[ImageJ-devel] IJ2 - headless operation

[Lee Kamentsky]

Thanks, Curtis, I'll take a look at the different strategies. Picking 
and choosing .jars is probably not so bad. Hopefully I can exclude a 
couple key ones and everything will work.

On 12/14/2012 4:25 PM, Curtis Rueden wrote:
> Hi Lee,
>
> > how should I start ImageJ headless
>
> It sounds like you want a full-featured ImageJ context with all 
> available services except for maybe a couple of them (the ones that 
> touch AWT).
>
> The easiest way to ensure your ImageJ context is headless is to 
> exclude problematic JARs from your distribution completely. 
> Specifically: do not include ij-legacy or any of the ij-ui-* UI 
> implementations (e.g., ij-ui-swing).
>
> Then you can create an ImageJ context simply with "new 
> imagej.ImageJ()" (note that this invocation changed a couple of days 
> ago from the previous static "imagej.ImageJ.createContext()" but it is 
> otherwise the same).
>
> If for some reason you need or want to include those problematic JARs 
> in your classpath, you can still avoid the ImageJ context including 
> them by passing an explicit list of services to the ImageJ 
> constructor. Or, if you would rather approach it from an "exclusion" 
> rather than "inclusion" standpoint, you could do something like:
>
>   final PluginIndex pluginIndex = new PluginIndex();
>   pluginIndex.discover();
>   final List<PluginInfo<Service>> services 
> = pluginIndex.getPlugins(Service.class);
>
> And then cherry-picking everything from the list that doesn't violate 
> your exclusion rules.
>
> For that latter approach though, we should probably provide some 
> helper routine somewhere to make this easier; if you take a look at 
> ServiceHelper#findServiceClasses, you'll see the code, but it's 
> currently private. We could make that a public static utility method 
> for you instead. Or provide something even higher level.
>
> > how headless is headless?
>
> Ideally, we want headless to truly mean no usage of AWT whatsoever. 
> That said, we do violate that rule in one big place right now: the 
> ThreadService. The DefaultThreadService uses java.awt.EventQueue to 
> queue and invoke operations. With a normal JVM with 
> java.awt.headless=true, this is unlikely to cause problems. But if it 
> does for some reason, you could provide your own ThreadService 
> implementation with a higher priority than that of 
> DefaultThreadService, and the ImageJ service loader will automagically 
> use it instead.
>
> Regards,
> Curtis
>
>
> On Fri, Dec 14, 2012 at 3:09 PM, Lee Kamentsky 
> <leek at broadinstitute.org <mailto:leek at broadinstitute.org>> wrote:
>
>
>
>     Hi all,
>     I'm getting pretty far along with the CellProfiler integration and I'm
>     at the point where I'd like to get a headless ImageJ context. My first
>     guess was that I should call imagej.ImageJ.createContext() with a list
>     containing only the ConsoleService.  The list (see below) has most of
>     what I want (module service, command service, dataset service, display
>     service), but is missing a few others (overlay service and scripting
>     service). I've been running ImageJ with the DefaultUIService while
>     running CellProfiler with a UI and it seems to operate pretty
>     smoothly -
>     some error messages when it can't find viewers for displays, but
>     otherwise without any apparent UI interaction.
>
>     So my first question is how should I start ImageJ headless and my
>     second
>     question is "how headless is headless?" (will it ever touch AWT?
>     Will it
>     exclude the legacy layer?).
>
>     Created service: imagej.thread.DefaultThreadService
>     Created service: imagej.event.DefaultEventService
>     Created service: imagej.plugin.DefaultPluginService
>     Created service: imagej.module.DefaultModuleService
>     Created service: imagej.command.DefaultCommandService
>     Created service: imagej.options.DefaultOptionsService
>     Created service: imagej.event.DefaultStatusService
>     Created service: imagej.object.DefaultObjectService
>     Created service: imagej.data.DefaultDatasetService
>     Created service: imagej.io.DefaultIOService
>     Created service: imagej.display.DefaultDisplayService
>
>
>
>
>
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>
>

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