Dependencies on other update sites

[StephanPreibisch]

Hi, it would be awesome if an update site could define another update site it depends on. In this specific case I have all the N5 libraries on the BigStitcher update site. Instead, I would love that when someones clicks the BigStitcher update site, the N5 update site is selected by default. Would this be possible somehow?

Thanks so much,
Stephan

[ctrueden]

General answer replicated from this post:

There is no formal support for dependencies across update sites. That is, there is no way to enforce an update site needing another update site to be enabled as well. (The only “solution” I know of is: code on the OpenSPIM update site has a horrible hack to force-enable the Micro-Manager update site… but this hack causes problems and I would not recommend replicating it.)

At the moment, your options are either: A) tell users they must enable the upstream update site also in order to use your update site; or B) upload the common third party dependencies to your update site as well, doing your best to ensure they are of the same/compatible versions as those on the upstream update site; or C) tell users they cannot have both update sites enabled at the same time, if the versions are not actually compatible.

If you choose route (B), the pom-scijava BOM is here to help you.

As for the future of Update Sites: some discussion happened on this thread. And we can certainly discuss further. My current thinking is that we should move away from update sites toward plugin-based granularity of installation, like how Icy does it. And that plugins should be published on maven.scijava.org (or Central), and the new slimmer Updater should just know which Maven coordinates correspond to installable ImageJ plugins.

In the meantime, specifically about N5: let's just ship them with Fiji, no? There should be no problems doing that, as long as @axtimwalde is OK with it. We're already testing them as part of the melting pot, so I don't foresee any conflicts.

[axtimwalde]

I am ok with that, which is why I added them to pom-scijava. But I couldn't wait for it :). Fiji would have to ship with imagej-updater-0.10.5, so I can use the opportunity to move the licenses to an appropriate place.

[ctrueden]

@axtimwalde In case you didn't already notice: the big Fiji update has now happened. It now ships imagej-updater 0.10.5 as well as the N5 libraries.