My ultimate goal is Invoking Eclipse plugin from Java. I see that an Eclipse plugin registers a class as Bundle-Activator in MANIFEST.MF. The start(BundleContext context) method will be called on this class. Where does this call come from?
Eclipse is made up of many repos that are mostly mirrored on GitHub. Some are deprecated and point to other repos. And it's a programming IDE and an OSGi framework at the same time? I find it hard to find the code for this core part of the framework that handles plugin loading. Where is it?
The project to interact with OSGi bundles is Eclipse Equinox. It is an implementation of the OSGi framework. You start equinox and load the bundle jar from there instead of putting them into the regular classpath.
Here you find some information how to do this in general:
http://njbartlett.github.io/2011/07/03/embedding-osgi.html
You can then interact with the bundles from you plain java application. This is not an easy thing though.
What makes things even more complex is that Eclipse is not plain OSGi. Eclipse predates OSGi and many of the concepts are still not fully adapted to plain OSGi.
So using eclipse plugins from a plain java application may be very hard.
I recommend to ask on the mailing list of the plugin you want to use if there is experience with using it outside eclipse.
Related
I'm looking to understand osgi and find it confusing that every tutorial requires eclipse or is developed using eclipse (which complicates my understanding)
Is it possible to work with equinox without eclipse and is there an example of how this can be done?
You can create OSGi applications without eclipse. What you see in many tutorials is using the Eclipse Plugin Development Environment(PDE) for OSGi development. This is one way but not the only.
In many Apache projects like Apache Karaf you can see a very different maven based OSGi development. In this case you create normal maven projects and simply add a plugin to enhance the jar with the OSGi metadata. For simple bundles this is all you need.
As an example see the karaf examples and tutorials. In the case of karaf as a OSGi server you have the choice between equinox and felix for the OSGi framework.
A third approach is using bndtools. This again is a eclipse plugin and maven plugins but a completely different development workflow than PDE. The new examples for bndtools are also maven based like in Apache Karaf but they use a different assembly. As an example see this. It can be built with just maven but using the bndtools eclipse plugin makes it easier.
While Karaf uses features as primary assembly unit bndtools uses a OSGi repository + requirments.
So you have the choice of three different styles. Each with different pros and cons.
Especially the karaf style is also very applicable for intellij.
OSGi is a standard. Equinox is an implementation of this standard. As it is mentioned on Equinox homepage, equinox is even the reference implementation (http://www.eclipse.org/equinox/) :
The Equinox OSGi core framework implementation is used as the reference implementation and as such it implements all the required features of the latest OSGi core framework specification
As a consequence, yes it is possible to use other OSGi implementations : Apache Felix, ... (see https://en.wikipedia.org/wiki/OSGi_Specification_Implementations ). If you choose Felix, you will no longer use Equinox. But both implements the OSGi specification : https://osgi.org/javadoc/osgi.core/7.0.0/
In addition, you must distinguish the OSGi implementation from the development environment you choose (IDE). Eclipse is an ambiguous term that fits both. Even if you choose Felix implementation, you can code in eclipse.
I think that if most of the samples you find are based on eclipse Equinox and developed in Eclipse, it the result of the fact that :
- Equinox is the reference implementation of OSGi
- Eclipse IDE includes many tools to develop OSGi application through the PDE (Plugin Development Environment : https://www.eclipse.org/pde/ )
In conclusion, I would say that Eclipse probably cumulate the best IDE & implementation to work with OSGi. As far as I can see, it's a good thing for you to follow eclipse based tutorials, just remember that equinox is an OSGi implementation that you could replace by another like Felix.
I am trying to embed Felix in an application of ours to handle plugins. Everything is working fine, however, development and debugging is very cumbersome.
Is there a solution where I can tell Felix to automatically reload a plugin bundle or its classes when I recompile a plugin in Eclipse?
I cannot use any OSGi specific launchers because Felix is embedded in our application
Felix' fileinstall supports directories, but expects a specific structure, which is incompatible with the layout of the Eclipse project.
Any help or pointers to a solution would be greatly appreciated.
You could take a look at Bndtools and the remote launcher. You only need to install a remote agent in your framework and then Bndtools can update any bundle that has changed in the workspace.
This is explained in remote launching. In OSGi enRoute you find an IoT tutorial that uses this model as well as a Karaf App Note.
I've been beating my head against a wall for about 6 months now and have not found a concise way of understanding the mechanism for developing an eclipse plugin with third-party resources.
We are attempting to develop an Eclipse ODA to ride on top of in-house Spring-based code that accesses a REST based info set.
In broad strokes - this is what I feel that we need to be able to do:
Augment our maven artifacts with Eclipse bundle information using tycho or a the felix bundle plugin.
Set up a plugin project through Eclipse for the ODA Implementation & UI.
Have Tycho generate the poms etc for the plugin.
Now here's where I get muddy. I understand that there are two approaches
Manifest-First - which is the standard mechanism for defining a plugin's dependencies
POM-First - which provides dependencies via Maven's resolution mechanisms.
I'm not entirely sure where to begin trying to start doing this as I've never worked on developing an eclipse plugin.
One of the other questions I have is, how does a developer of an eclipse plugin (maven aside) leverage already existing third-party code (i.e. Apache HttpClient 4.x)? Do they have to download the jars, dump them into a directory within the project, add to classpath, then go from there or is there a "repository" mechanism similar to what is used with ivy, maven, gradle?
Thanks in advance and I apologize if I was rambling a bit with that.
Disclaimer: Your question is very broad, so it is impossible to answer it completely. Still, I can give you some hints so that you know what to search for.
In the Eclipse universe, the primary source for libraries (in the sense of binary dependencies) are p2 repositories. However, since p2 repositories are rarely used outside of the Eclipse context, you won't e.g. find a p2 repository on the Apache HTTP Client project's download page.
To account for this problem, there is the Eclipse Orbit Project which provides libraries used by Eclipse projects in p2 repositories.
If you can't find the library or library version in the Eclipse Orbit, you may also be able to use the libraries from Maven repositories. This is for example supported by Tycho via the pomDependencies=consider mechanism.
Note however that Eclipse plug-ins can only depend on libraries which are OSGi bundles. So if the library in the Maven repository is not yet an OSGi bundle, you need to convert it to an OSGi bundle first, e.g. with the maven-bundle-plugin and the Embed-Dependency mechanism.
The best way for an Eclipse plugin to consume libraries is as OSGi bundles. You just install those bundles into your target platform and reference them in the same way as eclipse.org plugins. Some of the library providers already offer their libraries as OSGi bundles. Absent that, you can typically turn a plain library jar into an OSGi bundle simply by adding a few manifest entries.
Depending on the build system you use and whether the libraries you need are available as OSGi bundles packaged into an online p2 repository, you can reference the URL and rely on your build to download and install the bundle.
If question of choosing a build system for Eclipse plugins with dependencies is still relevant:
Today I released new gradle plugin: Wuff version 0.0.1, which (I think) completely solves the problem. It allows to build Eclipse bundles and applications as they would be "normal" Gradle projects. All OSGi woodoo is auto-generated (although customizable). All dependencies are usual maven dependencies - regardless of whether dependency is OSGi or "normal" library.
Sources and doc: https://github.com/akhikhl/wuff
The base of our enterprise application is OSGI and we have several Java projects that are logically OSGI bundles. We use Maven to compile the application using the Maven Bundle plugin. But this process is time consuming and makes it impossible to debug the application. We also use the Runner and Pax(:provison) plugins to run the application. If we could rely on the Auto build function of Eclipse and also debug the application it would make our lives so much easier. Is there a way to configure Eclipse to be able to compile (and may be run) an OSGI-based application?
I'm not entirely sure if I understand you, but here goes.
Well, running/debugging OSGi applications in Eclipse is really easy, as long as your bundles reside in PDE aware projects or at least are on your target platform.
Do you have the source of all your bundles? Debugging without source isn't all that useful. If you do, can you just import all the source of your bundles into your Eclipse workspace?
Otherwise you can create a target platform, add all your bundles to that. (as a first attempt, I'd say dump all your bundles in a directory and point the target platform there)
Either way, then you should be able to Run (or debug)-> OSGi framework -> New -> Pick your bundles -> Start
You can both pick bundles from or target platform and from your workspace.
For building, you can use Eclipse Plugin Development Environment (PDE). Despite its name, it isn't specific to building Eclipse plugins and can be used for working on pure OSGi bundles. Eclipse plugins are OSGi bundles with some extras.
Cannot help you with the running or debugging part, although I do know that some enterprise-oriented OSGi platforms provide extensions to PDE.
If you're already using the maven bundle plugin, you may find that PDE's manifest-first approach isn't a good fit with your existing code-first build (I assume at the end you want both an IDE build for development and debugging, and a command-line build for continuous integration and automated testing).
You have two choices. As others have suggested, you can use Eclipse's integrated PDE, and use Tycho for your maven build. Tycho uses the same data used by PDE, so you don't have to write things down more than once. Alternatively, you can stick with the maven bundle plugin and use bndtools within Eclipse. Like the bundle plugin, bndtools is code-first, so you won't need to worry about maintaining manifests. However, you may find there isn't quite as big a set of features in bndtools as in PDE, and I'd suggest still checking your manifests by hand to make sure you understand what's being generated. Whether you prefer manifest-first or code-first is a bit of a heated philosophical debate.
Look at bndtools. bndtools is using the same bnd that is underlying the maven bundle plugin. You can even use bndtools together with m2e. bndtools is available from the Eclipse market place.
What are some configuration changes to make Eclipse PDE best support working with both Equinox and Felix?
Here's an example problem I'm currently having. I can run my application ok via the Eclipse OSGi Framework launcher. Similarly, there are no compilation problems in PDE. However, when running in Felix I will get NoClassDefFoundErrors:
java.lang.NoClassDefFoundError: org/w3c/dom/DOMException
My understanding is it's my Eclipse setup that is at fault here; org.w3c.dom is not a 'default' OSGi package and shouldn't be loaded when I run it in Eclipse. Similarly, the import in my code for org.w3c.dom.DOMException should be an error.
I know how to fix this for Felix: declare an Import-Package. But that's not my question. My question is how to force Eclipse PDE to take on a closer configuration to Felix... basically to make it stricter in loading packages?
I think Equinox does behave like Felix, if you run it stand alone. It's more of an Eclipse legacy thing than an Equinox thing, as stated on osgi.org.
As far as I know, there isn't any way to override the boot delegation from Eclipse, but I'd love to be proven wrong, as I've faced this problem often.
If you are developing a server application I recommend to not use the PDE at all. I am using maven and the maven bundle plugin to develop my bundles. Then I deploy on Apache karaf. Debugging also is quite simple by using the karaf dev:watch command and remote debugging. I never really missed the PDE features and they never worked well with my maven build.
This sounds like that launcher is setting bootdelegation to legacy mode. See the following page on the OSGi Wiki: http://wiki.osgi.org/wiki/Why_does_Eclipse_find_javax.swing_but_not_Felix%3F