ZMQII-28: Bidirectional introduction on TCP connection establishment

19 files changed, 387 insertions, 459 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 0fdaf37..0f47e7b 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -115,12 +115,11 @@ libzmq_la_SOURCES = app_thread.hpp \
     ypollset.hpp \
     yqueue.hpp \
     zmq_connecter.hpp \
-    zmq_connecter_init.hpp \
     zmq_decoder.hpp \
     zmq_encoder.hpp \
     zmq_engine.hpp \
+    zmq_init.hpp \
     zmq_listener.hpp \
-    zmq_listener_init.hpp \
     app_thread.cpp \
     devpoll.cpp \
     dispatcher.cpp \
@@ -161,12 +160,11 @@ libzmq_la_SOURCES = app_thread.hpp \
     ypollset.cpp \
     zmq.cpp \
     zmq_connecter.cpp \
-    zmq_connecter_init.cpp \
     zmq_decoder.cpp \
     zmq_encoder.cpp \
     zmq_engine.cpp \
-    zmq_listener.cpp \
-    zmq_listener_init.cpp
+    zmq_init.cpp \
+    zmq_listener.cpp
 
 libzmq_la_LDFLAGS = -version-info @LTVER@ @LIBZMQ_EXTRA_LDFLAFS@
 
diff --git a/src/i_inout.hpp b/src/i_inout.hpp
index b82a476..8a0ce6a 100644
--- a/src/i_inout.hpp
+++ b/src/i_inout.hpp
@@ -22,6 +22,8 @@
 
 #include "../bindings/c/zmq.h"
 
+#include "stdint.hpp"
+
 namespace zmq
 {
 
@@ -47,8 +49,8 @@ namespace zmq
         //  Return pointer to the owning socket.
         virtual class socket_base_t *get_owner () = 0;
 
-        //  Returns the name of associated session.
-        virtual const char *get_session_name () = 0;
+        //  Return ordinal number of the session.
+        virtual uint64_t get_ordinal () = 0;
     };
 
 }
diff --git a/src/pgm_receiver.cpp b/src/pgm_receiver.cpp
index 2a24858..1d4d695 100644
--- a/src/pgm_receiver.cpp
+++ b/src/pgm_receiver.cpp
@@ -37,11 +37,10 @@
 #include "i_inout.hpp"
 
 zmq::pgm_receiver_t::pgm_receiver_t (class io_thread_t *parent_, 
-      const options_t &options_, const char *session_name_) :
+      const options_t &options_) :
     io_object_t (parent_),
     pgm_socket (true, options_),
     options (options_),
-    session_name (session_name_),
     inout (NULL)
 {
 }
diff --git a/src/pgm_receiver.hpp b/src/pgm_receiver.hpp
index fa84acb..91169f4 100644
--- a/src/pgm_receiver.hpp
+++ b/src/pgm_receiver.hpp
@@ -47,8 +47,7 @@ namespace zmq
 
         //  Creates gm_engine. Underlying PGM connection is initialised
         //  using network_ parameter.
-        pgm_receiver_t (class io_thread_t *parent_, const options_t &options_,
-            const char *session_name_);
+        pgm_receiver_t (class io_thread_t *parent_, const options_t &options_);
         ~pgm_receiver_t ();
 
         int init (bool udp_encapsulation_, const char *network_);
@@ -94,9 +93,6 @@ namespace zmq
         //  Socket options.
         options_t options;
 
-        //  Name of the session associated with the connecter.
-        std::string session_name;
-
         //  Parent session.
         i_inout *inout;
 
diff --git a/src/pgm_sender.cpp b/src/pgm_sender.cpp
index 676ed93..880bb09 100644
--- a/src/pgm_sender.cpp
+++ b/src/pgm_sender.cpp
@@ -33,12 +33,11 @@
 #include "wire.hpp"
 
 zmq::pgm_sender_t::pgm_sender_t (io_thread_t *parent_, 
-      const options_t &options_, const char *session_name_) :
+      const options_t &options_) :
     io_object_t (parent_),
     encoder (0, false),
     pgm_socket (false, options_),
     options (options_),
-    session_name (session_name_),
     inout (NULL),
     out_buffer (NULL),
     out_buffer_size (0),
diff --git a/src/pgm_sender.hpp b/src/pgm_sender.hpp
index 9a9844c..30b545d 100644
--- a/src/pgm_sender.hpp
+++ b/src/pgm_sender.hpp
@@ -42,8 +42,7 @@ namespace zmq
     {
 
     public:
-        pgm_sender_t (class io_thread_t *parent_, const options_t &options_, 
-            const char *session_name_);
+        pgm_sender_t (class io_thread_t *parent_, const options_t &options_);
         ~pgm_sender_t ();
 
         int init (bool udp_encapsulation_, const char *network_);
@@ -74,9 +73,6 @@ namespace zmq
         //  Socket options.
         options_t options;
 
-        //  Name of the session associated with the connecter.
-        std::string session_name;
-
         //  Poll handle associated with PGM socket.
         handle_t handle;
         handle_t uplink_handle;
diff --git a/src/session.cpp b/src/session.cpp
index 37f2720..a17e205 100644
--- a/src/session.cpp
+++ b/src/session.cpp
@@ -25,16 +25,41 @@
 #include "pipe.hpp"
 
 zmq::session_t::session_t (object_t *parent_, socket_base_t *owner_,
-      const char *name_, const options_t &options_, bool reconnect_) :
+      const options_t &options_) :
     owned_t (parent_, owner_),
     in_pipe (NULL),
     active (true),
     out_pipe (NULL),
     engine (NULL),
-    name (name_),
-    options (options_),
-    reconnect (reconnect_)
+    options (options_)
 {
+    type = unnamed;
+    
+    //  It's possible to register the session at this point as it will be
+    //  searched for only on reconnect, i.e. no race condition (session found
+    //  before it is plugged into it's I/O thread) is possible.
+    ordinal = owner->register_session (this);
+}
+
+zmq::session_t::session_t (object_t *parent_, socket_base_t *owner_,
+      const options_t &options_, const char *name_) :
+    owned_t (parent_, owner_),
+    in_pipe (NULL),
+    active (true),
+    out_pipe (NULL),
+    engine (NULL),
+    options (options_)
+{
+    if (name_) {
+        type = named;
+        name = name_;
+        ordinal = 0;
+    }
+    else {
+        type = transient;
+        //  TODO: Generate unique name here.
+        ordinal = 0;
+    }
 }
 
 zmq::session_t::~session_t ()
@@ -78,8 +103,8 @@ void zmq::session_t::detach (owned_t *reconnecter_)
     //  Engine is terminating itself. No need to deallocate it from here.
     engine = NULL;
 
-    //  In the case od anonymous connection, terminate the session.
-    if (name.empty ())
+    //  Terminate transient session.
+    if (type == transient)
         term ();
 }
 
@@ -93,9 +118,11 @@ class zmq::socket_base_t *zmq::session_t::get_owner ()
     return owner;
 }
 
-const char *zmq::session_t::get_session_name ()
+uint64_t zmq::session_t::get_ordinal ()
 {
-    return name.c_str ();
+    zmq_assert (type == unnamed);
+    zmq_assert (ordinal);
+    return ordinal;
 }
 
 void zmq::session_t::attach_pipes (class reader_t *inpipe_,
@@ -181,11 +208,12 @@ void zmq::session_t::process_plug ()
 
 void zmq::session_t::process_unplug ()
 {
-    //  Unregister the session from the socket.
-    if (!name.empty ()) {
-        bool ok = owner->unregister_session (name.c_str ());
-        zmq_assert (ok);
-    }
+    //  Unregister the session from the socket. There's nothing to do here
+    //  for transient sessions.
+    if (type == unnamed)
+        owner->unregister_session (ordinal);
+    else if (type == named)
+        owner->unregister_session (name.c_str ());
 
     //  Ask associated pipes to terminate.
     if (in_pipe) {
diff --git a/src/session.hpp b/src/session.hpp
index 72e1d59..c60cfc7 100644
--- a/src/session.hpp
+++ b/src/session.hpp
@@ -34,8 +34,14 @@ namespace zmq
     {
     public:
 
-        session_t (object_t *parent_, socket_base_t *owner_, const char *name_,
-            const options_t &options_, bool reconnect_);
+        //  Creates unnamed session.
+        session_t (object_t *parent_, socket_base_t *owner_,
+            const options_t &options_);
+
+        //  Creates named session. If name is NULL, transient session with
+        //  auto-generated name is created.
+        session_t (object_t *parent_, socket_base_t *owner_,
+            const options_t &options_, const char *name_);
 
         //  i_inout interface implementation.
         bool read (::zmq_msg_t *msg_);
@@ -44,7 +50,7 @@ namespace zmq
         void detach (owned_t *reconnecter_);
         class io_thread_t *get_io_thread ();
         class socket_base_t *get_owner ();
-        const char *get_session_name ();
+        uint64_t get_ordinal ();
 
         //  i_endpoint interface implementation.
         void attach_pipes (class reader_t *inpipe_, class writer_t *outpipe_);
@@ -73,6 +79,15 @@ namespace zmq
 
         struct i_engine *engine;
 
+        enum {
+            transient,
+            named,
+            unnamed
+        } type;
+
+        //  Ordinal of the session (if any).
+        uint64_t ordinal;
+
         //  The name of the session. One that is used to register it with
         //  socket-level repository of sessions.
         std::string name;
@@ -80,9 +95,6 @@ namespace zmq
         //  Inherited socket options.
         options_t options;
 
-        //  If true, reconnection is required after connection breaks.
-        bool reconnect;
-
         session_t (const session_t&);
         void operator = (const session_t&);
     };
diff --git a/src/socket_base.cpp b/src/socket_base.cpp
index fde258c..43209d5 100644
--- a/src/socket_base.cpp
+++ b/src/socket_base.cpp
@@ -32,7 +32,6 @@
 #include "session.hpp"
 #include "config.hpp"
 #include "owned.hpp"
-#include "uuid.hpp"
 #include "pipe.hpp"
 #include "err.hpp"
 #include "platform.hpp"
@@ -46,7 +45,8 @@ zmq::socket_base_t::socket_base_t (app_thread_t *parent_) :
     app_thread (parent_),
     shutting_down (false),
     sent_seqnum (0),
-    processed_seqnum (0)
+    processed_seqnum (0),
+    next_ordinal (1)
 {
 }
 
@@ -114,10 +114,6 @@ int zmq::socket_base_t::bind (const char *addr_)
 
 int zmq::socket_base_t::connect (const char *addr_)
 {
-    //  Generate a unique name for the session.
-    std::string session_name ("#");
-    session_name += uuid_t ().to_string ();
-
     //  Parse addr_ string.
     std::string addr_type;
     std::string addr_args;
@@ -170,10 +166,10 @@ int zmq::socket_base_t::connect (const char *addr_)
         return 0;
     }
 
-    //  Create the session.
+    //  Create unnamed session.
     io_thread_t *io_thread = choose_io_thread (options.affinity);
-    session_t *session = new (std::nothrow) session_t (io_thread, this,
-        session_name.c_str (), options, true);
+    session_t *session = new (std::nothrow) session_t (io_thread,
+        this, options);
     zmq_assert (session);
 
     pipe_t *in_pipe = NULL;
@@ -213,7 +209,7 @@ int zmq::socket_base_t::connect (const char *addr_)
         //  it is established.
         zmq_connecter_t *connecter = new (std::nothrow) zmq_connecter_t (
             choose_io_thread (options.affinity), this, options,
-            session_name.c_str (), false);
+            session->get_ordinal (), false);
         zmq_assert (connecter);
         int rc = connecter->set_address (addr_args.c_str ());
         if (rc != 0) {
@@ -245,8 +241,7 @@ int zmq::socket_base_t::connect (const char *addr_)
 
             //  PGM sender.
             pgm_sender_t *pgm_sender =  new (std::nothrow) pgm_sender_t (
-                choose_io_thread (options.affinity), options,
-                session_name.c_str ());
+                choose_io_thread (options.affinity), options);
             zmq_assert (pgm_sender);
 
             int rc = pgm_sender->init (udp_encapsulation, addr_args.c_str ());
@@ -261,8 +256,7 @@ int zmq::socket_base_t::connect (const char *addr_)
 
             //  PGM receiver.
             pgm_receiver_t *pgm_receiver =  new (std::nothrow) pgm_receiver_t (
-                choose_io_thread (options.affinity), options, 
-                session_name.c_str ());
+                choose_io_thread (options.affinity), options);
             zmq_assert (pgm_receiver);
 
             int rc = pgm_receiver->init (udp_encapsulation, addr_args.c_str ());
@@ -408,7 +402,8 @@ int zmq::socket_base_t::close ()
 
     //  Check whether there are no session leaks.
     sessions_sync.lock ();
-    zmq_assert (sessions.empty ());
+    zmq_assert (named_sessions.empty ());
+    zmq_assert (unnamed_sessions.empty ());
     sessions_sync.unlock ();
 
     delete this;
@@ -445,36 +440,74 @@ bool zmq::socket_base_t::register_session (const char *name_,
     session_t *session_)
 {
     sessions_sync.lock ();
-    bool registered = sessions.insert (std::make_pair (name_, session_)).second;
+    bool registered =
+        named_sessions.insert (std::make_pair (name_, session_)).second;
     sessions_sync.unlock ();
     return registered;
 }
 
-bool zmq::socket_base_t::unregister_session (const char *name_)
+void zmq::socket_base_t::unregister_session (const char *name_)
 {
     sessions_sync.lock ();
-    sessions_t::iterator it = sessions.find (name_);
-    bool unregistered = (it != sessions.end ());
-    sessions.erase (it);
+    named_sessions_t::iterator it = named_sessions.find (name_);
+    zmq_assert (it != named_sessions.end ());
+    named_sessions.erase (it);
     sessions_sync.unlock ();
-    return unregistered;
 }
 
 zmq::session_t *zmq::socket_base_t::find_session (const char *name_)
 {
     sessions_sync.lock ();
 
-    sessions_t::iterator it = sessions.find (name_);
-    if (it == sessions.end ()) {
+    named_sessions_t::iterator it = named_sessions.find (name_);
+    if (it == named_sessions.end ()) {
+        sessions_sync.unlock ();
+        return NULL;
+    }
+    session_t *session = it->second;
+
+    //  Prepare the session for subsequent attach command.
+    session->inc_seqnum ();
+
+    sessions_sync.unlock ();
+    return session;    
+}
+
+uint64_t zmq::socket_base_t::register_session (session_t *session_)
+{
+    sessions_sync.lock ();
+    uint64_t ordinal = next_ordinal;
+    next_ordinal++;
+    unnamed_sessions.insert (std::make_pair (ordinal, session_)).second;
+    sessions_sync.unlock ();
+    return ordinal;
+}
+
+void zmq::socket_base_t::unregister_session (uint64_t ordinal_)
+{
+    sessions_sync.lock ();
+    unnamed_sessions_t::iterator it = unnamed_sessions.find (ordinal_);
+    zmq_assert (it != unnamed_sessions.end ());
+    unnamed_sessions.erase (it);
+    sessions_sync.unlock ();
+}
+
+zmq::session_t *zmq::socket_base_t::find_session (uint64_t ordinal_)
+{
+    sessions_sync.lock ();
+
+    unnamed_sessions_t::iterator it = unnamed_sessions.find (ordinal_);
+    if (it == unnamed_sessions.end ()) {
         sessions_sync.unlock ();
         return NULL;
     }
+    session_t *session = it->second;
 
     //  Prepare the session for subsequent attach command.
-    it->second->inc_seqnum ();
+    session->inc_seqnum ();
 
     sessions_sync.unlock ();
-    return it->second;    
+    return session; 
 }
 
 void zmq::socket_base_t::kill (reader_t *pipe_)
diff --git a/src/socket_base.hpp b/src/socket_base.hpp
index 79a8340..16553ea 100644
--- a/src/socket_base.hpp
+++ b/src/socket_base.hpp
@@ -34,6 +34,7 @@
 #include "options.hpp"
 #include "stdint.hpp"
 #include "atomic_counter.hpp"
+#include "stdint.hpp"
 
 namespace zmq
 {
@@ -74,9 +75,15 @@ namespace zmq
         //  commands as it is unacceptable to wait for the completion of the
         //  action till user application yields control of the application
         //  thread to 0MQ. Locking is used instead.
+        //  There are two distinct types of sessions: those identified by name
+        //  and those identified by ordinal number. Thus two sets of session
+        //  management functions.
         bool register_session (const char *name_, class session_t *session_);
-        bool unregister_session (const char *name_);
+        void unregister_session (const char *name_);
         class session_t *find_session (const char *name_);
+        uint64_t register_session (class session_t *session_);
+        void unregister_session (uint64_t ordinal_);
+        class session_t *find_session (uint64_t ordinal_);
 
         //  i_endpoint interface implementation.
         void attach_pipes (class reader_t *inpipe_, class writer_t *outpipe_);
@@ -144,15 +151,15 @@ namespace zmq
         //  Sequence number of the last command processed by this object.
         uint64_t processed_seqnum;
 
-        //  List of existing sessions. This list is never referenced from within
-        //  the socket, instead it is used by I/O objects owned by the session.
-        //  As those objects can live in different threads, the access is
-        //  synchronised using 'sessions_sync' mutex.
-        //  Local sessions are those named by the local instance of 0MQ.
-        //  Remote sessions are the sessions who's identities are provided by
-        //  the remote party.
-        typedef std::map <std::string, session_t*> sessions_t;
-        sessions_t sessions;
+        //  Lists of existing sessions. This lists are never referenced from
+        //  within the socket, instead they are used by I/O objects owned by
+        //  the socket. As those objects can live in different threads,
+        //  the access is synchronised by mutex.
+        typedef std::map <std::string, session_t*> named_sessions_t;
+        named_sessions_t named_sessions;
+        typedef std::map <uint64_t, session_t*> unnamed_sessions_t;
+        unnamed_sessions_t unnamed_sessions;
+        uint64_t next_ordinal;
         mutex_t sessions_sync;
 
         socket_base_t (const socket_base_t&);
diff --git a/src/zmq_connecter.cpp b/src/zmq_connecter.cpp
index 5bda48d..8f95fc0 100644
--- a/src/zmq_connecter.cpp
+++ b/src/zmq_connecter.cpp
@@ -20,19 +20,20 @@
 #include <new>
 
 #include "zmq_connecter.hpp"
-#include "zmq_connecter_init.hpp"
+#include "zmq_engine.hpp"
+#include "zmq_init.hpp"
 #include "io_thread.hpp"
 #include "err.hpp"
 
 zmq::zmq_connecter_t::zmq_connecter_t (io_thread_t *parent_,
       socket_base_t *owner_, const options_t &options_,
-      const char *session_name_, bool wait_) :
+      uint64_t session_ordinal_, bool wait_) :
     owned_t (parent_, owner_),
     io_object_t (parent_),
     handle_valid (false),
     wait (wait_),
-    options (options_),
-    session_name (session_name_)
+    session_ordinal (session_ordinal_),
+    options (options_)
 {
 }
 
@@ -88,9 +89,9 @@ void zmq::zmq_connecter_t::out_event ()
     }
 
     //  Create an init object. 
-    io_thread_t *io_thread = choose_io_thread (options.affinity);
-    zmq_connecter_init_t *init = new (std::nothrow) zmq_connecter_init_t (
-        io_thread, owner, fd, options, session_name.c_str (), address.c_str ());
+    zmq_init_t *init = new (std::nothrow) zmq_init_t (
+        choose_io_thread (options.affinity), owner,
+        fd, options, true, address.c_str (), session_ordinal);
     zmq_assert (init);
     send_plug (init);
     send_own (owner, init);
diff --git a/src/zmq_connecter.hpp b/src/zmq_connecter.hpp
index acd3352..e5b4a70 100644
--- a/src/zmq_connecter.hpp
+++ b/src/zmq_connecter.hpp
@@ -36,7 +36,7 @@ namespace zmq
     public:
 
         zmq_connecter_t (class io_thread_t *parent_, socket_base_t *owner_,
-            const options_t &options_, const char *session_name_, bool wait_);
+            const options_t &options_, uint64_t session_ordinal_, bool wait_);
         ~zmq_connecter_t ();
 
         //  Set IP address to connect to.
@@ -69,12 +69,12 @@ namespace zmq
         //  If true, connecter is waiting a while before trying to connect.
         bool wait;
 
+        //  Ordinal of the session to attach to.
+        uint64_t session_ordinal;
+
         //  Associated socket options.
         options_t options;
 
-        //  Name of the session associated with the connecter.
-        std::string session_name;
-
         //  Address to connect to.
         std::string address;
 
diff --git a/src/zmq_connecter_init.cpp b/src/zmq_connecter_init.cpp
deleted file mode 100644
index f8436a3..0000000
--- a/src/zmq_connecter_init.cpp
+++ /dev/null
@@ -1,132 +0,0 @@
-/*
-    Copyright (c) 2007-2009 FastMQ Inc.
-
-    This file is part of 0MQ.
-
-    0MQ is free software; you can redistribute it and/or modify it under
-    the terms of the Lesser GNU General Public License as published by
-    the Free Software Foundation; either version 3 of the License, or
-    (at your option) any later version.
-
-    0MQ is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    Lesser GNU General Public License for more details.
-
-    You should have received a copy of the Lesser GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
-*/
-
-#include <new>
-
-#include "zmq_connecter_init.hpp"
-#include "zmq_connecter.hpp"
-#include "io_thread.hpp"
-#include "session.hpp"
-#include "err.hpp"
-
-zmq::zmq_connecter_init_t::zmq_connecter_init_t (io_thread_t *parent_,
-      socket_base_t *owner_, fd_t fd_, const options_t &options_,
-      const char *session_name_, const char *address_) :
-    owned_t (parent_, owner_),
-    options (options_),
-    session_name (session_name_)
-{
-    //  Create associated engine object.
-    engine = new (std::nothrow) zmq_engine_t (parent_, fd_, options, true,
-        address_);
-    zmq_assert (engine);
-}
-
-zmq::zmq_connecter_init_t::~zmq_connecter_init_t ()
-{
-    if (engine)
-        delete engine;
-}
-
-bool zmq::zmq_connecter_init_t::read (::zmq_msg_t *msg_)
-{
-    //  Send identity.
-    int rc = zmq_msg_init_size (msg_, options.identity.size ());
-    zmq_assert (rc == 0);
-    memcpy (zmq_msg_data (msg_), options.identity.c_str (),
-        options.identity.size ());
-
-    //  Initialisation is done at this point. Disconnect the engine from
-    //  the init object.
-    engine->unplug ();
-
-    //  Find the session associated with this connecter. If it doesn't exist
-    //  drop the newly created connection. If it does, attach it to the
-    //  connection.
-    session_t *session = NULL;
-    if (!session_name.empty ())
-        session = owner->find_session (session_name.c_str ());
-    if (!session) {
-
-        //  TODO:
-        //  The socket is already closing. The session is already shut down,
-        //  so no point in continuing with connecting. Shut the connection down.
-        zmq_assert (false);
-    }
-
-    //  No need to increment seqnum as it was alredy incremented above.
-    send_attach (session, engine, false);
-    engine = NULL;
-
-    //  Destroy the init object.
-    term ();
-
-    return true;
-}
-
-bool zmq::zmq_connecter_init_t::write (::zmq_msg_t *msg_)
-{
-    return false;
-}
-
-void zmq::zmq_connecter_init_t::flush ()
-{
-    //  We are not expecting any messages. No point in flushing.
-}
-
-void zmq::zmq_connecter_init_t::detach (owned_t *reconnecter_)
-{
-    //  Plug in the reconnecter object.
-    zmq_assert (reconnecter_);
-    send_plug (reconnecter_);
-    send_own (owner, reconnecter_);
-
-    //  This function is called by engine when disconnection occurs.
-    //  The engine will destroy itself, so we just drop the pointer here and
-    //  start termination of the init object.
-    engine = NULL;
-    term ();
-}
-
-zmq::io_thread_t *zmq::zmq_connecter_init_t::get_io_thread ()
-{
-    return choose_io_thread (options.affinity);
-}
-
-class zmq::socket_base_t *zmq::zmq_connecter_init_t::get_owner ()
-{
-    return owner;
-}
-
-const char *zmq::zmq_connecter_init_t::get_session_name ()
-{
-    return session_name.c_str ();
-}
-
-void zmq::zmq_connecter_init_t::process_plug ()
-{
-    zmq_assert (engine);
-    engine->plug (this);
-}
-
-void zmq::zmq_connecter_init_t::process_unplug ()
-{
-    if (engine)
-        engine->unplug ();
-}
diff --git a/src/zmq_connecter_init.hpp b/src/zmq_connecter_init.hpp
deleted file mode 100644
index 03ccd24..0000000
--- a/src/zmq_connecter_init.hpp
+++ /dev/null
@@ -1,79 +0,0 @@
-/*
-    Copyright (c) 2007-2009 FastMQ Inc.
-
-    This file is part of 0MQ.
-
-    0MQ is free software; you can redistribute it and/or modify it under
-    the terms of the Lesser GNU General Public License as published by
-    the Free Software Foundation; either version 3 of the License, or
-    (at your option) any later version.
-
-    0MQ is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    Lesser GNU General Public License for more details.
-
-    You should have received a copy of the Lesser GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
-*/
-
-#ifndef __ZMQ_ZMQ_CONNECTER_INIT_HPP_INCLUDED__
-#define __ZMQ_ZMQ_CONNECTER_INIT_HPP_INCLUDED__
-
-#include <string>
-
-#include "i_inout.hpp"
-#include "owned.hpp"
-#include "zmq_engine.hpp"
-#include "stdint.hpp"
-#include "fd.hpp"
-#include "options.hpp"
-
-namespace zmq
-{
-
-    //  The class handles initialisation phase of native 0MQ wire-level
-    //  protocol on the connecting side of the connection.
-
-    class zmq_connecter_init_t : public owned_t, public i_inout
-    {
-    public:
-
-        zmq_connecter_init_t (class io_thread_t *parent_, socket_base_t *owner_,
-            fd_t fd_, const options_t &options, const char *session_name_,
-            const char *address_);
-        ~zmq_connecter_init_t ();
-
-    private:
-
-        //  i_inout interface implementation.
-        bool read (::zmq_msg_t *msg_);
-        bool write (::zmq_msg_t *msg_);
-        void flush ();
-        void detach (owned_t *reconnecter_);
-        class io_thread_t *get_io_thread ();
-        class socket_base_t *get_owner ();
-        const char *get_session_name ();
-
-        //  Handlers for incoming commands.
-        void process_plug ();
-        void process_unplug ();
-
-        //  Engine is created by zmq_connecter_init_t object. Once the
-        //  initialisation phase is over it is passed to a session object,
-        //  possibly running in a different I/O thread.
-        zmq_engine_t *engine;
-
-        //  Associated socket options.
-        options_t options;
-
-        //  Name of the session to bind new connection to.
-        std::string session_name;
-
-        zmq_connecter_init_t (const zmq_connecter_init_t&);
-        void operator = (const zmq_connecter_init_t&);
-    };
-
-}
-
-#endif
diff --git a/src/zmq_engine.cpp b/src/zmq_engine.cpp
index c2878a7..cfc87a7 100644
--- a/src/zmq_engine.cpp
+++ b/src/zmq_engine.cpp
@@ -159,7 +159,7 @@ void zmq::zmq_engine_t::error ()
         //  Ask it to wait for a while before reconnecting.
         reconnecter = new (std::nothrow) zmq_connecter_t (
             inout->get_io_thread (), inout->get_owner (),
-            options, inout->get_session_name (), true);
+            options, inout->get_ordinal (), true);
         zmq_assert (reconnecter);
         reconnecter->set_address (address.c_str ());
     }
diff --git a/src/zmq_init.cpp b/src/zmq_init.cpp
new file mode 100644
index 0000000..e526b34
--- /dev/null
+++ b/src/zmq_init.cpp
@@ -0,0 +1,195 @@
+/*
+    Copyright (c) 2007-2009 FastMQ Inc.
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the Lesser GNU General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    Lesser GNU General Public License for more details.
+
+    You should have received a copy of the Lesser GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "zmq_init.hpp"
+#include "zmq_engine.hpp"
+#include "io_thread.hpp"
+#include "session.hpp"
+#include "err.hpp"
+
+zmq::zmq_init_t::zmq_init_t (io_thread_t *parent_, socket_base_t *owner_,
+      fd_t fd_, const options_t &options_, bool reconnect_,
+      const char *address_, uint64_t session_ordinal_) :
+    owned_t (parent_, owner_),
+    sent (false),
+    received (false),
+    session_ordinal (session_ordinal_),
+    options (options_)
+{
+    //  Create the engine object for this connection.
+    engine = new (std::nothrow) zmq_engine_t (parent_, fd_, options,
+        reconnect_, address_);
+    zmq_assert (engine);
+}
+
+zmq::zmq_init_t::~zmq_init_t ()
+{
+    if (engine)
+        delete engine;
+}
+
+bool zmq::zmq_init_t::read (::zmq_msg_t *msg_)
+{
+    //  If the identity was already sent, do nothing.
+    if (sent)
+        return false;
+
+    //  Send the identity.
+    int rc = zmq_msg_init_size (msg_, options.identity.size ());
+    zmq_assert (rc == 0);
+    memcpy (zmq_msg_data (msg_), options.identity.c_str (),
+        options.identity.size ());
+    sent = true;
+
+    //  If initialisation is done, pass the engine to the session and
+    //  destroy the init object.
+    finalise ();
+
+    return true;
+}
+
+bool zmq::zmq_init_t::write (::zmq_msg_t *msg_)
+{
+    //  If identity was already received, we are not interested
+    //  in subsequent messages.
+    if (received)
+        return false;
+
+    //  Retreieve the remote identity.
+    peer_identity.assign ((const char*) zmq_msg_data (msg_),
+        zmq_msg_size (msg_));
+    received = true;
+
+    return true;
+}
+
+void zmq::zmq_init_t::flush ()
+{
+    //  Check if there's anything to flush.
+    if (!received)
+        return;
+
+    //  If initialisation is done, pass the engine to the session and
+    //  destroy the init object.
+    finalise ();
+}
+
+void zmq::zmq_init_t::detach (owned_t *reconnecter_)
+{
+    //  This function is called by engine when disconnection occurs.
+
+    //  If required, launch the reconnecter.
+    if (reconnecter_) {
+        send_plug (reconnecter_);
+        send_own (owner, reconnecter_);
+    }
+
+    //  The engine will destroy itself, so let's just drop the pointer here and
+    //  start termination of the init object.
+    engine = NULL;
+    term ();
+}
+
+zmq::io_thread_t *zmq::zmq_init_t::get_io_thread ()
+{
+    return choose_io_thread (options.affinity);
+}
+
+class zmq::socket_base_t *zmq::zmq_init_t::get_owner ()
+{
+    return owner;
+}
+
+uint64_t zmq::zmq_init_t::get_ordinal ()
+{
+    zmq_assert (false);
+}
+
+void zmq::zmq_init_t::process_plug ()
+{
+    zmq_assert (engine);
+    engine->plug (this);
+}
+
+void zmq::zmq_init_t::process_unplug ()
+{
+    if (engine)
+        engine->unplug ();
+}
+
+void zmq::zmq_init_t::finalise ()
+{
+    if (sent && received) {
+
+        //  Disconnect the engine from the init object.
+        engine->unplug ();
+
+        session_t *session = NULL;
+        
+        //  If we have the session ordinal, let's use it to find the session.
+        //  If it is not found, it means socket is already being shut down
+        //  and the session have been deallocated.
+        //  TODO: We should check whether the name of the peer haven't changed
+        //  upon reconnection.
+        if (session_ordinal) {
+            session = owner->find_session (session_ordinal);
+            if (!session) {
+                term ();
+                return;
+            }
+        }
+
+        //  If the peer has a unique name, find the associated session. If it
+        //  doesn't exist, create it.
+        else if (!peer_identity.empty ()) {
+            session = owner->find_session (peer_identity.c_str ());
+            if (!session) {
+                session = new (std::nothrow) session_t (
+                    choose_io_thread (options.affinity), owner, options,
+                    peer_identity.c_str ());
+                zmq_assert (session);
+                send_plug (session);
+                send_own (owner, session);
+
+                //  Reserve a sequence number for following 'attach' command.
+                session->inc_seqnum ();
+            }
+        }
+
+        //  If the other party has no specific identity, let's create a
+        //  transient session.
+        else {
+            session = new (std::nothrow) session_t (
+                choose_io_thread (options.affinity), owner, options, NULL);
+            zmq_assert (session);
+            send_plug (session);
+            send_own (owner, session);
+
+            //  Reserve a sequence number for following 'attach' command.
+            session->inc_seqnum ();
+        }
+
+        //  No need to increment seqnum as it was laready incremented above.
+        send_attach (session, engine, false);
+
+        //  Destroy the init object.
+        engine = NULL;
+        term ();
+    }
+}
diff --git a/src/zmq_listener_init.hpp b/src/zmq_init.hpp
index d7fde02..a17d621 100644
--- a/src/zmq_listener_init.hpp
+++ b/src/zmq_init.hpp
@@ -17,34 +17,37 @@
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#ifndef __ZMQ_ZMQ_LISTENER_INIT_HPP_INCLUDED__
-#define __ZMQ_ZMQ_LISTENER_INIT_HPP_INCLUDED__
+#ifndef __ZMQ_ZMQ_INIT_HPP_INCLUDED__
+#define __ZMQ_ZMQ_INIT_HPP_INCLUDED__
 
 #include <string>
 
 #include "i_inout.hpp"
+#include "i_engine.hpp"
 #include "owned.hpp"
-#include "zmq_engine.hpp"
-#include "stdint.hpp"
 #include "fd.hpp"
+#include "stdint.hpp"
 #include "options.hpp"
+#include "stdint.hpp"
 
 namespace zmq
 {
 
-    //  The class handles initialisation phase of native 0MQ wire-level
-    //  protocol on the listening side of the connection.
+    //  The class handles initialisation phase of 0MQ wire-level protocol.
 
-    class zmq_listener_init_t : public owned_t, public i_inout
+    class zmq_init_t : public owned_t, public i_inout
     {
     public:
 
-        zmq_listener_init_t (class io_thread_t *parent_, socket_base_t *owner_,
-            fd_t fd_, const options_t &options);
-        ~zmq_listener_init_t ();
+        zmq_init_t (class io_thread_t *parent_, socket_base_t *owner_,
+            fd_t fd_, const options_t &options_, bool reconnect_,
+            const char *address_, uint64_t session_ordinal_);
+        ~zmq_init_t ();
 
     private:
 
+        void finalise ();
+
         //  i_inout interface implementation.
         bool read (::zmq_msg_t *msg_);
         bool write (::zmq_msg_t *msg_);
@@ -52,26 +55,33 @@ namespace zmq
         void detach (owned_t *reconnecter_);
         class io_thread_t *get_io_thread ();
         class socket_base_t *get_owner ();
-        const char *get_session_name ();
+        uint64_t get_ordinal ();
 
         //  Handlers for incoming commands.
         void process_plug ();
         void process_unplug ();
 
-        //  Engine is created by zmq_listener_init_t object. Once the
-        //  initialisation phase is over it is passed to a session object,
-        //  possibly running in a different I/O thread.
-        zmq_engine_t *engine;
+        //  Associated wite-protocol engine.
+        i_engine *engine;
 
-        //  Associated socket options.
-        options_t options;
+        //  True if our own identity was already sent to the peer.
+        bool sent;
 
-        //  Indetity on the other end of the connection.
-        bool has_peer_identity;
+        //  True if peer's identity was already received.
+        bool received;
+
+        //  Identity of the peer socket.
         std::string peer_identity;
 
-        zmq_listener_init_t (const zmq_listener_init_t&);
-        void operator = (const zmq_listener_init_t&);
+        //  TCP connecter creates session before the name of the peer is known.
+        //  Thus we know only its ordinal number.
+        uint64_t session_ordinal;
+
+        //  Associated socket options.
+        options_t options;
+
+        zmq_init_t (const zmq_init_t&);
+        void operator = (const zmq_init_t&);
     };
 
 }
diff --git a/src/zmq_listener.cpp b/src/zmq_listener.cpp
index 5c7552b..6a7e2fd 100644
--- a/src/zmq_listener.cpp
+++ b/src/zmq_listener.cpp
@@ -20,7 +20,7 @@
 #include <new>
 
 #include "zmq_listener.hpp"
-#include "zmq_listener_init.hpp"
+#include "zmq_init.hpp"
 #include "io_thread.hpp"
 #include "err.hpp"
 
@@ -64,8 +64,8 @@ void zmq::zmq_listener_t::in_event ()
 
     //  Create an init object. 
     io_thread_t *io_thread = choose_io_thread (options.affinity);
-    zmq_listener_init_t *init = new (std::nothrow) zmq_listener_init_t (
-        io_thread, owner, fd, options);
+    zmq_init_t *init = new (std::nothrow) zmq_init_t (
+        io_thread, owner, fd, options, false, NULL, 0);
     zmq_assert (init);
     send_plug (init);
     send_own (owner, init);
diff --git a/src/zmq_listener_init.cpp b/src/zmq_listener_init.cpp
deleted file mode 100644
index f7b3001..0000000
--- a/src/zmq_listener_init.cpp
+++ /dev/null
@@ -1,137 +0,0 @@
-/*
-    Copyright (c) 2007-2009 FastMQ Inc.
-
-    This file is part of 0MQ.
-
-    0MQ is free software; you can redistribute it and/or modify it under
-    the terms of the Lesser GNU General Public License as published by
-    the Free Software Foundation; either version 3 of the License, or
-    (at your option) any later version.
-
-    0MQ is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    Lesser GNU General Public License for more details.
-
-    You should have received a copy of the Lesser GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
-*/
-
-#include <new>
-
-#include "zmq_listener_init.hpp"
-#include "io_thread.hpp"
-#include "session.hpp"
-#include "err.hpp"
-
-zmq::zmq_listener_init_t::zmq_listener_init_t (io_thread_t *parent_,
-      socket_base_t *owner_, fd_t fd_, const options_t &options_) :
-    owned_t (parent_, owner_),
-    options (options_),
-    has_peer_identity (false)
-{
-    //  Create associated engine object.
-    engine = new (std::nothrow) zmq_engine_t (parent_, fd_, options,
-        false, NULL);
-    zmq_assert (engine);
-}
-
-zmq::zmq_listener_init_t::~zmq_listener_init_t ()
-{
-    if (engine)
-        delete engine;
-}
-
-bool zmq::zmq_listener_init_t::read (::zmq_msg_t *msg_)
-{
-    return false;
-}
-
-bool zmq::zmq_listener_init_t::write (::zmq_msg_t *msg_)
-{
-    //  Once we've got peer's identity we aren't interested in subsequent
-    //  messages.
-    if (has_peer_identity)
-        return false;
-
-    //  Retreieve the remote identity. We'll use it as a local session name.
-    has_peer_identity = true;
-    peer_identity.assign ((const char*) zmq_msg_data (msg_),
-        zmq_msg_size (msg_));
-
-    return true;
-}
-
-void zmq::zmq_listener_init_t::flush ()
-{
-    if (!has_peer_identity)
-        return;
-
-    //  Initialisation is done. Disconnect the engine from the init object.
-    engine->unplug ();
-
-    //  Have a look whether the session already exists. If it does, attach it
-    //  to the engine. If it doesn't create it first.
-    session_t *session = NULL;
-    if (!peer_identity.empty ())
-        session = owner->find_session (peer_identity.c_str ());
-    if (!session) {
-        io_thread_t *io_thread = choose_io_thread (options.affinity);
-        session = new (std::nothrow) session_t (io_thread, owner,
-            peer_identity.c_str (), options, false);
-        zmq_assert (session);
-        send_plug (session);
-        send_own (owner, session);
-
-        //  Reserve a sequence number for following 'attach' command.
-        session->inc_seqnum ();
-    }
-
-    //  No need to increment seqnum as it was laready incremented above.
-    send_attach (session, engine, false);
-
-    engine = NULL;
-
-    //  Destroy the init object.
-    term ();
-}
-
-void zmq::zmq_listener_init_t::detach (owned_t *reconnecter_)
-{
-    //  On the listening side of the connection we are never reconnecting.
-    zmq_assert (reconnecter_ == NULL);
-
-    //  This function is called by engine when disconnection occurs.
-    //  The engine will destroy itself, so we just drop the pointer here and
-    //  start termination of the init object.
-    engine = NULL;
-    term ();
-}
-
-zmq::io_thread_t *zmq::zmq_listener_init_t::get_io_thread ()
-{
-    return choose_io_thread (options.affinity);
-}
-
-class zmq::socket_base_t *zmq::zmq_listener_init_t::get_owner ()
-{
-    return owner;
-}
-
-const char *zmq::zmq_listener_init_t::get_session_name ()
-{
-    zmq_assert (false);
-    return NULL;
-}
-
-void zmq::zmq_listener_init_t::process_plug ()
-{
-    zmq_assert (engine);
-    engine->plug (this);
-}
-
-void zmq::zmq_listener_init_t::process_unplug ()
-{
-    if (engine)
-        engine->unplug ();
-}