Author: pderop
Date: Wed Feb 24 09:26:47 2016
New Revision: 1732044
URL: http://svn.apache.org/viewvc?rev=1732044&view=rev
Log:
updated dm doc for configuration types
Modified:
felix/site/trunk/content/documentation/subprojects/apache-felix-dependency-manager/reference/dependency-configuration.mdtext
Modified:
felix/site/trunk/content/documentation/subprojects/apache-felix-dependency-manager/reference/dependency-configuration.mdtext
URL:
http://svn.apache.org/viewvc/felix/site/trunk/content/documentation/subprojects/apache-felix-dependency-manager/reference/dependency-configuration.mdtext?rev=1732044&r1=1732043&r2=1732044&view=diff
==============================================================================
---
felix/site/trunk/content/documentation/subprojects/apache-felix-dependency-manager/reference/dependency-configuration.mdtext
(original)
+++
felix/site/trunk/content/documentation/subprojects/apache-felix-dependency-manager/reference/dependency-configuration.mdtext
Wed Feb 24 09:26:47 2016
@@ -2,24 +2,100 @@ Title: Dependency Manager - Configuratio
A configuration dependency is always required, and allows you to depend on the
availability of a valid configuration for your component. Optional
configuration dependencies are not supported because in that case you can just
as well register as a `ManagedService` yourself.
-## @ConfigurationDependency
+The dependency injects by default the configuration in an "updated" callback
which can accept the following parameters:
+
+- updated(Dictionary)
+- updated(Component, Dictionary)
+- updated(ConfigurationType)
+- updated(Component, ConfigurationType)
+
+If you only specify a pid, by default the callback method name is assumed to
be "updated".
+
+Configuration types are a new feature that allows you to specify an interface
that is implemented by DM and such interface is then injected to your callback
instead of the actual Dictionary. Using such configuration interface provides a
way for creating type-safe configurations from a actual Dictionary that is
normally injected by Dependency Manager. The callback accepts in argument an
interface that you have to provide, and DM will inject a proxy that converts
method calls from your configuration-type to lookups in the actual map or
dictionary. The results of these lookups are then converted to the expected
return type of the invoked configuration method.
+As proxies are injected, no implementations of the desired configuration-type
are necessary!
+
+The lookups performed are based on the name of the method called on the
configuration type. The method names are "mangled" to the following form:
[lower case letter] [any valid character]*. Method names starting with get or
is (JavaBean convention) are stripped from these prefixes. For example: given a
dictionary with the key "foo" can be accessed from a configuration-type using
the following method names: foo(), getFoo() and isFoo().
+
+The return values supported are: primitive types (or their object wrappers),
strings, enums, arrays of primitives/strings, Collection types, Map types,
Classes and interfaces. When an interface is returned, it is treated equally to
a configuration type, that is, it is returned as a proxy.
+
+Arrays can be represented either as comma-separated values, optionally
enclosed in square brackets. For example: [ a, b, c ] and a, b,c are both
considered an array of length 3 with the values "a", "b" and "c".
Alternatively, you can append the array index to the key in the dictionary to
obtain the same: a dictionary with "arr.0" => "a", "arr.1" => "b", "arr.2" =>
"c" would result in the same array as the earlier examples.
+
+Maps can be represented as single string values similarly as arrays, each
value consisting of both the key and value separated by a dot. Optionally, the
value can be enclosed in curly brackets. Similar to array, you can use the same
dot notation using the keys. For example, a dictionary with
+
+ "map" => "{key1.value1, key2.value2}"
+
+and a dictionary with
+
+ "map.key1" => "value1", "map2.key2" => "value2"
+
+result in the same map being returned. Instead of a map, you could also define
an interface with the methods getKey1() and getKey2 and use that interface as
return type instead of a Map.
-A configuration dependency is always required, and allows you to depend on the
availability of a valid configuration for your component. This dependency
requires the OSGi Configuration Admin Service.
+In case a lookup does not yield a value from the underlying map or dictionary,
the following rules are applied:
+- primitive types yield their default value, as defined by the Java
Specification;
+- string, Classes and enum values yield null;
+- for arrays, collections and maps, an empty array/collection/map is returned;
+- for other interface types that are treated as configuration type a
null-object is returned.
+
+Usage example where a component depends on a configuration:
+
+ :::java
+ public class ServiceImpl {
+ void modified(Dictionary<String, Object> cnf) {
+ if (cnf != null) {
+ String addr = (String) cnf.get("address");
+ int port = Integer.valueOf(cnf.get("port");
+ ...
+ }
+ }
+ }
+
+ public class Activator extends DependencyActivatorBase {
+ @Override
+ public void init(BundleContext ctx, DependencyManager dm) throws
Exception {
+ dm.add(createComponent()
+ .setImplementation(ServiceImpl.class)
+
.add(createConfigurationDependency().setPid(ServiceImpl.class.getName()));
+ }
+ }
+
+Here is the same example, but a custom configuration type interface is used
(by default, the fqdn of the configuration type is assumed to be the
configuration pid):
+
+ :::java
+ public interface MyConfig {
+ String getAddress();
+ int getPort();
+ }
+
+ public class ServiceImpl {
+ void modified(MyConfig cnf) {
+ if (cnf != null) {
+ String addr = cnf.getAddress();
+ int port = cnf.getPort();
+ ...
+ }
+ }
+ }
+
+ public class Activator extends DependencyActivatorBase {
+ @Override
+ public void init(BundleContext ctx, DependencyManager dm) throws
Exception {
+ dm.add(createComponent()
+ .setImplementation(ServiceImpl.class)
+ .add(createConfigurationDependency().setCallback("updated",
MyConfig.class);
+ }
+ }
+
+
+## @ConfigurationDependency
+
+Configuration dependencies can be defined usnig the @ConfigurationDependency.
Annotation attributes:
* *pid*: Returns the pid for a given service (by default, the pid is the
service class name).
-* *pidClass*: Will the the name of the specified class as the the pid for a
given service (by default, the pid is the service class name).
* *propagate*: Returns true if the configuration properties must be published
along with the service. Any additional service properties specified directly
are merged with these.
-* *name*: The name for this configuration dependency. When you give a name a
dependency, it won't be evaluated immediately, but after the component's init
method has been called,
-and from the init method, you can then return a map in order to dynamically
configure the
-configuration dependency (the map has to contain a "pid" and/or "propagate"
flag, prefixed
-with the dependency name). Then the dependency will be evaluated after the
component init
-method, and will be injected before the start method.
-
-## Usage Examples
-In the following example, the "Printer" component depends on a configuration
whose PID name is "org.apache.felix.sample.Printer". This service will
initialize its ip/port number from the provided configuration:
+In the following example, the "Printer" component depends on a configuration
with "org.apache.felix.sample.Printer" PID.
:::java
package org.apache.felix.sample;
@@ -37,7 +113,7 @@ WebConsole GUI. Using these meta data, y
configurations data, some descriptions, the cardinality of configuration
values, etc ...
(we use here standard bnd metatype annotations, [see bnd metatype
documentation here](http://www.aqute.biz/Bnd/MetaType).
- First, we define the configuration metadata, using standard bndtools
metatatype annotations:
+First, we define our PrinterConfiguration interface annotated with standard
bndtools metatatype annotations:
:::java
package sample;
@@ -53,7 +129,9 @@ configurations data, some descriptions,
int portNumber();
}
- Next, we define our Printer service which instantiates the
PrinterConfiguration using the *Configurable" bndlib helper:
+ Next, we define our Printer service with an `updated` method which is
injected with the
+PrinterConfiguration type that is implemented by DM (all interface methods
will lookup in the
+actual configuration dictionary).
:::java
package sample;
@@ -61,60 +139,15 @@ configurations data, some descriptions,
@Component
public class Printer {
- @ConfigurationDependency(pidClass = PrinterConfiguration.class) //
Will use pid "sample.PrinterConfiguration"
- void updated(Dictionary props) {
- // load configuration from the provided dictionary, or throw an
exception of any configuration error.
- PrinterConfig cnf =
Configurable.createConfigurable(PrinterConfig.class, props);
- String ip = cnf.ipAddress();
- int port = cnf.portNumber();
- ...
+ @ConfigurationDependency // Will use pid "sample.PrinterConfiguration"
+ void updated(PrinterConfiguration cnf) {
+ if (cnf != null) {
+ // load configuration from the provided dictionary, or throw
an exception of any configuration error.
+ String ip = cnf.ipAddress();
+ int port = cnf.portNumber();
+ ...
+ }
}
}
-Finally, the last example shows how to dynamically configure a configuration
dependency pid from the init method.
-The following component first depends on a "sample.MyComponent" configuration
pid. Then the init method gets from that configuration
-another pid for a second "global" configuration:
-
-
- :::java
- package sample;
-
- /**
- * A Service that dynamically defines an extra dynamic configuration
dependency from its init method.
- */
- @Component
- class MyComponent {
- private Dictionary m_config;
-
- // Inject initial Configuration (injected before any other required
dependencies)
- @ConfigurationDependency
- void componentConfiguration(Dictionary config) {
- // you must throw an exception if the configuration is not valid
- m_config = config;
- }
-
- /**
- * All unnamed dependencies are injected: we can now configure our
dynamic configuration whose dependency name is "global".
- */
- @Init
- Map init() {
- Map properties = new HashMap();
- properties.put("global.pid", m_config.get("globalConfig.pid"));
- properties.put("global.propagate",
m_config.get("globalConfig.propagate"));
- return properties;
- }
-
- // Injected after init, and dynamically configured by the init method.
- @ConfigurationDependency(name="global")
- void globalConfiguration(Dictionary globalConfig) {
- // you must throw an exception if the configuration is not valid
- }
-
- /**
- * All dependencies are injected and our service is now ready to be
published.
- */
- @Start
- void start() {
- }
- }
