tcp_acceptor

The os_tcp_acceptor template class extends the os_tcp_connection_server class. The os_tcp_connection_server class allows accepting incoming connections on a particular address. The os_tcp_acceptor extends it by providing functionality for creating and executing service handlers to serve the accepted connections. The type of the service handler, its creation, and its execution strategies can be specified as template instantiation parameters to the os_tcp_acceptor class.

The ServiceHandler , the first template parameter, requires a class to have following public interface.

• os_tcp_socket& tcp_socket() -Used by the os_tcp_acceptor object to establish a communication endpoint with the client application.
• void* run() -Called by the Executor object to initiate service handling for the client application.

Alternately, the ServiceHandler object could inherit from os_handler_stream class for the os_tcp_socket member data and os_tcp_socket& tcp_socket() member function, thereby not requiring to implement that functionality directly in its own class. The ServiceHandler object should delete itself in void* run() after it is done serving the client.

The Executor , the second template parameter, can be passed one of three concurrency strategy implementations provided (os_same_thread_executor , os_new_thread_executor , and os_thread_pool_executor ) or a custom implementation with the following public interface.

• template< class ServiceHandler > void execute( ServiceHandler* handler ) -Calls the void* run() method of the ServiceHandler within the thread context specified by the Executor concurrency strategy.

The Creator , the third template parameter, requires a class to have the following public interface.

• template< class ServiceHandler > -Templarizes the Creator class so that the ServiceHandler object does not have to inherit from a specific interface class.
• ServiceHandler* operator()() const -Decouples the creation of the ServiceHandler object to allow more flexibility.

Connection requests are handled in the handle_accept() method. A ServiceHandler object is created using the Creator function object. The created ServiceHandler object should contain an os_tcp_socket object member which is used to establish the connection with the client socket. A ServiceHandler object could inherit from os_handler_stream class for the os_tcp_socket object or alternatively implement the functionality of os_handler_stream class directly in its own class without inheriting from it. After the connection is established the ServiceHandler object is passed to the Executor object for execution. The Executor object calls the void* run() method of the ServiceHandler to initiate service handling.

The application can wait for the connection requests using the handle_accept() method or through the os_dispatcher instance. A single thread application could use os_dispatcher class and a multithread application could use a separate thread that repeated calls handle_accept() to accept connections and initiate service handlers.

The os_tcp_acceptor , os_tcp_connector , and os_dispatcher classes can be collectively used to synchronously or asynchronously establish connections and perform service processing at the two connection endpoints.

This class is implemented based on the Acceptor-Connector pattern described in the paper - "Acceptor-Connector - An Object Creational Pattern for connecting and Initializing Communication Services" by Douglas C. Schmidt published in the book "Pattern Languages of Program Design 3", Addison-Wesley 1997.

Use of member template feature gives the flexibility of not having the various classes to inherit from a specific interface class. Therefore, the compiler must be able to support member templates and OS_ENABLE_MEMBER_TEMPLATE_FEATURES must be defined to use this class.

Library

Framework<ToolKit>

Declaration

#include <ospace/framework/acceptor.h>

template< class ServiceHandler, class Executor, class Creator >
class os_tcp_acceptor : public os_tcp_connection_server

Interface

Throws: os_network_toolkit_error

Throws: os_network_toolkit_error

Throws: os_network_toolkit_error