ACE Tutorial 015
Building a protocol stream

We'll take a look first at the client application. As usual, our goal is to keep the main() application as simple as possible and delegate the tricky stuff to another object.

    // page02.html,v 1.17 2003/08/19 15:08:26 schmidt Exp

    /* The Client object will implement the nasty details of connecting to
       communicating with the server
    */
    #include "Client_i.h"

    int main(int argc, char *argv[])
    {
            // How many messages will we send?
        int mcount = argc > 1 ? ACE_OS::atoi(argv[1]) : 3;

            // Construct a Client with our desired endpoint.
        Client client(ACE_DEFAULT_SERVER_PORT,ACE_DEFAULT_SERVER_HOST);

            // Attempt to open the connection to the server.
        if( client.open() == -1 )
        {
            ACE_ERROR_RETURN ((LM_ERROR, "%p\n", "Client::open()"), -1);
        }

            // Send a few messages to the server and get some responses...
        for( int i = 0 ; i < mcount ; ++i )
        {
                // Since we'll be using a Protocol Stream (even though we
                // don't know that at this level) we require the use of
                // ACE_Message_Block objects to send/receive data.
            ACE_Message_Block * message = new ACE_Message_Block( 128 );

                // Construct a silly message to send to the server.
                // Notice that we're careful to add one to the strlen() so
                // that we also send the end-of-string NULL character.
            ACE_OS::sprintf (message->wr_ptr (), "This is message %d.", i);
            message->wr_ptr (strlen (message->rd_ptr ())+1);

                // client will take ownership of the message block so that
                // we don't have to remember to release().  We *do* have
                // to remember not to use it after put() since it may be
                // released almost immediately.
            client.put( message );

            ACE_Message_Block * response;

                // get() takes an ACE_Message_Block pointer reference.  We then
                // assume ownership of it and must release() when we're done.
            if( client.get( response ) == -1 )
            {
                ACE_DEBUG ((LM_INFO, "(%P|%t) Failed to get response from server\n" ));
                break;
            }

            ACE_DEBUG ((LM_INFO, "(%P|%t) The server's response:  (%s)\n",
                        response->rd_ptr()));

                // Now that we're through with the response we have to
                // release() it to avoid memory leaks.
            response->release();
        }

        ACE_DEBUG ((LM_INFO, "(%P|%t) Shutting down the stream\n" ));

            // Before we exit, it's a good idea to properly close() the connection.
        if( client.close() == -1 )
        {
            ACE_ERROR_RETURN ((LM_ERROR, "%p\n", "Client::close()"), -1);
        }

        return(0);
    }

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