I have recently used the Maven Assembly Plugin and also the Maven Shade Plugin in order to create a FAT JAR containing a specific plugin and its dependencies.
I did this because during the build phases our company uses private servers with no access to the internet so I can't depend on public repositories.
So I have this FAT-JAR-WITH-DEP.jar and to test if it works with my module, I removed the original plugin jar from the maven repo and pasted this instead.
I also removed its dependencies. the POM file remained the same.
What happens is that it still tries to download the dependencies because of the pom file.
How do I use a FAT JAR as a plugin that already includes it's dependencies?
Sorry, but building such a fat jar is not a good idea. You are trying to manipulate the "inner structure" of Maven.
If you want to use Maven in an offline environment, copy all the relevant plugins and dependencies to your company Nexus/Artifactory. The easiest way to do this is run a build once against a public repository and then copy all the stuff that was downloaded through Maven.
Related
I have my own java library created as maven project and has some dependencies included in pom.xml
I want to export project as jar and include it into others maven projects.
The problem is that I need to copy all dependencies from pom.xml of my library into maven projects where is imported my library to make it to work.
How to export my library to not be necessary to copy dependencies of my library.
That is easy to do; the central feature of Maven is that it manages the project dependencies for you.
You need to mvn install your project from the command line; that will install the jar and the pom files to your local repository.
You can then include your library as a Maven dependency in other Maven based projects; Maven will resolve the (transitive) dependencies for your project.
Normally you don't need to list all the dependencies in the project that imports your library. Maven should fetch them for you. What you need to do is to declare dependencies in your library.
Make sure you declare correct types of dependencies. Here is more info. In your case you need to make sure that dependencies you want to copy to the downstream projects are marked as 'compile'
There are tools that make 'Fat' jars by copying all dependencies inside. But they are mostly used to build the final project such as a deployable WAR file or a desktop app. Not in case of the libraries
I have a project that generates some classes and resources that should then be packaged into a jar.
The class that does the generating has several dependencies. The generated classes have no dependencies.
My initial solution was to use the maven assembly plugin to only include the generated files. Unfortunately, the packaged pom includes all the dependencies required to do the generation. Consumers of this jar pull in a bunch of unnecessary dependencies.
I looked into the maven shade plugin. I compile once, run the generator class with mojo's exec plugin, the compile a final time. Then shade of course runs in the package phase. It creates a dependency-reduced-pom.xml without the excessive dependencies. So run mvn clean package and look in target/foo.jar. I expect the jar in the meta-inf folder to be the reduced dependency jar. But it's the full pom. I don't know how have the generated pom replace the one that is packaged.
Another poor solution I tried was using multiple profiles with their own dependency section. I run maven once with the generating profile, then again with the packaging profile. This works, but sucks because you have to run multiple maven commands. It's not jenkins friendly.
Am I going about this the wrong way? How should I go about arranging a project that generates some code and some text files that are then packaged in a maven friendly artifact?
1) One possibility is to make all your dependencies <optional>true</optional>.
The pom will still have the dependencies but the projects using your library won't try to download them.
2) Use plugin dependencies with the exec plugin.
That works well if the generator class is defined on another project.
Ideally you would call your generator using a plugin and avoid adding those dependencies to your project. That may not be worth doing depending on what your project is for and how reusable your generator has to be.
3) If you are using maven-shade-plugin the dependency-reduced-pom.xml is normally used. Check your .m2 repository to see the contents of the pom that is copied there when you do mvn install. It's likely that its contents will match the dependency-reduced-pom.xml
We are using Maven and m2e tools for our development and today we encountered a problem.
One of our projects is small library that is required for other projects, so we packaged it into jar file and put in our private Maven repository.
For now, all of the jars that we put in this repository didn't have any external dependencies, but this library I mentioned uses some external jars.
Now, when I add information about this jar to other poms, this jar is downloaded from our private repository but Maven doesn't download dependencies needed by this jar.
I am wondering if I need to use some special target/add something to my pom.xml file that will inform Maven to include information about dependencies needed by this artifact.
EDIT:
Here is the workflow I perform when I upload jar to our private repository:
1.I generate jar file from Eclipse using m2e
2.mvn install:install-file -DgroupId=<your_group_name> -DartifactId=<your_artifact_name> -Dversion=<snapshot> -Dfile=<path_to_your_jar_file> -Dpackaging=jar -DgeneratePom=true -DcreateChecksum=true
3.I copy folder created in my local repository to remote repository
If your small library is a maven project as you state, there should be no reason to have eclipse build the jar and then use maven to install it and then manually copy to the remote repo. Instead you should use m2e to run the deploy goal:
mvn deploy
That will cause the jar to get built and then install it directly into your local maven repo then deploy it to the remote repo.
In eclipse this can be accomplished by right clicking your project, choosing Run As -> Maven Build... then in the run configuration window for Goals input type deploy then click Run. After this has been done once, you can just use Run As -> Maven Build to run the same config again.
I see you use -DgeneratePom=true during the installation of the jar file. What you need to do is create a pom.xml for your artifact. In the pom.xml, you can specify the dependencies that your jar file requires. When executing the install:install plugin goal, you use -DpomFile=pom.xml instead.
The best way to do this is to run mvn deploy
You have to setup the distribution repository to your private artifact manager (nexus or artifactory) in your settings.xml
see this for more details
I was given a maven project to compile and get deployed on a tomcat server. I have never used maven before today, but I have been googling quite a bit. It seems like the top level pom.xml files in this project have the packaging type set as pom.
What am I supposed to do after mvn install to get this application deployed? I was expecting to be able to find a war file somewhere or something, but I guess I am looking in the wrong place or missing a step.
pom is basically a container of submodules, each submodule is represented by a subdirectory in the same directory as pom.xml with pom packaging.
Somewhere, nested within the project structure you will find artifacts (modules) with war packaging. Maven generally builds everything into /target subdirectories of each module. So after mvn install look into target subdirectory in a module with war packaging.
Of course:
$ find . -iname "*.war"
works equally well ;-).
pom packaging is simply a specification that states the primary artifact is not a war or jar, but the pom.xml itself.
Often it is used in conjunction with "modules" which are typically contained in sub-directories of the project in question; however, it may also be used in certain scenarios where no primary binary was meant to be built, all the other important artifacts have been declared as secondary artifacts
Think of a "documentation" project, the primary artifact might be a PDF, but it's already built, and the work to declare it as a secondary artifact might be desired over the configuration to tell maven how to build a PDF that doesn't need compiled.
Packaging of pom is used in projects that aggregate other projects, and in projects whose only useful output is an attached artifact from some plugin. In your case, I'd guess that your top-level pom includes <modules>...</modules> to aggregate other directories, and the actual output is the result of one of the other (probably sub-) directories. It will, if coded sensibly for this purpose, have a packaging of war.
To simply answer your question when you do a mvn:install, maven will create a packaged artifact based on (packaging attribute in pom.xml), After you run your maven install you can find the file with .package extension
In target directory of the project workspace
Also where your maven 2 local repository is search for (.m2/respository) on your box, Your artifact is listed in .m2 repository under (groupId/artifactId/artifactId-version.packaging) directory
If you look under the directory you will find packaged extension file and also pom extension (pom extension is basically the pom.xml used to generate this package)
If your maven project is multi-module each module will two files as described above except for the top level project that will only have a pom
Packaging an artifact as POM means that it has a very simple lifecycle
package -> install -> deploy
http://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html
This is useful if you are deploying a pom.xml file or a project that doesn't fit with the other packaging types.
We use pom packaging for many of our projects and bind extra phases and goals as appropriate.
For example some of our applications use:
prepare-package -> test -> package -> install -> deploy
When you mvn install the application it should add it to your locally .m2 repository. To publish elsewhere you will need to set up correct distribution management information. You may also need to use the maven builder helper plugin, if artifacts aren't automatically attached to by Maven.
I suggest to see the classic example at: http://maven.apache.org/guides/getting-started/index.html#How_do_I_build_more_than_one_project_at_once
Here my-webapp is web project, which depends on the code at my-app project. So to bundle two projects in one, we have top level pom.xml which mentions which are the projects (modules as per maven terminology) to be bundled finally. Such top level pom.xml can use pom packaging.
my-webapp can have war packaging and can have dependency on my-app. my-app can have jar packaging.
“pom” packaging is nothing but the container, which contains other packages/modules like jar, war, and ear.
if you perform any operation on outer package/container like mvn clean compile install. then inner packages/modules also get clean compile install.
no need to perform a separate operation for each package/module.
Real life use case
At a Java-heavy company we had a python project that needed to go into a Nexus artifact repository. Python doesn't really have binaries, so simply just wanted to .tar or .zip the python files and push. The repo already had maven integration, so we used <packaging>pom</packaging> designator with the maven assembly plugin to package the python project as a .zip and upload it.
The steps are outlined in this SO post
https://maven.apache.org/pom.html
The packaging type required to be pom for parent and aggregation (multi-module) projects. These types define the goals bound to a set of lifecycle stages. For example, if packaging is jar, then the package phase will execute the jar:jar goal. If the packaging is pom, the goal executed will be site:attach-descriptor
POM(Project Object Model) is nothing but the automation script for building the project,we can write the automation script in XML,
the building script files are named diffrenetly in different Automation tools
like we call build.xml in ANT,pom.xml in MAVEN
MAVEN can packages jars,wars, ears and POM which new thing to all of us
if you want check WHAT IS POM.XML
What is an artifact and why does Maven need it?
An artifact is a file, usually a JAR, that gets deployed to a Maven repository.
A Maven build produces one or more artifacts, such as a compiled JAR and a "sources" JAR.
Each artifact has a group ID (usually a reversed domain name, like com.example.foo), an artifact ID (just a name), and a version string. The three together uniquely identify the artifact.
A project's dependencies are specified as artifacts.
In general software terms, an "artifact" is something produced by the software development process, whether it be software related documentation or an executable file.
In Maven terminology, the artifact is the resulting output of the maven build, generally a jar or war or other executable file. Artifacts in maven are identified by a coordinate system of groupId, artifactId, and version. Maven uses the groupId, artifactId, and version to identify dependencies (usually other jar files) needed to build and run your code.
I know this is an ancient thread but I wanted to add a few nuances.
There are Maven artifacts, repository manager artifacts and then there are Maven Artifacts.
A Maven artifact is just as other commenters/responders say: it is a thing that is spat out by building a Maven project. That could be a .jar file, or a .war file, or a .zip file, or a .dll, or what have you.
A repository manager artifact is a thing that is, well, managed by a repository manager. A repository manager is basically a highly performant naming service for software executables and libraries. A repository manager doesn't care where its artifacts come from (maybe they came from a Maven build, or a local file, or an Ant build, or a by-hand compilation...).
A Maven Artifact is a Java class that represents the kind of "name" that gets dereferenced by a repository manager into a repository manager artifact. When used in this sense, an Artifact is just a glorified name made up of such parts as groupId, artifactId, version, scope, classifier and so on.
To put it all together:
Your Maven project probably depends on several Artifacts by way of its <dependency> elements.
Maven interacts with a repository manager to resolve those Artifacts into files by instructing the repository manager to send it some repository manager artifacts that correspond to the internal Artifacts.
Finally, after resolution, Maven builds your project and produces a Maven artifact. You may choose to "turn this into" a repository manager artifact by, in turn, using whatever tool you like, sending it to the repository manager with enough coordinating information that other people can find it when they ask the repository manager for it.
Hope that helps.
Maven organizes its build in projects.
An artifact in maven is a resource generated by a maven project. Each maven project can have exactly one artifact like a jar, war, ear, etc.
The project's configuration file "pom.xml" describes how the artifact is build, how unit tests are run, etc.
Commonly a software project build with maven consists of many maven-projects that build artifacts (e.g. jars) that constitute the product.
E.g.
Root-Project // produces no artifact, simply triggers the build of the other projects
App-Project // The application, that uses the libraries
Lib1-Project // A project that creates a library (jar)
Lib2-Project // Another library
Doc-Project // A project that generates the user documentation from some resources
Maven artifacts are not limited to java resources. You can generate whatever resource you need. E.g. documentation, project-site, zip-archives, native-libraries, etc.
Each maven project has a unique identifier consiting of [groupId, artifactId, version]. When a maven project requires resources of another project a dependency is configured in it's pom.xml using the above-mentioned identifier. Maven then automatically resolves the dependencies when a build is triggered. The artifacts of the required projects are then loaded either from the local repository, which is a simple directory in your user's home, or from other (remote) repositories specified in you pom.xml.
Q. What is Artifact in maven?
ANS: ARTIFACT is a JAR,(WAR or EAR), but it could be also something else. Each artifact has,
a group ID (like com.your.package),
an artifact ID (just a name), and
a version string. The three together uniquely identify the artifact.
Q.Why does Maven need them?
Ans: Maven is used to make them available for our applications.
An artifact is a JAR or something that you store in a repository. Maven gets them out and builds your code.
To maven, the build process is arranged as a set of artifacts. Artifacts include:
The plugins that make up Maven itself.
Dependencies that your code depends on.
Anything that your build produces that can, in turn be consumed by something else.
Artifacts live in repositories.
usually we talking Maven Terminology about Group Id , Artifact Id and Snapshot Version
Group Id:identity of the group of the project
Artifact Id:identity of the project
Snapshot version:the version used by the project.
Artifact is nothing but some resulting file like Jar, War, Ear....
simply says Artifacts are nothing but packages.
Usually, when you create a Java project you want to use functionalities made in another Java projects.
For example, if your project wants to send one email you dont need to create all the necessary code for doing that. You can bring a java library that does the most part of the work.
Maven is a building tool that will help you in several tasks. One of those tasks is to bring these external dependencies or artifacts to your project in an automatic way ( only with some configuration in a XML file ).
Of course Maven has more details but, for your question this is enough.
And, of course too, Maven can build your project as an artifact (usually a jar file ) that can be used or imported in other projects.
This website has several articles talking about Maven :
https://connected2know.com/programming/what-is-maven/
https://connected2know.com/programming/maven-configuration/
An artifact is an element that a project can either use or produce. In Maven terminology, an artifact is an output generated after a Maven project build. It can be, for example, a jar, war, or any other executable file.
Also, Maven artifacts include five key elements, groupId, artifactId, version, packaging, and classifier. Those are the elements we use to identify the artifact and are known as Maven coordinates.
read it from here