JarCasting
Jolokia is a fresh way to access JMX MBeans remotely. It is different from JSR-160 connectors in that it is an agent-based approach which uses JSON over HTTP for its communication in a REST-stylish way.
Multiple agents are provided for different environments:
- WAR Agent for deployment as web application in a Java EE Server.
- OSGi Agent for deployment in an OSGi container. This agent is packaged as a bundle and comes in two flavors (minimal, all-in-one).
- Mule Agent for usage within a Mule ESB
- JVM JDK6 Agent which can be used with any Oracle/Sun JVM, Version 6 or later and which is able to attach to a running Java process dynamically.
Features
The agent approach as several advantages:
-
Firewall friendly
Since all communication is over HTTP, proxying through firewalls becomes mostly a none-issue (in contrast to RMI communication, which is the default mode for JSR-160)
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Polyglot
No Java installation is required on the client side. E.g. Jmx4Perl provides a rich Perl client library and Perl based tools for accessing the agents.
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Simple Setup
The Setup is done by a simple agent deployment. In contrast, exporting JMX via JSR-160 can be remarkable complicated (see these blog posts for setting up Weblogic and JBoss for native remote JMX exposure setup)
Additionally, the agents provide extra features not available with JSR-160 connectors:
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Bulk requests
In contrast to JSR-160 remoting, Jolokia can process many JMX requests with a single round trip. A single HTTP POST request puts those requests in its JSON payload which gets dispatched on the agent side. These bulk requests can increase performance drastically, especially for monitoring solutions. The Nagios plugin check_jmx4perl uses bulk requests for its multi-check feature.
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Fine grained security
In addition to standard HTTP security (SSL, HTTP-Authentication) Jolokia supports a custom policy with fine grained restrictions based on multiple properties like the client's IP address or subnet, and the MBean names, attributes, and operations. The policy is defined in an XML format with support for allow/deny sections and wildcards.
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Proxy mode
Jolokia can operate in an agentless mode where the only requirement on the target platform is the standard JSR-160 export of its MBeanServer. A proxy listens on the front side for Jolokia requests via JSON/HTTP and propagates these to the target server through remote JSR-160 JMX calls. Bulk requests get dispatched into multiple JSR-160 requests on the proxy transparently.
Resources
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The Jolokia Forum can be used for questions about Jolokia (and Jmx4perl).
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For bug reports, please use the Github Issue tracker.
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Most of the time, I'm hanging around at Freenode in
#jolokia, too.
Even more information on Jolokia can be found at www.jolokia.org, including a complete reference manual.
Contributions
Contributions in form of pull requests are highly appreciated. All your work must be donated under the Apache Public License, too. Please sign-off your work before doing a pull request. The sign-off is a simple line at the end of the patch description, which certifies that you wrote it or otherwise have the right to pass it on as an open-source patch. The rules are very simple: if you can certify the below (from developercertificate.org):
Developer Certificate of Origin
Version 1.1
Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
660 York Street, Suite 102,
San Francisco, CA 94110 USA
Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.
Developer's Certificate of Origin 1.1
By making a contribution to this project, I certify that:
(a) The contribution was created in whole or in part by me and I
have the right to submit it under the open source license
indicated in the file; or
(b) The contribution is based upon previous work that, to the best
of my knowledge, is covered under an appropriate open source
license and I have the right under that license to submit that
work with modifications, whether created in whole or in part
by me, under the same open source license (unless I am
permitted to submit under a different license), as indicated
in the file; or
(c) The contribution was provided directly to me by some other
person who certified (a), (b) or (c) and I have not modified
it.
(d) I understand and agree that this project and the contribution
are public and that a record of the contribution (including all
personal information I submit with it, including my sign-off) is
maintained indefinitely and may be redistributed consistent with
this project or the open source license(s) involved.
Then you just add a line to every git commit message:
Signed-off-by: Max Morlock <[email protected]>
Using your real name (sorry, no pseudonyms or anonymous contributions.)
If you set your user.name and user.email git configs, you can sign your commit automatically with git commit -s.
If you fix some documentation (typos, formatting, ...) you are not required to sign-off. It is possible to sign your commits in retrospective, too if you forgot it the first time.