Grails OSGi plugin

About

The Grails OSGi plugin adds support to package and run a Grails application as an OSGi bundle. The bundle(s) may be run in an ad hoc assembled OSGi container or deployed to an external OSGi app server such as SpringSource DM Server, Eclipse Virgo, or Apache Karaf.

See also Grails on OSGi for details on running Grails applications in an OSGi environment.

License

The OSGi plugin is released under the Apache License 2.0.

Installation

Simply call grails install-plugin osgi to install the OSGi plugin.

In Config.groovy, the java.util.logging Bridge must be disabled:

grails.logging.jul.usebridge = false

Usage

Creating an OSGi bundle from the Grails application

grails bundle
grails prod bundle

Running the bundle

grails run-bundle
grails prod run-bundle

The application can be accessed at http://localhost:8080/myapp-0.1/.

Note: at first start the OSGi runtime is assembled, which may take some time, while Ivy is downloading the Internet…

Note: if the bundle exists, it won’t be re-created automatically after changes. So for now use parameter -forceBundle after changing something in the Grails app: grails run-bundle -forceBundle

Accessing the bundle context

The bundle context is the primary interface to the OSGi framework. It can be used to find and register services and interact the environment.

The bundle context is available from Grails’ parent ApplicationContext as bean bundleContext. It can be injected into all Spring-managed beans, i.e. all Grails artifacts, like Controllers, Services, etc.

In order to get a reference to the BundleContext, an artifact needs to define a reference with the name bundleContext.

Example: controller accessing bundle context

class OsgiTestController {
    def bundleContext
    def index = {
        def bundles = []
        if (bundleContext) {
            bundles = bundleContext.bundles
        }
        else {
            flash.message = "bundleContext NOT available"
        }
        [ bundles: bundles ]
    }
}

Deployment

Automatic deployment is not yet implemented. In order to deploy the OSGi-fied Grails application, the generated bundle (i.e. the war file target/myapp-version.war) and all required bundles need to installed in your OSGi application server. A list of required bundles with download URLs can be generated with grails list-bundles. OSGi application servers, such as SpringSource dmServer, Apache Karaf, or Eclipse Virgo, usually offer a pickup directory, which can be used to hot deploy bundles. Simply drop the war file and all dependencies (if not installed otherwise) into this directory and you are good to go.

Later versions of the OSGi plugin will automate this process.

Roadmap

• make bundle generation configurable (e.g. include/exclude dependencies, …)
• make OSGi runtime created by grails run-bundle and grails assemble-osgi-runtime configurable
• support auto-reloading of changed artifacts
• create sub class of GrailsApplicationContext, which implements ConfigurableOsgiBundleApplicationContext
• export main Grails beans and application context as OSGi service
• export services as OSGi service (via static expose = 'osgi')
• implement deployment to SpringSource DM Server or its successor Eclipse Virgo
• implement deployment to Apache Karaf
• Spring DM has been donated to Eclipse, so it should be replaced by its successor Eclipse Gemini

History

0.2 (2010-07-11)

• using Spring DM instead of Pax Web as Web extender
• updated Apache Felix WebConsole
• replaced (most) dependencies from bundle by OSGi bundles from the SpringSource Enterprise Repository
• provide access to OSGi BundleContext to artifacts (controllers, services, …) via Spring injection as bean bundleContext:

0.1 (2010-01-03)

• initial version
• uses PAX Runner to run osgi-fied Grails app
• Grails app is war’ed and extended with required OSGi bundle headers to create a single, big, monolithic bundle

How it works

In order to be a valid OSGi bundle, the application is war’ed and provided with the necessary bundle manifest headers (see scripts/_Events.groovy for details).
The bundle can be created using grails bundle.

The OSGi runtime is assembled in the target/osgi directory and uses the Eclipse Equinox OSGi framework, Spring DM.

In the current version, most libraries from WEB-INF/lib are replaced by equivalent OSGi bundles from the SpringSource Enterprise Bundle Repository (EBR). Only Hibernate and Grails libs retain in the bundle.

Grails jars already are OSGi bundles, but they cannot currently be installed cleanly in a OSGi container, as they contain circular dependencies and some other dependencies can not be satisfied (e.g. the Radeox library used by the Grails Wiki is no longer maintained, but it shouldn’t be referenced from the Grails runtime anyway…).

There are bundles for Hibernate but due to a bug (possibly in Equinox), Hibernate Cache can not be resolved by the Spring ORM module (see SPR-7003 for a description of this problem).

The parent ApplicationContext has been replaced in web.xml by an OSGi-aware variant: OsgiBundleXmlWebApplicationContext. It knows how to export and import OSGi services as/from Spring beans through Spring XML files. These features are currently hidden, but they will be exposed in the next version of the OSGi plugin and made easier through the BeanBuilder DSL and the OSGi namespace.

Getting around the OSGi runtime

Web Console

The Felix Web Management Console provides excellent insight into the inner workings. It can be accessed at http://localhost:8081/system/console/ with user “admin” and password “admin” (Note: the web console runs on a different port!).

Shell Console

The command grails run-bundle drops the user in the Equinox Shell (press RETURN if you don’t see the osgi> prompt). Running grails run-bundle -remoteConsole [<port>] opens a console with telnet access on the specified port or on port 8023, if omitted. Only a single user can use the console at any time.

Typing help shows the available commands:

osgi> help
---Controlling the OSGi framework---
	launch - start the OSGi Framework
	shutdown - shutdown the OSGi Framework
	close - shutdown and exit
	exit - exit immediately (System.exit)
	init - uninstall all bundles
	setprop <key>=<value> - set the OSGi property
---Controlling Bundles---
	install - install and optionally start bundle from the given URL
	uninstall - uninstall the specified bundle(s)
	start - start the specified bundle(s)
	stop - stop the specified bundle(s)
	refresh - refresh the packages of the specified bundles
	update - update the specified bundle(s)
---Displaying Status---
	status [-s [<comma separated list of bundle states>]  [<segment of bsn>]] - display installed bundles and registered services
	ss [-s [<comma separated list of bundle states>]  [<segment of bsn>]] - display installed bundles (short status)
	services [filter] - display registered service details
	packages [<pkgname>|<id>|<location>] - display imported/exported package details
	bundles [-s [<comma separated list of bundle states>]  [<segment of bsn>]] - display details for all installed bundles
	bundle (<id>|<location>) - display details for the specified bundle(s)
	headers (<id>|<location>) - print bundle headers
	log (<id>|<location>) - display log entries
---Extras---
	exec <command> - execute a command in a separate process and wait
	fork <command> - execute a command in a separate process
	gc - perform a garbage collection
	getprop  [ name ] - displays the system properties with the given name, or all of them.
---Controlling Start Level---
	sl [<id>|<location>] - display the start level for the specified bundle, or for the framework if no bundle specified
	setfwsl <start level> - set the framework start level
	setbsl <start level> (<id>|<location>) - set the start level for the bundle(s)
	setibsl <start level> - set the initial bundle start level
---Controlling the Profiling---
	profilelog - Display & flush the profile log messages
---Eclipse Runtime commands---
	diag - Displays unsatisfied constraints for the specified bundle(s).
	enableBundle - enable the specified bundle(s)
	disableBundle - disable the specified bundle(s)
	disabledBundles - list disabled bundles in the system
---Controlling the Console---
	more - More prompt for console output

The command ss (for short status) shows all bundles with their respective state:

osgi> ss

Framework is launched.

id State Bundle
0 ACTIVE org.eclipse.osgi_3.6.0.v20100517
1 ACTIVE org.eclipse.osgi.util_3.2.100.v20100503
2 ACTIVE org.eclipse.osgi.services_3.2.100.v20100503
3 ACTIVE org.eclipse.equinox.common_3.6.0.v20100503
4 ACTIVE org.apache.felix.configadmin_1.2.4
5 ACTIVE org.apache.felix.fileinstall_2.0.8
6 ACTIVE com.springsource.org.apache.log4j_1.2.15
7 ACTIVE org.ops4j.pax.logging.pax-logging-api_1.4.0
8 ACTIVE org.ops4j.pax.logging.pax-logging-service_1.4.0
9 ACTIVE com.springsource.javax.annotation_1.0.0
10 ACTIVE com.springsource.javax.el_1.0.0
11 ACTIVE com.springsource.javax.ejb_3.0.0
12 ACTIVE com.springsource.javax.mail_1.4.1
13 ACTIVE com.springsource.javax.persistence_1.99.0
14 ACTIVE com.springsource.javax.transaction_1.1.0
15 ACTIVE com.springsource.javax.servlet_2.5.0
16 ACTIVE com.springsource.javax.servlet.jsp_2.1.0
17 ACTIVE com.springsource.javax.servlet.jsp.jstl_1.2.0
18 ACTIVE com.springsource.javax.jms_1.1.0
19 ACTIVE com.springsource.javax.xml.rpc_1.1.0
20 ACTIVE com.springsource.org.mortbay.jetty.server_6.1.9
21 ACTIVE com.springsource.org.mortbay.util_6.1.9
22 ACTIVE org.springframework.osgi.jetty.start.osgi_1.0.0
23 RESOLVED org.springframework.osgi.jetty.web.extender.fragment.osgi_1.0.1
Master=85
24 ACTIVE org.apache.felix.http.jetty_2.0.4
25 ACTIVE com.springsource.org.apache.commons.beanutils_1.8.0
26 ACTIVE com.springsource.org.apache.commons.collections_3.2.1
27 ACTIVE com.springsource.org.apache.commons.codec_1.3.0
28 ACTIVE com.springsource.org.apache.commons.dbcp_1.2.2.osgi
29 ACTIVE com.springsource.org.apache.commons.el_1.0.0
30 ACTIVE com.springsource.org.apache.commons.digester_1.8.1
31 ACTIVE com.springsource.org.apache.commons.fileupload_1.2.1
32 ACTIVE com.springsource.org.apache.commons.httpclient_3.1.0
33 ACTIVE com.springsource.org.apache.commons.io_1.4.0
34 ACTIVE com.springsource.org.apache.commons.lang_2.4.0
35 ACTIVE com.springsource.org.apache.commons.pool_1.5.3
36 ACTIVE com.springsource.org.apache.commons.validator_1.3.1
37 ACTIVE com.springsource.org.apache.oro_2.0.8
38 ACTIVE com.springsource.org.apache.ivy_2.1.0
39 ACTIVE com.springsource.org.apache.tools.ant_1.7.1
40 ACTIVE com.springsource.antlr_2.7.7
41 ACTIVE com.springsource.org.dom4j_1.6.1
42 ACTIVE com.springsource.org.aspectj.runtime_1.6.8.RELEASE
43 ACTIVE com.springsource.org.aspectj.weaver_1.6.8.RELEASE
44 ACTIVE com.springsource.com.opensymphony.sitemesh_2.4.1
45 ACTIVE com.springsource.javassist_3.9.0.GA
46 ACTIVE com.springsource.org.objectweb.asm_1.5.3
47 ACTIVE com.springsource.org.jboss.cache_3.2.0.GA
48 ACTIVE com.springsource.org.jboss.util_2.2.13.GA
49 ACTIVE com.springsource.org.jboss.logging_2.0.5.GA
50 ACTIVE com.springsource.org.jgroups_2.5.1
51 ACTIVE com.springsource.net.sf.ehcache_1.6.2
52 ACTIVE com.springsource.org.hibernate.annotations.common_3.3.0.ga
53 RESOLVED com.springsource.org.hibernate.annotations_3.4.0.GA
Master=54
54 ACTIVE com.springsource.org.hibernate_3.3.2.GA
Fragments=53
55 ACTIVE com.springsource.org.xmlpull_1.1.4.c
56 RESOLVED com.springsource.org.apache.xerces_2.9.1
Master=60
57 ACTIVE com.springsource.org.apache.xalan_2.7.1
58 ACTIVE com.springsource.org.apache.xml.serializer_2.7.1
59 ACTIVE com.springsource.org.apache.xml.resolver_1.2.0
60 ACTIVE com.springsource.org.apache.xmlcommons_1.3.4
Fragments=56
61 ACTIVE com.springsource.org.apache.xml.security_1.4.2
62 ACTIVE org.springframework.aop_3.0.3.RELEASE
63 ACTIVE org.springframework.asm_3.0.3.RELEASE
64 ACTIVE org.springframework.aspects_3.0.3.RELEASE
65 ACTIVE org.springframework.beans_3.0.3.RELEASE
66 ACTIVE org.springframework.context_3.0.3.RELEASE
67 ACTIVE org.springframework.context.support_3.0.3.RELEASE
68 ACTIVE org.springframework.core_3.0.3.RELEASE
69 ACTIVE org.springframework.expression_3.0.3.RELEASE
70 ACTIVE org.springframework.instrument_3.0.3.RELEASE
71 ACTIVE org.springframework.jdbc_3.0.3.RELEASE
72 ACTIVE org.springframework.jms_3.0.3.RELEASE
73 ACTIVE org.springframework.orm_3.0.3.RELEASE
74 ACTIVE org.springframework.oxm_3.0.3.RELEASE
75 ACTIVE org.springframework.transaction_3.0.3.RELEASE
76 ACTIVE org.springframework.web_3.0.3.RELEASE
77 ACTIVE org.springframework.web.servlet_3.0.3.RELEASE
78 ACTIVE com.springsource.org.aopalliance_1.0.0
79 ACTIVE com.springsource.net.sf.cglib_2.2.0
80 ACTIVE org.springframework.osgi.core_2.0.0.M1
81 ACTIVE org.springframework.osgi.extender_2.0.0.M1
82 ACTIVE org.springframework.osgi.io_2.0.0.M1
83 INSTALLED org.springframework.osgi.test_2.0.0.M1
84 ACTIVE org.springframework.osgi.web_2.0.0.M1
85 ACTIVE org.springframework.osgi.web.extender_2.0.0.M1
Fragments=23
86 INSTALLED org.grails.osgi_1.3.2
87 INSTALLED org.grails.crud_1.3.2
88 INSTALLED org.grails.gorm_1.3.2
89 INSTALLED org.grails.resources_1.3.2
90 INSTALLED org.grails.spring_1.3.2
91 INSTALLED org.grails.web_1.3.2
92 ACTIVE gant_1.9.1
93 ACTIVE groovy-all_1.7.3
94 ACTIVE gant_1.9.2
95 ACTIVE org.apache.felix.webconsole_2.0.2
96 ACTIVE tripper_0.1.0
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