Apache Felix Usage Documentation

+ +

Starting Felix
Felix Shell +
- Installing Bundles
- Web Proxy Issues when Installing Bundles
+
Configuring Felix +
+
Configuring Bundles
Feedback

+ + +

+ +

Starting Felix

+ +

Start Felix from the installation directory by typing:

+ +

java -jar bin/felix.jar
+

+ +

After Felix starts, the text-based shell interface is started. It is possible to change your default shell user interface. Felix stores all installed bundles into a bundle cache directory. By default, Felix creates a cache directory, called felix-cache, in your current working directory; this behavior is configurable, see the Apache Felix Bundle Cache document for more details.

+ +

If you want to start Felix using a different bundle cache directory, you can start Felix like this:

+ +

java -jar bin/felix.jar <cache-path>
+

+ +

Where <cache-path> is the path you want to use as the +bundle cache. If you specify a relative cache path, then it will be +treated as relative to the current working directory.

+ +

Useful Information
+

Previous versions of Felix prompted for a profile name when executed. The profile name was used to create a directory inside .felix/ +in the users home directory. This approach allowed user's to have +different sets of bundles for different purposes, e.g., testing, +production, etc. If this behavior is still desired, it is very easy to +mimic. Modify conf/config.properties to include "felix.cache.rootdir=${user.home}/.felix". Now, if you start Felix with something like "java -jar bin/felix.jar foo", it will use "${user.home}/.felix/foo/" +as the bundle cache directory, where "${user.home}" is automatically +substituted with the appropriate system property by the launcher.

+ +

Felix Shell

+ +

The main way to interact with Felix is via its shell service. Felix' +shell service is implemented as an OSGi service that, be default, uses +a simple text-based user interface. After starting Felix, type help into the shell to see the list of the available commands; these are the default commands:

+ +

bundlelevel <level> <id> ... | <id> - set or get bundle start level.
+cd [<base-URL>] - change or display base URL.
+headers [<id> ...] - display bundle header properties.
+help - display shell commands.
+install <URL> [<URL> ...] - install bundle(s).
+obr help - OSGi bundle repository.
+packages [<id> ...] - list exported packages.
+ps [-l | -u] - list installed bundles.
+refresh - refresh packages.
+services [-u] [-a] [<id> ...] - list registered or used services.
+shutdown - shutdown Felix.
+start <id> [<id> <URL> ...] - start bundle(s).
+startlevel [<level>] - get or set framework start level.
+stop <id> [<id> ...] - stop bundle(s).
+uninstall <id> [<id> ...] - uninstall bundle(s).
+update <id> [<URL>] - update bundle.
+version - display version of framework.
+

+ +

For a detailed description of how to install bundles into Felix refer to the next sub-section; the remainder of this section briefly describes shell behavior.

+ +

Despite the fact that the Felix shell tries to mimic a typical Unix-like shell, it is actually quite limited. The notion of cd, +for example, is only used to specify a default base URL in order to +save typing. To illustrate, assume that you want to install several +bundles from a directory on your disk, you could type:

+ +

cd file:/c:/projects/felix/bundle/
+

+ +

After issuing this cd command, you no longer need to type +the complete URL for bundles located in the above directory, only the +name of the bundle JAR file is necessary. It is not possible to perform +an equivalent ls command to list the contents of the current +base URL, since this operation is not possible with URLs. To view all +currently installed bundles, use the ps command.

+ +

To exit the Felix shell, simply type stop 0 to stop the +System Bundle; any installed bundles will automatically be reloaded the +next time you start the associated profile. Additionally, any active +bundles will be reactivated the next time you restart the framework +with the same bundle cache.

+ +

Installing Bundles

+ +

A bundle is the OSGi term for a component for the OSGi framework. A +bundle is simply a JAR file containing a manifest and some combination +of Java classes, embedded JAR files, native code, and resources. A +bundle may provide some specific functionality for the user or it may +implement a service that other bundles can use; bundles can only use +functionality from other bundles through shared services and packages.

+ +

Felix is packaged with four bundles, which are located in the bundle/ +directory of the Felix installation directory. There are bundles for +the Felix shell service, a text-based shell service user interface, a +bundle repository service, and a simple example bundle. In addition to +these bundles, the bundle repository services provides access to many +other bundles for easy installation. The bundle repository service +provides a shell command, named obr, to access available bundles; refer to the Apache Felix OSGi Bundle Repository for more information.

+ +

Before installing any bundles, it is important to understand how +bundles are manually deployed into the framework. Bundles are deployed +in two stages; first they are installed, then they are started. To +install a bundle use the install shell command followed by a bundle URL. For example, to install the simple.jar bundle included with Felix you type (assuming you have started Felix from its installation directory):

+ +

install file:bundle/simple.jar
+

+ +

Once a bundle is installed, it can then be started by using the start command and the bundle identifier of the desired bundle. The ps +shell command is used to list all installed bundles and to obtain the +bundle's identifier. The following Felix shell session capture +illustrates how to start the simple.jar bundle:

+ +

-> install [file:bundle/simple]
+-> ps
+START LEVEL 1
+   ID   State         Level  Name
+[   0] [Active     ] [    0] System Bundle (0.8.0)
+[   1] [Active     ] [    1] Shell Service (0.8.0)
+[   2] [Active     ] [    1] Shell TUI (0.8.0)
+[   3] [Active     ] [    1] Bundle Repository (0.8.0)
+[   4] [Installed  ] [    1] Simple (0.8.0)
+-> start 4
+Simple bundle 4 has started.
+From native: Hello!
+From embedded JAR: Hello!
+Entry: META-INF/
+Entry: org/
+Entry: libfoo.so
+The 'javax.servlet.http' package is not available.
+The 'javax.servlet' package is not available.
+->
+

+ +

The stop command is used to stop a bundle and the uninstall command is used to remove a bundle from the bundle cache. As an alternative to using the install and start commands explicitly, it is also possible to install and start a bundle in one step by using the start command with a bundle URL.

+ +

Bundles can be updated using the update command. The update +command allows you to specify an URL from which to retrieve the updated +bundle, but if one is not specified it will try to update the bundle +from the bundle's Bundle-UpdateLocation manifest attribute, if present, or the bundle's original location URL.

+ +

Important: When you update or uninstall a +bundle, the changes appear to take effect immediately, but in reality +the changes are only partially enacted. If a bundle is updated or +uninstalled and it was exporting packages, these packages are not +removed until the framework is refreshed using the PackageAdmin service. The Felix shell offers a convenient refresh command for this purpose.

+ +

For an introduction to writing bundles and services, refer to the Felix bundle tutorial.

+ +

Web Proxy Issues when Installing Bundles

+ +

If you use a proxy for Web access, then you may run into difficulty +using the Felix shell to install bundles from a remote URL. To remedy +this situation, certain system properties must be set to make Felix +work with your proxy. These properties are:

+ +

http.proxyHost - the name of the proxy host.
http.proxyPort - the port of the proxy host.
http.proxyAuth +- the user name and password to use when connecting to the proxy; this +string should be the user name and password separated by a colon (e.g., +rickhall:mypassword).

+ + +

These system properties can be set directly on the command line when starting the JVM using the standard "-D<prop>=<value>" syntax or you can put them in the lib/system.properties file of your Felix installation; see the next section on configuring Felix for more information.

+ +

Configuring Felix

+ +

Felix uses properties to configure certain aspects of its behavior. The Felix launcher (i.e., java -jar bin/felix.jar) reads configuration properties from two different locations in the installation directory: conf/system.properties and conf/config.properties. Both files use standard Java property file syntax.

+ +

The conf/system.properties file provides a convenient +mechanism for defining Java system properties, but it is largely +ignored by Felix, since Felix does not typically use system properties +for configuration purposes. Any properties placed in the conf/system.properties file are available at run time via System.getProperty() and BundleContext.getProperty(). It is also possible to specify a different location for the system properties file by using the felix.system.properties system property when executing Felix. For example:

+ +

java -Dfelix.system.properties=file:/home/rickhall/system.properties -jar bin/felix.jar
+

+ +

Nearly all Felix configuration occurs using properties in the conf/config.properties file. It is possible to change the location of the configuration properties file by specifying a new location value using the felix.config.properties +system property. It is necessary to use a system property here since +Felix needs this value to start execution. As an example, the following +command could be used to specify a custom location for the +configuration properties file:

+ +

java -Dfelix.config.properties=file:/home/rickhall/config.properties -jar bin/felix.jar
+

+ +

In this example the configuration properties will be read from the +specified URL. All remaining configuration properties should be defined +in the config.properties file itself. All configuration properties are accessible at run time via BundleContext.getProperty().

+ +

Some configuration properties are handled by Felix' launcher, while +others are handled by the Felix framework itself. Regardless, both +launcher and framework configuration properties are placed in the conf/config.properties files.

+ +

The following are launcher configuration properties:

+ +

felix.auto.install.<n> - Space-delimited list of bundle URLs to automatically install when Felix is started, where <n> is the start level into which the bundle will be installed (e.g., felix.auto.install.2).
felix.auto.start.<n> - Space-delimited list of bundle URLs to automatically install and start when Felix is started, where <n> is the start level into which the bundle will be installed (e.g., felix.auto.start.2).

+ + +

The following are framework configuration properties (properties starting with "felix" are specific to Felix, while those starting with "org.osgi" are standard OSGi properties):

+ +

org.osgi.framework.storage - Sets the directory to use as the bundle cache; by default bundle cache directory is felix-cache +in the current working directory. The value should be a valid directory +name. The directory name can be either absolute or relative. Relative +directory names are relative to the current working directory. The +specified directory will be created if it does not exist.
org.osgi.framework.storage.clean - Determines whether the bundle cache is flushed. The value can either be "none" or "onFirstInit", where "none" does not flush the bundle cache and "onFirstInit" flushes the bundle cache when the framework instance is first initialized. The default value is "none".
felix.cache.rootdir - Sets the root directory to use to calculate the bundle cache directory for relative directory names. If org.osgi.framework.storage +is set to a relative name, by default it is relative to the current +working directory. If this property is set, then it will be calculated +as being relative to the specified root directory.
felix.cache.bufsize +- Sets the buffer size to be used by the cache; the default value is +4096. The integer value of this string provides control over the size +of the internal buffer of the disk cache for performance reasons.
org.osgi.framework.system.packages +- Specifies a comma-delimited list of packages that should be exported +via the System Bundle from the parent class loader. The framework will +set this to a reasonable default. If the value is specified, it +replaces any default value.
org.osgi.framework.system.packages.extra +- Specifies a comma-delimited list of packages that should be exported +via the System Bundle from the parent class loader in addition to the +packages in org.osgi.framework.system.packages. The default value is empty. If a value is specified, it is appended to the list of default or specified packages in org.osgi.framework.system.packages.
org.osgi.framework.bootdelegation +- Specifies a comma-delimited list of packages that should be made +implicitly available to all bundles from the parent class loader. It is +recommended not to use this property since it breaks modularity. The +default value is empty.
felix.systembundle.activators - A List of BundleActivator +instances that are started/stopped when the System Bundle is +started/stopped. The specified instances will receive the System +Bundle's BundleContext when invoked. (This property cannot be +set in the configuration file since it requires instances; it can only +be passed into Felix' constructor directly.)
felix.log.logger - An instance of Logger +that the framework uses as its default logger. (This property cannot be +set in the configuration file since it requires an instance; it can +only be passed into Felix' constructor directly.)
felix.log.level +- An integer value indicating the degree of logging reported by the +framework; the higher the value the more logging is reported. If zero +('0') is specified, then logging is turned off completely. The log +levels match those specified in the OSGi Log Service (i.e., 1 = error, +2 = warning, 3 = information, and 4 = debug). The default value is 1.
org.osgi.framework.startlevel - The initial start level of the framework once it starts execution; the default value is 1.
felix.startlevel.bundle - The default start level for newly installed bundles; the default value is 1.
felix.service.urlhandlers - Flag to indicate whether to activate the URL Handlers service for the framework instance; the default value is "true". Activating the URL Handlers service will result in the URL.setURLStreamHandlerFactory() and URLConnection.setContentHandlerFactory() being called.
felix.fragment.validation - Determines if installing unsupported fragment bundles throws an exception or logs a warning. Possible values are "exception" or "warning". The default value is "exception".

+ + +

The Felix installation contains a default conf/config.properties file for automatically starting the shell-related bundles.

+ +

Migrating from Earlier Versions

+ +

The release of Felix 1.4.0 introduced some configuration property changes. This section describes the differences from older versions of Felix.

+ +

Removed +
- felix.embedded.execution - No longer needed, since the framework now never calls System.exit(); the creator of the framework is now always responsible for exiting the VM.
- felix.strict.osgi - No longer needed, since all non-specification features have been removed.
- felix.cache.dir - No longer needed, since Felix no longer uses bundle cache profiles for saving sets of bundles.
- felix.cache.profile - No longer needed, since Felix no longer uses bundle cache profiles for saving sets of bundles.
+
Renamed +
- felix.cache.profiledir - The equivalent of this property is now named org.osgi.framework.storage.
- felix.startlevel.framework - The equivalent of this property is now named org.osgi.framework.startlevel.
+
Introduced +
- org.osgi.framework.system.packages.extra - New property, as described above, added to align with standard framework API.
- org.osgi.framework.storage.clean - New property, as described above, added to align with standard framework API.
- felix.cache.rootdir - Introduced as a result of removing bundle profiles to help resolve relative bundle cache directories.
- felix.fragment.validation - Introduced to control fragment validation, since the default behavior introduced in 1.2.0 of throwing an exception for fragments using unsupported features was causing issues for some users.
+

+ + +

For the most part, these changes are minor and previous behavior +achieved from older configuration properties is either easily attained +with the new properties or no longer necessary.

+ +

System Property Substituion

It is possible to use system properties to specify the values of properties in the conf/config.properties file. This is achieved through system property substitution, which is instigated by using ${<property>} syntax, where <property> +is the name of a system property to substitute. When such a property +value is retrieved by a bundle, the system property value will be +substituted into the bundle property value as appropriate. It is +possible to have nested system property substitution, in which case the +inner-most property is substituted first, then the next inner most, +until reaching the outer most.

+ +

Changing the Command Shell User Interface

+ +

Felix' shell service supports multiple user interface +implementations; the default shell user interface is text-based, but a +simple graphical shell is also available. To change the default shell +user interface, you must download the Shell GUI and Shell GUI Plugin +bundles. Then you must modify the felix.auto.start property in the conf/config.properties file of your Felix installation. For the text-based user interface, the property value should look like this:

+ +

felix.auto.start.1=file:bundle/shell.jar file:bundle/shelltui.jar \
+ file:bundle/bundlerepository.jar
+

+ +

This property value instructs Felix to automatically start the shell +service, the shell textual user interface, and the bundle repository. (Note: +The "\" character at the end of the above line indicates that the +property value continues on the next line; it is also possible to +specify the property value on one line.) For the GUI-based shell user interface, the property value should look something like this:

+ +

felix.auto.start.1=file:bundle/shell.jar file:bundle/bundlerepository.jar \
+ file:bundle/shellgui.jar file:bundle/shellplugin.jar
+

+ +

This property value instructs Felix to automatically start the shell +service, the bundle repository, the shell GUI, and the shell GUI +plugins.

+ +

Configuring Bundles

+ +

Some bundles use properties to configure certain aspects of their behavior. As an example, the default URL for the cd command of the shell service can be specified using the property felix.shell.baseurl. +It is a good idea, when implementing bundles, to parameterize them with +properties where appropriate. To learn about the configuration options +for specific bundles, refer to the documentation that accompanies them.

+ +

Bundle properties are also defined in the conf/config.properties property file. Any property placed in this file will be accessible via BundleContext.getProperty() +at run time. The property file uses the standard Java property file +syntax (i.e., attribute-value pairs). For information on changing the +default location of this file, refer to the section on configuring Felix.

+ +

Feedback

+ +

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