I know there is an example helloworld program in gRPC source. However, being new to this, I don't understand how to write more than one async services in the server. The example here talks about spawning new instances of a class to handle SayHello service calls.
SayBye, so that I can make calls to it from client?
See this
thread and
the relevant
example.
The suggestion is to add a bool parameter to CallData (hello_ in
this example), instantiate two CallData objects, one with hello_ =
true, and one with hello_ = false, and have each one request a
different RPC.
if (hello_) {
service_->RequestSayHello(...);
} else {
service_->RequestSayBye(...);
}
For more than two types of calls, you could achieve the same behavior
with an enum instead of a bool.
A more flexible approach would be to have a different CallData-like
class for each RPC. However when you get a tag from cq_->Next(), you
know that it is a pointer to an object of one of these classes, but you
don't know its exact type. To overcome this, you can have them all
inherit from a class with a virtual Proceed() member function,
implement it as needed in each subclass, and when you get a tag, cast it
as CallData and call Proceed().
class CallData {
public:
virtual void Proceed() = 0;
};
class HelloCallData final : public CallData {...};
class ByeCallData final : public CallData {...};
...
new HelloCallData(...);
new ByeCallData(...);
cq_->Next(&tag, &ok);
static_cast<CallData*>(tag)->Proceed();
...
