Simple Mavenization of existing Ant build files - maven-2

If you have an existing ant file, what is the best way to convert the project to Maven. I've checked out things like fAnt, but if I'm going to mess with this stuff, I might as well go full-bore for Maven. I expected something to exist that can just start the pom.xml for me based on the existing build.xml, but I haven't found anything yet. Suggestions?

I don't know any good automated way to do such a migration because things may just be too different so I would do it manually, step by step, and keep the existing ant build in parallel of the future new one until the whole migration is done (from both technical and human points of view).
First, refactor the existing Ant build to align it on Maven conventions:
Make things modular: if your existing build is a big monolithic build producing several artifacts from a single source tree, break it down into separate modules, one for each artifact.
Update directory structure: Maven comes with a standard directory layout and, while it is possible to customize this layout (i.e. to configure plugins for another layout), this is not really recommended and is more a source of troubles than benefits. So I'd move existing app sources, configuration files, tests, etc to match Maven's layout (e.g. src/main/java for application sources, etc).
Then, start to create the Maven build:
Create POMs for each module: Create a POM, declare external libraries as Maven dependencies (maybe add them to a corporate repository, using an enterprise repository is a good practice in an enterprise context anyway), add dependencies between modules.
Finalize the multi-modules build: Add parent(s) POM(s) and inheritance/aggregating relationships. Test that there is no regression with the created artifacts.
You could do this work in a separate VCS branch if you don't want to change anything until the work is done and create scripts to move things. And when ready, merge the Maven specific stuff and apply the scripts.

You could run the Ant script from Maven with the maven-antrun-plugin. Your pom.xml would look something like this:
<project>
...
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-antrun-plugin</artifactId>
<dependencies>
<dependency>
<groupId>org.apache.ant</groupId>
<artifactId>ant-nodeps</artifactId>
<version>${ant-nodeps.version}</version>
</dependency>
</dependencies>
<executions>
<execution>
<id>init</id>
<phase>compile</phase>
<configuration>
<tasks>
<!-- Ant code goes here -->
</tasks>
</configuration>
<goals>
<goal>run</goal>
</goals>
</execution>
</executions>
</plugin>
</build>
</project>
That way you can start to move your dependencies into Maven, and reference them in the Ant script like so
${com.foo.bar:my-lib:jar}
Then just start slowly moving pieces of your Ant into pure Maven stuff.

Related

New at Maven: Using the shade plugin and 3rd party jars

This should be pretty simple, but I can't the around to it. I need to create an uberjar using 3rd party jars. I've already followed these instructions: Including a non-Mavenized dependency so it works with maven-shade-plugin and added them to the local repository. But now what? Every Maven tutorial/example is kinda shady (pun intended) and I just don't know how to edit the .pom file properly in order to make it work.
Besides, I'm confused about the shade "plugin" overall. I mean, I followed the basic Maven tutorials and it went all fine and dandy. But when I look into the shade plugin page, I can't find it to download, except for the source code. I mean, isn't it a plugin? Shouldn't I download the binaries and install it into Maven somehow?
Sorry about the extreme noobish question but, needless to say, I know squat about Maven.
To create your shaded (uber) jar, you just need to declare the shade plugin in your pom.xml.
With regards to installation of the shade plugin, simply declaring it in the plugins section of your pom.xml is all you need do. Maven plugins are not installed manually, but are automatically downloaded by Maven (if not already downloaded; just like dependencies), stored in your local repository, and used whenever a project needs them.
As to using it, much like other plugins, declare it in your pom.xml by adding a <plugin> element with your configuration needs. This plugin does nothing automatically (some do, some don't) - you have to specify which "goal" to execute (think "method of a class"), and in which "phase" (think "step" of the build process). Unless you have strange needs, specify the "shade" goal in the "package" phase (see below).
For more configuration possibilities, see the shade usage page, and their examples (especially selecting contents for uber jar). Here is a simple example which, when you run mvn package, replaces your original jar in the target/ directory with the uber jar. It only includes the runtime dependencies, not the ones used at test time (notice the <scope> element of the junit dependency, which is not included in the uber jar).
<project>
<groupId>com.sample</groupId>
<artifactId>test</artifactId>
<version>1.0</version>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>1.5</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>com.sample</groupId>
<artifactId>test-core</artifactId>
<version>1.0</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>
If you have already downloaded the binaries and installed them into your local Maven repository all that remains is to declare them as dependencies in the POM. If the shade plugin is also declared in the POM a simple "mvn install" should generate a standalone JAR in the target directory.

Aggregate Dependencies in a Multi-Module Maven Project

I am trying to figure out how to aggregate my maven dependencies in a multi-module project. For example, if I have:
root pom/project1
root pom/project2
and I run mvn dependency:copy-dependencies, I end up with the dependencies in:
root pom/project1/target/dependency
root pom/project2/target/dependency
What I really want is that if I run the mvn command in the root pom folder, all of the dependencies to be copied to root pom/dependency. Is there a maven property that gets me the output directory of the root pom? (similar to ${project.build.directory})? I realize that I can just copy all the dependency folders to the same place after the fact, but I was hoping for something a little cleaner.
You will have to configure the dependency plugin to copy depdendencies to a particular location. This can be done by the outputDirectory configuration property.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${outputDir}</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
But if you trying to do this for distribution, I'd recommend you create an assembly using the maven assembly plugin
The documentation says:
The Assembly Plugin for Maven 2.0 is primarily intended to allow users to aggregate the
project output along with its dependencies, modules, site documentation, and other files
into a single distributable archive.
What I really want is that if I run the mvn command in the root pom folder, all of the dependencies to be copied to root pom/dependency. Is there a maven property that gets me the output directory of the root pom? (similar to ${project.build.directory})?
No, because modules shouldn't actually be aware of that.
I realize that I can just copy all the dependency folders to the same place after the fact, but I was hoping for something a little cleaner.
The Maven way would to use the Maven Assembly Plugin and a custom descriptor. But if you're not familiar with the Maven Assembly Plugin and its descriptor format, it won't be easy.
A less clean but easier approach would be to configure the Maven Dependency plugin to copy the dependencies into the parent project using a relative path. Something like this:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.1</version>
<configuration>
<outputDirectory>../root_pom/target/dependency</outputDirectory>
</configuration>
</plugin>
But as I said, this introduces tight coupling between modules and the root project which is not good at all (and I wouldn't go further by including the goal invocation as part of the build, modules should remain independent and you should be able to build one module without "checkouting" the parent).

Maven Plugin error

Im a new user in maven. I have few doubts.
I have some BAT files that has to executed via maven
While executing my default commands, I need to echo the status like "Started first task"
When the task gets failed user should get error message popup etc.,
Automatic repository update through maven
Maven calling ant to build *.war
Copying the new created build file(*.war) to local folder with date/time
Auto upload/deploy from build machine to server
Testing particular URLs/products to test the site flow
Sending mail regarding deployment status
Below is my example pom.xml, which trying only (a)
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.example.maven</groupId>
<artifactId>test</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<name>test</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>1.1.1</version>
<executions>
<execution>
<goals>
<goal>exec</goal>
</goals>
</execution>
</executions>
<!--echo>Starting CVS Update</echo-->
<configuration>
<tasks>
<exec>
<directory>D:\</directory>
<executable>"D:\test.bat"</executable>
<!--failonerror="true" -->
<!-- optional -->
<!--workingDirectory>"cd C:\repo\projects\mcsandbox"</workingDirectory-->
</exec>
</tasks>
</configuration>
</plugin>
</plugins>
</build>
</project>
I guess this is not the expected answer but I don't think that you're on the right path and I don't see the point of using Maven the way you'd like to use it. From your description, my impression is that you aren't really adopting Maven but rather trying to insert something existing into it and, believe me, this isn't the easiest way to get started with Maven:
This is going to add an extra layer of complexity.
This requires a deeper understanding of the way maven works than "just" adopting it.
You're going to fight against the tool (and there are good chances that the tool will win).
This will generate more troubles than benefits.
I don't really know where to start so I'll just try to quickly cover your points first:
I have some BAT files that has to executed via maven
This is possible but this is not really the Maven way (depending on the logic, you should move it to Maven or keep it outside maven), and I don't think this is going to be very robust (might be wrong though). On top of that, this already requires some knowledge of the build lifecycle (where to hook things) and of plugin configuration. And from what I've seen (I do not mean to be rude), you don't have it.
While executing my default commands, I need to echo the status like "Started first task"
This is not how things work with Maven. Maven isn't procedural like Ant, Maven has conventions, Maven is declarative, Maven has a lifecycle.
When the task gets failed user should get error message popup etc.,
User? Popup? Maven is not really targeted at end users, Maven is a developer tool and what you get in case of an error is a message in a console.
Automatic repository update through maven
Do you mean a CVS update? This is not impossible but is usually not Maven's job (it's more a Continuous Integration engine task).
Maven calling ant to build *.war
This is possible using the Maven Antrun Plugin but that's not the spirit and may go against some maven rules (like one artifact per project). Also, Maven will not magically be aware of things built by Ant. Why don't you just stick with Ant?
Copying the new created build file(*.war) to local folder with date/time
Possible. But that's not how things work by default.
Auto upload/deploy from build machine to server
Maven has plugins (e.g. Cargo) that can help at doing this but you have to tell him to.
Testing particular URLs/products to test the site flow
Maven itself won't do that. But it can run (integration) tests doing that.
Sending mail regarding deployment status
That's not maven's responsibility (more a Continuous Integration engine task).
My global feeling is that you are thinking too much Ant oriented and maybe expecting too much from Maven. Maven is different, it doesn't really work the way you described, it doesn't work like Ant. My recommendation would be to either fully migrate to Maven and adopt its philosophy or to stick with your current Ant solution (and maybe consider using the Maven Ant Tasks or Ivy to leverage things such as dependency management, artifact deployment).
See also
How to convert from Ant to Maven (...)
Differences between Ant and Maven
Maven: The Definitive Guide

How to run jetty:run-war using a war defined by maven coordinates?

Background: I'm setting up a functional tests module in a maven project. We use the maven-jetty-plugin for testing.
I've got the jetty plugin set up as described here (to play nicely with the Failsafe plugin), but what I'd like to do is deploy the war artifact from our main web module using jetty (which has just been installed into the local maven repo by the time the functional test module is running).
The jetty plugin's run-war goal has a <webApp> element which takes a string path to a war to deploy. I'd much rather specify the war to deploy using the maven coordinates defined by our web module. Is there any way to do this?
Possible workarounds:
Section 4.13 of "Better Builds with Maven" describes using cargo to deploy a war specified using maven coordinates, but that's serious overkill given that we're using jetty.
More reasonable IMO is using dependency:copy to copy the just-built-and-installed war artifact to a fixed path in the functional tests module's target directory, which I can then provide in the jetty plugin's <webApp> configuration element.
The jetty plugin's run-war goal has a element which takes a string path to a war to deploy. I'd much rather specify the war to deploy using the maven coordinates defined by our web module. Is there any way to do this?
This is not really the maven jetty plugin is supposed to be used, the plugin deploys the war of the current module, what you want to do is not supported by default.
Section 4.13 of "Better Builds with Maven" describes using cargo to deploy a war specified using maven coordinates,
Yes, Cargo can do this in a clean way.
but that's serious overkill given that we're using jetty.
I don't agree. First, the jetty plugin doesn't support what you want to do out of the box (so it may not be the right tool). Second, serious overkill is highly exaggerated, a misconception actually, especially given that cargo requires very little configuration (zero?) for an embedded Jetty.
More reasonable IMO is using dependency:copy to copy the just-built-and-installed war artifact to a fixed path in the functional tests module's target directory
No offense but your whole question sounds a bit like: I have a hammer, it was fine for a nail, can I use it for a screw given that getting a screw driver seems a serious overkill? To answer this question (which is somehow what you are saying), you can use dependency:copy and get the whole thing working with the maven jetty plugin, but this is a hack (and since you're actually not asking any question, I guess you wanted an opinion on this). Of course the final decision belongs to you :)
Just in case, here is how I would implement this with Cargo:
<dependencies>
<dependency>
<groupId>war group id</groupId>
<artifactId>war artifact id</artifactId>
<type>war</type>
<version>war version</version>
</dependency>
...
</dependencies>
...
<build>
<plugins>
<plugin>
<groupId>org.codehaus.cargo</groupId>
<artifactId>cargo-maven2-plugin</artifactId>
<configuration>
<!-- Container configuration -->
<container>
<containerId>jetty6x</containerId>
<type>embedded</type>
</container>
<!-- Configuration to use with the container or the deployer -->
<configuration>
<deployables>
<deployable>
<groupId>war group id</groupId>
<artifactId>war artifact id</artifactId>
<type>war</type>
<properties>
<context>war context</context>
</properties>
</deployable>
</deployables>
</configuration>
<!-- Don't wait, execute the tests after the container is started -->
<wait>false</wait>
</configuration>
<executions>
<execution>
<id>start-container</id>
<phase>pre-integration-test</phase>
<goals>
<goal>start</goal>
</goals>
</execution>
<execution>
<id>stop-container</id>
<phase>post-integration-test</phase>
<goals>
<goal>stop</goal>
</goals>
</execution>
</executions>
</plugin>
...
</plugins>
...
</build>
And I don't think that this can be objectively qualified as a "serious overkill".

Trigger a maven install command from another maven install command

Is there a way to trigger a maven install command from another maven install command?
In other words, I would like to be able to execute a maven install command on a maven project (in eclipse) and I want that this will automatically cause an install command on another maven project.
Is that possible?
The Maven way to "trigger" another build is to define a multi-module build. A parent pom project can specify modules, that will all be built using the standard lifecycle. So running mvn install on the parent would mean that each module is built in turn.
The parent is defined with pom packagin, and would have a modules declaration like this:
<modules>
<module>module-a</module>
<module>module-b</module>
</modules>
Alternatively it is possible to attach additional artifacts to a build so they are deployed alongside the primary artifacts (assuming they've already been packaged, you can use the build-helper-maven-plugin to attach an arbitrary file to your pom, so it will be deployed with the specified classifier. The following configuration will attach the specified file as my-artifact-1.0-extra.jar
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<version>1.3</version>
<executions>
<execution>
<id>attach-artifacts</id>
<phase>package</phase>
<goals>
<goal>attach-artifact</goal>
</goals>
<configuration>
<artifacts>
<artifact>
<file>/path/to/extra/file.jar</file>
<type>jar</type><!--or specify your required extension-->
<classifier>extra</classifier>
</artifact>
</artifacts>
</configuration>
</execution>
</executions>
</plugin>
As pointed out, the maven way to launch a goal (lets say mvn install) on a set of modules is to organize them as a multi-module project and to launch the goal on the parent pom. Behind the scene, Maven will use a "Maven reactor" for this work. The reactor will calculate the build order by doing a topological sort of the nodes of the directed graph constructed by the dependency relation between modules. This graph is constructed by looking at <modules> and <dependencies> tags in poms.
But launching maven from a parent is not the only option and maven offers more possibilities to play with the reactor (e.g. making a project and its dependencies or those that depend on it):
With maven 2.0.x you have to use the reactor plugin : http://maven.apache.org/plugins/maven-reactor-plugin/ (see Reactor: My New Favourite Maven Plugin too)
With maven 2.1+ you can use native command line options : http://www.sonatype.com/people/2009/03/maven-210-released/ (see the new build mode options -amd, -rf, -am, -pl)
Check it out, it might help you to achieve your goal.