Aether/New and Noteworthy
0.9.0.M3 (Not Yet Released)
See our issue tracker for a list of resolved issues.
To ease working with version ranges, the version syntax recognized by GenericVersionScheme has been extended to recognize the case-insensitive tokens "min" and "max". These tokens can be used as the last segment of a version string to denote the minimum and maximum value for that segment. For example, using the new syntax, the requirement "depend on version 2.x" translates to the version range "[2.min, 2.max]". Unlike the common attempt to achieve this using "[2.0, 3.0)", the new syntax properly includes "2.0-SNAPSHOT" and excludes "3.0-rc-1". Last but not least, a range of the form "[M.N.min, M.N.max]" can be specified more compact as "[M.N.*]".
Furthermore, a new hook named VersionFilter has been added to the dependency collection process. This hook allows clients to control which of the available versions matching a range are actually acceptable for the dependency graph. The aether-util module ships with a ready-made ContextualSnapshotVersionFilter that clients might find useful.
This is the first release of Eclipse Aether for which a compatible maven-aether-provider exists. Said component enables users to access Maven repositories and can be obtained from the Central repository using these coordinates:
<dependency> <groupId>io.tesla.maven</groupId> <artifactId>maven-aether-provider</artifactId> <version>3.1.0</version> </dependency>
See our issue tracker for a list of resolved issues.
In previous versions, the JavaEffectiveScopeCalculator and NearestVersionConflictResolver were responsible to resolve scope and version conflicts and deliver a cleaned up dependency tree. However, the separation of scope and version handling in two isolated dependency graph transformers suffers from a conceptual flaw and caused subtle bugs regarding the effective scope of dependencies. The mentioned classes have been replaced with the new ConflictResolver transformer. This new transformer handles both version and scope conflicts and provides hooks to customize the conflict resolution. To achieve the same kind of conflict resolution as offered previously by the broken transformers, use new ConflictResolver( new NearestVersionSelector(), new JavaScopeSelector(), new SimpleOptionalitySelector(), new JavaScopeDeriver() ).
The SimpleOptionalitySelector hints at another significant fix: The optional flag now gets similar processing during transitive dependency resolution as the scope, i.e. the effective optional flag is subject to the optionality of ancestor nodes and conflict resolution. For instance, transitive dependencies of optional dependencies are now considered optional as well.
As detailed in the API docs of the ConflictResolver, the new graph transformer also supports a verbose mode. This mode can be used to obtain a dependency tree which resembles the dependency hierarchy tab in m2e.
Last but not least, early feedback suggests the new conflict resolution code executes significantly faster than the old code.
Is a remote repository with the URL "file:/whatever" accessible in offline mode? To allow clients to answer this question appropriately, the internal implementation has been refactored to centralize the offline decision in a new component called OfflineController. The default implementation of this component supports two configuration properties to address common requirements:
- aether.offline.protocols: Comma-separated list of protocols which are accessible even in offline mode, e.g. "file"
- aether.offline.hosts: Comma-separated list of hostnames which are accessible even in offline mode, e.g. "localhost"
Pre-managed Dependency Attributes
Previously, the methods DependencyNode.getPremanaged*() could be used to obtain the version and scope of a dependency before it was updated by dependency management. To reduce memory consumption for ordinary dependency resolution, these methods have been removed and their backing data is no longer recorded for each node by default. The pre-managed attributes can still be obtained via a new configuration property, see DependencyManagerUtils for details regarding its usage.
P2 Update Site
Starting with this milestone, we provide a P2 update site for Aether Core, powered by Tycho. This site provides two features, one for the binaries and another one for the sources. You'll find the relevant links on the download page.
This is the first release of Aether since its migration to the Eclipse Foundation. As such the items listed below indicate changes compared to the previous Sonatype Aether codebase.
Note: There is currently no released version of the maven-aether-provider that builds upon this release of Aether Core so this milestone release is not of direct interest to users seeking access to Maven repositories. Early adopters interested in evaluating the new codebase can find an updated maven-aether-provider at https://github.com/bentmann/maven-3.
See our issue tracker for a list of fixed issues.
All code has been moved into the package org.eclipse.aether and sub packages. Likewise, the group ID of the artifacts deployed to the Central Repository has changed to org.eclipse.aether.
Clean up of API
Besides the new package namespace, the API has been changed in some places to ease usage and maintenance. The list below is not exhaustive but focuses on changes where updates to client code are not obvious:
- TransferEvent.RequestType.GET_EXISTENCE was introduced to allow transfer listeners to distinguish between actual downloads and mere existence checks.
- FilteredRepositorySystemSession was removed and its usages should be replaced with DefaultRepositorySystemSession and its copy constructor.
- The properties transferErrorCachingEnabled and notFoundCachingEnabled of RepositorySystemSession have been replaced by ResolutionErrorPolicy, SimpleResolutionErrorPolicy provides a stock implementation.
- The properties ignoreMissingArtifactDescriptor and ignoreInvalidArtifactDescriptor of RepositorySystemSession have been replaced by ArtifactDescriptorPolicy, SimpleArtifactDescriptorPolicy provides a stock implementation.
- Authentication was remodeled into an interface, the new AuthenticationBuilder provides a way to obtain a stock implementation.
- RemoteRepository instances have been made immutable, RemoteRepository.Builder assists in their instantiation.
Thanks to a contributor, the JAR manifests have been extended with attributes to support use of Aether in an OSGi container. Providing an update site for Aether is an unresolved todo in our issue tracker, contributions welcome.
Support for JSR-330
The components making up the implemenation of Aether have been enriched with javax.inject annotations to support wiring by a JSR-330 compliant container. The class AetherModule helps to set up bindings for the popular Guice container. Likewise, the JARs are equipped with Sisu index files to support efficient component discovery when using Sisu.