ddpserver

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DDP Server for C++

This C++ library implements server endpoint for Meteor's DDP protocol v1.

Use cases

• Provide a custom live data source from your C++ application to Meteor frontend
• Call your C++ methods from Meteor

Dependencies

• CMake 2.8+
• jvar - low-memory JSON serialization library (will be fetched and built automatically by CMake)

Build & install

• wget https://github.com/andrei-markeev/ddpserver/archive/master.tar.gz
• tar zxf master.tar.gz
• cd ddpserver-master
• mkdir build
• cd build
• cmake ..
• make
• make install

Use

DdpServer only processes DDP protocol itself. It should be used with some websocket library. Examples of integrating with following libraries are available:

• mongoose - examples/mongoose.cpp.
• websocketpp - examples/websocketpp.cpp.
• libwebsockets - examples/libwebsockets.cpp.

Other libraries can be integrated similarly.

Example below uses websocketpp.

C++:

jvar::Variant myMethod1(void *context, jvar::Variant& args)
{
	return args[0] + args[1];
}

void emitCallback(void *context, const std::string &output)
{
    websocketpp::connection_hdl hdl = *(websocketpp::connection_hdl *)context;
    wsServer->send(hdl, output.c_str(), output.length(), websocketpp::frame::opcode::text);
}

void websocket_on_message(websocketpp::connection_hdl hdl, websocket_server::message_ptr msg)
{
    ddpServer->setContext(&hdl);
    ddpServer->process(msg->get_payload());
}

// .. skipped ..

int main(int argc, char** argv)
{
	ddpServer = new DdpServer(emitCallback);
	ddpServer->registerMethod("myMethod1", myMethod1);

	// .. skipped ..
}

JavaScript (client-side):

MyConnection = DDP.connect("http://localhost:9002");

MyConnection.call("myMethod1", "param1", "param2", (error, result) => {
	if (error)
		alert(error.reason);
	else
		console.log(result);
});

Result:

Live data

It is also possible to implement Meteor live data:

C++:

jvar::Variant data;
data.createObject();
data.addProperty("banana", "value");
data.addProperty("tomato", 1234);
data.addProperty("kiwi", "something");
ddpServer->emitAdd("coll1", "element1_id", data);

// ...

jvar::Variant changeData;
changeData.createObject();
changeData.addProperty("banana", "new_value");
ddpServer->emitChange("coll1", "element1_id", changeData);

// ...

ddpServer->emitRemove("coll1", "element1_id");	

JS:

Collection1 = new Mongo.Collection("coll1", { connection: MyConnection });

Subscriptions aren't supported for now, all emits will be immediately published to the frontend. Subscriptions are planned, but for now you can easily emulate them using methods.

Meteor auth integration

It is possible to integrate Meteor authentication with DDP server. Meteor stores loginToken on client. Idea is to pass it along with the user id to C++ application, and then verify it by performing a separate request to Meteor REST API:

Example code:

• examples/meteor_auth.js.
• examples/meteor_auth.cpp.

Project roadmap

• Subscriptions support