The factual accuracy of parts of this article (those related to article) may be compromised due to out-of-date information. (February 2013)
|Developer(s)||Apache Software Foundation|
|Written in||C, Java|
|Operating system||Windows, Linux|
|Type||Java Virtual Machine, Java Library|
|License||Apache License 2.0|
Apache Harmony is a retired open source, free Java implementation, developed by the Apache Software Foundation. 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 J2SE 5.0, and 97% for Java SE 6. The Android operating system has historically been a major user of Harmony, although since Android Nougat it increasingly relies on OpenJDK libraries.
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[clarification needed] the GNU, Apache and other communities. GNU developers were invited into and participated during the initial, preparatory planning.
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. 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.
One major point of incompatibility between the GNU Classpath and Apache Harmony projects was their incompatible licenses: Classpath's GNU General Public License with the linking exception versus Harmony's Apache License.
Difficulties to obtain a TCK license from Sun
On April 10, 2007, the Apache Software Foundation sent an open 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. 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.
Sun answered on a company blog that it intended to create an open source implementation of the Java platform under GPL, including the TCK, but that their current priority was to make the Java Platform accessible to the GNU/Linux community under GPL as quickly as possible.
This answer triggered some reactions, either criticizing Sun for not responding "in a sufficiently open manner" to an open letter, or rather Apache Software Foundation; some think that ASF acted unwisely to aggressively demand something they could have obtained with more diplomacy from Sun, especially considering the timescale of the opening class library.
Sun released the OpenJDK in May 2007, along with a specific license to allow to run the TCK in the OpenJDK context for any GPL implementation deriving substantially from OpenJDK. This does not cover Apache Harmony, which is not GPL-licensed. On December 9, 2010, the Apache Software Foundation resigned from the Java Community Process Executive Committee, in protest over the difficulty in obtaining a license acceptable to Apache for use with the Harmony project.
Use in Android SDK
The virtual machine that is used in Google's Android platform (Dalvik up to version 4.4, and its successor, Android Runtime (ART)) uses a subset of Harmony for the core of its Class Library. However, Dalvik does not align to Java SE nor Java ME Class Library profiles (for example J2ME classes, AWT and Swing are not supported).
End of the project
On October 11, 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. 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". On March 2011, IBM's Tim Ellison announced that he resigned as Project Management Chair for Harmony After IBM's disengagement, the project's activity level greatly declined.
On October 29, 2011, a poll was started on the harmony-dev mailing list by the project lead Tim Ellison whether to retire the project. The outcome on November 3, was 20 to 2 in favor of retirement. On November 16, 2011, the Apache Software Foundation board of directors passed a motion to terminate the project. One director, Larry Rosen, cast a "no" vote, based on the timing rather than the merits of the proposal; it was otherwise unanimous. The project was retired on November 16, 2011.
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," and it seemed that their efforts were successful.
Last development status
Apache Harmony was accepted among the official Apache projects on October 29, 2006.
The Dynamic Runtime Layer virtual machine consists of the following components:
- The VM core: with its subcomponents concentrates most of the JVM control functions.
- The porting layer: hides platform-specific details from other VM components behind a single interface and is based on the Apache Portable Runtime layer.
- The garbage collector: allocates Java objects in the heap memory and reclaims unreachable objects using various algorithms
- Execution Manager: selects the execution engine for compiling a method, handles profiles and the dynamic recompilation logic.
- Class Library: is a Java standard library.
- The thread manager that handle operating system threading
- The execution engine: consists of the following:
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.
|Windows 2000||Windows XP, Server 2003, Vista||Linux RHEL, SLES, Debian, Gentoo, Fedora||FreeBSD||AIX||Mac OS X|
|IA-32 (Pentium III or better)||No||Yes||Yes||No||N/A||N/A|
|x86-64 (Intel 64, AMD64)||N/A||Yes||Yes||N/A||N/A||N/A|
|Itanium (IA64, IPF)||N/A||No||Yes||N/A||N/A||N/A|
Class library coverage
The Harmony project currently achieve (as of February 2011) 99% completeness for JDK 5.0, and 97% for Java SE 6.
The progress of the Apache Harmony project can be tracked against J2SE 1.4 and Java SE 5.0. 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.
|ICU||Mature C/C++ and Java libraries for Unicode support and software internationalization and 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|
Harmony is currently less documented than the alternative free Java implementations. For instance, in GNU Classpath every method of the central CORBA class (ORB) has the explaining comment both in the standard abstract API class and implementation. In the Yoko project, used by Harmony, most methods both in the standard declaration and implementing class were undocumented at the end of October 2006. Also, GNU Classpath supported both older and current CORBA features (same as Sun's implementation). Harmony, differently, left the central method of the older standard (
ORB.connect(Object)) fully unimplemented.
A complete implementation of the Java platform also needs a compiler that translates Java source code into bytecodes, a program that manages JAR files, a debugger, and an applet viewer and web browser plugin, to name a few. Harmony currently has the compiler, appletviewer, jarsigner, javah, javap, keytool, policytool, and unpack200.
Virtual machine support
Harmony currently has seven virtual machine implementations that run Harmony Class Library, all of which were donations by external groups:
- JC Harmony Edition VM, "JCHEVM," based on the JCVM's interpreter, contributed by the author, Archie Cobbs.
- BootJVM, a simple bootstrapping virtual machine, contributed by Daniel Lydick.
- SableVM, an advanced, portable interpreter, contributed by authors from the Sable Research Group; and the Dynamic Runtime Layer Virtual Machine.
- DRLVM, a just-in-time compiler contributed by Intel.
- BEA announced the availability of an evaluation version of JRockit VM running Apache Harmony Class Library.
- JikesRVM, an open-source meta-circular JVM that use the Apache Harmony Class Library.
- Ja.NET SE, an open source project providing a Java 5 JDK (class libraries, tools, etc.) that run on the .NET Framework CLR. Ja.NET SE is based on the Apache Harmony Class Libraries.
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).
- Eclipse: 99.3% of the 36000 reference implementation (RI) test pass on Harmony's DRLVM + class library.
- Apache Tomcat: 100% of the RI tests pass.
- JUnit: 100% of the RI tests pass.
- Apache Ant: 97% of the RI tests pass.
- Other applications pass with a high success rate, such as Apache Derby, Apache Axis, Log4j, Apache Velocity, Apache Cocoon, jEdit, and Apache Commons.
However, Harmony's incomplete library prevented it from launching some other applications:
- ArgoUML: because it needs a Java applet implementation, which was still unavailable in Harmony.
- Apache Geronimo runs on Apache Harmony with some issues and workarounds.
- Vuze, formerly Azureus, because of unimplemented security classes.
- GNU Classpath
- List of Java virtual machines
- Free Java implementations
- Java Class Library
- "The end of (Apache) Harmony". The H. November 4, 2011.
- "Original FAQ Questions from Project Launch". harmony.apache.org. Retrieved February 27, 2011.
We are starting with Java SE 5, as that is the first version of Java SE for which the licensing allows an open source implementation, but we'll continue with Java SE 6 and any subsequent versions that follow.
- "Class Library Component Status". harmony.apache.org. Retrieved February 27, 2011.
- Amadeo, Ron (January 7, 2016). "Android N switches to OpenJDK, Google tells Oracle it is protected by the GPL". Ars Technica. Condé Nast. Retrieved July 1, 2016.
- Ellison, Tim (November 3, 2011). "Move Apache Harmony to the Attic (updated)". org.apache.harmony.dev. Archived from the original on November 3, 2011.
- Ellison, Tim (November 16, 2011). "Board accepted attic resolution". org.apache.harmony.dev. Archived from the original on November 16, 2011. Retrieved November 27, 2011.
- Mark Wielaard (May 9, 2005). "Harmony!". Archived from the original on May 16, 2008. Retrieved October 21, 2010.
Apache has set up a proposal for discussion around a full free j2se implementation. Which they call "Harmony". This is (at the moment) not about code, but about finding out a direction for getting to such a beast. Dalibor, Tom, Jeroen and I were asked to help them in that discussion and possibly show them how to set up a good architecture for it.
- Geir Magnusson Jr. (May 24, 2006). "A proposal for a free Java implementation". Apache.
- Mark Wielaard (May 24, 2006). "Toward a free Java". LWN.net.
All this means that, despite the fact that there is now some code available donated by Intel, there is no practical cooperation between the original free software projects backing Harmony and the project now known as Apache Harmony. All this made some people think of Harmony as a company consortium in the guise of an ASF project and not a full community project.
- "Open Letter to Sun Microsystems - JCK". apache.org.
- According to ASF, 1) a specification lead cannot impose any contractual condition or covenant that would limit or restrict the right of any licensee to create or distribute such Independent Implementations (section 5.C.III), and 2) a specification lead must license all necessary IP royalty-free to any compatible implementation of a specification (section 5.B).
- "On the Record". Archived from the original on April 21, 2007.
- "Sun to Apache: "Open Source Process is a Journey" - Java IoT".
- "The Silence from an Open Sun". Ian Skerrett.
- "Mark J. Wielaard".
- Gilbert, Dave (April 16, 2007). "Five Reasons Why Apache Will Regret That Open Letter". Archived from the original on April 18, 2007. Retrieved March 8, 2008.
- "OpenJDK Community TCK License Agreement V 1.1" (PDF). Sun Microsystems. Retrieved March 8, 2008.
Subject to and conditioned upon its Licensee Implementation being substantially derived from OpenJDK Code and, if such Implementation has or is to be distributed to a third party, its being distributed under the GPL License, Sun hereby grants to Licensee, to the extent of Sun's Intellectual Property Rights in the TCK, a worldwide, personal, non-exclusive, non-transferable, limited license to use the TCK internally and solely for the purpose of developing and testing Licensee Implementation.
- "The ASF Resigns From the JCP Executive Committee". Apache Software Foundation.
- "Apache quits Java governance group in protest of Oracle abuses". Ars Technica.
- "Google's Android SDK Bypasses Java ME in Favor of Java Lite and Apache Harmon". infoq.com. November 12, 2007. Retrieved May 31, 2009.
Instead of providing a full version of the Java SE or Java ME Google has diverged on two fronts. First, a limited subset of the core Java packages is provided. (...) By going this route Android is following in the footsteps of another Google project GWT which uses Java as its development language but does not support the full JDK.
- "Package Index". Open Handset Alliance. Archived from the original on June 27, 2009. Retrieved May 31, 2009.
- "Oracle and IBM Collaborate to Accelerate Java Innovation Through OpenJDK". Oracle Corporation. Archived from the original on October 14, 2010. Retrieved October 22, 2010.
- Ryan Paul. "Java wars: IBM joins OpenJDK as Oracle shuns Apache Harmony". Ars Technica. Archived from the original on October 19, 2010. Retrieved October 22, 2010.
- Bob Sutor. "IBM joins the OpenJDK community, will help unify open source Java efforts". Archived from the original on October 18, 2010. Retrieved October 22, 2010.
IBM will be shifting its development effort from the Apache Project Harmony to OpenJDK. For others who wish to do the same, we’ll work together to make the transition as easy as possible. IBM will still be vigorously involved in other Apache projects.
- Tim Ellison (March 14, 2011). "Rebooting the Harmony project". Retrieved March 20, 2011.
- "What is the Future of Apache Harmony?". infoq.com. March 14, 2011. Retrieved March 20, 2011.
- "Mailing list archives: email@example.com". apache.org. Retrieved September 11, 2011.
- "Board of Directors Meeting Minutes". Apache Software Foundation. November 16, 2011. Retrieved August 8, 2012.
Larry wishes it to be noted that he is not against termination, he simply would have preferred to have more time to work on the messaging.
- Leo Simons (July 24, 2006). "We would like all the development to happen right here". Archived from the original on September 29, 2007. Retrieved July 28, 2006.
- "The Apache Way". Archived from the original on August 21, 2006. Retrieved July 28, 2006.
- Harmony Documentation Team. "Apache Harmony - Supported Platforms". harmony.apache.org.
- "Results of comparison between JDK_5.0 and Harmony_5.0".
- http://cvs.savannah.gnu.org/viewcvs/*checkout*/classpath/org/omg/CORBA/ORB.java?rev=18.104.22.168&root=classpath[permanent dead link]
- http://cvs.savannah.gnu.org/viewcvs/*checkout*/classpath/gnu/CORBA/OrbFunctional.java?rev=1.6&root=classpath[permanent dead link]
- "Harmony uses latest Yoko jars..." September 27, 2006.
- "Apache Harmony - Project Roadmap".
- "[general] JRockit H27.2.1 for Harmony Class Library released now".
- "Announcing Jikes RVM 3.0 + Apache Harmony!".
- "Janet Dev". Janet Dev.
- "Subversion Commits". harmony.apache.org. Retrieved May 28, 2011.
- "Application_Status". apache.org. Archived from the original on August 10, 2007. Retrieved November 4, 2006.
- "Archived copy". Archived from the original on February 8, 2007. Retrieved November 4, 2006.CS1 maint: archived copy as title (link)
- "Apache_Tomcat". apache.org. Archived from the original on February 10, 2007. Retrieved November 4, 2006.
- "JUnit". apache.org.
- "Apache_Ant". apache.org. Archived from the original on February 10, 2007. Retrieved November 4, 2006.
- "Apache Harmony". apache.org.
- Official website
- Apache Harmony FAQ
- Apache Harmony source code repository
- JavaOne 2006 Online Harmony Session
- JavaOne 2007 Online Harmony Session
- Apache Harmony by Geir Magnusson Jr at JavaPolis 2006
- The Java open source debate - a good summary of the debate
- What is the Future of Apache Harmony?
- Apache Harmony loses project manager