Creating a RepositorySystemSession

Resolver (former Aether) and its components are designed to be stateless and as such all configuration/state has to be passed into the methods. When one makes multiple requests to resolve dependencies, a fair amount of settings usually remains the same across these method calls, like the proxy settings or the path to the local repository. Those settings that tend to be the same for an entire usage session of the repository system are represented by an instance of org.eclipse.aether.RepositorySystemSession. Using classes from maven-resolver-supplier, creating such a session that mimics Maven's setup can be done like this:

import org.eclipse.aether.supplier.RepositorySystemSupplier;

...
    private static RepositorySystemSession newSession( RepositorySystem system )
    {
        RepositorySystemSession.SessionBuilder sessionBuilder = SessionBuilderSupplier.get();

        LocalRepository localRepo = new LocalRepository( "target/local-repo" );
        sessionBuilder.setLocalRepositoryManager( system.newLocalRepositoryManager( session, localRepo ) );

        return session.build();
    }

As you see, the only setting that must be specified is the local repository, other settings are initialized with default values. Please have a look at the API docs for RepositorySystemSession.SessionBuilder to learn about all the other things you can configure for a session.

In case of Maven plugin, or when code runs embedded in Maven, the session is already created for you, but you can still “derive” using copy constructor of DefaultRepositorySystemSession if some session alteration is needed.

If you seek a closer cooperation with Apache Maven and want to read configuration from the user's settings.xml, you should have a look at the library MIMA which provides the necessary bits. Please direct any questions regarding usage of that library to the Maven mailing list.