OSGi容器中Bundle之间Synchronous Communication

  OSGi Core定义了一个服务层，提供了一个Bundle之间交互的简单机制，通过注册Java Object 至OSGi service registry。      Blueprint Container

    (1) Blueprint Configuration

    默认配置文件位于：ProjectDir/src/main/resources/OSGI-INF/blueprint

    默认XML文件命名空间：

 <? xml   version = "1.0"   encoding = "UTF-8" ?>
 < blueprint   xmlns = "http://www.osgi.org/xmlns/blueprint/v1.0.0" >
     ...
 </ blueprint >

     自定义配置文件地址：

     Bundle-Blueprint: lib/account.xml, security.bp, cnf/*.xml

 

     Mandatory dependencies：

     OSGi Service 中Dependencies默认是必须的，但可通过设置reference和reference-list元素的availability为optional

     来改变这中现象。正常情况下，当Bluepring Container初始化时，通过一定范围的时间来允许Dependencies

     Resolve, 该时间么哦人为：5秒，可通过下面的方式自定义：

 Bundle-SymbolicName: org.fusesource.example.osgi-client;
 blueprint.graceperiod: = true ;
 blueprint.timeout: =  10000

    (2) Defining a Service Bean

    (3) Exporting a Service

    1. Exporting with a single interface

 < blueprint   xmlns = "http://www.osgi.org/xmlns/blueprint/v1.0.0" >
     < bean   id = "savings"   class = "org.fusesource.example.SavingsAccountImpl"   />
     < service   ref = "savings"   interface = "org.fusesource.example.Account"   />
 </ blueprint >

     2. Exporting with multiple interfaces

 < blueprint   xmlns = "http://www.osgi.org/xmlns/blueprint/v1.0.0" >

     < bean   id = "savings"   class = "org.fusesource.example.SavingsAccountImpl"   />
     < service   ref = "savings" >
         < interfaces >
             < value > org.fusesource.example.Account </ value >
             < value > org.fusesource.example.SavingsAccount </ value >
         </ interfaces >
     </ service >
 </ blueprint >

    注意：interface和interfaces不能同时在service元素中使用。

    3. Exporting with auto-export

    例如：下面的代码中Blueprint将自动注册所有SavingsAccountImpl实现的public接口：

 < blueprint   xmlns = "http://www.osgi.org/xmlns/blueprint/v1.0.0" >
     < bean   id = "savings"   class = "org.fusesource.example.SavingsAccountImpl"   />
     < service   ref = "savings"   auto-export = "interfaces"   />
 </ blueprint >

     其中auto-export默认值为：disabled,其他可选值为：

     interfaces：注册该类实现的所有public的接口；

     class-hierarchy：注册该类自己以及他的父类，但不包含Object类；

     all-classes：注册该类自己以及他的父类，同时包括该类实现的接口。

     4. Setting service properties

 < blueprint   xmlns = "http://www.osgi.org/xmlns/blueprint/v1.0.0" >
     < bean   id = "savings"   class = "org.fusesource.example.SavingsAccountImpl"   />
     < service   ref = "savings"   auto-export = "interfaces"   ranking = "10" >
         < service-properties >
             < beans:entry   key = "bank.name"   value = "HighStreetBank"   />
         </ service-properties >
     </ service >
 </ blueprint >

    说明：A.  注册的service默认的Properties有：osgi.service.blueprint.compname值为service  bean 的id

                B.  service.ranking 是系统自动设置。

                C.  当系统查找服务时返回对个匹配的服务时，默认选择ranking值最高的服务，因此可配置该属性用以服务

     之间的区分。

     5. Specifying a registration listener

 < blueprint   xmlns = "http://www.osgi.org/xmlns/blueprint/v1.0.0"  . >
     < bean   id = "listenerBean"   class = "org.fusesource.example.Listener"   />
     < service   ref = "savings"   auto-export = "interfaces" >
         < registration-listener   ref = "listenerBean"
             registration-method = "register"   unregistration-method = "unregister"   />
     </ service >
 </ blueprint >

 

 //Java
 package  org.fusesource.example;

 public   class  Listener {
     public   void  register(Account service, java.util.Map serviceProperties) {
     }

     public   void  unregister(Account service, java.util.Map serviceProperties) {
     }
 }

     说明：register和unregister方法的参数，第一个参数可以是service class或service class 实现的接口，因为该

     参数包含service instance,  如果该service bean 被声明为property, 在注册的时候是没有service instance可用

     的，因此此时该参数的值为null.

     第二个参数可以是java.util.Map或java.util.Dictionary，这个Map包含service 注册时的Properties.

     (4) Importing a Service

     使用reference和reference-list元素Import Service, 两者之间的区别是：reference用于访问stateless service,

     而reference-list用于访问stateful service.

     1. Matching by interface (stateless)

 < blueprint   xmlns = "http://www.osgi.org/xmlns/blueprint/v1.0.0" >
     < reference   id = "savingsRef"   interface = "org.fusesource.example.SavingsAccount"   />
     < bean   id = "client"   class = "org.fusesource.example.client.Client" >
         < property   name = "savingsAccount"   ref = "savingsRef"   />
     </ bean >
 </ blueprint >

 

 package  org.fusesource.example.client;

 import  org.fusesource.example.SavingsAccount;

 public   class  Client {
     SavingsAccount savingsAccount;

     // Bean properties
     public  SavingsAccount getSavingsAccount() {
         return  savingsAccount;
     }

     public   void  setSavingsAccount(SavingsAccount savingsAccount) {
         this .savingsAccount = savingsAccount;
     }
 }

     2.  Matching by interface (stateful)    

 < blueprint   xmlns = "http://www.osgi.org/xmlns/blueprint/v1.0.0" >
     < reference-list   id = "savingsListRef"
         interface = "org.fusesource.example.SavingsAccount"   />
     < bean   id = "client"   class = "org.fusesource.example.client.Client" >
         < property   name = "savingsAccountList"   ref = "savingsListRef"   />
     </ bean >
 </ blueprint >

 

 package  org.fusesource.example.client;

 import  org.fusesource.example.SavingsAccount;

 public   class  Client {
     java.util.List<SavingsAccount> accountList;

     // Bean properties
     public  java.util.List<SavingsAccount> getSavingsAccountList() {
         return  accountList;
     }

     public   void  setSavingsAccountList(java.util.List<SavingsAccount> accountList) {
         this .accountList = accountList;
     }
 }

     3. Matching service properties with a filter

 < reference   id = "savingsRef"   interface = "org.fusesource.example.SavingsAccount"   filter = "(bank.name=HighStreetBank)"   />

 < reference-list   id = "savingsRef"   interface = "org.fusesource.example.SavingsAccount"   filter = "(bank.name=HighStreetBank)"   />

     4. Specifying whether mandatory or optional

     默认值：mandatory

 < reference   id = "savingsRef"   interface = "org.fusesource.example.SavingsAccount"   availability = "mandatory"   />

     5. Specifying a reference listener

 < blueprint   xmlns = "http://www.osgi.org/xmlns/blueprint/v1.0.0" >
     < reference   id = "savingsRef"   interface = "org.fusesource.example.SavingsAccount" >
         < reference-listener   bind-method = "onBind"
             unbind-meth od = "onUnbind" >
             < bean   class = "org.fusesource.example.client.Listener"   />
         </ reference-listener >
     </ reference >
     < bean   id = "client"   class = "org.fusesource.example.client.Client" >
         < property   name = "savingsAcc"   ref = "savingsRef"   />
     </ bean >
 </ blueprint >

 

 package  org.fusesource.example.client;

 import  org.osgi.framework.ServiceReference;

 public   class  Listener {
     public   void  onBind(ServiceReference ref) {
         System.out.println("Bound service: "  + ref);
     }

     public   void  onUnbind(ServiceReference ref) {
         System.out.println("Unbound service: "  + ref);
     }
 }