Java Packaging Guidelines

This page represents Fedora guidelines for packaging libraries and applications written in Java and related languages that use the Java Virtual Machine as a bytecode interpreter.

It does not aim to extensively describe packaging techniques and tips. RPM macros and commands used here are documented in man pages. Furthermore, a separate Java Packaging HOWTO describes Java packaging techniques in detail and includes examples, templates and documentation aimed at packagers and Java developers who are taking their first steps in Java RPM packaging.

Fedora Java packaging is originally based on the JPackage Project standards. Over time, we have diverged in packaging tools in most areas but we mostly keep backward compatibility with older packages that make use of JPackage standards.

Package naming

Packages MUST follow the standard Fedora package naming guidelines.

Java API documentation MUST be placed into a sub-package called %{name}-javadoc.

Release tags

Packages MUST follow the standard Fedora package versioning guidelines.

Architecture support

The system JDK / JRE might not be available on all architectures that are supported by any given Fedora release.

For this reason, all Java packages MUST contain an ExclusiveArch tag:

  • Packages that build only noarch sub-packages MUST use ExclusiveArch: %{java_arches} noarch.

  • Packages that include architecture-dependent build artifacts (i.e. Packaging JAR files that use JNI modules) MUST use ExclusiveArch: %{java_arches}.

The %{java_arches} macro contains a list of all the architectures where the system JRE / JDK is available and is defined on all Fedora releases.

Pre-built dependencies

Packages MUST follow the standard Fedora dependency bundling guidelines.

In particular, *.class and *.jar files from upstream releases MUST NOT be used during build of Fedora packages and they MUST NOT be included in binary RPM.

JAR file installation

The following applies to all JAR files except JNI-using JAR files and application-specific JAR files (i.e., JAR files that can only reasonably be used as part of an application and therefore constitute application-private data).

Split JAR files

If a project offers the choice of packaging it as a single monolithic JAR or as several separate JARs, the split packaging SHOULD be preferred.

Installation directory

  • All architecture-independent JAR files MUST go into %{_javadir} or its subdirectory.

  • For installation of architecture dependent JAR files, see Packaging JAR files that use JNI.

Filenames

  • If the package provides a single JAR file installed filename SHOULD be %{name}.jar.

  • If the package provides multiple JAR files, they SHOULD be installed in a %{name} subdirectory.

  • Versioned JAR files (*-%{version}.jar) MUST NOT be installed unless the package is a compatibility package.

  • Packages MAY provide alternative filenames, as long as they do not conflict with other packages.

BuildRequires and Requires

Java packages MUST BuildRequire their respective build system:

  • BuildRequires: maven-local for packages built with Maven

  • BuildRequires: ant for packages built with ant

  • BuildRequires: java-devel for packages built with javac

Java applications or their dependencies MUST have Requires on:

  • java-headless or java-headless >= 1:minimal_required_version

  • javapackages-filesystem

If a java-headless requirement is insufficient, then the package MUST have Requires for java or java >= 1:minimal_required_version.

Javadoc installation

  • JavaDoc documentation MAY be generated.

  • If javadoc documentation is generated, it MUST be installed into a directory of %{_javadocdir}/%{name} as part of the -javadoc subpackage.

  • Directory or symlink %{_javadocdir}/%{name}-%{version} SHOULD NOT exist.

  • The javadoc subpackage MUST be declared noarch, even if main package is architecture specific.

No class-path in MANIFEST.MF

JAR files MUST NOT include a class-path entry in their META-INF/MANIFEST.MF file.

Hardcoded paths

Packages MUST NOT hardcode paths to JAR files they use. When a package needs to reference a JAR file, the packager SHOULD use one of tools that are designed for locating JAR files in the system.

Maven pom.xml files

If upstream project is shipping Maven pom.xml files, these MUST be installed. Additionally, the package MUST install a mapping between the upstream artifact and the filesystem by using the %mvn_install macro.

If upstream project does not ship Maven pom.xml file, the official maven repository should be consulted and if the project publishes pom.xml files there, they SHOULD be included.

If modifications to Maven pom.xml files are needed, the %pom_* family of macros SHOULD be used.

Wrapper Scripts

Applications wishing to provide a convenient method of execution SHOULD provide a wrapper script in %{_bindir}. Packages SHOULD use %jpackage_script to create these wrapper scripts.

Compatibility packages

In certain cases it might be necessary to create compatibility packages that provide older API/ABI level of the same library. However, creating these compatibility packages is strongly discouraged.

To standardize and simplify packaging of such compatibility packages, the following rules apply:

  • Compatibility packages MUST be named in the same way as the original package except the addition of the version to the package’s name.

  • Any JAR and POM files MUST be versioned, as well.

Packaging JAR files that use JNI

Aplicabilidade

Java programs that wish to make calls into native libraries do so via the Java Native Interface (JNI). A Java package uses JNI if it contains a .so file. Note that this file can be embedded within JAR files themselves.

Guideline

JNI packages MUST follow guidelines of ordinary Java packages, with these exceptions:

  • JAR files using JNI or containing JNI shared objects themselves MUST be placed in %{_jnidir}, but MAY be symlinked to %{_libdir}/%{name}.

  • JNI shared objects MUST be placed in %{_libdir}/%{name}.

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