Apache Harmony in Encyclopedia

Apache Harmony was an open source, free Java implementation, developed by the Apache Software Foundation^[1]. It was announced in early May 2005 and on October 25, 2006, the Board of Directors voted to make Apache Harmony a top-level project. The Harmony project achieved (as of February 2011) 99% completeness for JDK 5.0, and 97% for Java SE 6.^[2]

On October 29, 2011 a vote was started by the project lead Tim Ellison whether to retire the project. The outcome was 20 to 2 in favor^[3], and the project was retired on November 16, 2011^[4].

History

Initiation

The Harmony project was initially conceived as an effort to unite all developers of the free Java implementations. Many developers expected that it would be the project above the GNU, Apache and other communities. GNU developers were invited into and participated during the initial, preparatory planning.^[5]

Incompatibility with GNU Classpath

Despite the impression given by the preparatory planning, it was decided not to use the code from GNU Classpath, and that Harmony would use an incompatible license; therefore blocking the collaboration between Harmony and existing free Java projects.^[6] Apache developers would then write the needed classes from scratch and expect necessary large code donations from software companies. Various misunderstandings at the start of the project, and the fact that major companies like IBM proposed to give large amount of existing code, created some confusion in the free Java community about the real objectives of the project.^[7]

Difficulties to obtain a TCK license from Sun

On April 10, 2007, the Apache Software Foundation sent a letter to Sun Microsystems CEO, Jonathan Schwartz regarding their inability to acquire an acceptable license for the Java SE 5 Technology Compatibility Kit (TCK), a test kit needed by the project to demonstrate compatibility with the Java SE 5 specification, as needed by the Sun specification license for Java SE 5.^[8] What makes the license unacceptable for ASF is the fact that it imposes rights restrictions through limits on the "field of use" available to users of Harmony, not compliant with the Java Community Process rules.^[9]

Since Sun's release of OpenJDK, Sun has released a specific license to allow to run the TCK in the OpenJDK context for any GPL implementation deriving substantially from OpenJDK.^[11]

On December 9, 2010, the Apache Software Foundation resigned from the Java Community Process Executive Committee,^[12] in protest over the difficulty in obtaining a license acceptable to Apache for use with the Harmony project.^[13]

Use in Android SDK

Dalvik, the virtual machine used in Google's Android platform, uses a subset of Harmony for the core of its Class Library.^[14] However, Dalvik does not align to Java SE nor Java ME Class Library profiles (for example J2ME classes, AWT and Swing are not supported). Instead it uses its own library,^[15] built on a subset of Harmony.

Disengagement from IBM

On 11 October 2010, IBM, by far the biggest participant in the project, decided to join Oracle on the OpenJDK project, effectively shifting its efforts from Harmony to the Oracle reference implementation.^[16]^[17] Bob Sutor, IBM's head of Linux and open source, blogged that "IBM will be shifting its development effort from the Apache Project Harmony to OpenJDK".^[18]

On March 2011, IBM's Tim Ellison announced that he resigned as Project Management Chair for Harmony, a move which brought questions about the future of the project.^[19]^[20]. Since the beginning of 2011, there has been almost no more development on the project, nor discussions on the mailing list^[21].

End of the project

On October 29, 2011 a vote was started by the project lead Tim Ellison whether to retire the project. The outcome was 20 to 2 in favor^[3], and the project was retired on November 16, 2011^[4].

Development team

At the start, Apache Harmony received some large code contributions from several companies. Development discussions have taken place on open mailing lists. Later, the Apache Software foundation mentors put a lot of effort into bringing the development process more in line with "the Apache way,"^[22]^[23] and it seems that their efforts were successful.

Last development status

Apache Harmony was accepted among the official Apache projects on 29 October 2006.

Architecture

Support platform and operating system

The project provided a portable implementation that ease development on many platforms and operating systems. The main focus was on Windows and Linux operating systems on x86 and x86-64 architectures.^[24]

Class library coverage

The expected donations from software companies were actually received. The Apache Harmony now contains the working code, including the Swing, AWT and Java 2D code which were contributed by Intel.

The Harmony project currently achieve (as of February 2011) 99% completeness for JDK 5.0, and 97% for Java SE 6.^[2]

The progress of the Apache Harmony project can be tracked against J2SE 1.4 and Java SE 5.0.^[25] Also, there is a branch for Harmony v6.0 in development for Java SE 6.0.

Apache Harmony developers integrate several existing, field-tested open-source projects to meet their goal (not reinventing the wheel). Many of these projects are mature and well known and other parts of the library needed to be written from scratch.

This is a list of existing open source components that are used in the Apache Harmony project; some of them were in use before the project started.

Component	Description
ICU	Mature C/C++ and Java libraries for Unicode support, software internationalization and software globalization
Apache Xalan	XSLT stylesheet processor for Java, C++ which implements XPath language
Apache Xerces	XML parser library for Java, C++, Perl
Apache Portable Runtime	Cross-platform abstraction library, provides platform independence
Apache CXF	Robust, high performance Web services framework work over protocols such as SOAP, XML/HTTP, RESTful HTTP, CORBA
BCEL	Libraries to decompose, modify, and recompose binary Java classes, i.e., bytecode
MX4J	Java Management Extensions (JMX) tools to manage and monitor applications, system objects, devices and service oriented networks
VM Magic	Set of extensions to Java language to facilitate systems programming in Java by adding direct memory operations, etc.
Bouncy Castle	Libraries collection of lightweight cryptography for Java and C#
ANTLR	Language tool, provides a framework to construct recognizers, interpreters, compilers, and translators from grammatical descriptions containing actions in many target languages

Documentation

Tools

Virtual machine support

Harmony currently has seven virtual machine implementations that run Harmony Class Library, all of which were donations by external groups:

In the end of November, 2006, the language support provided by these virtual machine was still incomplete, and the build instructions recommended to use IBM's proprietary J9 instead to run the class library test suite. However, this is not necessary anymore (as of July 2007).

As for the rest of the project, DRLVM virtual machine development has now stalled (as of May 2011).^[29]

Application status

Since its conception, Harmony has steadily grown in its ability to execute non-trivial Java applications (see here). , supported applications include:

However, Harmony's incomplete library prevented it from launching some other applications:

Apache Harmony

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