[ImageJ-devel] external plugins

Thu Mar 19 13:15:01 CDT 2015

Hi Jay,

> What might be the best way to include these compiled jars in my class
> path upon launching the binary?

Well, one option would be to make JEX into a plugin for ImageJ, with a JEX
update site. Then JARs in the jars/ and plugins/ directories would
automatically be on the classpath, thanks to the ImageJ launcher.

Otherwise, deployment of Java applications is a rough issue, man. If you
don't want to use ImageJ's solution (the Launcher), then you can research
it yourself and go your own way. There are a million and one ways to do it,
and they all have their pros and cons. One popular option is launch4j [1].
Actually, I would love to switch ImageJ to something more industry standard
like that, but it's quite a lot of effort and surely there would be some
serious backwards incompatibilities...

Regards,
Curtis

[1] http://launch4j.sourceforge.net/

On Thu, Mar 19, 2015 at 12:50 PM, Jay Warrick <jay.w.warrick at gmail.com>
wrote:

> Sweet. Thanks for the clarification. I'm fine with requiring compiled
> jars. I was prepared to use something like the addPlugins API but certainly
> see the simplicity of the restart method and will likely try that for now.
>
> What might be the best way to include these compiled jars in my class path
> upon launching the binary? Would one option be to edit the simple launch
> script for the software by adding a classpath argument to the "java ..."
> command?
>
>
> On Mar 19, 2015, at 11:36 AM, Curtis Rueden <ctrueden at wisc.edu> wrote:
>
> Hi Jay,
>
> > Person (A) also downloads the .java/.class file of a just a plugin
> > that would work within my software from third person (C).
>
> This is the scenario we are trying to move away from: distributing bare
> .java or .class files. As long as plugins are distributed as .jar files
> which contain the plugin annotation metadata (in
> META-INF/json/org.scijava.plugin.Plugin), then all is well.
>
> > Person (A) wants to run my binary and load/use the plugin from person
> > (C) at runtime. How would the SciJava plugin framework know how to
> > automatically discover this plugin?
>
> The plugin (as a .jar file) is placed somewhere where it will be included
> in the classpath at launch time. As long as the new .jar file is on the
> classpath, it will be discovered at runtime.
>
> > I thought that if my program is already compiled and running before I
> > specify where this "external plugin" resides and load the class, the
> > PluginService would be unaware of the external plugin.
>
> Is it really a requirement that users be able to load additional plugins
> _after_ your program starts up, without restarting the program? If not,
> then I wouldn't worry about making this work, as it adds complexity for
> little gain. Just put the new plugin somewhere on the classpath, start JEX,
> and all is well.
>
> If you really need to be able to load plugins after startup, this _can_ be
> done. But you have to manually add them to the plugin service via the
> addPlugins API method.
>
> Regards,
> Curtis
>
> On Thu, Mar 19, 2015 at 11:32 AM, Jay Warrick <jay.w.warrick at gmail.com>
> wrote:
>
>> Thanks, Mark. I should likely be using this Handler methodology in a few
>> places in my software, including in this case. However, I'm still concerned
>> about detection of the plugin given the scenario I'm thinking of. But,
>> maybe you can help me understand. I have already been able to build my
>> software project around the SciJava plugin framework and ImageJ's
>> PluginService to automatically recognize the plugins that are part of my
>> own software project. The SciJava framework does its job beautifully to
>> automatically discover the plugins I've developed within my software.
>> However, what about the following scenario?
>>
>> Person (A) downloads the binary of my software from me (B). Person (A)
>> also downloads the .java/.class file of a just a plugin that would work
>> within my software from third person (C). Person (A) wants to run my binary
>> and load/use the plugin from person (C) at runtime. How would the SciJava
>> plugin framework know how to automatically discover this plugin?
>>
>> My recollection is that the list of plugins loaded by the PluginService
>> are determined from a java annotation index file that is created during
>> early in the build process. Thus, I thought that if my program is already
>> compiled and running before I specify where this "external plugin" resides
>> and load the class, the PluginService would be unaware of the external
>> plugin. Am I correct? If it can detect it, then it appears I'm home free
>> and am worrying for nothing, which would be awesome.
>>
>> Thanks!
>>
>> Jay
>>
>>
>> On Mar 19, 2015, at 8:51 AM, Mark Hiner <hiner at wisc.edu> wrote:
>>
>> Hi Jay,
>>
>> >One of the main things I can't quite envision is how to process the
>> annotations of an external .java file at runtime so that I can utilize that
>> information
>>
>> You shouldn't have to do this yourself. By using the SciJava plugin
>> framework you get discovery of all annotated plugins on your classpath, and
>> processing/indexing of those plugins, for free.
>>
>> I'm assuming the paradigm that would match your needs is a
>> HandlerService[1]. The service would perform some function (e.g. opening a
>> path) and the behavior of that function would be extensible via
>> HandlerPlugins[2] (e.g. a plugin for handling URLs, files on disk, files in
>> a database, etc...).
>>
>> The simplest example of "service chooses a plugin appropriate for the
>> circumstances" is the AnimalService tutorial[3]. Note that it's not
>> actually a HandlerService but could easily be converted to one. More
>> complex examples would be the IOService[4] or SCIFIO's FormatService[5].
>>
>> Best,
>> Mark
>>
>> [1]
>> https://github.com/scijava/scijava-common/blob/scijava-common-2.39.0/src/main/java/org/scijava/plugin/HandlerService.java
>> [2]
>> https://github.com/scijava/scijava-common/blob/scijava-common-2.39.0/src/main/java/org/scijava/plugin/HandlerPlugin.java
>> [3]
>> https://github.com/imagej/imagej-tutorials/tree/00394f9f5010d1787b9bf584b6e90eed01beec0d/create-a-new-plugin-type/src/main/java
>> [4]
>> https://github.com/scijava/scijava-common/blob/scijava-common-2.39.0/src/main/java/org/scijava/io/IOService.java
>> [5]
>> https://github.com/scifio/scifio/blob/scifio-0.21.1/src/main/java/io/scif/services/FormatService.java
>>
>> On Wed, Mar 18, 2015 at 6:42 PM, Jay Warrick <jay.w.warrick at gmail.com>
>> wrote:
>>
>>> Hi All,
>>>
>>> I am using the scijava plugin framework, ImageJ2, and its Plugin
>>> service. I would like to allow other people to write a plugin for my
>>> software. I'm open to suggestions but I'd probably like to enable them to
>>> place their java/jar/class plugin file in a folder, and I could look into
>>> that folder to load their plugin. I'm thinking along the lines of how how
>>> old ImageJ did things. Does anyone have suggestions or example code (e.g.,
>>> in FIJI somewhere) for loading/compiling such plugin files during runtime.
>>> One of the main things I can't quite envision is how to process the
>>> annotations of an external .java file at runtime so that I can utilize that
>>> information (e.g., in conjunction with the PluginService). If there is an
>>> inherent problem in what I'm hoping to do, please let me know :-) (e.g., if
>>> I am provided compiled code, I suspect I might need an annotation index to
>>> go with it if I need that information).
>>>
>>> I figured you guys have tackled this problem thoroughly already and thus
>>> would be a good resource. Thanks in advance!
>>>
>>> Regards,
>>>
>>> Jay
>>>
>>>
>>> _______________________________________________
>>> ImageJ-devel mailing list
>>> ImageJ-devel at imagej.net
>>> http://imagej.net/mailman/listinfo/imagej-devel
>>>
>>
>>
>>
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>>
>
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