namespace libt2n
{
+/** @brief provide access to client_connection singletons and call-handling function
+
+ This is an abstact base class for use with T2nSingletonWrapper. It provides access
+ to the singleton-client_connection and offers a handle-method which is used for
+ every call to a method on a t2n-server.
+*/
class ConnectionWrapper
{
private:
virtual ~ConnectionWrapper()
{ }
+ /** @brief return active connection, create new one if not existing
+
+ Return a pointer to an active client_connection. Use detail-data
+ stored within the derived class to create a new connection if needed,
+ otherwise return an alredy active connection. The derived class has
+ to take care of destroying the connection when not needed anymore.
+ */
virtual client_connection* get_connection()=0;
- virtual void handle(command_client* stubBase, boost::function< void() > f)
+ /** @brief this function is called on every execution of a method on a server
+
+ @param stubBase pointer to the command_client executing the call
+ @param f boost::function object containing the method to call and all parameters
+ @retval true if the call was successful and the original return-value of the called function can be used
+ false if T2nSingletonWrapper has to create a return-value with the default-constructor
+
+ T2nSingletonWrapper will call this function on every execution of a server-side
+ method. This version will just call the function without any special treatment.
+ You can overload this function to implement different error handling strategies.
+ */
+ virtual bool handle(command_client* stubBase, boost::function< void() > f)
{
f();
+ return true;
}
long long get_command_timeout_usec(void)
static const char* NotInitializedMessage;
};
+/** @brief wrap calls to server-side-functions with different error-handling strategies
+
+ Template class to access a process-wide singleton server-connection and to wrap all
+ calls using this connection with an error-handling strategy (e.g. to reconnect when
+ the connection broke). The source looks very complicated due to heavy use of templates,
+ look at the 3rd codegen example to see how to use it.
+*/
template< class Client >
class T2nSingletonWrapper : public T2nSingletonWrapperMessages
{
if (WrappedConnection.get() == NULL)
throw std::logic_error(NotInitializedMessage);
- std::auto_ptr<Client> stub(new Client(*(WrappedConnection->get_connection()),
+ std::auto_ptr<Client> stub(new Client(WrappedConnection->get_connection(),
WrappedConnection->get_command_timeout_usec(),
WrappedConnection->get_hello_timeout_usec()));
ensure_singleton_there();
typename detail::TypeWrap<R>::type result;
+
+ // bind our Client-object and the local result
detail::Call<R> call( boost::bind( f, SingletonObject->Stub.get()), result );
- WrappedConnection->handle(SingletonObject->Stub.get(),call);
+
+ // let the wrapper-handler call the fully-bound function
+ if (!WrappedConnection->handle(SingletonObject->Stub.get(),call))
+ {
+ // create an result with default-constructor if the handler could not
+ // successfully do a call but no exception occured
+ result=typename detail::TypeWrap<R>::type();
+ }
return result;
}