I created a maven multi modules project with 2 modules: core and service.
Service module is using core module (core is declared as a dependency on service module).
The parent pom version is 1.0-SNAPSHOT (so the modules too).
During the maven clean package phase, maven is not fetching core module neither from my local repo nor from remote repo (nexus). It is always building with core module within the project and not fetching any more recent SNAPSHOT version from repo (local/remote).
Is that the expected behaviour?
If you build the project, it will build everything. The command clean package will resolve the inter-module dependencies inside the project.
Everything else would probably lead to surprising results.
If you really just want to build just one module, use the -pl parameter.
Related
I created a maven multi modules project with 2 modules: core and service.
Service module is using core module (core is declared as a dependency on service module).
The parent pom version is 1.0-SNAPSHOT (so the modules too).
During the maven clean package phase, maven is not fetching core module neither from my local repo nor from remote repo (nexus). It is always building with core module within the project and not fetching any more recent SNAPSHOT version from repo (local/remote).
Is that the expected behaviour?
If you build the project, it will build everything. The command clean package will resolve the inter-module dependencies inside the project.
Everything else would probably lead to surprising results.
If you really just want to build just one module, use the -pl parameter.
I have a question about how the Maven dependency resolving mechanism is working in a multi module project.
Normally I only use 'mvn clean install' when I build my multi module projects and my assumption was that if any module in the project needs a previous module, dependency will be resolved by going local repository and loading the corresponding 'jar'.
For project internal reason, I have to use 'mvn clean compile,' this command naturally does not create any 'jar' while 'install' is not there. So here I started wondering, how the dependency resolution for a multi module project works, while jar' is not created but project still able to see the changes from the previous builds. Does the target directories used for dependency management?
Or for 'mvn clean compile' target directory used but for 'mvn clean install' the local repository.
Can anybody explain me how the dependency resolution works in a 'multi module' project.
Thx for answers.....
I think you will understand better if you look at https://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html
There is a life cycle in the process of building the jar. The compile target will compile the code and create a complete classes folder in your target directory. This target will resolve all your dependencies in your poms and download any dependencies to your local repo, not already there.
The install target will create the jar from the classes directory and install it in your local repository.
I really think you will need to run the install target to get anything useful.
Maven is made of separate components.
There a component that deal with a given module and among other things try to get its dependencies. It ALWAYS get the dependencies from the local repository, eventually after having downloaded such dependencies. If the dependencies are not there and can't be dowloaded, it will fail. Eventually the module will create its own artifact that it will publish to the local repo.
Then there a compoment that when you ask it to build several maven modules, for example calling mvn at the root of a project does order the various module use the dependencies to find the best ordering for the build so that if a given module depend on another, it will be build after the module it depend on. It then call the previous compoent I described, building each module in order.
In all cases, a given module dependencies are always taken from the local repo. The expectation is that the previous modules that were built before actually pushed their artifact to the local repo typically with the mvn install but you could force it do it at any step thanks to proper configuration (may not be a good idea).
In all case if the previous component jar was not built and put into the repo, there no way such jar can be added in the classpath for the next module to be compiled.
Doing compile only on multiple projets isn't going to be any useful.
I cloned the git repository of Apache ActiveMQ Artemis project (https://github.com/apache/activemq-artemis) and then typed
mvn -Ptests test -pl :integration-tests
I was surprised to see log messages like the following
...
Downloading: http://repository.apache.org/snapshots/org/apache/activemq/artemis-selector/1.4.0-SNAPSHOT/artemis-selector-1.4.0-20160625.030221-11.jar
Downloading: http://repository.apache.org/snapshots/org/apache/activemq/artemis-core-client/1.4.0-SNAPSHOT/artemis-core-client-1.4.0-20160625.030211-11.jar
...
Since e.g. artemis-core-client is contained in the git repository I cloned in the beginning, I'd have expected maven just builds it from there.
That way, when I make changes in the core client source, they get picked up by the integration tests.
Instead, maven is downloading the jar from the repository.
Question: How do I configure maven to always build all modules that are in the git repository and download only "true" dependencies, which I mean things not in the git repository?
You are not executing the Maven build on the main project, on the main pom.xml which indeed defines the artemis-selector and artemis-core-client modules, among others.
You are executing the Maven build on the tests and its pom.xml, where only tests modules are defined. This is a side/test project, which has as parent the previous pom file, but it doesn't play any role in its parent modules definition. Hence, dependencies are not resolved as modules but as Maven dependencies.
You should firstly install (via mvn clean install) the former project, so that libraries will be available in your local Maven cache (hence no downloading would be triggered), then execute the tests project.
Check the Maven docs for a inheritance vs aggregation difference to further clarify it.
From the Stack Overflow, the follow threads could also be interesting:
What is the difference between using maven -pl option and running maven from module level?
Maven multi module project cannot find sibling module
Main Goal: deploy a project as jar and eclipse-plugin
current state: project builds fine as jar package
Now i want to create a second project which wraps the jar project as eclipse plugin
use tycho-maven-plugin to create eclipse-plugin
add the jar of the original project (with copy-dependency)
add an Activator
export packages from jar
create correct MANIFEST.MF
i tried to copy the jar with copy-dependencies bound to create-resources. This works as long the jar is found in repository, but the local project gets ignored.
This results in a build failure since the jar is not found.
Is it possible to tell copy-dependencies to take the jar from the target directory of the project? Or should i use some other method than using tycho?
Edit:
I solved my problem with 4 projects:
normal project (nothing special here)
the wrapper project using tycho maven and copy-dependencies.
bound copy dependencies to some goal before compile (e.g. generate-resources). Excluded all artefactid which were set as dependency in the MANIFEST.MF.
a prepare project, which calls the normal project and installs it into the repo. This is needed because the tycho-maven-plugin is bound to validate and it is not possible to call the exec plugin beforehand (at least not easy).
a multi module project which calls the prepare project before the wrapper project.
Build your local project (which artifact was missed) with "mvm install". It will be deployed in your local repository ($USER_HOME$/.m2/repositories). After this dependency should be resolved.
Alternatively you can "mvn deploy" if you have local company maven repository like Artifactory or Nexus.
I have a multimodule maven project. the service module depends on domain module using dependency tag. Every time i build the service module, i want it to automatically build the domain module and pick up the most recent domain module from local repository. How can I do it. Right now it pick from the local repository but that may not be the latest copy.
I build the project from my service module dir and not from the parent directory. Because my parent module has lot of other submodules that I am not interested in building.
One thing you can possibly do is to build the service module from the parent directory with the following parameters.
mvn compile -pl service-module -am
What this does is builds only the service module, along with its dependant modules (which would include the domain module).
The options are described by mvn --help (Maven 2.2.0):
-am,--also-make
If project list is specified, also build projects required by the list
-pl,--projects <arg>
Build specified reactor projects instead of all projects