenCitations), integrates a general structure for fechting reference metadata and integrates a general websocket server for JabRef

[systemoperator]

This PR integrates fetching citation counts online from Google Scholar, Semantic Scholar and OpenCitations, as well as a general structure for fechting reference metadata. Furthermore it integrates a general websocket server for JabRef, which currently communicates with the JabRef-Browser-Extension (JabFox) for fetching citation counts from Google Scholar.

References:

• Retrieve and show (e.g. google scholar's) citation count for each table entry #5849

• Integrates Google Scholar's citation count functionality, a websocket client for JabRef and other extensions/fixes JabRef-Browser-Extension#131

• Change in CHANGELOG.md described (if applicable)

• Manually tested changed features in running JabRef (always required)

• Screenshots added in PR description (for bigger UI changes)

• Checked documentation: Is the information available and up to date? If not: Issue created at https://github.com/JabRef/user-documentation/issues.

[systemoperator]

Good news:

• In the course of integrating this feature, JabRef got a robust, flexible WebSocket server, which can be used for many different requirements and use cases. :)
  • examples:
    • bidirectional communication (requests and responses in both ways) with other applications
    • remote control of JabRef
    • connecting to services (local or remote)
    • ...
• With this system, I could successfully fetch several citation counts from Google Scholar via the JabRef-Browser-Extension.

May many future features flourish well! 🎉

[systemoperator]

Is it possible to show a dialog at this point

jabref/src/main/java/org/jabref/gui/referencemetadata/ReferenceMetadataFetcherGoogleScholar.java

Line 38 in 4325489

dialogService.showInformationDialogAndWait(Localization.lang("Test"),Localization.lang("Test")); // TODO: test

(this is within a TaskExecutor thread, where a ProgressDialogAndWait dialog is shown in parallel) which is waiting for some user interaction?

The corresponding task is created here:

jabref/src/main/java/org/jabref/gui/referencemetadata/ReferenceMetadataFetcher.java

Line 57 in 4325489

Task<List<BibEntry>> fetchReferenceMetadataTask = new Task<List<BibEntry>>() {

I found the error IllegalStateException: Not on FX application thread. Thus, I tried the following wrapper:

Platform.runLater(() -> {
    dialogService.showInformationDialogAndWait(Localization.lang("JabRef-Browser-Extension Required"),Localization.lang("JabRef cannot connect to the JabRef-Browser-Extension. In order to use this functionality, please make sure that a web browser is running, where the JabRef-Browser-Extension is installed."));
});

But then the application does not wait on this line anymore. My intention is to integrate some simple user interaction.

[systemoperator]

This approach looks promising: https://www.java-forum.org/thema/alert-confirmation-dialog-aus-einem-service-thread.184035/ I will try that.

[systemoperator]

Cool, works as expected. :)

[koppor]

This is a major architectural change. With JabRef Online currently developed, this kind of architecture changes could be outdated. @systemoperator in case you have time and energy to join discussions with us on architecture, please contact us. For me it could be interesting, when thinking of integrating the MindMap feature into JabRef Desktop. See koppor#433 for details.

[tobiasdiez]

To expand on @koppor's comment:

First of all, thank you very much for your contribution and I'm truly sorry that it took us so long to come to a conclusion how to proceed with this PR.

That we close this PR now shouldn't be meant as a criticism of your work. In the contrary, we really like the feature to get the citations for a given entry, so feature-wise this PR goes in a very good direction. However, the implementation using the browser as a middleman is not robust enough in our opinion. Thus, we hope to implement the citation feature very soon using the new and shiny JabRef Online. https://github.com/JabRef/JabRefOnline (contributions there are warmly welcome of course)

That being said, the websocket interface for JabRef is in itself a very nice addition. So if you still have the energy to go the extra mile, we would like to ask you if you could extract this part of the PR (without the citation count) to a new PR. Uses cases are to provide an alternative for the browser extension to communicate with JabRef (i.e. send references from the browser to JabRef) and for the integration with the word plugin.

Thanks again!