深入浅出Alljoyn——实例分析之远程调用（Method)篇

深入浅出就是很深入的学习了很久，还是只学了毛皮，呵呵！

服务端完整代码：

 #include <qcc/platform.h>

 #include <assert.h>
 #include <signal.h>
 #include <stdio.h>
 #include <vector>

 #include <qcc/String.h>

 #include <alljoyn/BusAttachment.h>
 #include <alljoyn/DBusStd.h>
 #include <alljoyn/AllJoynStd.h>
 #include <alljoyn/BusObject.h>
 #include <alljoyn/MsgArg.h>
 #include <alljoyn/version.h>

 #include <alljoyn/Status.h>

 using namespace std;
 using namespace qcc;
 using namespace ajn;

 /*constants*/
 static const char* INTERFACE_NAME = "org.alljoyn.Bus.sample";
 static const char* SERVICE_NAME = "org.alljoyn.Bus.sample";
 static const char* SERVICE_PATH = "/sample";
 static const SessionPort SERVICE_PORT = ;

 static volatile sig_atomic_t s_interrupt = false;

 static void SigIntHandler(int sig)
 {
     s_interrupt = true;
 }

 class BasicSampleObject : public BusObject {
   public:
     BasicSampleObject(BusAttachment& bus, const char* path) :
         BusObject(path)
     {
         /** Add the test interface to this object */
         const InterfaceDescription* exampleIntf = bus.GetInterface(INTERFACE_NAME);
         assert(exampleIntf);
         AddInterface(*exampleIntf);

         /** Register the method handlers with the object */
         const MethodEntry methodEntries[] = {
             { exampleIntf->GetMember("cat"), static_cast<MessageReceiver::MethodHandler>(&BasicSampleObject::Cat) }
         };
         QStatus status = AddMethodHandlers(methodEntries, sizeof(methodEntries) / sizeof(methodEntries[]));
         if (ER_OK != status) {
             printf("Failed to register method handlers for BasicSampleObject.\n");
         }
     }

     void ObjectRegistered()
     {
         BusObject::ObjectRegistered();
         printf("ObjectRegistered has been called.\n");
     }

     void Cat(const InterfaceDescription::Member* member, Message& msg)
     {
         /* Concatenate the two input strings and reply with the result. */
         qcc::String inStr1 = msg->GetArg()->v_string.str;
         qcc::String inStr2 = msg->GetArg()->v_string.str;
         qcc::String outStr = inStr1 + inStr2;

         MsgArg outArg("s", outStr.c_str());
         QStatus status = MethodReply(msg, &outArg, );
         if (ER_OK != status) {
             printf("Ping: Error sending reply.\n");
         }
     }
 };

 class MyBusListener : public BusListener, public SessionPortListener {
     void NameOwnerChanged(const char* busName, const char* previousOwner, const char* newOwner)
     {
         if (newOwner && ( == strcmp(busName, SERVICE_NAME))) {
             printf("NameOwnerChanged: name=%s, oldOwner=%s, newOwner=%s.\n",
                    busName,
                    previousOwner ? previousOwner : "<none>",
                    newOwner ? newOwner : "<none>");
         }
     }
     bool AcceptSessionJoiner(SessionPort sessionPort, const char* joiner, const SessionOpts& opts)
     {
         if (sessionPort != SERVICE_PORT) {
             printf("Rejecting join attempt on unexpected session port %d.\n", sessionPort);
             return false;
         }
         printf("Accepting join session request from %s (opts.proximity=%x, opts.traffic=%x, opts.transports=%x).\n",
                joiner, opts.proximity, opts.traffic, opts.transports);
         return true;
     }
 };

 /** The bus listener object. */
 static MyBusListener s_busListener;

 /** Top level message bus object. */
 static BusAttachment* s_msgBus = NULL;

 /** Create the interface, report the result to stdout, and return the result status. */
 QStatus CreateInterface(void)
 {
     /* Add org.alljoyn.Bus.method_sample interface */
     InterfaceDescription* testIntf = NULL;
     QStatus status = s_msgBus->CreateInterface(INTERFACE_NAME, testIntf);

     if (status == ER_OK) {
         printf("Interface created.\n");
         testIntf->AddMethod("cat", "ss",  "s", "inStr1,inStr2,outStr", );
         testIntf->Activate();
     } else {
         printf("Failed to create interface '%s'.\n", INTERFACE_NAME);
     }

     return status;
 }

 /** Register the bus object and connect, report the result to stdout, and return the status code. */
 QStatus RegisterBusObject(BasicSampleObject* obj)
 {
     QStatus status = s_msgBus->RegisterBusObject(*obj);

     if (ER_OK == status) {
         printf("RegisterBusObject succeeded.\n");
     } else {
         printf("RegisterBusObject failed (%s).\n", QCC_StatusText(status));
     }

     return status;
 }

 /** Connect, report the result to stdout, and return the status code. */
 QStatus ConnectBusAttachment(void)
 {
     QStatus status = s_msgBus->Connect();

     if (ER_OK == status) {
         printf("Connect to '%s' succeeded.\n", s_msgBus->GetConnectSpec().c_str());
     } else {
         printf("Failed to connect to '%s' (%s).\n", s_msgBus->GetConnectSpec().c_str(), QCC_StatusText(status));
     }

     return status;
 }

 /** Start the message bus, report the result to stdout, and return the status code. */
 QStatus StartMessageBus(void)
 {
     QStatus status = s_msgBus->Start();

     if (ER_OK == status) {
         printf("BusAttachment started.\n");
     } else {
         printf("Start of BusAttachment failed (%s).\n", QCC_StatusText(status));
     }

     return status;
 }

 /** Create the session, report the result to stdout, and return the status code. */
 QStatus CreateSession(TransportMask mask)
 {
     SessionOpts opts(SessionOpts::TRAFFIC_MESSAGES, false, SessionOpts::PROXIMITY_ANY, mask);
     SessionPort sp = SERVICE_PORT;
     QStatus status = s_msgBus->BindSessionPort(sp, opts, s_busListener);

     if (ER_OK == status) {
         printf("BindSessionPort succeeded.\n");
     } else {
         printf("BindSessionPort failed (%s).\n", QCC_StatusText(status));
     }

     return status;
 }

 /** Advertise the service name, report the result to stdout, and return the status code. */
 QStatus AdvertiseName(TransportMask mask)
 {
     QStatus status = s_msgBus->AdvertiseName(SERVICE_NAME, mask);

     if (ER_OK == status) {
         printf("Advertisement of the service name '%s' succeeded.\n", SERVICE_NAME);
     } else {
         printf("Failed to advertise name '%s' (%s).\n", SERVICE_NAME, QCC_StatusText(status));
     }

     return status;
 }

 /** Request the service name, report the result to stdout, and return the status code. */
 QStatus RequestName(void)
 {
     const uint32_t flags = DBUS_NAME_FLAG_REPLACE_EXISTING | DBUS_NAME_FLAG_DO_NOT_QUEUE;
     QStatus status = s_msgBus->RequestName(SERVICE_NAME, flags);

     if (ER_OK == status) {
         printf("RequestName('%s') succeeded.\n", SERVICE_NAME);
     } else {
         printf("RequestName('%s') failed (status=%s).\n", SERVICE_NAME, QCC_StatusText(status));
     }

     return status;
 }

 /** Wait for SIGINT before continuing. */
 void WaitForSigInt(void)
 {
     while (s_interrupt == false) {
 #ifdef _WIN32
         Sleep();
 #else
         usleep( * );
 #endif
     }
 }

 /** Main entry point */
 int main(int argc, char** argv, char** envArg)
 {
     printf("AllJoyn Library version: %s.\n", ajn::GetVersion());
     printf("AllJoyn Library build info: %s.\n", ajn::GetBuildInfo());

     /* Install SIGINT handler */
     signal(SIGINT, SigIntHandler);

     QStatus status = ER_OK;

     /* Create message bus */
     s_msgBus = new BusAttachment("myApp", true);

     if (!s_msgBus) {
         status = ER_OUT_OF_MEMORY;
     }

     if (ER_OK == status) {
         status = CreateInterface();
     }

     if (ER_OK == status) {
         s_msgBus->RegisterBusListener(s_busListener);
     }

     if (ER_OK == status) {
         status = StartMessageBus();
     }

     BasicSampleObject testObj(*s_msgBus, SERVICE_PATH);

     if (ER_OK == status) {
         status = RegisterBusObject(&testObj);
     }

     if (ER_OK == status) {
         status = ConnectBusAttachment();
     }

     /*
      * Advertise this service on the bus.
      * There are three steps to advertising this service on the bus.
      * 1) Request a well-known name that will be used by the client to discover
      *    this service.
      * 2) Create a session.
      * 3) Advertise the well-known name.
      */
     if (ER_OK == status) {
         status = RequestName();
     }

     const TransportMask SERVICE_TRANSPORT_TYPE = TRANSPORT_ANY;

     if (ER_OK == status) {
         status = CreateSession(SERVICE_TRANSPORT_TYPE);
     }

     if (ER_OK == status) {
         status = AdvertiseName(SERVICE_TRANSPORT_TYPE);
     }

     /* Perform the service asynchronously until the user signals for an exit. */
     if (ER_OK == status) {
         WaitForSigInt();
     }

     /* Clean up msg bus */
     delete s_msgBus;
     s_msgBus = NULL;

     printf("Basic service exiting with status 0x%04x (%s).\n", status, QCC_StatusText(status));

     return (int) status;
 }

服务端主流程解析：

int main(int argc, char** argv, char** envArg)
{
    /* 注册系统信号回调函数*/
    signal(SIGINT, SigIntHandler);

    /* 创建Bus连接器 */
    s_msgBus = new BusAttachment("myApp", true);

    /* 创建object 的接口*/
        status = CreateInterface();

    /*绑定总线监听器*/
        s_msgBus->RegisterBusListener(s_busListener);

    /*开启总线*/
        status = StartMessageBus();

    /*实例化对象*/
    BasicSampleObject testObj(*s_msgBus, SERVICE_PATH);

    /*总线附件上注册对象*/
        status = RegisterBusObject(&testObj);

    /*连接到总线上*/
        status = ConnectToDaemon();

    /*请求一个服务名即wellknow name*/
        status = RequestName();

    const TransportMask SERVICE_TRANSPORT_TYPE = TRANSPORT_ANY;

    /*创建一个会话*/
        status = CreateSession(SERVICE_TRANSPORT_TYPE);

    /*在总线上广播服务名*/
        status = AdvertiseName(SERVICE_TRANSPORT_TYPE);

    /* 等待用户终止 */
        WaitForSigInt();

    /* 释放资源 */
    delete s_msgBus;
    s_msgBus = NULL;

    return (int) status;
}

客户端完整代码：

 #include <qcc/platform.h>

 #include <assert.h>
 #include <signal.h>
 #include <stdio.h>
 #include <vector>

 #include <qcc/String.h>

 #include <alljoyn/BusAttachment.h>
 #include <alljoyn/version.h>
 #include <alljoyn/AllJoynStd.h>
 #include <alljoyn/Status.h>

 using namespace std;
 using namespace qcc;
 using namespace ajn;

 /** Static top level message bus object */
 static BusAttachment* g_msgBus = NULL;

 /*constants*/
 static const char* INTERFACE_NAME = "org.alljoyn.Bus.sample";
 static const char* SERVICE_NAME = "org.alljoyn.Bus.sample";
 static const char* SERVICE_PATH = "/sample";
 static const SessionPort SERVICE_PORT = ;

 static bool s_joinComplete = false;
 static SessionId s_sessionId = ;

 static volatile sig_atomic_t s_interrupt = false;

 static void SigIntHandler(int sig)
 {
     s_interrupt = true;
 }

 /** AllJoynListener receives discovery events from AllJoyn */
 class MyBusListener : public BusListener, public SessionListener {
   public:
     void FoundAdvertisedName(const char* name, TransportMask transport, const char* namePrefix)
     {
         if ( == strcmp(name, SERVICE_NAME)) {
             printf("FoundAdvertisedName(name='%s', prefix='%s')\n", name, namePrefix);

             /* We found a remote bus that is advertising basic service's well-known name so connect to it. */
             /* Since we are in a callback we must enable concurrent callbacks before calling a synchronous method. */
             g_msgBus->EnableConcurrentCallbacks();
             SessionOpts opts(SessionOpts::TRAFFIC_MESSAGES, false, SessionOpts::PROXIMITY_ANY, TRANSPORT_ANY);
             QStatus status = g_msgBus->JoinSession(name, SERVICE_PORT, this, s_sessionId, opts);
             if (ER_OK == status) {
                 printf("JoinSession SUCCESS (Session id=%d).\n", s_sessionId);
             } else {
                 printf("JoinSession failed (status=%s).\n", QCC_StatusText(status));
             }
         }
         s_joinComplete = true;
     }

     void NameOwnerChanged(const char* busName, const char* previousOwner, const char* newOwner)
     {
         if (newOwner && ( == strcmp(busName, SERVICE_NAME))) {
             printf("NameOwnerChanged: name='%s', oldOwner='%s', newOwner='%s'.\n",
                    busName,
                    previousOwner ? previousOwner : "<none>",
                    newOwner ? newOwner : "<none>");
         }
     }
 };

 /** Create the interface, report the result to stdout, and return the result status. */
 QStatus CreateInterface(void)
 {
     /* Add org.alljoyn.Bus.method_sample interface */
     InterfaceDescription* testIntf = NULL;
     QStatus status = g_msgBus->CreateInterface(INTERFACE_NAME, testIntf);

     if (status == ER_OK) {
         printf("Interface '%s' created.\n", INTERFACE_NAME);
         testIntf->AddMethod("cat", "ss",  "s", "inStr1,inStr2,outStr", );
         testIntf->Activate();
     } else {
         printf("Failed to create interface '%s'.\n", INTERFACE_NAME);
     }

     return status;
 }

 /** Start the message bus, report the result to stdout, and return the result status. */
 QStatus StartMessageBus(void)
 {
     QStatus status = g_msgBus->Start();

     if (ER_OK == status) {
         printf("BusAttachment started.\n");
     } else {
         printf("BusAttachment::Start failed.\n");
     }

     return status;
 }

 /** Handle the connection to the bus, report the result to stdout, and return the result status. */
 QStatus ConnectToBus(void)
 {
     QStatus status = g_msgBus->Connect();

     if (ER_OK == status) {
         printf("BusAttachment connected to '%s'.\n", g_msgBus->GetConnectSpec().c_str());
     } else {
         printf("BusAttachment::Connect('%s') failed.\n", g_msgBus->GetConnectSpec().c_str());
     }

     return status;
 }

 /** Register a bus listener in order to get discovery indications and report the event to stdout. */
 void RegisterBusListener(void)
 {
     /* Static bus listener */
     static MyBusListener s_busListener;

     g_msgBus->RegisterBusListener(s_busListener);
     printf("BusListener Registered.\n");
 }

 /** Begin discovery on the well-known name of the service to be called, report the result to
    stdout, and return the result status. */
 QStatus FindAdvertisedName(void)
 {
     /* Begin discovery on the well-known name of the service to be called */
     QStatus status = g_msgBus->FindAdvertisedName(SERVICE_NAME);

     if (status == ER_OK) {
         printf("org.alljoyn.Bus.FindAdvertisedName ('%s') succeeded.\n", SERVICE_NAME);
     } else {
         printf("org.alljoyn.Bus.FindAdvertisedName ('%s') failed (%s).\n", SERVICE_NAME, QCC_StatusText(status));
     }

     return status;
 }

 /** Wait for join session to complete, report the event to stdout, and return the result status. */
 QStatus WaitForJoinSessionCompletion(void)
 {
     unsigned int count = ;

     while (!s_joinComplete && !s_interrupt) {
         if ( == (count++ % )) {
             printf("Waited %u seconds for JoinSession completion.\n", count / );
         }

 #ifdef _WIN32
         Sleep();
 #else
         usleep( * );
 #endif
     }

     return s_joinComplete && !s_interrupt ? ER_OK : ER_ALLJOYN_JOINSESSION_REPLY_CONNECT_FAILED;
 }

 /** Do a method call, report the result to stdout, and return the result status. */
 QStatus MakeMethodCall(void)
 {
     ProxyBusObject remoteObj(*g_msgBus, SERVICE_NAME, SERVICE_PATH, s_sessionId);
     const InterfaceDescription* alljoynTestIntf = g_msgBus->GetInterface(INTERFACE_NAME);

     assert(alljoynTestIntf);
     remoteObj.AddInterface(*alljoynTestIntf);

     Message reply(*g_msgBus);
     MsgArg inputs[];

     inputs[].Set("s", "Hello ");
     inputs[].Set("s", "World!");

     QStatus status = remoteObj.MethodCall(SERVICE_NAME, "cat", inputs, , reply, );

     if (ER_OK == status) {
         printf("'%s.%s' (path='%s') returned '%s'.\n", SERVICE_NAME, "cat",
                SERVICE_PATH, reply->GetArg()->v_string.str);
     } else {
         printf("MethodCall on '%s.%s' failed.", SERVICE_NAME, "cat");
     }

     return status;
 }

 /** Main entry point */
 int main(int argc, char** argv, char** envArg)
 {
     printf("AllJoyn Library version: %s.\n", ajn::GetVersion());
     printf("AllJoyn Library build info: %s.\n", ajn::GetBuildInfo());

     /* Install SIGINT handler. */
     signal(SIGINT, SigIntHandler);

     QStatus status = ER_OK;

     /* Create message bus. */
     g_msgBus = new BusAttachment("myApp", true);

     /* This test for NULL is only required if new() behavior is to return NULL
      * instead of throwing an exception upon an out of memory failure.
      */
     if (!g_msgBus) {
         status = ER_OUT_OF_MEMORY;
     }

     if (ER_OK == status) {
         status = CreateInterface();
     }

     if (ER_OK == status) {
         status = StartMessageBus();
     }

     if (ER_OK == status) {
         status = ConnectToBus();
     }

     if (ER_OK == status) {
         RegisterBusListener();
         status = FindAdvertisedName();
     }

     if (ER_OK == status) {
         status = WaitForJoinSessionCompletion();
     }

     if (ER_OK == status) {
         status = MakeMethodCall();
     }

     /* Deallocate bus */
     delete g_msgBus;
     g_msgBus = NULL;

     printf("Basic client exiting with status 0x%04x (%s).\n", status, QCC_StatusText(status));

     return (int) status;
 }

客户端主流程解析：

int main(int argc, char** argv, char** envArg)
{
    printf("AllJoyn Library version: %s.\n", ajn::GetVersion());
    printf("AllJoyn Library build info: %s.\n", ajn::GetBuildInfo());

    /* 注册系统信号回调函数*/
    signal(SIGINT, SigIntHandler);

    QStatus status = ER_OK;

    /* 创建Bus连接器 */
    g_msgBus = new BusAttachment("myApp", true);

    /* This test for NULL is only required if new() behavior is to return NULL
     * instead of throwing an exception upon an out of memory failure.
     */
    if (!g_msgBus) {
        status = ER_OUT_OF_MEMORY;
    }
    /* 创建object 的接口*/
    if (ER_OK == status) {
        status = CreateInterface();
    }
    /*开启总线*/
    if (ER_OK == status) {
        status = StartMessageBus();
    }
    /*连接到总线上*/

    if (ER_OK == status) {
        status = ConnectToBus();
    }

    if (ER_OK == status) {
        RegisterBusListener();/*绑定总线监听器*/
        status = FindAdvertisedName();/*在总线上发现服务名*/
    }

    if (ER_OK == status) {
        status = WaitForJoinSessionCompletion();
    }

    /*远程调用方法*/

    if (ER_OK == status) {
        status = MakeMethodCall();
    }

    /* 释放资源 */
    delete g_msgBus;
    g_msgBus = NULL;

    printf("Basic client exiting with status 0x%04x (%s).\n", status, QCC_StatusText(status));

    return (int) status;
}

通信过程中比较重要的几点：

1、 接口由bus连接器创建和保存所以创建的实例

2、 对象具体实现接口的属性（方法，属性和信号），与具体接口绑定，作为对象对外的接口。（可以含有多个接口）

3、连接总线s_msgBus->Connect()是通过dbus方式实现的，利用了dbus中现存的方法和消息。

用下面的图可能表达的更清楚：

通过Bus建立好连接后，服务端的object提供接口比如说方法， 那么客户端的object只需产生一个object的代理，即可调用服务端的object提供接口，是不是比较好玩。

服务端方法调用的代码：

服务端：通过接受客户端提供的参数，并通过MethodReply（）给客户端返回结果
void Cat(const InterfaceDescription::Member* member, Message& msg)
    {
        /* Concatenate the two input strings and reply with the result. */
        qcc::String inStr1 = msg->GetArg()->v_string.str;
        qcc::String inStr2 = msg->GetArg()->v_string.str;
        qcc::String outStr = inStr1 + inStr2;

        MsgArg outArg("s", outStr.c_str());
        QStatus status = MethodReply(msg, &outArg, );
        if (ER_OK != status) {
            printf("Ping: Error sending reply.\n");
        }
}

客户端方法调用的代码：

QStatus status = remoteObj.MethodCall(SERVICE_NAME, "cat", inputs, , reply, );

　　说了这么多，这个代码的作用是干嘛呢，就是服务端提供一个连接字符串（str1+str2)的方法，并将结果返回给客户端。当然这只是一个很简单sample，如果你将你家电视定义了换台方法的话，用手机就可以通过调用这个方法进行控制了，当然前提是你的电视和手机在一个网内！

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