The Java Application Isolation API

JSR-121 Interest Site

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Note from 2022:
This web page was created by me, Pete Soper in early 2001 as the JSR-121 expert group was forming and starting work. After the architecture was delivered and the reference implementation became the critical path and I stopped being involved I decided to leave this site up. The rest of the expert group and I (from memory Doug Lea, Miles Sabin, Pat Tullman, Greg Czajkowski, Norbert Kuck and others [you know who you are!]) worked very hard for a long time crafting Isolate and Link to play nicely with three radically different implementation styles. I hope our work is still appreciated.

This web page contains extra resources related to the JSR-121 effort and is intended to support general interest and informal activities and communication.[1]


Ciaran Bryce has written "Isolates: A New Approach to Multi-Programming in Java Platforms", providing a nice overview of isolation and related topics.[2] This article is the best starting point for newcomers.


JSR-121 version 1 is final and the expert group is being led by Krzysztof Palacz. The specification can be downloaded from here and additional details are available from the email interest list described below.

The long awaited resource management API to go along with isolates is now in preparation as JSR-284. More details are available here. Additional questions should probably be directed to the isolate interest email list described below until something is set up for this JSR. (Update: Doug apparently needed the disc space or something and the email list is no more but I'm leaving the link in place in case he can restore it.)



There is an email list open to anyone and this list is archived.


Here is a bibliography of references related to JSR-121.


JSR-121 has involved a lot of work by a lot of people.  There are lists at the end of the JSR-121 presentation slides in the bibliography and another in the public review draft HTML.

[1]Current expert group membership and formal JSR-121 process details can be found on the Java Community Process web page.
[2]This article is a copy of the original article posted at OT Land, with permission of LogOn Technology Transfer. The series of original articles available at OT Land, can be downloaded at no cost at:

last update September 20, 2022