org.apache.felix.main
Class Main

java.lang.Object
  extended by org.apache.felix.main.Main

public class Main
extends Object

This class is the default way to instantiate and execute the framework. It is not intended to be the only way to instantiate and execute the framework; rather, it is one example of how to do so. When embedding the framework in a host application, this class can serve as a simple guide of how to do so. It may even be worthwhile to reuse some of its property handling capabilities.


Field Summary
static String CONFIG_DIRECTORY
          Name of the configuration directory.
static String CONFIG_PROPERTIES_FILE_VALUE
          The default name used for the configuration properties file.
static String CONFIG_PROPERTIES_PROP
          The property name used to specify an URL to the configuration property file to be used for the created the framework instance.
static String SYSTEM_PROPERTIES_FILE_VALUE
          The default name used for the system properties file.
static String SYSTEM_PROPERTIES_PROP
          The property name used to specify an URL to the system property file.
 
Constructor Summary
Main()
           
 
Method Summary
static void copySystemProperties(Properties configProps)
           
static Properties loadConfigProperties()
           Loads the configuration properties in the configuration property file associated with the framework installation; these properties are accessible to the framework and to bundles and are intended for configuration purposes.
static void loadSystemProperties()
           Loads the properties in the system property file associated with the framework installation into System.setProperty().
static void main(String[] args)
           This method performs the main task of constructing an framework instance and starting its execution.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

SYSTEM_PROPERTIES_PROP

public static final String SYSTEM_PROPERTIES_PROP
The property name used to specify an URL to the system property file.

See Also:
Constant Field Values

SYSTEM_PROPERTIES_FILE_VALUE

public static final String SYSTEM_PROPERTIES_FILE_VALUE
The default name used for the system properties file.

See Also:
Constant Field Values

CONFIG_PROPERTIES_PROP

public static final String CONFIG_PROPERTIES_PROP
The property name used to specify an URL to the configuration property file to be used for the created the framework instance.

See Also:
Constant Field Values

CONFIG_PROPERTIES_FILE_VALUE

public static final String CONFIG_PROPERTIES_FILE_VALUE
The default name used for the configuration properties file.

See Also:
Constant Field Values

CONFIG_DIRECTORY

public static final String CONFIG_DIRECTORY
Name of the configuration directory.

See Also:
Constant Field Values
Constructor Detail

Main

public Main()
Method Detail

main

public static void main(String[] args)
                 throws Exception

This method performs the main task of constructing an framework instance and starting its execution. The following functions are performed when invoked:

  1. Read the system properties file. This is a file containing properties to be pushed into System.setProperty() before starting the framework. This mechanism is mainly shorthand for people starting the framework from the command line to avoid having to specify a bunch of -D system property definitions. The only properties defined in this file that will impact the framework's behavior are the those concerning setting HTTP proxies, such as http.proxyHost, http.proxyPort, and http.proxyAuth. Generally speaking, the framework does not use system properties at all.
  2. Perform system property variable substitution on system properties. Any system properties in the system property file whose value adheres to ${<system-prop-name>} syntax will have their value substituted with the appropriate system property value.
  3. Read the framework's configuration property file. This is a file containing properties used to configure the framework instance and to pass configuration information into bundles installed into the framework instance. The configuration property file is called config.properties by default and is located in the conf/ directory of the Felix installation directory, which is the parent directory of the directory containing the felix.jar file. It is possible to use a different location for the property file by specifying the desired URL using the felix.config.properties system property; this should be set using the -D syntax when executing the JVM. If the config.properties file cannot be found, then default values are used for all configuration properties. Refer to the Felix constructor documentation for more information on framework configuration properties.
  4. Perform system property variable substitution on configuration properties. Any configuration properties whose value adheres to ${<system-prop-name>} syntax will have their value substituted with the appropriate system property value.
  5. Copy configuration properties specified as system properties into the set of configuration properties. Even though the Felix framework does not consult system properties for configuration information, sometimes it is convenient to specify them on the command line when launching Felix. To make this possible, the Felix launcher copies any configuration properties specified as system properties into the set of configuration properties passed into Felix.
  6. Creates and starts a framework instance. The configuration properties are passed into the Felix constructor and the {{Felix.start()}} method is called to start the framework.

It should be noted that simply starting an instance of the framework is not enough to create an interactive session with it. It is necessary to install and start bundles that provide a some means to interact with the framework; this is generally done by specifying an "auto-start" property in the configuration property file. If no bundles providing a means to interact with the framework are installed or if the configuration property file cannot be found, the framework will appear to be hung or deadlocked. This is not the case, it is executing correctly, there is just no way to interact with it. The default launcher provides two configuration properties to help you automatically install and/or start bundles, which are:

  • felix.auto.install.<n> - Space-delimited list of bundle URLs to automatically install into start level n when the framework is started. Append a specific start level to this property name to assign the bundles' start level (e.g., felix.auto.install.2); otherwise, bundles are installed into the default bundle start level.
  • felix.auto.start.<n> - Space-delimited list of bundle URLs to automatically install and start into start level n when the framework is started. Append a specific start level to this property name to assign the bundles' start level(e.g., felix.auto.start.2); otherwise, bundles are installed into the default bundle start level.

These properties should be specified in the config.properties so that they can be processed by the launcher during the framework startup process.

Parameters:
argv - Accepts a single argument, which is the path to use as the framework's bundle cache.
Throws:
Exception - If an error occurs.

loadSystemProperties

public static void loadSystemProperties()

Loads the properties in the system property file associated with the framework installation into System.setProperty(). These properties are not directly used by the framework in anyway. By default, the system property file is located in the conf/ directory of the Felix installation directory and is called "system.properties". The installation directory of Felix is assumed to be the parent directory of the felix.jar file as found on the system class path property. The precise file from which to load system properties can be set by initializing the "felix.system.properties" system property to an arbitrary URL.


loadConfigProperties

public static Properties loadConfigProperties()

Loads the configuration properties in the configuration property file associated with the framework installation; these properties are accessible to the framework and to bundles and are intended for configuration purposes. By default, the configuration property file is located in the conf/ directory of the Felix installation directory and is called "config.properties". The installation directory of Felix is assumed to be the parent directory of the felix.jar file as found on the system class path property. The precise file from which to load configuration properties can be set by initializing the "felix.config.properties" system property to an arbitrary URL.

Returns:
A Properties instance or null if there was an error.

copySystemProperties

public static void copySystemProperties(Properties configProps)


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