org.osgi.service.cm

Interface ConfigurationAdmin

@ProviderType
public interface ConfigurationAdmin

Service for administering configuration data.

The main purpose of this interface is to store bundle configuration data persistently. This information is represented in Configuration objects. The actual configuration data is a Dictionary of properties inside a Configuration object.

There are two principally different ways to manage configurations. First there is the concept of a Managed Service, where configuration data is uniquely associated with an object registered with the service registry.

Next, there is the concept of a factory where the Configuration Admin service will maintain 0 or more Configuration objects for a Managed Service Factory that is registered with the Framework.

The first concept is intended for configuration data about "things/services" whose existence is defined externally, e.g. a specific printer. Factories are intended for "things/services" that can be created any number of times, e.g. a configuration for a DHCP server for different networks.

Bundles that require configuration should register a Managed Service or a Managed Service Factory in the service registry. A registration property named service.pid (persistent identifier or PID) must be used to identify this Managed Service or Managed Service Factory to the Configuration Admin service.

When the ConfigurationAdmin detects the registration of a Managed Service, it checks its persistent storage for a configuration object whose service.pid property matches the PID service property ( service.pid) of the Managed Service. If found, it calls ManagedService.updated(Dictionary) method with the new properties. The implementation of a Configuration Admin service must run these call-backs asynchronously to allow proper synchronization.

When the Configuration Admin service detects a Managed Service Factory registration, it checks its storage for configuration objects whose service.factoryPid property matches the PID service property of the Managed Service Factory. For each such Configuration objects, it calls the ManagedServiceFactory.updated method asynchronously with the new properties. The calls to the updated method of a ManagedServiceFactory must be executed sequentially and not overlap in time.

In general, bundles having permission to use the Configuration Admin service can only access and modify their own configuration information. Accessing or modifying the configuration of other bundles requires ConfigurationPermission[location,CONFIGURE], where location is the configuration location.

Configuration objects can be bound to a specified bundle location or to a region (configuration location starts with ?). If a location is not set, it will be learned the first time a target is registered. If the location is learned this way, the Configuration Admin service must detect if the bundle corresponding to the location is uninstalled. If this occurs, the Configuration object must be unbound, that is its location field is set back to null.

If target's bundle location matches the configuration location it is always updated.

If the configuration location starts with ?, that is, the location is a region, then the configuration must be delivered to all targets registered with the given PID. If security is on, the target bundle must have Configuration Permission[location,TARGET], where location matches given the configuration location with wildcards as in the Filter substring match. The security must be verified using the Bundle.hasPermission(Object) method on the target bundle.

If a target cannot be updated because the location does not match or it has no permission and security is active then the Configuration Admin service must not do the normal callback.

The method descriptions of this class refer to a concept of "the calling bundle". This is a loose way of referring to the bundle which obtained the Configuration Admin service from the service registry. Implementations of ConfigurationAdmin must use a ServiceFactory to support this concept.

"ThreadSafe"

Field Summary

Fields

Modifier and Type	Field and Description
static String	SERVICE_BUNDLELOCATION Configuration property naming the location of the bundle that is associated with a Configuration object.
static String	SERVICE_FACTORYPID Configuration property naming the Factory PID in the configuration dictionary.

Method Summary

Methods

Modifier and Type	Method and Description
Configuration	createFactoryConfiguration(String factoryPid) Create a new factory Configuration object with a new PID.
Configuration	createFactoryConfiguration(String factoryPid, String location) Create a new factory Configuration object with a new PID.
Configuration	getConfiguration(String pid) Get an existing or new Configuration object from the persistent store.
Configuration	getConfiguration(String pid, String location) Get an existing Configuration object from the persistent store, or create a new Configuration object.
Configuration[]	listConfigurations(String filter) List the current Configuration objects which match the filter.

Field Detail

SERVICE_FACTORYPID

static final String SERVICE_FACTORYPID

Configuration property naming the Factory PID in the configuration dictionary. The property's value is of type String.

Since:

1.1

See Also:

Constant Field Values

SERVICE_BUNDLELOCATION

static final String SERVICE_BUNDLELOCATION

Configuration property naming the location of the bundle that is associated with a Configuration object. This property can be searched for but must not appear in the configuration dictionary for security reason. The property's value is of type String.

Since:

1.1

See Also:

Constant Field Values

Method Detail

createFactoryConfiguration

Configuration createFactoryConfiguration(String factoryPid)
                                         throws IOException

Create a new factory Configuration object with a new PID. The properties of the new Configuration object are null until the first time that its Configuration.update(Dictionary) method is called.

It is not required that the factoryPid maps to a registered Managed Service Factory.

The Configuration object is bound to the location of the calling bundle. It is possible that the same factoryPid has associated configurations that are bound to different bundles. Bundles should only see the factory configurations that they are bound to or have the proper permission.

Parameters:

factoryPid - PID of factory (not null).

Returns:

A new Configuration object.

Throws:

IOException - if access to persistent storage fails.

createFactoryConfiguration

Configuration createFactoryConfiguration(String factoryPid,
                                       String location)
                                         throws IOException

Create a new factory Configuration object with a new PID. The properties of the new Configuration object are null until the first time that its Configuration.update(Dictionary) method is called.

It is not required that the factoryPid maps to a registered Managed Service Factory.

The Configuration is bound to the location specified. If this location is null it will be bound to the location of the first bundle that registers a Managed Service Factory with a corresponding PID. It is possible that the same factoryPid has associated configurations that are bound to different bundles. Bundles should only see the factory configurations that they are bound to or have the proper permission.

If the location starts with ? then the configuration must be delivered to all targets with the corresponding PID.

Parameters:

factoryPid - PID of factory (not null).

location - A bundle location string, or null.

Returns:

a new Configuration object.

Throws:

IOException - if access to persistent storage fails.

SecurityException - when the require permissions are not available

"Required Permissions"

ConfigurationPermission[location,CONFIGURE] if location is not null, ConfigurationPermission["*",CONFIGURE] if location is null

getConfiguration

Configuration getConfiguration(String pid,
                             String location)
                               throws IOException

Get an existing Configuration object from the persistent store, or create a new Configuration object.

If a Configuration with this PID already exists in Configuration Admin service return it. The location parameter is ignored in this case though it is still used for a security check.

Else, return a new Configuration object. This new object is bound to the location and the properties are set to null. If the location parameter is null, it will be set when a Managed Service with the corresponding PID is registered for the first time. If the location starts with ? then the configuration is bound to all targets that are registered with the corresponding PID.

Parameters:

pid - Persistent identifier.

location - The bundle location string, or null.

Returns:

An existing or new Configuration object.

Throws:

IOException - if access to persistent storage fails.

SecurityException - when the require permissions are not available

"Required Permissions"

ConfigurationPermission[*,CONFIGURE] if location is null or if the returned configuration c already exists and c.location is null, ConfigurationPermission[location,CONFIGURE] if location is not null, ConfigurationPermission[c.location,CONFIGURE] if the returned configuration c already exists and c.location is not null

getConfiguration

Configuration getConfiguration(String pid)
                               throws IOException

Get an existing or new Configuration object from the persistent store. If the Configuration object for this PID does not exist, create a new Configuration object for that PID, where properties are null. Bind its location to the calling bundle's location.

Otherwise, if the location of the existing Configuration object is null, set it to the calling bundle's location.

Parameters:

pid - persistent identifier.

Returns:

an existing or new Configuration matching the PID.

Throws:

IOException - if access to persistent storage fails.

SecurityException - when the required permission is not available

"Required Permissions"

ConfigurationPermission[c.location,CONFIGURE] If the configuration c already exists and c.location is not null

listConfigurations

Configuration[] listConfigurations(String filter)
                                   throws IOException,
                                          InvalidSyntaxException

List the current Configuration objects which match the filter.

Only Configuration objects with non- null properties are considered current. That is, Configuration.getProperties() is guaranteed not to return null for each of the returned Configuration objects.

When there is no security on then all configurations can be returned. If security is on, the caller must have ConfigurationPermission[location,CONFIGURE].

The syntax of the filter string is as defined in the Filter class. The filter can test any configuration properties including the following:

• service.pid - the persistent identity
• service.factoryPid - the factory PID, if applicable
• service.bundleLocation - the bundle location

The filter can also be null, meaning that all Configuration objects should be returned.

Parameters:

filter - A filter string, or null to retrieve all Configuration objects.

Returns:

All matching Configuration objects, or null if there aren't any.

Throws:

IOException - if access to persistent storage fails

InvalidSyntaxException - if the filter string is invalid

"Required Permissions"

ConfigurationPermission[c.location,CONFIGURE] Only configurations c are returned for which the caller has this permission