postMessageAndAwaitResponse: Uncaught Error: The plugin has not registered a handler for synchronous messages. See the documentation for PPB_Messaging::RegisterMessageHandler and PPP_MessageHandler.

[Alex Ivasyuv]

Hello!

I'm new to NaCl, and I'm not a C++ developer :) I'm trying to emulate blocking thread in JS. I use postMessageAndAwaitResponse.

The issue, that I get an exception:

Uncaught Error: The plugin has not registered a handler for synchronous messages. See the documentation for PPB_Messaging::RegisterMessageHandler and PPP_MessageHandler.

Here's my C++ code:

#include "ppapi/cpp/instance.h"
#include "ppapi/cpp/message_handler.h"
#include "ppapi/cpp/module_impl.h"
#include "ppapi/cpp/var.h"
#include "ppapi/cpp/message_loop.h"

class HelloTutorialInstance : public pp::MessageHandler, public pp::Instance {
public:
    explicit HelloTutorialInstance(PP_Instance instance)
            : pp::Instance(instance) {

        pp::MessageLoop loop;

        this->RegisterMessageHandler(this, loop);
    }

    virtual pp::Var HandleBlockingMessage(pp::InstanceHandle instance,
            const pp::Var &var) {
        return var;
    }

    virtual void HandleMessage(const pp::Var &message) {
    }

    virtual void HandleMessage(pp::InstanceHandle instance, const pp::Var &var) {
    }

    virtual void WasUnregistered(pp::InstanceHandle instance) {
    }
};

class HelloTutorialModule : public pp::Module {
public:
    HelloTutorialModule() : pp::Module() {
    }

    virtual ~HelloTutorialModule() {
    }

    virtual pp::Instance *CreateInstance(PP_Instance instance) {
        return new HelloTutorialInstance(instance);
    }
};

namespace pp {
    Module *CreateModule() {
        return new HelloTutorialModule();
    }
}

But after code rebuild I still get the same error. What is wrong with my code?

[Ben Smith]

Hi Alex,

You need to register the message handler on a different thread. Take a look at the messaging example in the SDK.

HTH,

-Ben

[Alex Ivasyuv]

Thank you so much!

[TOM HU]

Hi, Alex Ivasyuv

Do you have solve this problem? using  like the messaging example in the SDK ?

[TOM HU]

Hi, Ben Smith

Do you have try to  compile the messaging example with "win" toolchain?  The output file is messaging.dll.

When sending a message to PPAPI module by javascript with function "postMessage",  the PPAPI module  doesn't receive it, no respone.