includefile(include/header)

COMMENT(manpage, section, releasedate, archive, short name)
manpage(FBB::ServerSocket)(3bobcat)
    (_CurYrs_)(libbobcat-dev__CurVers_)
                    (Server Socket)

manpagename(FBB::ServerSocket)
            (Server socket accepting Internet connection requests)

manpagesynopsis()
    bf(#include <bobcat/serversocket>)nl()
    Linking option: tt(-lbobcat) 

manpagedescription()
    An bf(FBB::ServerSocket) may be constructed to listen for connection
requests from the Internet or from the local host. Connection requests may be
accepted in either em(blocking) or em(non-blocking) modes. When a connection
is accepted a socket is returned which may be used to read information from or
write information to the client that requested the connection. The socket that
is made available is a em(file descriptor) which may be used to initialize a
bf(std::istream) and/or bf(std::ostream). The bf(std::istream) is used to read
information from the client process; the bf(std::ostream) is used to send
information to the client process.  Since a socket may be considered a em(file
descriptor) the available bf(FBB::IFdStream), bf(FBB::IFdStreamBuf),
bf(FBB::OFdStream), and bf(FBB::OFdStreamBuf) classes may be used profitably
here. Note that having available a socket does not mean that this defines the
communication protocol. It is (still) the responsibility of the programmer to
comply with an existing protocol or to implement a tailor-made protocol. The
latter situation implies that the sequence of input- and output operations is
defined by the programmer.

    A Unix Domain server socket can be defined using
tt(FBB::LocalServerSocket). 

includefile(include/namespace)

manpagesection(INHERITS FROM)
    bf(FBB::SocketBase)

manpagesection(CONSTRUCTOR)
    itemization(
    itb(ServerSocket(size_t  port))
        This constructor initializes an bf(FBB::ServerSocket) object, which
will listen for connections at the specified port.  The construction of the
socket does not mean that the bf(FBB::ServerSocket) object is actually
listening for connections. To start listening, the member bf(listen()) should
be used.
    )

    Copy and move constructors (and assignment operators) are not available.

manpagesection(MEMBER FUNCTIONS)
     All members of bf(FBB::SocketBase) (and thus of bf(FBB::InetAddress)) are
available, as bf(FBB::ServerSocket) inherits from bf(FBB::SocketBase).
    itemization(
    itb(void listen(size_t backlog = 5, bool blocking = true))
        The bf(listen()) member defines the way the bf(FBB::ServerSocket) will
listen for clients requesting a connection.  It can be used only once with a
bf(FBB::ServerSocket). An bf(FBB::Exception) object is thrown if listening
fails, if the constructor could not create a socket, or if the bf(SocketBase)
base class could not properly be constructed.

     The bf(listen()) member's tt(backlog) parameter defines the size of the
bf(FBB::ServerSocket)'s internal queue in which connection requests may be
stored waiting for their turn to be serviced. When tt(backlog) requests are
waiting and another request arrives, then that request is lost. 

    The member's second parameter, tt(blocking), is used to control the
blocking mode. By default, blocking is used, and tt(listen()) will wait until
a connection is established. This is ok in situations where clients connect
infrquently and for relatively short time intervals. Otherwise, in more
complex programs, an bf(FBB::Selector) object can be used to sense input on
the server socket and/or on various client sockets.

    itb(SocketBase accept())
        The bf(accept()) member returns an bf(FBB::SocketBase) object
containing information about the client whose connection request was
accepted. The bf(FBB::SocketBase) object's socket value may be used to
initialize streams that can be used to communicate with the client. In more
complex programs the bf(FBB::SocketBase) could be passed to a class derived
from bf(FBB::Fork), handling the communication with the child as a separate
(child) process. 
    )


manpagesection(EXAMPLE)
    See also the bf(clientsocket)(3bobcat) example.
        verb(
    #include <iostream>
    #include <bobcat/serversocket>
    #include <bobcat/ifdstream>
    #include <bobcat/ofdstream>
    
    #include <bobcat/a2x>
    
    using namespace std;
    using namespace FBB;
    
    int main(int argc, char **argv)
    try
    {
        if (argc == 1)
        {
            cerr << "Provide server port number\n";
            return 1;
        }
    
        size_t portnr = A2x(argv[1]);
    
        ServerSocket server(portnr);
    
        cerr << "server listens on port " << argv[1] << endl;
    
        cerr << "serversocket returns:\n" <<
            "address = " << server.dottedDecimalAddress() << "\n"
            "port    = " << server.port() << endl;
    
        int fd = server.socket();       // open the socket's descriptor
    
        cout << "File descriptor of the socket is " << fd << "\n"
            "The server terminates when it receives a "
                                        "single `q' on a line\n"
            "A connection is terminated when no input "
                                        "is received anymore.\n"
            "Then another connection is possible" << endl;
    
        server.listen();                // listen in blocking mode
    
        while (true)
        {
            SocketBase fdb = server.accept();
            int fd = fdb.socket();
    
            cerr << "Client FD = " << fd << ", " << endl <<
                    "address = " << fdb.dottedDecimalAddress() << ", " << 
                    endl <<
                    "communication through port " << fdb.port() << endl;
    
            IFdStream in(fd);           // stream to read from client
            OFdStream out(fd);          // stream to write to client
            string cmd;
            
            while (getline(in, cmd))
            {
                cout << "Got: " << cmd << endl;
                out << "Got: " << cmd << "\r" << endl;
    
                if (cmd[0] == 'q')
                    return 0;
            }
            cout << "Ready for another connection\n";
        }
    }
    catch (Exception const &err)
    {
        cerr <<
            err.what() << endl <<
            "Server socket on port " << argv[1] << 
            " can't be opened" << endl;
        return -1;
    }        
        )

manpagefiles()
    em(bobcat/serversocket) - defines the class interface

manpageseealso()
    bf(bobcat)(7), bf(clientsocket)(3bobcat), bf(fork)(3bobcat),
bf(ifdstream)(3bobcat), bf(ifdbuf)(3bobcat), bf(inetaddress)(3bobcat),
bf(localserversocket)(3bobcat), bf(ofdstream)(3bobcat),
bf(ofdstream)(3bobcat), bf(select)(2), bf(selector)(3bobcat),
bf(socketbase)(3bobcat)

manpagebugs()
    None Reported.

includefile(include/trailer)
