ChorusOS

{{Short description|Microkernel real-time operating system}}

{{More citations needed|date=November 2012}}

{{Use dmy dates|date=October 2021}}

{{Infobox OS

| name = ChorusOS

| logo =

| screenshot =

| caption =

| developer = Chorus Systèmes
Sun Microsystems

| kernel type = Microkernel real-time operating system

| ui =

| family = POSIX

| working state = Discontinued

| source model = Closed-source (pre-v5)
Open source (v5)

| released = {{Start date and age|1979}}

| discontinued =

| latest release version = 5.1

| latest release date = {{Start date and age|2011}}

| marketing target = Embedded systems

| programmed in =

| language = English

| update model =

| package manager =

| supported platforms = x86, 680x0, PowerPC, SPARC, ARM, MIPS

| license =

| preceded by =

| succeeded by = VirtualLogix C5

}}

ChorusOS is a microkernel real-time operating system designed as a message passing computing model. ChorusOS began as the Chorus distributed real-time operating system research project at the French Institute for Research in Computer Science and Automation (INRIA) in 1979.{{cite book |last1=Coulouris |first1=George |last2=Dollimore |first2=Jean |last3=Kindberg |first3=Tim |year=1994 |title=Distributed systems: concepts and design |publisher=Addison-Wesley |isbn=978-0-201-62433-5 |pages=[https://archive.org/details/distributedsyste00coul/page/566 566–79] |url=https://archive.org/details/distributedsyste00coul/page/566 |access-date=2 December 2012 }} During the 1980s, Chorus was one of two earliest microkernels (the other being Mach) and was developed commercially by startup company Chorus Systèmes SA.{{cite book |last=Doeppner |first=Thomas W. |date=20 December 2010 |title=Operating Systems In Depth: Design and Programming |publisher=John Wiley & Sons |isbn=978-0-471-68723-8 |page=36,145 |url=https://books.google.com/books?id=xX5tfrAQQ8cC |access-date=29 November 2012}} Over time, development effort shifted away from distribution aspects to real-time for embedded systems.{{cite conference |last=Gien |first=Michel |year=1995 |title=Evolution of the CHORUS Open Microkernel Architecture: The STREAM Project |conference=FTDCS '95 Proceedings of the 5th IEEE Workshop on Future Trends of Distributed Computing Systems |publisher=IEEE Computer Society |page=10 |url=http://dl.acm.org/citation.cfm?id=875713 |access-date=2 December 2012}}

In 1997, Sun Microsystems acquired Chorus Systèmes for its microkernel technology, which went toward the new JavaOS.{{cite book |last1=Saulpaugh |first1=Tom |last2=Mirho |first2=Charles |date=January 1999 |title=Inside the JavaOS Operating System |series=Java series |publisher=Addison-Wesley |isbn=0-201-18393-5 |oclc=924842439 |page=XIII |url=https://archive.org/details/insidejavaosoper00saul }} Sun (and henceforth Oracle) no longer supports ChorusOS. The founders of Chorus Systèmes started a new company called Jaluna in August 2002. Jaluna then became VirtualLogix, which was then acquired by Red Bend in September 2010. VirtualLogix designed embedded systems using Linux and ChorusOS (which they named VirtualLogix C5). C5 was described by them as a carrier grade operating system, and was actively maintained by them.

The latest source tree of ChorusOS, an evolution of version 5.0, was released as open-source software by Sun and is available at the Sun Download Center.{{Cite web |url=https://cds.sun.com/is-bin/INTERSHOP.enfinity/WFS/CDS-CDS_SMI-Site/en_US/-/USD/ViewProductDetail-Start?ProductRef=ES-ChorusOS-5.0-G-F@CDS-CDS_SMI |title=Sun Download Center |website=Oracle |archive-url=https://archive.today/20111006194155/https://cds.sun.com/is-bin/INTERSHOP.enfinity/WFS/CDS-CDS_SMI-Site/en_US/-/USD/ViewProductDetail-Start?ProductRef=ES-ChorusOS-5.0-G-F@CDS-CDS_SMI |archive-date=6 October 2011 |url-status=dead}} The Jaluna project has completed these sources and published it online. Jaluna-1 is described there as a real-time Portable Operating System Interface (RT-POSIX) layer based on FreeBSD 4.1, and the CDE cross-platform software development environment. ChorusOS is supported by popular Secure Socket Layer and Transport Layer Security (SSL/TLS) libraries such as wolfSSL.