" ... No pom.xml, no sources, no compilation ...

... Just grab jars from nexus, and run! "

Maven standalone runner

Maven is used heavily for java project management with main support for development, unit testing and deployment automation.

But maven infrastructure is very powerful, as it has unified repositories of artifacts (e.g. jars), and pom.xml files describing dependencies in an abstract way, and provides a mechanism of transforming the abstract coordinates into jars (download to local repository) and automatic dependency resolution.

This maven plugin - maven standalone runner is shifting it's capabilities towards running the java packages, using the power and user simplicity of maven.

Given a maven project with main class defined in the jar manifest, you can run it as simple as:

mvn foundation.fluent.api:run:main -Dartifact=foundation.fluent.api:sample-main-artifact:1.0

The plugin will take care of resolving the provided artifact and all it's dependencies, and running it's main class.

For all possibilities, see description of it's individual goals.

Goal: main

This goal serves for execution of any main class either explicitly provided via property, or defined in the manifest.

Example

mvn foundation.fluent.api:run:main -Dartifact=foundation.fluent.api:sample-main-artifact:1.0

Parameters

Parameter	Description	Example
artifact	Main artifact coordinates	-Dartifact=com.example:exampleArtifactId:version
mainClass	Explicitly provided main class. It may not be needed, if the main class is defined in jar manifest.	-DmainClass=com.example.Main
args	Optional main method arguments (a.k.a command line arguments).	"-Dargs=A B"
argFile	Optional file with main method arguments, one per line.	-DargFile=args.txt
allowSnapshot	Allow snapshot artifact to be used. By default it is not allowed.	-DallowSnapshot=true

Goal: class-path

This goal simply resolves (and downloads) all dependencies, and only constructs a classpath in the format for given platform.

Good to note

E.g. Spring boot applications are often having entry point main class, so it's very simple to use this plugin to run spring boot application.

Example

mvn foundation.fluent.api:run:class-path -Dartifact=foundation.fluent.api:sample-main-artifact:1.0

Parameters

Parameter	Description	Example
artifact	Main artifact coordinates	-Dartifact=com.example:exampleArtifactId:version
allowSnapshot	Allow snapshot artifact to be used. By default it is not allowed.	-DallowSnapshot=true

Goal: testng

This goal simplifies invocation of TestNG tests directly from jar.

This may be often used in higher level (non-unit) test automation, where tests are not unit tests of the code within the same maven module, but tests are extra delivery, executed against external SUT (system under test), maybe installed and brought up automatically too, or prepared in dedicated test environment.

Parameter	Description	Example
artifact	Main artifact coordinates	-Dartifact=com.example:exampleArtifactId:version
args	Optional main method arguments (a.k.a command line arguments).	"-Dargs=A B"
argFile	Optional file with main method arguments, one per line.	-DargFile=args.txt
allowSnapshot	Allow snapshot artifact to be used. By default it is not allowed.	-DallowSnapshot=true

Parameter handling

TestNG goal's objective is to simplify the execution. By default, the main artifact's jar is used as -testjar TestNG parameter, so tests or default testNG suite (testng.xml) are taken from that jar. However via -Dargs parameter, one can override this, and specify different jar to be a test jar. That argument can be also translated from artifact coordinates (abstract representation) to it's corresponding (resolved) specific jar file.

More on TestNG command-line parameters can be found int TestNG documentation: https://testng.org/doc/documentation-main.html#running-testng

Plan

The plan is to provide few additional goals.

1. Support for "preparing" (a.k.a. installing) of the artifact for pure local execution. That should use the class-path capability, and prepare startup script.
2. Support for convenient additional common frameworks. E.g. JUnit5.