Identities re-introduced

However, the "durable socket" behaviour wasn't re-added.
Identities are used solely for routing in REQ/REP pattern.

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

src/pipe.hpp

@@ -1,6 +1,7 @@
 /*
     Copyright (c) 2009-2011 250bpm s.r.o.
     Copyright (c) 2007-2009 iMatix Corporation
+    Copyright (c) 2011 VMware, Inc.
     Copyright (c) 2007-2011 Other contributors as noted in the AUTHORS file
 
     This file is part of 0MQ.
@@ -28,6 +29,7 @@
 #include "object.hpp"
 #include "stdint.hpp"
 #include "array.hpp"
+#include "blob.hpp"
 
 namespace zmq
 {
@@ -71,8 +73,8 @@ namespace zmq
         void set_event_sink (i_pipe_events *sink_);
 
         //  Pipe endpoint can store an opaque ID to be used by its clients.
-        void set_pipe_id (uint32_t id_);
-        uint32_t get_pipe_id ();
+        void set_identity (const blob_t &identity_);
+        blob_t get_identity ();
 
         //  Returns true if there is at least one message to read in the pipe.
         bool check_read ();
@@ -183,8 +185,8 @@ namespace zmq
         //  asks us to.
         bool delay;
 
-        //  Opaque ID. To be used by the clients, not the pipe itself.
-        uint32_t pipe_id;
+        //  Identity of the writer. Used uniquely by the reader side.
+        blob_t identity;
 
         //  Returns true if the message is delimiter; false otherwise.
         static bool is_delimiter (msg_t &msg_);