We are developing an Eclipse plugin that is split into several Eclipse Projects. We want to export some of the classes that are defined in these external projects (via Export-Package in MANIFEST.MF). The problem is that Eclipse gives an error "Package xxx does not exist in this plug-in".
To give an example, let's assume that the plug-in is project P1 and this one uses some classes defined in a separate Eclipse project P2. We want to bundle P2 together with P1 and export some of the classes of P2 via the MANIFEST.MF of P1.
This works if I generate a jar file (P2.jar) and add this in the build path of P1, however it does not work if I simply add P2 as a dependency of P1.
Any suggestions what is the reason of the "Package xxx does not exist in this plug-in"?
Any suggestions how to get rid of it?
Adding the project P2 as dependency of P2 simply add the build classes of P2 (assuming P2 is a Java project) to the classpath of P1. This will allow P1 to compile but will result in wrong behavior at run-time.
Because your project P1 is a plugin project all its dependencies must be added ever through the dependencies tab of the manifest editor or through a jar file included as you mentioned.
So the only solution is to transform P2 project into plugin project and then let your P1 plugin depends on it. This kind of plugin only exporting code but not contributing anything to the ide are often referenced as library plugins. More and more java libraries are now delivered also in this way to let clients use them in Eclipse context (for example log4j).
Related
Background
My Eclipse RCP application is built using Tycho. It consists of multiple components (in the form of OSGi bundles/Eclipse plug-ins). One of these component contains the product file and materializes the product.
There is a reactor POM at the application root, which builds all components in order, but I also want to build other components independently (using mvn deploy) .
Building such a single component works as follows:
Retrieve the latest versions of all the component's dependencies from our company (p2) repository.
Build the component.
Deploy the component to our company repository to be used as a dependency for other components itself.
Note: Our repository is a normal maven2 repository hosted on a Nexus, whose RCP artifacts are automatically mapped to a p2 repository format as well. This way, Tycho can use the p2 repository format to find dependencies, while the standard Maven deployment can be used. This works fine.
Note: My parent POM makes sure that we look for dependencies at the p2 repository URL. The deployment URL is the default maven2 format location of the repository. This works fine.
Problem
When building such a single component through the command-line (mvn deploy), Maven looks for intra-project dependencies in the p2 repository and they are correctly resolved (i.e. latest version is automatically downloaded and used in build).
However, when developing in Eclipse, the IDE cannot resolve them. The manifest files gives an error at each of my intra-project dependencies that they cannot be resolved.
Question
My question is: How can I make the Eclipse IDE look for dependencies (and new versions of dependencies) in either:
My local p2 repository (~/.m2/repository/p2/osgi/bundles)
My company p2 repository (nexus.mycompany.com/myproduct-snapshots/.meta/p2)
Ideally, it would look for them every time and fetch the latest version if a newer version is available.
If it does not use the p2 repository URLs in the POM, how should I configure Eclipse?
Example
Consider an eclipse plug-in com.mycompany.myproduct.fancy, which depends on another eclipse plug-in com.mycompany.myproduct.core.
Both also have a POM (configured for Tycho use), which (through their parent POM) have my Nexus repositories configured correctly: maven2 repository URL for deployment and p2 repository URL to look for dependencies.
First I deploy the core plug-in to my maven repository (using the default mvn deploy). The Nexus repository will provide this deployed plug-in in both maven and p2 format.
When I build the fancy component through the command line (using mvn install), the (earlier deployed) core component is found and downloaded automatically.
project/com.mycompany.myproduct.fancy$ mvn clean install
<searches in p2 repository, download core>
<builds fancy>
<SUCCESS>
When I open a new Eclipse workspace and open the fancy component, its Manifest (which contains its dependencies) gives the following error:
Bundle 'com.mycompany.myproduct.core' cannot be resolved.
My question is: how can I develop the fancy component in the Eclipse IDE without the need to open core as project in Eclipse.
Speculation
This is some speculation from my side. Please correct me if I'm wrong and any other solution to the actual problem is also welcome!
I know the m2e plug-in of the Eclipse IDE currently maps Maven POMs to Eclipse concepts (using m2e connectors). I have installed the dedicated Tycho connectors. For example, the mvn compile step is actually performed by the Eclipse JDT compiler.
I also know that when a complete Tycho product is started in Eclipse, it is run in the Eclipse PDE environment. For example, I need to a specify a target platform in my Run configuration.
I know I can open all components in my Eclipse workspace. This would solve the problem, but is not feasible as I have many components and this would break independent component development.
I assume the Eclipse m2e mapping and/or the PDE build environment is not smart enough to fetch (latest) dependencies automatically at build time. Please correct me if I'm wrong. :)
Therefore, I assume I need to specify the target platform at build time too. I have taken a look at Window > Preferences > Plug-in Development > Target Platform. I can add our p2 repository to the Target Platform, which solves the problem. However this gives many problems:
I need a feature containing all components for this to work. Only features can be added.
Every time I deploy a new build of a single component, I would have to rebuild the complete feature (to create a new feature version on our p2 repository).
Every time I update a component and build the feature, I would have to manually change the Target Platform.
If the above is all correct, I speculate I need an m2e connector (or a different one from the current one) that actually checks the p2 repositories specified in the POM when resolving the OSGi dependencies and automatically adds those to the target platform.
As indicated by Nick Wilson, you will need to install the m2e Tycho Configurator, which basically "links up" Eclipse and Tycho (i.e., makes Tycho available in Eclipse).
You should've been pointed towards it after having installed m2e, but you can also install it manually:
Go to Window > Preferences > Maven > Discovery.
Click the "Open Catalog" button. This will open the "m2e Marketplace" window.
Search for "tycho", this should give you the "Tycho Configurator" as sole search result.
Click "Finish", you're done.
I've had this issue as well, and it isn't simple to find the solution, so I hope this helps!
The "most automated" way to configure your target platform in Eclipse is to use a target file. That file can be checked in with your sources, so every developer only needs to open the file and click on "Set as Target Platform" to activate it. AFAIK there is no m2e connector or Eclipse plug-in which does that automatically.
Given your development process, setting up this target file is a little more tricky. Since you don't have a feature which contains the latest version of all your bundles, you need to include the bundles directly in the target file. This is not possible via the rich editor, but can be done with a text editor:
Create a target definition file, add your p2 repository, and select any feature from that p2 repository. Save the file.
Open the target file in a text editor, remove the <unit> entry for the feature you added.
Instead, add an entry for each of your bundles:
<unit id="a.bundle.symbolic.name" version="0.0.0"/>
This target file then contains the latest version of each of the listed bundles. To see the content, open the file with the "Target Editor" again and switch to the "Content" tab. This file can now be used by all developers.
Note: When a new version of one of the bundles is deployed to Nexus, the developers will only see that new version if they open the target file and choose "Set as Target Platform" again.
I'm working one an Eclipse RCP project. Currently we create a dependencies plug-in project and put all jars libraries into that project and export all packages. This method will give a huge repo, thus we want to use Tycho/Maven and let it figure out the dependencies for us.
The first approach is removing dependenciec project and use p2-maven-pluging to transform existing jars libraries to p2 format repo. Install all libraries from p2 repos and add required bundle in Require-Bundle section in each MANIFEST.MF. This is a little bit tedious since in every project having dependencies in Require-Bundle, I have to manually replace it to corresponding bundle names. And in the end, the project build using Tycho could successfully run, but in Eclipse it gives me java.lan.NoClassDefFoundError: Could not initialize class X.
I think there are few configuration files, where Tycho depends on some of them and Eclipse depends on the rest, but I'm not sure what it is.
The second approach is removing all jars in dependencies project but adding them in Require-Bundle or Import-Package. However, both won't work since in Export-Package section Eclipse will complain these packages are not existed. Thus other projects depends on this dependencies project won't find those packages they need, which causing more errors in Eclipse.
Does anyone know the best practice to deal with this issue?
Update:
I'm using basically the first approach, but add dependencies in Import-Package in each project instead of Require-Bundle. This would eliminate the need to specify the specific bundle version, as long as they provide the same API and they are compatible, your application would work. So everytimes I update private p2 repository, I don't need to change MANIFEST.MF in each project.
The only MANIFEST.MF I need to manually add dependencies in Require-Bundle is a library developed by our self. Without it, Tycho won't fetch required dependencies from private p2 repository. If still get NoClassDefFoundError, try adding all plugins in Run -> Run Configuration .. -> plug-ins, it may help.
I definitely not apply your approach 1, with the mega-plugin of exports. There's a related discussion here: Handling non-OSGi dependencies when integrating Maven, Tycho and Eclipse
As a rule, use Import-Package instead of Require-Bundle.
To get bundles will appear in the Export-Package section Eclipse:
if they are non-Eclipse (maven libraries), then build the project and reference the libraries in the Eclipse runtime section.
if they are Eclipse dependences, they should be in your workspace or Target Platform.
More generally, it may help for you to define a Target Platform. You can build/deploy all of your locally created plugins into a local p2 repository (see http://www.sonatype.org/nexus/). Then add that p2 site to your Target Platform.
I'm trying to implement the p2 update mechanism into an RCP application that contains DLLs (integrated via JNI). The whole RCP application (including these DLLs) has to be kept up to date.
Currently the PDE build is not aware of the DLLs - make/gcc generates and copies them into the delivery in the end.
How to make p2 aware of the DLLs? They have to be added to the p2 repository and p2 within the RCP application has to update them, when newer versions are available.
Include the DLLs in your plugin.
After you have gnerated them, copy them into a folder in your plugin project. Then add the folder containing the DLLs to the Binary Build section in your plugin.xml editor. You can make the plugin aware of the DLLS using the Bundle-NativeCode: entry in the Mainfest.mf of the plugin. This way the DLLs are included inside your plugin's jar and are therefore automatically included in your p2 repository.
In a Java project in Eclipse, I am trying to debug project A.
Project A has a dependency on B.jar, normally B.jar comes from my .m2/repository.
but now I want to make some temp changes to B's code, and have it reflected in A,
so I directly edit the source code in B project in eclipse, and set B as a dependency project in A's build path. Additionally, both A and B refer to C.jar as their dependencies.
This builds A fine, but when it is run, A's classpath contains 2 copies of all the classes and resources in C.jar. this creates a problem for those hibernate hbm.xml mapping files in C.jar and I got errors saying duplicate mapping for...
This looks to be a defect in eclipse, in that it lacks the resolution ability as maven posseses. is there a way to work around this? (apart from building B and installing to .m2 instead of having it as a dependency project)
Thanks
You mentioned "[setting] B as a dependency project in A's build path" - do you mean editing eclipse's build path or editing the project's POM? I'm guessing the former, in which case make sure that you have the latest version of the m2eclipse plugin installed and that both projects A & B are Maven eclipse projects. If it is set up correctly then your projects should look have an 'M' on their project icons, and the icons of any workspace dependencies should look like folders.
I have a dependency on clj-record in my CounterClockwise project. What's the best way to manage this? Copy the source code or compile to a JAR and add it as a referenced library?
There are tools to help you:
http://github.com/technomancy/leiningen <- project based
http://github.com/liebke/cljr <- dependencies not project based
http://github.com/ninjudd/cake <- alternative build tool
Assuming your dependencies are available in a Maven repo (like central or clojars), you have a couple of options.
First, if you're using Leiningen, there is an eclipse plugin for it now that will manage project dependencies for you, based on the dependencies you define in your project.clj file. The plugin is in beta now, but has been working great for me so far. (Note that it uses Leiningen 2.0 under the covers, though that detail won't matter for many (most?) simple cases.)
If you're using Maven, the m2eclipse plugin makes it so that the dependencies you declare in your Maven pom.xml are automatically added to your eclipse project's build path, and are therefore available in CCW REPLs and such.
there seems to be no pattern for specifying dependencies apart from hacking the code into your project or building a jar externally.
Of course you can, just as with any java project. While dependency resolution isn't tied into eclipse (yet), once you retrieve the deps (via one of the command line tools nickik listed), you can specify which jars are to be included in the java build path of your eclipse project:
Retrieve the deps via cake, leiningen, etc.
Refresh the eclipse project so you see the deps (usually in the lib directory)
Highlight the jars you want eclipse to know about
Right-click, select Build Path > Add to Build Path
That's it. You can fiddle with the build path by going to the Java Build Path section of the project's properties window.