bionic (3) localserversocket.3bobcat.gz
NAME
FBB::LocalServerSocket - Unix Domain Server socket accepting connection requests
SYNOPSIS
#include <bobcat/localserversocket>
Linking option: -lbobcat
DESCRIPTION
An FBB::LocalServerSocket defines a Unix Domain server socket, listening for connection requests from the
local host using a Unix Domain socket. 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 requesting 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.
NAMESPACE
FBB
All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the
namespace FBB.
INHERITS FROM
FBB::LocalSocketBase
ENUMERATION
The following enumeration is defined in th class FBB::LocalServerSocket:
enum Socket
This enumeration holds two values:
o KEEP:
When this value is specified at construction time, the file representing the Unix Domain Socket is
not removed when the LocalServerSocket is destroyed.
o UNLINK:
When this value is specified at construction time, the file representing the Unix Domain Socket is
removed when the LocalServerSocket is destroyed. As a socket cannot be reused, this is the default
value used with the LocalServerSocket constructor.
CONSTRUCTOR
o LocalServerSocket():
This constructor creates an empty (non-functioning) FBB::LocalServerSocket object. Before it can
be used, the open() member must be called (see below).
o LocalServerSocket(string const &name, Socket action = UNLINK) throw (Exception):
This constructor initializes an FBB::LocalServerSocket object, which will listen for connection
requests using the named Unix Domain socket. An FBB::Exception is thrown if the socket could not
be constructed. If the constructor is given a second argument FBB::LocalServerSocket::KEEP, the
constructed socket is not unlinked when the FBB::LocalServerSocket object is destroyed. The
construction of the socket does not mean that the FBB::LocalServerSocket object is actually
listening for connections. To start listening, the member listen() should be called. The copy
constructor is not available.
MEMBER FUNCTIONS
o size_t accept():
The accept() member returns an size_t which is a file descriptor (socket) that may be used to
communicate with the client requesting the connection. In more complex programs the returned file
descriptor (socket) could be passed to a class derived from FBB::Fork, handling the communication
with the child as a separate (child) process.
o void listen(size_t backlog = 5, bool blocking = true):
The listen() member defines the way the FBB::LocalServerSocket will listen for clients requesting
a connection. It can be used only once with a FBB::LocalServerSocket. An FBB::Exception object is
thrown if listening fails.
The listen() member’s backlog parameter defines the size of the FBB::LocalServerSocket’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.
o void open(string const &name, Socket action = UNLINK):
This member prepares a FBB::LocalServerSocket object for use. It should only be used in
combination with the default constructor. Following open() the FBB:::LocalServerSocket object will
be able to listen for connection requests using the named Unix Domain socket. An FBB::Exception
is thrown if the socket could not be constructed. If the a second argument
FBB::LocalServerSocket::KEEP, is provided the constructed socket is not unlinked when the
FBB::LocalServerSocket object is destroyed. The construction of the socket does not mean that the
FBB::LocalServerSocket object is actually listening for connections. To start listening, the
member listen() should be called next.
EXAMPLE
See also the localclientsocket(3bobcat) example. #include <iostream> #include <bobcat/localserversocket> #include <bobcat/ifdstream> #include <bobcat/ofdstream> using namespace std; using namespace FBB; int main(int argc, char **argv) try { if (argc == 1) { cerr << "Provide local filename, e.g., /tmp/uds\n"; return 1; } LocalServerSocket server(argv[1]); cerr << "server using `" << argv[1] << "’" << endl; cout << "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) { int fd = server.accept(); cerr << "Client FD = " << fd << ", " << 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; }
FILES
bobcat/serversocket - defines the class interface
SEE ALSO
bobcat(7), localclientsocket(3bobcat), fork(3bobcat), ifdstream(3bobcat), ifdstreambuf(3bobcat), localsocketbase(3bobcat), ofdstream(3bobcat), ofdstream(3bobcat), select(2), selector(3bobcat), serversocket(3bobcat)
BUGS
None Reported.
DISTRIBUTION FILES
o bobcat_4.08.02-x.dsc: detached signature;
o bobcat_4.08.02-x.tar.gz: source archive;
o bobcat_4.08.02-x_i386.changes: change log;
o libbobcat1_4.08.02-x_*.deb: debian package holding the libraries;
o libbobcat1-dev_4.08.02-x_*.deb: debian package holding the libraries, headers and manual pages;
o http://sourceforge.net/projects/bobcat: public archive location;
BOBCAT
Bobcat is an acronym of `Brokken’s Own Base Classes And Templates’.
COPYRIGHT
This is free software, distributed under the terms of the GNU General Public License (GPL).
AUTHOR
Frank B. Brokken (f.b.brokken@rug.nl).