FBB::ServerSocket - Server socket accepting Internet connection requests
Linking option: -lbobcat
An 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 blocking or 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 file descriptor which may be used to initialize a std::istream and/or std::ostream. The std::istream is used to read information from the client process; the std::ostream is used to send information to the client process. Since a socket may be considered a file descriptor the available FBB::IFdStream, FBB::IFdStreamBuf, FBB::OFdStream, and 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 FBB::LocalServerSocket.
All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the namespace FBB.
- ServerSocket(size_t port):
This constructor initializes an FBB::ServerSocket object, which will listen for connections at the specified port. The construction of the socket does not mean that the FBB::ServerSocket object is actually listening for connections. To start listening, the member listen() should be used.
Copy and move constructors (and assignment operators) are not available.
All members of FBB::SocketBase (and thus of FBB::InetAddress) are available, as FBB::ServerSocket inherits from FBB::SocketBase.
- void listen(size_t backlog = 5, bool blocking = true):
The listen() member defines the way the FBB::ServerSocket will listen for clients requesting a connection. It can be used only once with a FBB::ServerSocket. An FBB::Exception object is thrown if listening fails, if the constructor could not create a socket, or if the SocketBase base class could not properly be constructed.
- The listen() member’s backlog parameter defines the size of the FBB::ServerSocket’s internal queue in which connection requests may be stored waiting for their turn to be serviced. When backlog requests are waiting and another request arrives, then that request is lost.
- The member’s second parameter, blocking, is used to control the blocking mode. By default, blocking is used, and 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 FBB::Selector object can be used to sense input on the server socket and/or on various client sockets.
- SocketBase accept():
The accept() member returns an FBB::SocketBase object containing information about the client whose connection request was accepted. The 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 FBB::SocketBase could be passed to a class derived from FBB::Fork, handling the communication with the child as a separate (child) process.
See also the clientsocket(3bobcat) example.
using namespace std;
using namespace FBB;
int main(int argc, char **argv)
if (argc == 1)
cerr << "Provide server port number\n";
size_t portnr = stoul(argv);
cerr << "server listens on port " << argv << 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
SocketBase fdb = server.accept();
int fd = fdb.socket();
cerr << "Client FD = " << fd << ", " << endl <<
"address = " << fdb.dottedDecimalAddress() << ", " <<
"communication through port " << fdb.port() << endl;
IFdStream in(fd); // stream to read from client
OFdStream out(fd); // stream to write to client
while (getline(in, cmd))
cout << "Got: " << cmd << endl;
out << "Got: " << cmd << "\r" << endl;
if (cmd == ’q’)
cout << "Ready for another connection\n";
catch (Exception const &err)
err.what() << endl <<
"Server socket on port " << argv <<
" can’t be opened" << endl;
bobcat/serversocket - defines the class interface
bobcat(7), clientsocket(3bobcat), fork(3bobcat), ifdstream(3bobcat), ifdbuf(3bobcat), inetaddress(3bobcat), localserversocket(3bobcat), ofdstream(3bobcat), ofdstream(3bobcat), select(2), selector(3bobcat), socketbase(3bobcat)
- https://fbb-git.gitlab.io/bobcat/: gitlab project page;
- bobcat_6.02.02-x.dsc: detached signature;
- bobcat_6.02.02-x.tar.gz: source archive;
- bobcat_6.02.02-x_i386.changes: change log;
- libbobcat1_6.02.02-x_*.deb: debian package containing the libraries;
- libbobcat1-dev_6.02.02-x_*.deb: debian package containing the libraries, headers and manual pages;
Bobcat is an acronym of `Brokken’s Own Base Classes And Templates’.
This is free software, distributed under the terms of the GNU General Public License (GPL).
Frank B. Brokken (firstname.lastname@example.org).