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446 lines
18 KiB
Markdown
Executable File
446 lines
18 KiB
Markdown
Executable File
# IPC/RPC组件<a name="ZH-CN_TOPIC_0000001103602398"></a>
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- [简介](#section11660541593)
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- [系统架构](#section1950291414611)
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- [目录](#section161941989596)
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- [约束](#section119744591305)
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- [编译构建](#section137768191623)
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- [说明](#section1312121216216)
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- [接口说明](#section1551164914237)
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- [使用说明](#section129654513264)
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- [相关仓](#section1371113476307)
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## 简介<a name="section11660541593"></a>
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IPC（Inter-Process Communication）与RPC（Remote Procedure Call）机制用于实现跨进程通信，不同的是前者使用Binder驱动，用于设备内的跨进程通信，而后者使用软总线驱动，用于跨设备跨进程通信。IPC和RPC通常采用客户端-服务器（Client-Server）模型，服务请求方（Client）可获取提供服务提供方（Server）的代理 （Proxy），并通过此代理读写数据来实现进程间的数据通信。通常，系统能力（System Ability）Server侧会先注册到系统能力管理者（System Ability Manager，缩写SAMgr）中，SAMgr负责管理这些SA并向Client提供相关的接口。Client要和某个具体的SA通信，必须先从SAMgr中获取该SA的代理，然后使用代理和SA通信。三方应用可以使用FA提供的接口绑定服务提供方的Ability，获取代理，进行通信。下文使用Proxy表示服务请求方，Stub表示服务提供方。
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## 系统架构<a name="section1950291414611"></a>
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**图 1** IPC通信机制架构图<a name="fig312319321710"></a>
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## 目录<a name="section161941989596"></a>
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```
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/foundation/communication/ipc
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├── interfaces # 对外接口存放目录
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│ └── innerkits # 对内部子系统暴露的头文件存放目录
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│ ├── ipc_core # ipc 接口存放目录
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│ └── libdbinder # dbinder 接口存放目录
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├── ipc # ipc 框架代码
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│ ├── native # ipc native 实现存放目录
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│ ├── src # ipc native 源代码存放目录
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│ └── test # ipc native 单元测试用例存放目录
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│ └── test # ipc native 模块测试用例存放目录
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├── service # dbinder 实现存放目录
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│ └── dbinder # dbinder 源代码存放目录
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```
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## 约束<a name="section119744591305"></a>
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1. 单个设备上跨进程通信时，传输的数据量最大约为1MB，过大的数据量请使用匿名共享内存。
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2. 不支持把跨设备的Proxy对象传递回该Proxy对象所指向的Stub对象所在的设备。
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## 编译构建<a name="section137768191623"></a>
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**JS侧依赖**
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```
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import rpc from "@ohos.rpc"
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import featureAbility from "@ohos.ability.featureAbility"
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```
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**Native侧编译依赖**
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sdk依赖：
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```
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external_deps = [
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"ipc:ipc_core",
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]
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```
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此外， IPC/RPC依赖的refbase实现在公共基础库实现//utils下，请增加对utils的源码依赖：
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```
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deps = [
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"//utils/native/base:utils",
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]
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```
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## 说明<a name="section1312121216216"></a>
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**JS侧实现跨进程通信基本步骤：**
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1. 获取代理
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使用ohos.ability.featureAbility提供的connectAbility方法绑定Ability，在参数里指定要绑定的Ability所在应用的包名、组件名，如果是跨设备的情况，还需要指定所在设备的ID。用户需要在服务端的onConnect方法里返回一个继承自ohos.rpc.RemoteObject的对象，此对象会在onRemoteRequest方法里接收到请求。
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2. 发送请求
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客户端在connectAbility参数指定的回调函数接收到代理对象后，使用ohos.rpc模块提供的方法完成RPC通信，其中MessageParcel提供了读写各种类型数据的方法，IRemoteObject提供了发送请求的方法，RemoteObject提供了处理请求的方法onRemoteRequest，用户需要重写。
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**Native侧实现跨进程通信的基本步骤：**
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1. 定义接口类
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接口类继承IRemoteBroker，定义描述符、业务函数和消息码。
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2. 实现服务提供端\(Stub\)
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Stub继承IRemoteStub\(Native\)，除了接口类中未实现方法外，还需要实现AsObject方法及OnRemoteRequest方法。
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3. 实现服务请求端\(Proxy\)
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Proxy继承IRemoteProxy\(Native\)，封装业务函数，调用SendRequest将请求发送到Stub。
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4. 注册SA
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服务提供方所在进程启动后，申请SA的唯一标识，将Stub注册到SAMgr。
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5. 获取SA
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6. 通过SA的标识和设备标识，从SAMgr获取Proxy，通过Proxy实现与Stub的跨进程通信。
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### 接口说明<a name="section1551164914237"></a>
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**表 1** JS侧IPC关键API
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| 模块 | 方法 | 功能说明 |
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| --------------------------- | ------------------------------------------------------------ | ------------------------------------------- |
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| ohos.ability.featureAbility | connectAbility(request: Want, options:ConnectOptions ): number | 绑定指定的Ability，在回调函数里接收代理对象 |
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| ohos.rpc.RemoteObject | onRemoteRequest(code: number, data: MessageParcel, reply: MessageParcel, options: MessageOption): boolean | 服务端处理请求，返回结果 |
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| ohos.rpc.IRemoteObject | sendRequest(code: number, data: MessageParcel, reply: MessageParcel, options: MessageOption): Promise<SendRequestResult> | 发送请求，在期约里接收结果 |
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| ohos.rpc.IRemoteObject | sendRequest(code: number, data: MessageParcel, reply: MessageParcel, options: MessageOption, callback: AsyncCallback<SendRequestResult>): void | 发送请求，在回调函数里接收结果 |
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| ohos.rpc.MessageParcel | writeRemoteObject(object: IRemoteObject): boolean | 序列化IRemoteObject对象 |
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| ohos.rpc.MessageParcel | readRemoteObject(): IRemoteObject | 反序列化IRemoteObject对象 |
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**表 2** Native侧IPC接口
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<a name="table178849240013"></a>
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<table><thead align="left"><tr id="row6884924608"><th class="cellrowborder" valign="top" width="14.12141214121412%" id="mcps1.2.4.1.1"><p id="p98846241706"><a name="p98846241706"></a><a name="p98846241706"></a>类/接口</p>
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</th>
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<th class="cellrowborder" valign="top" width="52.54525452545254%" id="mcps1.2.4.1.2"><p id="p1488482414020"><a name="p1488482414020"></a><a name="p1488482414020"></a>方法</p>
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</th>
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<th class="cellrowborder" valign="top" width="33.33333333333333%" id="mcps1.2.4.1.3"><p id="p388516244016"><a name="p388516244016"></a><a name="p388516244016"></a>功能说明</p>
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</th>
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</tr>
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</thead>
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<tbody><tr id="row15885824402"><td class="cellrowborder" valign="top" width="14.12141214121412%" headers="mcps1.2.4.1.1 "><p id="p08859241008"><a name="p08859241008"></a><a name="p08859241008"></a>IRemoteBroker</p>
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</td>
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<td class="cellrowborder" valign="top" width="52.54525452545254%" headers="mcps1.2.4.1.2 "><p id="p388572412010"><a name="p388572412010"></a><a name="p388572412010"></a>sptr<IRemoteObject> AsObject()</p>
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</td>
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<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.2.4.1.3 "><p id="p13885724405"><a name="p13885724405"></a><a name="p13885724405"></a>返回通信对象。派生类需要实现，Stub端返回RemoteObject对象本身，Proxy端返回代理对象。</p>
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</td>
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</tr>
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<tr id="row138859241808"><td class="cellrowborder" valign="top" width="14.12141214121412%" headers="mcps1.2.4.1.1 "><p id="p1888515245012"><a name="p1888515245012"></a><a name="p1888515245012"></a>IRemoteStub</p>
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</td>
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<td class="cellrowborder" valign="top" width="52.54525452545254%" headers="mcps1.2.4.1.2 "><p id="p1388516240011"><a name="p1388516240011"></a><a name="p1388516240011"></a>virtual int OnRemoteRequest(uint32_t code, MessageParcel &data, MessageParcel &reply, MessageOption &option)</p>
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</td>
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<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.2.4.1.3 "><p id="p1188582414016"><a name="p1188582414016"></a><a name="p1188582414016"></a>请求处理方法，派生类需要重写，处理Proxy的请求并返回结果。</p>
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</td>
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</tr>
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<tr id="row108856241904"><td class="cellrowborder" valign="top" width="14.12141214121412%" headers="mcps1.2.4.1.1 "><p id="p6885924609"><a name="p6885924609"></a><a name="p6885924609"></a>IRemoteProxy</p>
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</td>
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<td class="cellrowborder" valign="top" width="52.54525452545254%" headers="mcps1.2.4.1.2 "> </td>
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<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.2.4.1.3 "><p id="p688592413018"><a name="p688592413018"></a><a name="p688592413018"></a>业务Proxy类派生自IRemoteProxy类。</p>
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</td>
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</tr>
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</tbody>
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</table>
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### 使用说明<a name="section129654513264"></a>
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**JS侧使用说明**
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1. 客户端构造变量want，指定要绑定的Ability所在应用的包名、组件名，如果是跨设备的场景，还需要目标设备ID。构造变量connect，指定绑定成功、绑定失败、断开连接时的回调函数。使用featureAbility提供的接口绑定Ability。
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```
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import rpc from "@ohos.rpc"
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import featureAbility from "@ohos.ability.featureAbility"
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let proxy = null
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let connectId = null
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// 单个设备
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let want = {
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// 包名和组件名写实际的值
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"bundleName": "ohos.rpc.test.server",
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"abilityName": "ohos.rpc.test.server.ServiceAbility",
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}
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let connect = {
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onConnect:function(elementName, remote) {
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proxy = remote
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},
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onDisconnect:function(elementName) {
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},
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onFailed:function() {
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proxy = null
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}
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}
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connectId = featureAbility.connectAbility(want, connect)
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// 如果是跨设备绑定，可以使用deviceManager获取目标设备ID
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import deviceManager from '@ohos.distributedHardware.deviceManager'
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function deviceManagerCallback(deviceManager) {
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let deviceList = deviceManager.getTrustedDeviceListSync()
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let deviceId = deviceList[0].deviceId
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let want = {
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"bundleName": "ohos.rpc.test.server",
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"abilityName": "ohos.rpc.test.service.ServiceAbility",
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"deviceId": deviceId,
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"flags": 256
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}
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connectId = featureAbility.connectAbility(want, connect)
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}
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// 第一个参数是本应用的包名，第二个参数是接收deviceManager的回调函数
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deviceManager.createDeviceManager("ohos.rpc.test", deviceManagerCallback)
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```
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2. 服务端被绑定的Ability在onConnect方法里返回继承自rpc.RemoteObject的对象，该对象需要实现onRemoteRequest方法，处理客户端的请求。
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```
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import rpc from "@ohos.rpc"
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onConnect(want) {
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return new Stub("rpcTestAbility")
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}
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class Stub extends rpc.RemoteObject {
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constructor(descriptor) {
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super(descriptor)
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}
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onRemoteRequest(code, data, reply, option) {
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// 根据code处理客户端的请求
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return true
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}
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}
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```
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3. 客户端在onConnect回调里接收到代理对象，调用sendRequest方法发起请求，在期约或者回调函数里接收结果。
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```
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import rpc from "@ohos.rpc"
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// 使用期约
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let option = new rpc.MessageOption()
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let data = rpc.MessageParcel.create()
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let reply = rpc.MessageParcel.create()
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// 往data里写入参数
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proxy.sendRequest(1, data, reply, option)
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.then(function(result) {
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if (result.errCode != 0) {
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console.error("send request failed, errCode: " + result.errCode)
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return
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}
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// 从result.reply里读取结果
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})
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.catch(function(e) {
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console.error("send request got exception: " + e)
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}
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.finally(() => {
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data.reclaim()
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reply.reclaim()
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}
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// 使用回调函数
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function sendRequestCallback(result) {
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try {
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if (result.errCode != 0) {
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console.error("send request failed, errCode: " + result.errCode)
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return
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}
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// 从result.reply里读取结果
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} finally {
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result.data.reclaim()
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result.reply.reclaim()
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}
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}
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let option = new rpc.MessageOption()
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let data = rpc.MessageParcel.create()
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let reply = rpc.MessageParcel.create()
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// 往data里写入参数
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proxy.sendRequest(1, data, reply, option, sendRequestCallback)
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```
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4. IPC通信结束后，使用featureAbility的接口断开连接。
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```
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import rpc from "@ohos.rpc"
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import featureAbility from "@ohos.ability.featureAbility"
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function disconnectCallback() {
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console.info("disconnect ability done")
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}
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featureAbility.disconnectAbility(connectId, disconnectCallback)
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```
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**Native侧使用说明**
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1. 定义IPC接口ITestAbility
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IPC接口继承IPC基类接口IRemoteBroker，接口里定义描述符、业务函数和消息码，其中业务函数在Proxy端和Stub端都需要实现。
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```
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class ITestAbility : public IRemoteBroker {
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public:
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// DECLARE_INTERFACE_DESCRIPTOR是必须的， 入参需使用std::u16string；
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DECLARE_INTERFACE_DESCRIPTOR(u"test.ITestAbility"); // DESCRIPTOR接口描述符建议使用"组件名.类名"的格式
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int TRANS_ID_PING_ABILITY = 1; // 定义消息码
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virtual int TestPingAbility(const std::u16string &dummy) = 0; // 定义业务函数
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};
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```
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2. 定义和实现服务端TestAbilityStub
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该类是和IPC框架相关的实现，需要继承 IRemoteStub<ITestAbility\>。Stub端作为接收请求的一端，需重写OnRemoteRequest方法用于接收客户端调用。
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```
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class TestAbilityStub : public IRemoteStub<ITestAbility> {
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public:
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virtual int OnRemoteRequest(uint32_t code, MessageParcel &data, MessageParcel &reply, MessageOption &option) override;
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int TestPingAbility(const std::u16string &dummy) override;
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};
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int TestServiceStub::OnRemoteRequest(uint32_t code,
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MessageParcel &data, MessageParcel &reply, MessageOption &option)
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{
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if (data.ReadInterfaceToken() != GetDescriptor()) { //校验是否为本服务的接口描述符，避免中继攻击
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return -1;
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}
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switch (code) {
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case TRANS_ID_PING_ABILITY: {
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std::u16string dummy = data.ReadString16();
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int result = TestPingAbility(dummy);
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reply.WriteInt32(result);
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return 0;
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}
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default:
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return IPCObjectStub::OnRemoteRequest(code, data, reply, option);
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}
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}
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```
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3. 定义服务端业务函数具体实现类TestAbility
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```
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class TestAbility : public TestAbilityStub {
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public:
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int TestPingAbility(const std::u16string &dummy);
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}
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int TestAbility::TestPingAbility(const std::u16string &dummy) {
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return 0;
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}
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```
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4. 定义和实现客户端TestAbilityProxy
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该类是Proxy端实现，继承IRemoteProxy<ITestAbility\>，调用SendRequest接口向Stub端发送请求，对外暴露服务端提供的能力。
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```
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class TestAbilityProxy : public IRemoteProxy<ITestAbility> {
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public:
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explicit TestAbilityProxy(const sptr<IRemoteObject> &impl);
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int TestPingService(const std::u16string &dummy) override;
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private:
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static inline BrokerDelegator<TestAbilityProxy> delegator_; // 方便使用iface_cast宏
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}
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TestAbilityProxy::TestAbilityProxy(const sptr<IRemoteObject> &impl)
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: IRemoteProxy<ITestAbility>(impl)
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{
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}
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int TestAbilityProxy::TestPingService(const std::u16string &dummy) {
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MessageOption option;
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MessageParcel dataParcel, replyParcel;
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if(!dataParcel.WriteInterfaceToken(GetDescriptor())) { //所有对外接口的proxy实现都要写入接口描述符，用于stub端检验
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return -1;
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}
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if(!dataParcel.WriteString16(dummy)) {
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return -1;
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}
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int error = Remote()->SendRequest(TRANS_ID_PING_ABILITY, dataParcel, replyParcel, option);
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int result = (error == ERR_NONE) ? replyParcel.ReadInt32() : -1;
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return result;
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}
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```
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5. 同步调用与异步调用
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|
||
essageOption作为发送接口（原型如下）的入参，可设定同步（TF\_SYNC）、异步（TF\_ASYNC）、接收FD（TF\_ACCEPT\_FDS），默认情况下设定为同步，其余可通过MessageOption构造方法或void SetFlags\(int flags\)设定。
|
||
|
||
```
|
||
int SendRequest(uint32_t code, MessageParcel &data,
|
||
MessageParcel &reply, MessageOption &option) override;
|
||
MessageOption option = { MessageOption::TF_ASYNC };
|
||
```
|
||
|
||
|
||
|
||
6. SA注册与启动
|
||
|
||
SA需要将自己的TestAbilityStub实例通过AddSystemAbility接口注册到SystemAbilityManager，设备内与分布式的注册参数不同。
|
||
|
||
```
|
||
// 注册到本设备内
|
||
auto samgr = SystemAbilityManagerClient::GetInstance().GetSystemAbilityManager();
|
||
samgr->AddSystemAbility(said, new TestAbility());
|
||
|
||
// 在组网场景下，会被同步到其他设备上
|
||
auto samgr = SystemAbilityManagerClient::GetInstance().GetSystemAbilityManager();
|
||
ISystemAbilityManager::SAExtraProp saExtra;
|
||
saExtra.isDistributed = true; // 设置为分布式SA
|
||
int result = samgr->AddSystemAbility(said, new TestAbility(), saExtra);
|
||
```
|
||
|
||
|
||
|
||
7. SA获取与调用
|
||
|
||
通过SystemAbilityManager的GetSystemAbility方法可获取到对应SA的代理IRemoteObject，然后构造TestAbilityProxy即可。
|
||
|
||
```
|
||
// 获取本设备内注册的SA的proxy
|
||
sptr<ISystemAbilityManager> samgr = SystemAbilityManagerClient::GetInstance().GetSystemAbilityManager();
|
||
sptr<IRemoteObject> remoteObject = samgr->GetSystemAbility(said);
|
||
sptr<ITestAbility> testAbility = iface_cast<ITestAbility>(remoteObject); // 使用iface_cast宏转换成具体类型
|
||
|
||
// 获取其他设备注册的SA的Proxy
|
||
sptr<ISystemAbilityManager> samgr = SystemAbilityManagerClient::GetInstance().GetSystemAbilityManager();
|
||
sptr<IRemoteObject> remoteObject = samgr->GetSystemAbility(sdid, deviceId); // deviceId是指定设备的标识符
|
||
sptr<TestAbilityProxy> proxy(new TestAbilityProxy(remoteObject)); // 直接构造具体Proxy
|
||
```
|
||
|
||
|
||
|
||
## 相关仓<a name="section1371113476307"></a>
|
||
|
||
分布式软总线子系统
|
||
|
||
**communication\_ipc**
|
||
|
||
utils
|
||
|
||
utils\_native
|
||
|
||
distributedschedule\_samgr
|
||
|