DNA_Client

dna

1998 12-06

CLASS

DNA_Client - C++ network connection client

SYNOPSIS

DNA_Client performs the role of client in the client-server paradigm for network connections (e.g., TCP/IP).

MEMBER FUNCTIONS

virtual const DNA_Error & GetError(void) const

long GetTimeout(void) const
Return the timeout.

virtual GPL_Boolean IsConnected(void) const
Return TRUE if the client is connected to the server. Return FALSE otherwise.

void SetTimeout(const long t)
Set the timeout used for waiting to t.

virtual GPL_Boolean Initialize(void)
Initialize the client. This must be called before the first call to Request() or Reply() . Return TRUE if the initialization succeeded. Return FALSE if the initialization failed.

virtual void Finalize(void)
Finalize the client.

virtual GPL_Boolean Reconnect(void)
Clean up a broken connection and attempt reconnection to the server. Return TRUE if the reconnection succeeded. Return FALSE if the reconnection failed.

void SetDestination(DNA_IPPoint *d)
Set the address of the server to d.

void SetImp(DNA_UDPBindingImp *i)
Set the implementation used to i. The default implementation is an instance of DNA_TCPConnectionImp.

virtual void Process(void)
Check for any messages on the connection. While a message is received from the connection, call ProcessMessage() for that message.

virtual void ProcessMessage(DNA_Message & message)
Process the message message that was received from the connection. By default, the message handlers are invoked in order until one of them handles the message and marks it as consumed. Handlers which expire are removed from the handler list. Sub-classes that wish to perform additional processing should over-ride this function.

virtual GPL_Boolean Request(DNA_Message & message)
Send the request message to the server. Return TRUE if the send succeeds and FALSE if it fails.

virtual GPL_Boolean Reply(DNA_Message & message)
Send the reply message to the server. Return TRUE if the send succeeds and FALSE if it fails.

virtual GPL_Boolean Receive(DNA_Message & message)
Receive a message from the server. Return TRUE if the receive succeeds and FALSE if it fails. This call implies a synchronous behavior. Although not mutually exclusive with the supported asynchronous handler based paradigm, care should be taken if mixing the two.

virtual unsigned long GetNumberHandlers(void) const
Return the number of installed message handlers.

virtual void AppendHandler(const GPL_Pointer<DNA_MessageHandler> & handler)
Append the message handler, handler to the list of message handlers.

virtual void InsertHandler(const GPL_Pointer<DNA_MessageHandler> & handler, const unsigned long at)
Insert the message handler, handler at position at in the list of message handlers.

NOTES

Message handlers are given the opportunity to handle messages in the same order as the list of message handlers for the client. Thus, appending a handler will cause it to be given the opportunity to handle the message if and only if all preceding message handlers have not consumed the message. Conversely, inserting a message handler at position zero will cause it to be given the opportunity to handle the message regardless of subsequent handlers' consumption of the message.