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);
    }
}