Author: pderop
Date: Thu Mar 12 23:13:00 2015
New Revision: 1666333
URL: http://svn.apache.org/r1666333
Log:
Added more documentation about Service Compositions.
Modified:
felix/site/trunk/content/documentation/subprojects/apache-felix-dependency-manager/reference/components.mdtext
Modified:
felix/site/trunk/content/documentation/subprojects/apache-felix-dependency-manager/reference/components.mdtext
URL:
http://svn.apache.org/viewvc/felix/site/trunk/content/documentation/subprojects/apache-felix-dependency-manager/reference/components.mdtext?rev=1666333&r1=1666332&r2=1666333&view=diff
==============================================================================
---
felix/site/trunk/content/documentation/subprojects/apache-felix-dependency-manager/reference/components.mdtext
(original)
+++
felix/site/trunk/content/documentation/subprojects/apache-felix-dependency-manager/reference/components.mdtext
Thu Mar 12 23:13:00 2015
@@ -94,7 +94,104 @@ Components in the context of the depende
## Composition
-When implementing more complex components, you often find yourself using more
than one instance. However, several of these instances might want to have
dependencies injected. In such cases you need to tell the dependency manager
which instances to consider. This has to be a fixed set of instances however.
+When implementing more complex components, you often find yourself using more
than one
+instance. However, several of these instances might want to have dependencies
injected.
+In such cases you need to tell the dependency manager which instances to
consider.
+This has to be a fixed set of instances however.
+
+We now describe how to declare a service composition using the Api, and the
Annotations:
+
+### Composition / API
+
+When using the DependencyManager API, you can use the
*Component.setComposition* method to declare a special callback in your
component that
+returns the list of object that are part of the component, and all
dependencies and lifecycle callbacks will be invoked
+on the objects returned by the method. Let's take an example, with a
*ProviderImpl* top-level service implementation
+that is internally implemented using three Pojos: *ProviderImpl*,
*ProviderParticipant1*, and
+*ProviderParticipant2*:
+
+ :::java
+ public class ProviderImpl implements Provider {
+ private final ProviderParticipant1 m_participant1 = new
ProviderParticipant1();
+ private final ProviderParticipant2 m_participant2 = new
ProviderParticipant2();
+ private volatile LogService m_log; // injected
+
+ Object[] getComposition() {
+ return new Object[] { this, m_participant1, m_participant2 };
+ }
+
+ void start() {
+ m_log.log(LogService.LOG_INFO, "ProviderImpl.start():
participants=" + m_participant1 + "," + m_participant2
+ + ", conf=" + m_conf);
+ }
+ }
+
+ public class ProviderParticipant1 {
+ private volatile LogService m_log; // also injected since we are part
of the composition
+
+ void start() {
+ m_log.log(LogService.LOG_INFO, "ProviderParticipant1.start()");
+ }
+ }
+
+ public class ProviderParticipant2 {
+ private volatile LogService m_log; // also injected since we are part
of the composition
+
+ void start() {
+ m_log.log(LogService.LOG_INFO, "ProviderParticipant2.start()");
+ }
+ }
+
+And here is the Activator, which uses the *setComposition* method:
+
+ :::java
+ public class Activator extends DependencyActivatorBase {
+ public void init(BundleContext ctx, DependencyManager m) throws
Exception {
+ m.add(createComponent()
+ .setImplementation(ProviderImpl.class)
+ .setComposition("getComposition")
+
.add(createServiceDependency().setService(LogService.class).setRequired(true)));
+ }
+ }
+
+### Composition / Annotations
+
+Here is the same example as above, but using Annotations:
+
+ :::java
+ @Component
+ public class ProviderImpl implements Provider {
+ private final ProviderParticipant1 m_participant1 = new
ProviderParticipant1();
+ private final ProviderParticipant2 m_participant2 = new
ProviderParticipant2();
+ private volatile LogService m_log; // injected
+
+ @Composition
+ Object[] getComposition() {
+ return new Object[] { this, m_participant1, m_participant2 };
+ }
+
+ @Start
+ void start() {
+ m_log.log(LogService.LOG_INFO, "ProviderImpl.start():
participants=" + m_participant1 + "," + m_participant2
+ + ", conf=" + m_conf);
+ }
+ }
+
+ public class ProviderParticipant1 {
+ private volatile LogService m_log; // also injected, since we are part
of the composition
+
+ void start() {
+ m_log.log(LogService.LOG_INFO, "ProviderParticipant1.start()");
+ }
+ }
+
+ public class ProviderParticipant2 {
+ private volatile LogService m_log; // also injected, since we are part
of the composition
+
+ void start() {
+ m_log.log(LogService.LOG_INFO, "ProviderParticipant2.start()");
+ }
+ }
+
## Factories
