Finished implementation of UA layer (to be tested)

git-svn-id: http://svn.pjsip.org/repos/pjproject/trunk@127 74dad513-b988-da41-8d7b-12977e46ad98

14 files changed, 991 insertions, 753 deletions

diff --git a/pjsip/include/pjsip-ua/sip_dialog.h b/pjsip/include/pjsip-ua/sip_dialog.h
deleted file mode 100644
index d46e3873..00000000
--- a/pjsip/include/pjsip-ua/sip_dialog.h
+++ /dev/null
@@ -1,635 +0,0 @@
-/* $Id$ */
-/* 
- * Copyright (C) 2003-2006 Benny Prijono <benny@prijono.org>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program 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
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
- */
-#ifndef __PJSIP_DIALOG_H__
-#define __PJSIP_DIALOG_H__
-
-/**
- * @file dialog.h
- * @brief SIP Dialog abstraction
- */
-
-#include <pjsip/sip_msg.h>
-#include <pjsip/sip_auth.h>
-#include <pj/sock.h>
-
-PJ_BEGIN_DECL
-
-/**
- * @defgroup PJSUA_DIALOG SIP Dialog
- * @ingroup PJSUA
- * @{
- * \brief
- *   This file contains SIP dialog, a higher level abstraction of SIP session.
- *
- * \par Overview
- * A SIP dialog is an abstraction of communication session between two user 
- * agents that persist for some time. The dialog facilitates sequencing of 
- * messages between the user agents and proper routing of requests between both
- * of them. The dialog represents a context in which to interpret SIP messages.
- * However method independent User Agent processing for requests and responses 
- * outside of a dialog exists, hence a dialog is not necessary for message 
- * processing.
- *
- * A dialog is identified at each User Agent with a dialog Id, which consists 
- * of a Call-Id value, a local tag and a remote tag. 
- *
- * A dialog contains certain pieces of data needed for further message 
- * transmissions within the dialog. This data consists of:
- *  - Dialog Id - used to identify the dialog.
- *  - Local sequence number - used to order requests from the UA to its peer.
- *  - Remote sequence number - used to order requests from its peer to the UA.
- *  - Local URI - the address of the local party.
- *  - Remote URI - the address of the remote party.
- *  - Remote target - the address from the Contact header field of the request 
- *    or response or refresh request or response.
- *  - "secure" boolean - determines if the dialog is secure.
- *  - Route set - an ordered list of URIs. The route set is the list of servers
- *    that need to be traversed to send a request to the peer. 
- *  - Authentication info - array of authentication credentials to be used
- *    by the dialog to authenticate to proxies and servers.
- *
- * \par Manipulating Dialog
- * Application should use functions declared in this file to do something with 
- * the dialog. Among other things, application can:
- *   - create outgoing dialog (#pjsip_dlg_init()).
- *   - sends outgoing invitation (#pjsip_dlg_invite()).
- *   - sends response (provisional and final) to incoming invitation
- *     (#pjsip_dlg_answer())
- *   - disconnect dialog (#pjsip_dlg_disconnect()).
- *   - send other request (#pjsip_dlg_create_request() and #pjsip_dlg_send_msg())
- *
- * \par Getting Dialog's Notification
- * Dialog emits notification about various things that's happening to it (e.g.
- * a message is received, dialog state has changed, etc.). Normally it is in
- * the interest of the application to capture these notifications, by
- * supplying the function to be called when the event occurs in #pjsip_dlg_callback
- * structure, and register this structure to user agent by calling 
- * #pjsip_ua_set_dialog_callback().
- *
- * \par Incoming Invitation
- * Upon receiving a new incoming invitation, user agent will automatically create
- * a new dialog, and inform application via \b pjsip_dlg_callback.
- */
-
-/** Forward declaration for user agent structure. */
-typedef struct pjsip_user_agent pjsip_user_agent;
-
-/** Forward declaration for dialog structure. */
-typedef struct pjsip_dlg pjsip_dlg;
-
-/**
- * \brief Type of events that are reported by the dialog to the application callback
- * function.
- */
-typedef enum pjsip_dlg_event_e
-{
-    /** Dialog state has changed. */
-    PJSIP_DIALOG_EVENT_STATE_CHANGED,
-
-    /** Any mid-call messages (reinvitation, message, etc.). */
-    PJSIP_DIALOG_EVENT_MID_CALL_REQUEST,
-
-    /** Other events (low level events). */
-    PJSIP_DIALOG_EVENT_OTHER,
-
-} pjsip_dlg_event_e;
-
-
-/** 
- * \brief Structure registered by applications to receive dialog notifications 
- * from the User Agent. 
- *
- * Applications registers this structure to get notifications from the User Agent
- * about dialog state changes and other events. Application can set any of
- * the callback function to NULL if it doesn't want to handle the notification,
- * however, setting some callbacks to NULL probably will cause some undesired
- * result (such as setting \b on_incoming to NULL will cause the creation of
- * a lot of dialogs with no owner).
- */
-struct pjsip_dlg_callback
-{
-    /**
-     * This is a low level, uninterpreted callback that is called by framework 
-     * for all kinds of events, such as transaction events, dialog events, etc.
-     * @param dlg	The dialog.
-     * @param dlg_event The type of dialog event.
-     * @param event	The event descriptor.
-     */
-    void (*on_all_events)(pjsip_dlg *dlg, pjsip_dlg_event_e dlg_event, 
-			  pjsip_event *event );
-
-    /**
-     * This is a low level callback that is called by the framework when the
-     * underlying transaction is about to send outgoing message. This callback
-     * is provided to allow application to modify the message before it is 
-     * transmitted. 
-     * @param dlg	The dialog.
-     * @param tsx	The transaction that transmits the message.
-     * @param tdata	The transmission data, which contains the message.
-     * @param retransmission The number of times this message has been sent.
-     *			Zero indicates the message is about to be sent the first time,
-     *			one indicates this is the first retransmission, etc.
-     */
-    void (*on_before_tx)(pjsip_dlg *dlg, pjsip_transaction *tsx,
-			 pjsip_tx_data *tdata, pj_bool_t retransmission);
-
-    /**
-     * This is a low level callback that is called by the framework when the dialog
-     * has sent a message. Note that a receive of retransmission will not trigger
-     * this callback since retransmission is handled internally by transaction.
-     * @param dlg	The dialog.
-     * @param tsx	The transaction that transmits the message.
-     * @param tdata	The transmission data, which contains the message.
-     */
-    void (*on_tx_msg)(pjsip_dlg *dlg, pjsip_transaction *tsx, 
-		      pjsip_tx_data *tdata);
-
-    /**
-     * This is a low level callback that is called by the framework when the
-     * dialog has received a message. Note that a receipt of retransmission 
-     * will not trigger this callback since retransmission is handled internally
-     * by transaction.
-     * @param dlg	The dialog.
-     * @param tsx	The transaction that receives the message.
-     * @param rdata	The receive data, which contains the message.
-     */
-    void (*on_rx_msg)(pjsip_dlg *dlg, pjsip_transaction *tsx, 
-		      pjsip_rx_data *rdata);
-
-    /**
-     * This callback is called by the framework when the user agent
-     * instance receives an incoming INVITE message.
-     * @param dlg	The new dialog that's just created to handle the incoming call.
-     * @param tsx	The INVITE transaction that's just created.
-     * @param rdata	The receive data, which contains the INVITE message.
-     */
-    void (*on_incoming)(pjsip_dlg *dlg, pjsip_transaction *tsx,
-		        pjsip_rx_data *rdata);
-
-    /**
-     * This callback is called by the framework when the dialog is sending
-     * the first outgoing INVITE message.
-     * @param dlg	The dialog.
-     * @param tsx	The INVITE transaction.
-     * @param tdata	The transmit data, which contains the INVITE message.
-     */
-    void (*on_calling)(pjsip_dlg *dlg, pjsip_transaction *tsx,
-		       pjsip_tx_data *tdata);
-
-    /**
-     * This callback is called by the framework when the initial INVITE
-     * transaction has sent/received provisional response.
-     * @param dlg	The dialog.
-     * @param tsx	The transaction.
-     * @param event	The event, which src_type will always be either
-     *			PJSIP_EVENT_RX_MSG or PJSIP_EVENT_TX_MSG. The provisional
-     *			response message itself will be in either \b rdata or \b tdata.
-     * @see pjsip_event.
-     */
-    void (*on_provisional)(pjsip_dlg *dlg, pjsip_transaction *tsx,
-			   pjsip_event *event);
-
-    /**
-     * This callback is called for both UAS and UAC dialog when 200 response
-     * to INVITE is sent or received.
-     * @param dlg	The dialog.
-     * @param event	The event, which src_type can only be either 
-     *			PJSIP_EVENT_TX_MSG or PJSIP_EVENT_RX_MSG.
-     * @see pjsip_event
-     */
-    void (*on_connecting)(pjsip_dlg *dlg, pjsip_event *event);
-
-    /**
-     * This callback is called for both UAS and UAC when an ACK request is
-     * sent or received by the dialog.
-     * @param dlg	The dialog.
-     * @param event	The event, which src_type can only be either 
-     *			PJSIP_EVENT_TX_MSG or PJSIP_EVENT_RX_MSG.
-     * @see pjsip_event
-     */
-    void (*on_established)(pjsip_dlg *dlg, pjsip_event *event);
-
-    /**
-     * This callback is called when the dialog is disconnected, i.e. upon
-     * sending/receiving non-200 response to INVITE, sending/receiving
-     * CANCEL to initial INVITE, and sending/receiving BYE.
-     *
-     * @param dlg	The dialog.
-     * @param event	The event.
-     * @see pjsip_event
-     */
-    void (*on_disconnected)(pjsip_dlg *dlg, pjsip_event *event);
-
-    /**
-     * This callback is called when the dialog is about to be destroyed.
-     * @param dlg The dialog.
-     */
-    void (*on_terminated)(pjsip_dlg *dlg);
-
-    /**
-     * This callback will be called when the dialog receives mid call events
-     * such as re-invitation or incoming pager.
-     *
-     * @param dlg	The dialog.
-     * @param event	The event.
-     */
-    void (*on_mid_call_events)(pjsip_dlg *dlg, pjsip_event *event);
-
-};  /* struct pjsip_dlg_callback */
-
-
-
-/**
- * Dialog state.
- */
-typedef enum pjsip_dlg_state_e
-{
-    /** 
-     * State NULL is after the dialog is instantiated but before any
-     * initialization is done. 
-     */
-    PJSIP_DIALOG_STATE_NULL,
-
-    /**
-     * State INCOMING is after the (callee) dialog has been initialized with
-     * the incoming request, but before any responses is sent by the dialog.
-     */
-    PJSIP_DIALOG_STATE_INCOMING,
-
-    /**
-     * State CALLING is after the (caller) dialog has sent outgoing invitation
-     * but before any responses are received.
-     */
-    PJSIP_DIALOG_STATE_CALLING,
-
-    /**
-     * State PROCEEDING is after the dialog sent/received provisional 
-     * responses, but before final response is sent/received.
-     */
-    PJSIP_DIALOG_STATE_PROCEEDING,
-
-    /**
-     * State CONNECTING is after the dialog has sent/received final response
-     * to the invitation, but before acknowledgement is sent.
-     */
-    PJSIP_DIALOG_STATE_CONNECTING,
-
-    /**
-     * State ESTABLISHED occurs after the invitation has been accepted and
-     * acknowledged.
-     */
-    PJSIP_DIALOG_STATE_ESTABLISHED,
-
-    /**
-     * State DISCONNECTED occurs after either party successfully disconnect
-     * the session.
-     */
-    PJSIP_DIALOG_STATE_DISCONNECTED,
-
-    /**
-     * State TERMINATE occurs when the dialog is ready to be destroyed.
-     */
-    PJSIP_DIALOG_STATE_TERMINATED,
-
-} pjsip_dlg_state_e;
-
-
-/**
- * Get the dialog string state.
- *
- * @param state	    Dialog state.
- * @return	    The string describing the state.
- */
-const char *pjsip_dlg_state_str(pjsip_dlg_state_e state);
-
-/**
- * This structure is used to describe dialog's participants, which in this
- * case is local party (i.e. us) and remote party.
- */
-typedef struct pjsip_dlg_party
-{
-    pjsip_uri		*target;    /**< Target URL.			*/
-    pjsip_fromto_hdr	*info;	    /**< URL in From/To header.		*/
-    pj_str_t		 tag;	    /**< Tag.				*/
-    pjsip_contact_hdr	*contact;   /**< URL in Contact.		*/
-    pj_sockaddr_in	 addr;	    /**< The current transport address. */
-    int			 cseq;	    /**< Sequence number counter.	*/
-} pjsip_dlg_party;
-
-
-/**
- * This structure describes the dialog structure.
- */
-struct pjsip_dlg
-{
-    PJ_DECL_LIST_MEMBER(struct pjsip_dlg)
-
-    char	        obj_name[PJ_MAX_OBJ_NAME];  /**< Log identification.	*/
-
-    pjsip_user_agent   *ua;			    /**< User agent instance.	*/
-    pj_pool_t	       *pool;			    /**< Dialog's pool.		*/
-    pjsip_dlg_state_e   state;			    /**< Dialog's call state.	*/
-    pjsip_role_e	role;			    /**< Dialog's role.		*/
-    pj_mutex_t	       *mutex;			    /**< Dialog's mutex.	*/
-
-    pjsip_dlg_party     local;			    /**< Local party info.	*/
-    pjsip_dlg_party     remote;			    /**< Remote party info.	*/
-
-    pjsip_cid_hdr      *call_id;		    /**< Call-ID		*/
-    pj_bool_t	        secure;			    /**< Use secure transport?	*/
-
-    pjsip_route_hdr     route_set;		    /**< Dialog's route set.	*/
-    pjsip_transaction  *invite_tsx;		    /**< Current INVITE transaction. */
-    int			pending_tsx_count;	    /**< Total pending tsx count. */
-
-    int			cred_count;		    /**< Number of credentials. */
-    pjsip_cred_info    *cred_info;		    /**< Array of credentials.	*/
-
-    pjsip_auth_session	auth_sess;		    /**< List of auth session. */
-
-    pjsip_msg_body     *body;
-
-    void	       *user_data;		    /**< Application's data.	*/
-
-    int  (*handle_tsx_event)(struct pjsip_dlg *,    /**< Internal state handler.*/
-			     pjsip_transaction *,
-			     pjsip_event *);
-};
-
-
-/**
- * Initialize dialog with local and remote info. This function is normally
- * called after application creates the dialog with #pjsip_ua_create_dialog
- * for UAC dialogs.
- *
- * This function will initialize local and remote info from the URL, generate
- * a globally unique Call-ID, initialize CSeq, and initialize other dialog's
- * internal attributes.
- *
- * @param dlg		The dialog to initialize.
- * @param local_info	URI/name address to be used as local info 
- *			(From and Contact headers).
- * @param remote_info	URI/name address to be used as remote info (To header).
- * @param target	URI for initial remote's target, or NULL to set the
- *			initial target the same as remote_info.
- *
- * @return		zero on success.
- */
-PJ_DECL(pj_status_t) pjsip_dlg_init( pjsip_dlg *dlg,
-				     const pj_str_t *local_info,
-				     const pj_str_t *remote_info,
-				     const pj_str_t *target);
-
-
-/**
- * Set authentication credentials to be used by this dialog.
- *
- * If authentication credentials are set for the dialog, the dialog will try to
- * perform authentication automatically using the credentials supplied, and 
- * also cache the last Authorization or Proxy-Authorization headers for next 
- * requests.
- * 
- * If none of the credentials are suitable or accepted by remote, then
- * the dialog will just pass the authorization failure response back to
- * application.
- *
- * @param dlg		The dialog.
- * @param count		Number of credentials in the array.
- * @param cred		Array of credentials.
- *
- * @return		Zero on success.
- */
-PJ_DECL(pj_status_t) pjsip_dlg_set_credentials( pjsip_dlg *dlg,
-					        int count,
-						const pjsip_cred_info cred[]);
-
-/**
- * Override local contact details.
- *
- * Call this function to change the contact details to be advertised in Contact
- * header. Application normally need to call this function for incoming calls
- * before answering the call with 200/OK, because for an incoming dialogs, the
- * initial local contact info are generated from the To header, which is 
- * normally not the appropriate one.
- *
- * @param dlg		The dialog.
- * @param contact	The contact to use.
- *
- * @return		Zero on success.
- */
-PJ_DECL(pj_status_t) pjsip_dlg_set_contact( pjsip_dlg *dlg,
-					    const pj_str_t *contact );
-
-
-/**
- * Set initial route set to be used by the dialog. This initial route set
- * governs where and how the initial INVITE request will be routed. This
- * initial route set will be overwritten with the route set found in the
- * 2xx response of INVITE.
- *
- * Application only needs to call this function if it wants to have custom
- * route for individual dialogs. If only a single route for all dialogs is
- * needed, then application can set the global route by calling function
- * #pjsip_endpt_set_proxies().
- *
- * @param dlg		The dialog.
- * @param route_set	The route set list.
- *
- * @return		Zero on success.
- */
-PJ_DECL(pj_status_t) pjsip_dlg_set_route_set( pjsip_dlg *dlg,
-					      const pjsip_route_hdr *route_set );
-
-
-/**
- * Variation of #pjsip_dlg_set_route_set where the headers will be used
- * as it is (i.e. without cloned).
- *
- * @param dlg		The dialog.
- * @param route_set	The route set list.
- *
- * @return		Zero on success.
- */
-PJ_DECL(pj_status_t) pjsip_dlg_set_route_set_np( pjsip_dlg *dlg,
-						 pjsip_route_hdr *route_set);
-
-/**
- * Create initial outgoing INVITE message.
- *
- * This function is just a simple wrapper to #pjsip_dlg_create_request(),
- * so it follows the same rule there. In addition, this function also adds
- * \b Allow header to the outgoing request.
- *
- * After the message is successfully created, application must call
- * #pjsip_dlg_send_msg() to actually send the message and update the dialog's
- * state. Note that upon return the reference counter of the transmit data
- * will be set to one.
- *
- * @param dlg		The dialog.
- *
- * @return		The dialog transmit data, or NULL.
- */
-PJ_DECL(pjsip_tx_data*) pjsip_dlg_invite( pjsip_dlg *dlg );
-
-
-/**
- * Answer incoming dialog invitation, with either provisional responses
- * or a final response. Application can only call this function when there's
- * a pending invitation to be answered.
- *
- * After the message is successfully created, application must call
- * #pjsip_dlg_send_msg() to actually send the message and update the dialog's
- * state. Note that upon return the reference counter of the transmit data
- * will be set to one.
- *
- * @param dlg	The dialog.
- * @param code	The response code, which can be:
- *		- 100-199 Provisional response (application can issue multiple 
- *                        provisional responses).
- *		- 200-299 To answer the invitation (normally status code 200
- *                        is sent).
- *              - 300-699 To reject the invitation.
- * @return	Transmit data if successfull.
- */
-PJ_DECL(pjsip_tx_data*) pjsip_dlg_answer( pjsip_dlg *dlg, int code );
-
-
-/**
- * High level function to create message to disconnect dialog. Depending 
- * on dialog's  state, this function will either create CANCEL, final response,
- * or BYE message. A status code must be supplied, which will be set if dialog 
- * will be transmitting a final response to INVITE.
- *
- * After the message is successfully created, application must call
- * #pjsip_dlg_send_msg to actually send the message and update the dialog's
- * state. Note that upon return the reference counter of the transmit data
- * will be set to one.
- *
- * @param dlg		The dialog.
- * @param status_code	The status code for disconnection.
- * @return		Transmit data if successfull.
- */
-PJ_DECL(pjsip_tx_data*) pjsip_dlg_disconnect( pjsip_dlg *dlg, int status_code);
-
-/**
- * Create CANCEL message to cancel pending outgoing dialog invitation. 
- * Normally application should call #pjsip_dlg_disconnect() instead, because
- * that function will create the correct message regardless of the state of 
- * the dialog. 
- *
- * Application can call this function at anytime after it issues outgoing 
- * invitation and before receiving final response. However, there's no 
- * guarantee that the invitation will be successfully cancelled, since the 
- * CANCEL request and the final response can pass over in the wire. So the 
- * application must prepare to have the dialog connected even after the 
- * dialog is cancelled.
- *
- * The final state of the dialog will be reported in the dialog callback.
- * If the CANCEL request succeeded, then the dialog will be disconnected with
- * status code \a PJSIP_SC_REQUEST_TERMINATED.
- *
- * After the message is successfully created, application must call
- * #pjsip_dlg_send_msg() to actually send the message and update the dialog's
- * state. 
- *
- * Upon return of this function, the reference counter of the transmit data
- * will be set to one.
- *
- * @param dlg		The dialog.
- * @return		The dialog transmit data containing the CANCEL message,
- *			or NULL.
- */
-PJ_DECL(pjsip_tx_data*) pjsip_dlg_cancel( pjsip_dlg *dlg );
-
-
-/**
- * Create BYE message. Application shouldn't normally need to use this function,
- * but rather it's preferable to use #pjsip_dlg_disconnect() instead because
- * that function will work to disconnect the session no matter what the state
- * is.
- *
- * After the message is successfully created, application must call
- * #pjsip_dlg_send_msg() to actually send the message and update the dialog's
- * state. Note that upon return the reference counter of the transmit data
- * will be set to one.
- *
- * @param dlg		The dialog.
- * @return		The BYE message or NULL.
- */
-PJ_DECL(pjsip_tx_data*) pjsip_dlg_bye( pjsip_dlg *dlg );
-
-/**
- * This function is called by application to create new outgoing request
- * message for this dialog. After the request is created, application can
- * modify the message (such adding headers), and eventually send the request
- * by calling #pjsip_dlg_send_msg().
- *
- * This function will initialize the request message with dialog's properties
- * as follows:
- *  - the request line is initialized with the method and the target is
- *    initialized from current remote target.
- *  - \b From, \b To, \b Contact, and \b Call-Id headers will be added.
- *  - An initial \b CSeq header will be provided (although the value will be
- *    verified again when the message is actually sent with #pjsip_dlg_send_msg().
- *  - \b Route headers will be added from dialog's route set.
- *  - Authentication headers (\b Authorization or \b Proxy-Authorization) will
- *    be added from dialog's authorization cache.
- *
- * Note that upon return the reference counter of the transmit data
- * will be set to one. When the message is sent, #pjsip_dlg_send_msg() will
- * decrement the reference counter, and when the reference counter reach zero,
- * the message will be deleted.
- *
- * @param dlg		The dialog.
- * @param method	The request method.
- * @param cseq		Specify CSeq, or -1 to let the dialog specify CSeq.
- *
- * @return		Transmit data for the new request.
- *
- * @see pjsip_dlg_send_msg()
- */
-PJ_DECL(pjsip_tx_data*) pjsip_dlg_create_request( pjsip_dlg *dlg,
-						  const pjsip_method *method,
-						  int cseq);
-
-
-/**
- * This function can be called by application to send outgoing message (request
- * or response) to remote party. Note that after calling this function, the
- * transmit data will be deleted regardless of the return status. To prevent
- * deletion, application must increase the reference count, but then it will
- * be responsible to delete this transmit data itself (by decreasing the
- * reference count).
- *
- * @param dlg		The dialog.
- * @param tdata		The transmit data, which contains the request message.
- * @return		zero on success.
- */
-PJ_DECL(pj_status_t) pjsip_dlg_send_msg( pjsip_dlg *dlg,
-					 pjsip_tx_data *tdata );
-
-
-/**
- * @}
- */
-
-PJ_END_DECL
-
-#endif	/* __PJSIP_DIALOG_H__ */
-
diff --git a/pjsip/include/pjsip_core.h b/pjsip/include/pjsip.h
index 5947d4b1..b7f2dd95 100644
--- a/pjsip/include/pjsip_core.h
+++ b/pjsip/include/pjsip.h
@@ -16,25 +16,41 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
  */
-#ifndef __PJSIP_CORE_H__
-#define __PJSIP_CORE_H__
+#ifndef __PJSIP_H__
+#define __PJSIP_H__
 
+/* Base types. */
 #include <pjsip/sip_types.h>
-#include <pjsip/sip_auth.h>
-#include <pjsip/sip_endpoint.h>
 #include <pjsip/sip_errno.h>
-#include <pjsip/sip_event.h>
-#include <pjsip/sip_module.h>
+
+/* Messaging and parsing. */
+#include <pjsip/sip_uri.h>
+#include <pjsip/sip_tel_uri.h>
 #include <pjsip/sip_msg.h>
 #include <pjsip/sip_parser.h>
-#include <pjsip/sip_resolve.h>
-#include <pjsip/sip_tel_uri.h>
-#include <pjsip/sip_transaction.h>
+
+/* Core */
+#include <pjsip/sip_event.h>
+#include <pjsip/sip_module.h>
+#include <pjsip/sip_endpoint.h>
+#include <pjsip/sip_util.h>
+
+/* Transport layer */
 #include <pjsip/sip_transport.h>
 #include <pjsip/sip_transport_udp.h>
 #include <pjsip/sip_transport_loop.h>
-#include <pjsip/sip_uri.h>
-#include <pjsip/sip_util.h>
+#include <pjsip/sip_resolve.h>
+
+/* Authentication. */
+#include <pjsip/sip_auth.h>
+
+/* Transaction layer. */
+#include <pjsip/sip_transaction.h>
+
+/* UA Layer. */
+#include <pjsip/sip_ua_layer.h>
+#include <pjsip/sip_dialog.h>
+
 
-#endif	/* __PJSIP_CORE_H__ */
+#endif	/* __PJSIP_H__ */
 
diff --git a/pjsip/include/pjsip/sip_auth.h b/pjsip/include/pjsip/sip_auth.h
index e5f80655..7a8eb610 100644
--- a/pjsip/include/pjsip/sip_auth.h
+++ b/pjsip/include/pjsip/sip_auth.h
@@ -187,6 +187,18 @@ PJ_DECL(pj_status_t) pjsip_auth_clt_init( pjsip_auth_clt_sess *sess,
 					  unsigned options);
 
 
+/**
+ * Clone client initialization session. 
+ *
+ * @param pool		Pool to use.
+ * @param sess		Structure to put the duplicated session.
+ * @param rhs		The client session to be cloned.
+ *
+ * @return		PJ_SUCCESS on success;
+ */
+PJ_DECL(pj_status_t) pjsip_auth_clt_clone( pj_pool_t *pool,
+					   pjsip_auth_clt_sess *sess,
+					   const pjsip_auth_clt_sess *rhs);
 
 /**
  * Set the credentials to be used during the session. This will duplicate 
diff --git a/pjsip/include/pjsip/sip_config.h b/pjsip/include/pjsip/sip_config.h
index 158d4a75..ec4a4aad 100644
--- a/pjsip/include/pjsip/sip_config.h
+++ b/pjsip/include/pjsip/sip_config.h
@@ -53,6 +53,10 @@
 #define PJSIP_POOL_TSX_INC		256
 #define PJSIP_MAX_TSX_KEY_LEN		(PJSIP_MAX_URL_SIZE*2)
 
+/* User agent. */
+#define PJSIP_POOL_LEN_USER_AGENT	1024
+#define PJSIP_POOL_INC_USER_AGENT	1024
+
 /* Message/URL related constants. */
 #define PJSIP_MAX_CALL_ID_LEN		PJ_GUID_STRING_LENGTH
 #define PJSIP_MAX_TAG_LEN		PJ_GUID_STRING_LENGTH
diff --git a/pjsip/include/pjsip/sip_dialog.h b/pjsip/include/pjsip/sip_dialog.h
new file mode 100644
index 00000000..9e827c78
--- /dev/null
+++ b/pjsip/include/pjsip/sip_dialog.h
@@ -0,0 +1,324 @@
+/* $Id$ */
+/* 
+ * Copyright (C) 2003-2006 Benny Prijono <benny@prijono.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
+ */
+#ifndef __PJSIP_SIP_DIALOG_H__
+#define __PJSIP_SIP_DIALOG_H__
+
+
+/**
+ * @file dialog.h
+ * @brief SIP Dialog abstraction
+ */
+
+#include <pjsip/sip_msg.h>
+#include <pjsip/sip_auth.h>
+#include <pjsip/sip_errno.h>
+#include <pj/sock.h>
+#include <pj/assert.h>
+
+PJ_BEGIN_DECL
+
+
+/**
+ * This structure is used to describe dialog's participants, which in this
+ * case is local party (i.e. us) and remote party.
+ */
+typedef struct pjsip_dlg_party
+{
+    pjsip_fromto_hdr	*info;	    /**< From/To header, inc tag.	*/
+    pj_uint32_t		 tag_hval;  /**< Hashed value of the tag.	*/
+    pjsip_contact_hdr	*contact;   /**< Contact header.		*/
+    pj_int32_t		 first_cseq;/**< First CSeq seen.		*/
+    pj_int32_t		 cseq;	    /**< Next sequence number.		*/
+} pjsip_dlg_party;
+
+
+/**
+ * This structure describes the dialog structure.
+ */
+struct pjsip_dialog
+{
+    /** The dialog set list. */
+    PJ_DECL_LIST_MEMBER(pjsip_dialog);
+
+    /* Dialog's system properties. */
+    char		obj_name[PJ_MAX_OBJ_NAME];  /**< Standard id.	    */
+    pj_pool_t	       *pool;	    /**< Dialog's pool.			    */
+    pj_mutex_t	       *mutex;	    /**< Dialog's mutex.		    */
+    pjsip_user_agent   *ua;	    /**< User agent instance.		    */
+
+    /* The dialog set. */
+    void	       *dlg_set;
+
+    /* Dialog's session properties. */
+    pjsip_uri	       *target;	    /**< Current target.		    */
+    pjsip_dlg_party     local;	    /**< Local party info.		    */
+    pjsip_dlg_party     remote;	    /**< Remote party info.		    */
+    pjsip_role_e	role;	    /**< Initial role.			    */
+    pj_bool_t		secure;	    /**< Use secure transport?		    */
+    pjsip_cid_hdr      *call_id;    /**< Call-ID header.		    */
+    pjsip_route_hdr	route_set;  /**< Route set.			    */
+    pjsip_auth_clt_sess	auth_sess;  /**< Client authentication session.	    */
+
+    /** Session counter. */
+    int			sess_count;
+
+    /** Transaction counter. */
+    int			tsx_count;
+
+    /* Dialog usages. */
+    unsigned		usage_cnt;  /**< Number of registered usages.	    */
+    pjsip_module       *usage[PJSIP_MAX_MODULE]; /**< Array of usages, priority sorted   */
+
+    /** Module specific data. */
+    void	       *mod_data[PJSIP_MAX_MODULE];
+};
+
+
+/**
+ * This utility function returns PJ_TRUE if the specified method is a
+ * dialog creating request. This method property is used to determine
+ * whether Contact header should be included in outgoing request.
+ */
+PJ_DECL(pj_bool_t) pjsip_method_creates_dialog(const pjsip_method *m);
+
+/**
+ * Create a new dialog and return the instance in p_dlg parameter. 
+ * After creating  the dialog, application can add modules as dialog usages
+ * by calling  #pjsip_dlg_add_usage(). 
+ *
+ * If the request has To tag parameter, dialog's local tag will be initialized 
+ * from this value. Otherwise a globally unique id generator will be invoked to
+ * create dialog's local tag.
+ *
+ * This function also initializes the dialog's route set based on the 
+ * Record-Route headers in the request, if present.
+ *
+ * Note that initially, the session count in the dialog will be initialized 
+ * to zero.
+ */
+PJ_DECL(pj_status_t) pjsip_dlg_create_uac( pjsip_user_agent *ua,
+					   const pj_str_t *local_uri,
+					   const pj_str_t *local_contact_uri,
+					   const pj_str_t *remote_uri,
+					   const pj_str_t *target,
+					   pjsip_dialog **p_dlg);
+
+
+/**
+ * Initialize UAS dialog from the information found in the incoming request 
+ * that creates a dialog (such as INVITE, REFER, or SUBSCRIBE), and set the 
+ * local Contact to contact. If contact is not specified, the local contact 
+ * is initialized from the URI in the To header in the request. 
+ *
+ * Note that initially, the session count in the dialog will be initialized 
+ * to zero.
+ */
+PJ_DECL(pj_status_t) pjsip_dlg_create_uas(  pjsip_user_agent *ua,
+					    pjsip_rx_data *rdata,
+					    const pj_str_t *contact,
+					    pjsip_dialog **p_dlg);
+
+
+/**
+ * Create a new (forked) dialog on receipt on forked response in rdata. 
+ * The new dialog will be created from original_dlg, except that it will have
+ * new remote tag as copied from the To header in the response. Upon return, 
+ * the new_dlg will have been registered to the user agent. Applications just 
+ * need to add modules as dialog's usages.
+ *
+ * Note that initially, the session count in the dialog will be initialized 
+ * to zero.
+ */
+PJ_DECL(pj_status_t) pjsip_dlg_fork(const pjsip_dialog *original_dlg,
+				    const pjsip_rx_data *rdata,
+				    pjsip_dialog **new_dlg );
+
+/**
+ * Set dialog's initial route set to route_set list. This can only be called
+ * for UAC dialog, before any request is sent. After dialog has been 
+ * established, the route set can not be changed.
+ *
+ * For UAS dialog,the route set will be initialized in pjsip_dlg_create_uas()
+ * from the Record-Route headers in the incoming request.
+ *
+ * The route_set argument is standard list of Route headers (i.e. with 
+ * sentinel).
+ */
+PJ_DECL(pj_status_t) pjsip_dlg_set_route_set( pjsip_dialog *dlg,
+					      const pjsip_route_hdr *route_set );
+
+/**
+ * Increment the number of sessions in the dialog. Note that initially 
+ * (after created) the dialog has the session counter set to zero.
+ */
+PJ_DECL(pj_status_t) pjsip_dlg_inc_session( pjsip_dialog *dlg );
+
+
+/**
+ * Decrement the number of sessions in the dialog. Once the session counter 
+ * reach zero and there is no pending transaction, the dialog will be 
+ * destroyed. Note that this function may destroy the dialog immediately 
+ * if there is no pending transaction when this function is called.
+ */
+PJ_DECL(pj_status_t) pjsip_dlg_dec_session( pjsip_dialog *dlg );
+
+/**
+ * Add a module as dialog usage, and optionally set the module specific data.
+ */
+PJ_DECL(pj_status_t) pjsip_dlg_add_usage( pjsip_dialog *dlg,
+					  pjsip_module *module,
+					  void *mod_data );
+
+/**
+ * Attach module specific data to the dialog. Application can also set 
+ * the value directly by accessing dlg->mod_data[module_id].
+ */
+PJ_INLINE(pj_status_t) pjsip_dlg_set_mod_data( pjsip_dialog *dlg,
+					       int mod_id,
+					       void *data )
+{
+    PJ_ASSERT_RETURN(dlg, PJ_EINVAL);
+    PJ_ASSERT_RETURN(mod_id >= 0 && mod_id < PJSIP_MAX_MODULE,
+		     PJ_EINVAL);
+    dlg->mod_data[mod_id] = data;
+    return PJ_SUCCESS;
+}
+
+/**
+ * Get module specific data previously attached to the dialog. Application
+ * can also get value directly by accessing dlg->mod_data[module_id].
+ */
+PJ_INLINE(void*) pjsip_dlg_get_mod_data(pjsip_dialog *dlg,
+					int mod_id)
+{
+    PJ_ASSERT_RETURN(dlg, NULL);
+    PJ_ASSERT_RETURN(mod_id >= 0 && mod_id < PJSIP_MAX_MODULE,
+		     NULL);
+    return dlg->mod_data[mod_id];
+}
+
+
+
+/**
+ * Get the dialog instance in the incoming rdata. If an incoming message 
+ * matches an existing dialog, the user agent must have put the matching 
+ * dialog instance in the rdata, or otherwise this function will return 
+ * NULL if the message didn't match any existing dialog.
+ */
+PJ_DECL(pjsip_dialog*) pjsip_rdata_get_dlg( pjsip_rx_data *rdata );
+
+/**
+ * Get the associated dialog in a transaction.
+ */
+PJ_DECL(pjsip_dialog*) pjsip_tsx_get_dlg( pjsip_transaction *tsx );
+
+
+/**
+ * Create a basic/generic request with the specified method and optionally
+ * specify the cseq. Use value -1 for cseq to have the dialog automatically
+ * put next cseq number for the request. Otherwise for some requests, 
+ * e.q. CANCEL and ACK, application must put the CSeq in the original 
+ * INVITE request as the parameter. 
+ *
+ * This function will also put Contact header where appropriate.
+ */
+PJ_DECL(pj_status_t) pjsip_dlg_create_request(	pjsip_dialog *dlg,
+						const pjsip_method *method,
+						int cseq,
+						pjsip_tx_data **tdata);
+
+
+/**
+ * Send request message to remote peer. If the request is not an ACK request, 
+ * the dialog will send the request statefully, by creating an UAC transaction
+ * and send the request with the transaction. 
+ *
+ * Also when the request is not ACK or CANCEL, the dialog will increment its
+ * local cseq number and update the cseq in the request according to dialog's 
+ * cseq.
+ *
+ * If p_tsx is not null, this argument will be set with the transaction 
+ * instance that was used to send the request.
+ *
+ * This function will decrement the transmit data's reference counter
+ * regardless the status of the operation.
+ */
+PJ_DECL(pj_status_t) pjsip_dlg_send_request (	pjsip_dialog *dlg,
+						pjsip_tx_data *tdata,
+						pjsip_transaction **p_tsx );
+
+
+/**
+ * Create a response message for the incoming request in rdata with status
+ * code st_code and optional status text st_text. This function is different
+ * than endpoint's API #pjsip_endpt_create_response() in that the dialog 
+ * function adds Contact header and Record-Routes headers in the response 
+ * where appropriate.
+ */
+PJ_DECL(pj_status_t) pjsip_dlg_create_response(	pjsip_dialog *dlg,
+						pjsip_rx_data *rdata,
+						int st_code,
+						const pj_str_t *st_text,
+						pjsip_tx_data **tdata);
+
+
+/**
+ * Modify previously sent response with other status code. Contact header 
+ * will be added when appropriate.
+ */
+PJ_DECL(pj_status_t) pjsip_dlg_modify_response(	pjsip_dialog *dlg,
+						pjsip_tx_data *tdata,
+						int st_code,
+						const pj_str_t *st_text);
+
+
+/**
+ * Send response message statefully. The transaction instance MUST be the 
+ * transaction that was reported on on_rx_request() callback.
+ *
+ * This function decrements the transmit data's reference counter regardless
+ * the status of the operation.
+ */
+PJ_DECL(pj_status_t) pjsip_dlg_send_response(	pjsip_dialog *dlg,
+						pjsip_transaction *tsx,
+						pjsip_tx_data *tdata);
+
+
+
+/* Receives transaction event (called by user_agent module) */
+void pjsip_dlg_on_tsx_state( pjsip_dialog *dlg,
+			     pjsip_transaction *tsx,
+			     pjsip_event *e );
+
+void pjsip_dlg_on_rx_request( pjsip_dialog *dlg,
+			      pjsip_rx_data *rdata );
+
+void pjsip_dlg_on_rx_response( pjsip_dialog *dlg,
+			       pjsip_rx_data *rdata );
+
+
+/**
+ * @}
+ */
+
+PJ_END_DECL
+
+
+#endif	/* __PJSIP_SIP_DIALOG_H__ */
+
diff --git a/pjsip/include/pjsip/sip_endpoint.h b/pjsip/include/pjsip/sip_endpoint.h
index 527cd886..ef9d44c9 100644
--- a/pjsip/include/pjsip/sip_endpoint.h
+++ b/pjsip/include/pjsip/sip_endpoint.h
@@ -228,6 +228,19 @@ PJ_DECL(pj_status_t) pjsip_endpt_create_tsx(pjsip_endpoint *endpt,
 					    pjsip_transaction **p_tsx);
 
 /**
+ * Find transaction in endpoint's transaction table by the transaction's key.
+ * This function normally is only used by modules. The key for a transaction
+ * can be created by calling #pjsip_tsx_create_key.
+ *
+ * @param endpt	    The endpoint instance.
+ * @param key	    Transaction key, as created with #pjsip_tsx_create_key.
+ *
+ * @return	    The transaction, or NULL if it's not found.
+ */
+PJ_DECL(pjsip_transaction*) pjsip_endpt_find_tsx( pjsip_endpoint *endpt,
+					          const pj_str_t *key );
+
+/**
  * Register the transaction to the endpoint's transaction table.
  * Before the transaction is registered, it must have been initialized as
  * either UAS or UAC by calling #pjsip_tsx_init_uac or #pjsip_tsx_init_uas.
@@ -316,40 +329,78 @@ pjsip_endpt_acquire_transport( pjsip_endpoint *endpt,
 			       int addr_len,
 			       pjsip_transport **p_transport);
 
-/**
- * Get additional headers to be put in outgoing request message. 
- * This function is normally called by transaction layer when sending outgoing
- * requests.
- * 
- * @param endpt	    The endpoint.
+
+/*****************************************************************************
  *
- * @return	    List of additional headers to be put in outgoing requests.
+ * Capabilities Management
+ *
+ * Modules may implement new capabilities to the stack. These capabilities
+ * are indicated by the appropriate SIP header fields, such as Accept,
+ * Accept-Encoding, Accept-Language, Allow, Supported, etc.
+ *
+ * When a module provides new capabilities to the stack, it registers these
+ * capabilities to the endpoint by supplying new tags (strings) to the
+ * appropriate header fields. Application (or other modules) can then query
+ * these header fields to get the list of supported capabilities, and may
+ * include these headers in the outgoing message.
+ *****************************************************************************
  */
-PJ_DECL(const pjsip_hdr*) pjsip_endpt_get_request_headers(pjsip_endpoint *endpt);
 
 /**
- * Get "Allow" header from endpoint. The endpoint builds the "Allow" header
- * from the list of methods supported by modules.
+ * Get the value of the specified capability header field.
  *
  * @param endpt	    The endpoint.
+ * @param htype	    The header type to be retrieved, which value may be:
+ *		    - PJSIP_H_ACCEPT
+ *		    - PJSIP_H_ALLOW
+ *		    - PJSIP_H_SUPPORTED
+ * @param hname	    If htype specifies PJSIP_H_OTHER, then the header name
+ *		    must be supplied in this argument. Otherwise the value
+ *		    must be set to NULL.
  *
- * @return	    "Allow" header, or NULL if endpoint doesn't have "Allow" header.
+ * @return	    The appropriate header, or NULL if the header is not
+ *		    available.
  */
-PJ_DECL(const pjsip_allow_hdr*) pjsip_endpt_get_allow_hdr( pjsip_endpoint *endpt );
+PJ_DECL(const pjsip_hdr*) pjsip_endpt_get_capability( pjsip_endpoint *endpt,
+						      int htype,
+						      const pj_str_t *hname);
 
 
 /**
- * Find transaction in endpoint's transaction table by the transaction's key.
- * This function normally is only used by modules. The key for a transaction
- * can be created by calling #pjsip_tsx_create_key.
+ * Add or register new capabilities as indicated by the tags to the
+ * appropriate header fields in the endpoint.
  *
- * @param endpt	    The endpoint instance.
- * @param key	    Transaction key, as created with #pjsip_tsx_create_key.
+ * @param endpt	    The endpoint.
+ * @param mod	    The module which registers the capability.
+ * @param htype	    The header type to be set, which value may be:
+ *		    - PJSIP_H_ACCEPT
+ *		    - PJSIP_H_ALLOW
+ *		    - PJSIP_H_SUPPORTED
+ * @param hname	    If htype specifies PJSIP_H_OTHER, then the header name
+ *		    must be supplied in this argument. Otherwise the value
+ *		    must be set to NULL.
+ * @param count	    The number of tags in the array.
+ * @param tags	    Array of tags describing the capabilities or extensions
+ *		    to be added to the appropriate header.
+ *
+ * @return	    PJ_SUCCESS on success.
+ */
+PJ_DECL(pj_status_t) pjsip_endpt_add_capability( pjsip_endpoint *endpt,
+						 pjsip_module *mod,
+						 int htype,
+						 const pj_str_t *hname,
+						 unsigned count,
+						 const pj_str_t tags[]);
+
+/**
+ * Get list of additional headers to be put in outgoing request message.
  *
- * @return	    The transaction, or NULL if it's not found.
+ * @param e	    The endpoint.
+ *
+ * @return	    List of headers.
  */
-PJ_DECL(pjsip_transaction*) pjsip_endpt_find_tsx( pjsip_endpoint *endpt,
-					          const pj_str_t *key );
+PJ_DECL(const pjsip_hdr*) pjsip_endpt_get_request_headers(pjsip_endpoint *e);
+
 
 /**
  * Set list of SIP proxies to be visited for all outbound request messages.
diff --git a/pjsip/include/pjsip/sip_errno.h b/pjsip/include/pjsip/sip_errno.h
index 9c04c755..f7dc18cc 100644
--- a/pjsip/include/pjsip/sip_errno.h
+++ b/pjsip/include/pjsip/sip_errno.h
@@ -140,6 +140,11 @@ PJ_DECL(pj_str_t) pjsip_strerror( pj_status_t status, char *buffer,
 
 /**
  * @hideinitializer
+ * General Invalid URI error.
+ */
+#define PJSIP_EINVALIDURI	(PJSIP_ERRNO_START_PJSIP + 39)	/* 171039 */
+/**
+ * @hideinitializer
  * Unsupported URL scheme.
  */
 #define PJSIP_EINVALIDSCHEME    (PJSIP_ERRNO_START_PJSIP + 40)	/* 171040 */
@@ -347,6 +352,17 @@ PJ_DECL(pj_str_t) pjsip_strerror( pj_status_t status, char *buffer,
 #define PJSIP_EAUTHINVALIDDIGEST (PJSIP_ERRNO_START_PJSIP+110)	/* 171110 */
 
 
+/************************************************************
+ * UA AND DIALOG ERRORS
+ ***********************************************************/
+/**
+ * @hideinitializer
+ * Missing From/To tag.
+ */
+#define PJSIP_EMISSINGTAG	 (PJSIP_ERRNO_START_PJSIP+120)	/* 171120 */
+
+
+
 PJ_END_DECL
 
 #endif	/* __PJSIP_SIP_ERRNO_H__ */
diff --git a/pjsip/include/pjsip/sip_module.h b/pjsip/include/pjsip/sip_module.h
index 161e43d2..57d1652d 100644
--- a/pjsip/include/pjsip/sip_module.h
+++ b/pjsip/include/pjsip/sip_module.h
@@ -24,6 +24,7 @@
  * @brief Module helpers
  */
 #include <pjsip/sip_types.h>
+#include <pj/list.h>
 
 PJ_BEGIN_DECL
 
@@ -68,16 +69,6 @@ struct pjsip_module
     void *user_data;
 
     /**
-     * Number of methods supported by this module.
-     */
-    int method_cnt;
-
-    /**
-     * Array of methods supported by this module.
-     */
-    const pjsip_method *methods[8];
-
-    /**
      * Pointer to function to be called to initialize the module.
      *
      * @param endpt	The endpoint instance.
diff --git a/pjsip/include/pjsip/sip_msg.h b/pjsip/include/pjsip/sip_msg.h
index 3be3c2f8..cebaf3f0 100644
--- a/pjsip/include/pjsip/sip_msg.h
+++ b/pjsip/include/pjsip/sip_msg.h
@@ -173,48 +173,48 @@ typedef enum pjsip_hdr_e
      * DO NOT CHANGE THE VALUE/ORDER OF THE HEADER IDs!!!.
      */
     PJSIP_H_ACCEPT,
-    PJSIP_H_ACCEPT_ENCODING_UNIMP,
-    PJSIP_H_ACCEPT_LANGUAGE_UNIMP,
-    PJSIP_H_ALERT_INFO_UNIMP,
+    PJSIP_H_ACCEPT_ENCODING_UNIMP,	/* N/A, use pjsip_generic_string_hdr */
+    PJSIP_H_ACCEPT_LANGUAGE_UNIMP,	/* N/A, use pjsip_generic_string_hdr */
+    PJSIP_H_ALERT_INFO_UNIMP,		/* N/A, use pjsip_generic_string_hdr */
     PJSIP_H_ALLOW,
-    PJSIP_H_AUTHENTICATION_INFO_UNIMP,
+    PJSIP_H_AUTHENTICATION_INFO_UNIMP,	/* N/A, use pjsip_generic_string_hdr */
     PJSIP_H_AUTHORIZATION,
     PJSIP_H_CALL_ID,
-    PJSIP_H_CALL_INFO_UNIMP,
+    PJSIP_H_CALL_INFO_UNIMP,		/* N/A, use pjsip_generic_string_hdr */
     PJSIP_H_CONTACT,
-    PJSIP_H_CONTENT_DISPOSITION_UNIMP,
-    PJSIP_H_CONTENT_ENCODING_UNIMP,
-    PJSIP_H_CONTENT_LANGUAGE_UNIMP,
+    PJSIP_H_CONTENT_DISPOSITION_UNIMP,	/* N/A, use pjsip_generic_string_hdr */
+    PJSIP_H_CONTENT_ENCODING_UNIMP,	/* N/A, use pjsip_generic_string_hdr */
+    PJSIP_H_CONTENT_LANGUAGE_UNIMP,	/* N/A, use pjsip_generic_string_hdr */
     PJSIP_H_CONTENT_LENGTH,
     PJSIP_H_CONTENT_TYPE,
     PJSIP_H_CSEQ,
-    PJSIP_H_DATE_UNIMP,
-    PJSIP_H_ERROR_INFO_UNIMP,
+    PJSIP_H_DATE_UNIMP,			/* N/A, use pjsip_generic_string_hdr */
+    PJSIP_H_ERROR_INFO_UNIMP,		/* N/A, use pjsip_generic_string_hdr */
     PJSIP_H_EXPIRES,
     PJSIP_H_FROM,
-    PJSIP_H_IN_REPLY_TO_UNIMP,
+    PJSIP_H_IN_REPLY_TO_UNIMP,		/* N/A, use pjsip_generic_string_hdr */
     PJSIP_H_MAX_FORWARDS,
-    PJSIP_H_MIME_VERSION_UNIMP,
+    PJSIP_H_MIME_VERSION_UNIMP,		/* N/A, use pjsip_generic_string_hdr */
     PJSIP_H_MIN_EXPIRES,
-    PJSIP_H_ORGANIZATION_UNIMP,
-    PJSIP_H_PRIORITY_UNIMP,
+    PJSIP_H_ORGANIZATION_UNIMP,		/* N/A, use pjsip_generic_string_hdr */
+    PJSIP_H_PRIORITY_UNIMP,		/* N/A, use pjsip_generic_string_hdr */
     PJSIP_H_PROXY_AUTHENTICATE,
     PJSIP_H_PROXY_AUTHORIZATION,
-    PJSIP_H_PROXY_REQUIRE_UNIMP,
+    PJSIP_H_PROXY_REQUIRE_UNIMP,	/* N/A, use pjsip_generic_string_hdr */
     PJSIP_H_RECORD_ROUTE,
-    PJSIP_H_REPLY_TO_UNIMP,
+    PJSIP_H_REPLY_TO_UNIMP,		/* N/A, use pjsip_generic_string_hdr */
     PJSIP_H_REQUIRE,
     PJSIP_H_RETRY_AFTER,
     PJSIP_H_ROUTE,
-    PJSIP_H_SERVER_UNIMP,
-    PJSIP_H_SUBJECT_UNIMP,
+    PJSIP_H_SERVER_UNIMP,		/* N/A, use pjsip_generic_string_hdr */
+    PJSIP_H_SUBJECT_UNIMP,		/* N/A, use pjsip_generic_string_hdr */
     PJSIP_H_SUPPORTED,
-    PJSIP_H_TIMESTAMP_UNIMP,
+    PJSIP_H_TIMESTAMP_UNIMP,		/* N/A, use pjsip_generic_string_hdr */
     PJSIP_H_TO,
     PJSIP_H_UNSUPPORTED,
-    PJSIP_H_USER_AGENT_UNIMP,
+    PJSIP_H_USER_AGENT_UNIMP,		/* N/A, use pjsip_generic_string_hdr */
     PJSIP_H_VIA,
-    PJSIP_H_WARNING_UNIMP,
+    PJSIP_H_WARNING_UNIMP,		/* N/A, use pjsip_generic_string_hdr */
     PJSIP_H_WWW_AUTHENTICATE,
 
     PJSIP_H_OTHER,
@@ -748,6 +748,49 @@ PJ_INLINE(void) pjsip_msg_insert_first_hdr( pjsip_msg *msg, pjsip_hdr *hdr )
 PJ_DECL(pj_ssize_t) pjsip_msg_print(const pjsip_msg *msg, 
 				    char *buf, pj_size_t size);
 
+
+/*
+ * Some usefull macros to find common headers.
+ */
+
+
+/**
+ * Find Call-ID header.
+ *
+ * @param msg	The message.
+ * @return	Call-ID header instance.
+ */
+#define PJSIP_MSG_CID_HDR(msg) \
+	    ((pjsip_cid_hdr*)pjsip_msg_find_hdr(msg, PJSIP_H_CALL_ID, NULL))
+
+/**
+ * Find CSeq header.
+ *
+ * @param msg	The message.
+ * @return	CSeq header instance.
+ */
+#define PJSIP_MSG_CSEQ_HDR(msg) \
+	    ((pjsip_cseq_hdr*)pjsip_msg_find_hdr(msg, PJSIP_H_CSEQ, NULL))
+
+/**
+ * Find From header.
+ *
+ * @param msg	The message.
+ * @return	From header instance.
+ */
+#define PJSIP_MSG_FROM_HDR(msg) \
+	    ((pjsip_from_hdr*)pjsip_msg_find_hdr(msg, PJSIP_H_FROM, NULL))
+
+/**
+ * Find To header.
+ *
+ * @param msg	The message.
+ * @return	To header instance.
+ */
+#define PJSIP_MSG_TO_HDR(msg) \
+	    ((pjsip_to_hdr*)pjsip_msg_find_hdr(msg, PJSIP_H_TO, NULL))
+
+
 /**
  * @}
  */
@@ -766,8 +809,10 @@ PJ_DECL(pj_ssize_t) pjsip_msg_print(const pjsip_msg *msg,
  */
 typedef struct pjsip_generic_string_hdr
 {
-    PJSIP_DECL_HDR_MEMBER(struct pjsip_generic_string_hdr); /**< Standard header field. */
-    pj_str_t hvalue;				    /**< hvalue */
+    /** Standard header field. */
+    PJSIP_DECL_HDR_MEMBER(struct pjsip_generic_string_hdr);
+    /** hvalue */
+    pj_str_t hvalue;
 } pjsip_generic_string_hdr;
 
 
@@ -778,25 +823,38 @@ typedef struct pjsip_generic_string_hdr
  * @param pool	    The pool.
  * @param hname	    The header name to be assigned to the header, or NULL to
  *		    assign the header name with some string.
+ * @param hvalue    Optional string to be assigned as the value.
  *
  * @return	    The header, or THROW exception.
  */
-PJ_DECL(pjsip_generic_string_hdr*) pjsip_generic_string_hdr_create( pj_pool_t *pool, 
-						      const pj_str_t *hname );
+PJ_DECL(pjsip_generic_string_hdr*) 
+pjsip_generic_string_hdr_create( pj_pool_t *pool, 
+				 const pj_str_t *hname,
+				 const pj_str_t *hvalue);
 
 /**
- * Create a generic header along with the text content.
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
  *
- * @param pool	    The pool.
- * @param hname	    The header name.
- * @param hvalue    The header text content.
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ * @param hname	    The header name to be assigned to the header, or NULL to
+ *		    assign the header name with some string later.
+ * @param hvalue    Optional string to be assigned as the value.
  *
- * @return	    The header instance.
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
  */
 PJ_DECL(pjsip_generic_string_hdr*) 
-pjsip_generic_string_hdr_create_with_text( pj_pool_t *pool,
-					   const pj_str_t *hname,
-					   const pj_str_t *hvalue);
+pjsip_generic_string_hdr_init( pj_pool_t *pool,
+			       void *mem,
+			       const pj_str_t *hname,
+			       const pj_str_t *hvalue);
+
 
 /**
  * @}
@@ -827,25 +885,36 @@ typedef struct pjsip_generic_int_hdr
  * @param pool	    The pool.
  * @param hname	    The header name to be assigned to the header, or NULL to
  *		    assign the header name with some string.
+ * @param hvalue    The value to be assigned to the header.
  *
  * @return	    The header, or THROW exception.
  */
-PJ_DECL(pjsip_generic_int_hdr*) pjsip_generic_int_hdr_create( pj_pool_t *pool, 
-						      const pj_str_t *hname );
+PJ_DECL(pjsip_generic_int_hdr*) pjsip_generic_int_hdr_create( pj_pool_t *pool,
+						      const pj_str_t *hname,
+						      int hvalue );
+
 
 /**
- * Create a generic header along with the value.
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
  *
- * @param pool	    The pool.
- * @param hname	    The header name.
- * @param value     The header value content.
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ * @param hname	    The header name to be assigned to the header, or NULL to
+ *		    assign the header name with some string later.
+ * @param value	    Value to be assigned to the header.
  *
- * @return	    The header instance.
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
  */
-PJ_DECL(pjsip_generic_int_hdr*) 
-pjsip_generic_int_hdr_create_with_value( pj_pool_t *pool,
-					 const pj_str_t *hname,
-					 int value);
+PJ_DECL(pjsip_generic_int_hdr*) pjsip_generic_int_hdr_init( pj_pool_t *pool,
+							    void *mem,
+							    const pj_str_t *hname,
+							    int value );
 
 /**
  * @}
@@ -873,11 +942,33 @@ typedef struct pjsip_generic_array_hdr
  * Create generic array header.
  *
  * @param pool	    Pool to allocate memory from.
+ * @param hname	    Header name.
  *
  * @return	    New generic array header.
  */
-PJ_DECL(pjsip_generic_array_hdr*) pjsip_generic_array_create(pj_pool_t *pool,
-							     const pj_str_t *hnames);
+PJ_DECL(pjsip_generic_array_hdr*) pjsip_generic_array_hdr_create(pj_pool_t *pool,
+							     const pj_str_t *hname);
+
+/**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ * @param hname	    The header name to be assigned to the header, or NULL to
+ *		    assign the header name with some string later.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_generic_array_hdr*) pjsip_generic_array_hdr_init(pj_pool_t *pool,
+							       void *mem,
+							       const pj_str_t *hname);
+
 
 /**
  * @}
@@ -905,6 +996,22 @@ typedef pjsip_generic_array_hdr pjsip_accept_hdr;
  */
 PJ_DECL(pjsip_accept_hdr*) pjsip_accept_hdr_create(pj_pool_t *pool);
 
+/**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_accept_hdr*) pjsip_accept_hdr_init( pj_pool_t *pool,
+						  void *mem );
 
 /**
  * @}
@@ -929,6 +1036,24 @@ typedef pjsip_generic_array_hdr pjsip_allow_hdr;
 PJ_DECL(pjsip_allow_hdr*) pjsip_allow_hdr_create(pj_pool_t *pool);
 
 
+
+/**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_allow_hdr*) pjsip_allow_hdr_init( pj_pool_t *pool,
+						void *mem );
+
 /**
  * @}
  */
@@ -961,6 +1086,24 @@ PJ_DECL(pjsip_cid_hdr*) pjsip_cid_hdr_create( pj_pool_t *pool );
 
 
 /**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_cid_hdr*) pjsip_cid_hdr_init( pj_pool_t *pool,
+					    void *mem );
+
+
+/**
  * @}
  */
 
@@ -989,6 +1132,24 @@ typedef struct pjsip_clen_hdr
 PJ_DECL(pjsip_clen_hdr*) pjsip_clen_hdr_create( pj_pool_t *pool );
 
 /**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_clen_hdr*) pjsip_clen_hdr_init( pj_pool_t *pool,
+					      void *mem );
+
+
+/**
  * @}
  */
 
@@ -1018,6 +1179,23 @@ typedef struct pjsip_cseq_hdr
 PJ_DECL(pjsip_cseq_hdr*) pjsip_cseq_hdr_create( pj_pool_t *pool );
 
 /**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_cseq_hdr*) pjsip_cseq_hdr_init( pj_pool_t *pool,
+					      void *mem );
+
+/**
  * @}
  */
 
@@ -1054,6 +1232,23 @@ typedef struct pjsip_contact_hdr
 PJ_DECL(pjsip_contact_hdr*) pjsip_contact_hdr_create( pj_pool_t *pool );
 
 /**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_contact_hdr*) pjsip_contact_hdr_init( pj_pool_t *pool,
+						    void *mem );
+
+/**
  * @}
  */
 
@@ -1083,6 +1278,23 @@ typedef struct pjsip_ctype_hdr
 PJ_DECL(pjsip_ctype_hdr*) pjsip_ctype_hdr_create( pj_pool_t *pool );
 
 /**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_ctype_hdr*) pjsip_ctype_hdr_init( pj_pool_t *pool,
+						void *mem );
+
+/**
  * @}
  */
 
@@ -1099,10 +1311,33 @@ typedef pjsip_generic_int_hdr pjsip_expires_hdr;
 /**
  * Create a new Expires header.
  *
- * @param pool	The pool.
- * @return	A new Expires header.
+ * @param pool	    The pool.
+ * @param value	    The expiration value.
+ *
+ * @return	    A new Expires header.
  */
-PJ_DECL(pjsip_expires_hdr*) pjsip_expires_hdr_create( pj_pool_t *pool );
+PJ_DECL(pjsip_expires_hdr*) pjsip_expires_hdr_create( pj_pool_t *pool,
+						      int value);
+
+/**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ * @param value	    The expiration value.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_expires_hdr*) pjsip_expires_hdr_init( pj_pool_t *pool,
+						    void *mem,
+						    int value );
+
 
 /**
  * @}
@@ -1141,6 +1376,23 @@ typedef pjsip_fromto_hdr pjsip_to_hdr;
 PJ_DECL(pjsip_from_hdr*) pjsip_from_hdr_create( pj_pool_t *pool );
 
 /**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_from_hdr*) pjsip_from_hdr_init( pj_pool_t *pool,
+					      void *mem );
+
+/**
  * Create a To header.
  *
  * @param pool	The pool.
@@ -1149,12 +1401,29 @@ PJ_DECL(pjsip_from_hdr*) pjsip_from_hdr_create( pj_pool_t *pool );
 PJ_DECL(pjsip_to_hdr*)   pjsip_to_hdr_create( pj_pool_t *pool );
 
 /**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_to_hdr*) pjsip_to_hdr_init( pj_pool_t *pool,
+					  void *mem );
+
+/**
  * Convert the header to a From header.
  *
  * @param pool	The pool.
  * @return	"From" header.
  */
-PJ_DECL(pjsip_from_hdr*) pjsip_fromto_set_from( pjsip_fromto_hdr *hdr );
+PJ_DECL(pjsip_from_hdr*) pjsip_fromto_hdr_set_from( pjsip_fromto_hdr *hdr );
 
 /**
  * Convert the header to a To header.
@@ -1162,7 +1431,7 @@ PJ_DECL(pjsip_from_hdr*) pjsip_fromto_set_from( pjsip_fromto_hdr *hdr );
  * @param pool	The pool.
  * @return	"To" header.
  */
-PJ_DECL(pjsip_to_hdr*)   pjsip_fromto_set_to( pjsip_fromto_hdr *hdr );
+PJ_DECL(pjsip_to_hdr*)   pjsip_fromto_hdr_set_to( pjsip_fromto_hdr *hdr );
 
 /**
  * @}
@@ -1176,19 +1445,39 @@ PJ_DECL(pjsip_to_hdr*)   pjsip_fromto_set_to( pjsip_fromto_hdr *hdr );
  * @ingroup PJSIP_MSG
  * @{
  */
-typedef pjsip_generic_int_hdr pjsip_max_forwards_hdr;
+typedef pjsip_generic_int_hdr pjsip_max_fwd_hdr;
 
 /**
  * Create new Max-Forwards header instance.
  *
  * @param pool	    The pool.
+ * @param value	    The Max-Forwards value.
  *
  * @return	    New Max-Forwards header instance.
  */
-PJ_DECL(pjsip_max_forwards_hdr*) pjsip_max_forwards_hdr_create(pj_pool_t *pool);
+PJ_DECL(pjsip_max_fwd_hdr*) 
+pjsip_max_fwd_hdr_create(pj_pool_t *pool, int value);
 
 
 /**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ * @param value	    The Max-Forwards value.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_max_fwd_hdr*) 
+pjsip_max_fwd_hdr_init( pj_pool_t *pool, void *mem, int value );
+
+/**
  * @}
  */
 
@@ -1203,16 +1492,37 @@ PJ_DECL(pjsip_max_forwards_hdr*) pjsip_max_forwards_hdr_create(pj_pool_t *pool);
 typedef pjsip_generic_int_hdr pjsip_min_expires_hdr;
 
 /**
- * Create new Max-Forwards header instance.
+ * Create new Min-Expires header instance.
  *
  * @param pool	    The pool.
+ * @param value	    The Min-Expires value.
  *
- * @return	    New Max-Forwards header instance.
+ * @return	    New Min-Expires header instance.
  */
-PJ_DECL(pjsip_min_expires_hdr*) pjsip_min_expires_hdr_create(pj_pool_t *pool);
+PJ_DECL(pjsip_min_expires_hdr*) pjsip_min_expires_hdr_create(pj_pool_t *pool,
+							     int value);
 
 
 /**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ * @param value	    The Min-Expires value.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_min_expires_hdr*) pjsip_min_expires_hdr_init( pj_pool_t *pool,
+							    void *mem,
+							    int value );
+
+/**
  * @}
  */
 
@@ -1249,6 +1559,23 @@ typedef pjsip_routing_hdr pjsip_route_hdr;
  */
 PJ_DECL(pjsip_rr_hdr*)	    pjsip_rr_hdr_create( pj_pool_t *pool );
 
+/**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_rr_hdr*) pjsip_rr_hdr_init( pj_pool_t *pool,
+					  void *mem );
+
 /** 
  * Create new Route header from the pool. 
  *
@@ -1257,6 +1584,23 @@ PJ_DECL(pjsip_rr_hdr*)	    pjsip_rr_hdr_create( pj_pool_t *pool );
  */
 PJ_DECL(pjsip_route_hdr*)   pjsip_route_hdr_create( pj_pool_t *pool );
 
+/**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_route_hdr*) pjsip_route_hdr_init( pj_pool_t *pool,
+					        void *mem );
+
 /** 
  * Convert generic routing header to Record-Route header. 
  *
@@ -1295,6 +1639,22 @@ typedef pjsip_generic_array_hdr pjsip_require_hdr;
  */
 PJ_DECL(pjsip_require_hdr*) pjsip_require_hdr_create(pj_pool_t *pool);
 
+/**
+ * Initialize a preallocated memory with the header structure. This function
+ * should only be called when application uses its own memory allocation to
+ * allocate memory block for the specified header (e.g. in C++, when the 
+ * header is allocated with "new" operator).
+ * For normal applications, they should use pjsip_xxx_hdr_create() instead,
+ * which allocates memory and initialize it in one go.
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_require_hdr*) pjsip_require_hdr_init( pj_pool_t *pool,
+						    void *mem );
 
 /**
  * @}
@@ -1314,10 +1674,26 @@ typedef pjsip_generic_int_hdr pjsip_retry_after_hdr;
  * Create new Retry-After header instance.
  *
  * @param pool	    The pool.
+ * @param value	    The Retry-After value.
  *
  * @return	    New Retry-After header instance.
  */
-PJ_DECL(pjsip_retry_after_hdr*) pjsip_retry_after_hdr_create(pj_pool_t *pool);
+PJ_DECL(pjsip_retry_after_hdr*) pjsip_retry_after_hdr_create(pj_pool_t *pool,
+							     int value);
+
+/**
+ * Initialize a preallocated memory with the header structure. 
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ * @param value	    The Retry-After value.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_retry_after_hdr*) pjsip_retry_after_hdr_init( pj_pool_t *pool,
+							    void *mem,
+							    int value );
 
 
 /**
@@ -1342,6 +1718,17 @@ typedef pjsip_generic_array_hdr pjsip_supported_hdr;
  */
 PJ_DECL(pjsip_supported_hdr*) pjsip_supported_hdr_create(pj_pool_t *pool);
 
+/**
+ * Initialize a preallocated memory with the header structure. 
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_supported_hdr*) pjsip_supported_hdr_init( pj_pool_t *pool,
+							void *mem );
 
 /**
  * @}
@@ -1365,6 +1752,17 @@ typedef pjsip_generic_array_hdr pjsip_unsupported_hdr;
  */
 PJ_DECL(pjsip_unsupported_hdr*) pjsip_unsupported_hdr_create(pj_pool_t *pool);
 
+/**
+ * Initialize a preallocated memory with the header structure. 
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_unsupported_hdr*) pjsip_unsupported_hdr_init( pj_pool_t *pool,
+							    void *mem );
 
 /**
  * @}
@@ -1408,6 +1806,18 @@ typedef struct pjsip_via_hdr
 PJ_DECL(pjsip_via_hdr*) pjsip_via_hdr_create( pj_pool_t *pool );
 
 /**
+ * Initialize a preallocated memory with the header structure. 
+ *
+ * @param pool	    Pool for additional memory allocation if required.
+ * @param mem	    Pre-allocated memory to be initialized as the header.
+ *
+ * @return	    The header instance, which points to the same memory 
+ *		    location as the mem argument.
+ */
+PJ_DECL(pjsip_via_hdr*) pjsip_via_hdr_init( pj_pool_t *pool,
+					    void *mem );
+
+/**
  * @}
  */
 
diff --git a/pjsip/include/pjsip/sip_transaction.h b/pjsip/include/pjsip/sip_transaction.h
index 065b71c2..712fa8ad 100644
--- a/pjsip/include/pjsip/sip_transaction.h
+++ b/pjsip/include/pjsip/sip_transaction.h
@@ -75,6 +75,7 @@ struct pjsip_transaction
     pjsip_method		method;         /**< The method.            */
     int				cseq;           /**< The CSeq               */
     pj_str_t			transaction_key;/**< Hash table key.        */
+    pj_uint32_t			hashed_key;	/**< Key's hashed value.    */
     pj_str_t			branch;         /**< The branch Id.         */
 
     /*
diff --git a/pjsip/include/pjsip/sip_transport.h b/pjsip/include/pjsip/sip_transport.h
index f8968f90..5dd23c1f 100644
--- a/pjsip/include/pjsip/sip_transport.h
+++ b/pjsip/include/pjsip/sip_transport.h
@@ -67,6 +67,12 @@ enum pjsip_transport_flags_e
 	    ((tp)->flag & PJSIP_TRANSPORT_RELIABLE)
 
 /**
+ * Check if transport tp is secure.
+ */
+#define PJSIP_TRANSPORT_IS_SECURE(tp)	    \
+	    ((tp)->flag & PJSIP_TRANSPORT_SECURE)
+
+/**
  * Get the transport type from the transport name.
  *
  * @param name	    Transport name, such as "TCP", or "UDP".
@@ -233,7 +239,7 @@ struct pjsip_rx_data
 	pjsip_cseq_hdr		*cseq;
 
 	/** Max forwards header. */
-	pjsip_max_forwards_hdr	*max_fwd;
+	pjsip_max_fwd_hdr	*max_fwd;
 
 	/** The first route header. */
 	pjsip_route_hdr		*route;
diff --git a/pjsip/include/pjsip/sip_types.h b/pjsip/include/pjsip/sip_types.h
index 72fe3af5..fc79f95a 100644
--- a/pjsip/include/pjsip/sip_types.h
+++ b/pjsip/include/pjsip/sip_types.h
@@ -102,6 +102,11 @@ typedef struct pjsip_hdr pjsip_hdr;
 typedef struct pjsip_uri pjsip_uri;
 
 /**
+ * Forward declaration for SIP method (sip_msg.h)
+ */
+typedef struct pjsip_method pjsip_method;
+
+/**
  * Opaque data type for the resolver engine (sip_resolve.h).
  */
 typedef struct pjsip_resolver_t pjsip_resolver_t;
@@ -117,6 +122,18 @@ typedef struct pjsip_cred_info pjsip_cred_info;
  */
 typedef struct pjsip_module pjsip_module;
 
+
+/** 
+ * Forward declaration for user agent type (sip_ua_layer.h). 
+ */
+typedef pjsip_module pjsip_user_agent;
+
+/**
+ * Forward declaration for dialog (sip_dialog.h).
+ */
+typedef struct pjsip_dialog pjsip_dialog;
+
+
 /**
  * Transaction role.
  */
diff --git a/pjsip/include/pjsip-ua/sip_ua.h b/pjsip/include/pjsip/sip_ua_layer.h
index a1d7c423..e12a55a8 100644
--- a/pjsip/include/pjsip-ua/sip_ua.h
+++ b/pjsip/include/pjsip/sip_ua_layer.h
@@ -16,13 +16,14 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
  */
-#ifndef __PJSIP_SIP_UA_H__
-#define __PJSIP_SIP_UA_H__
+#ifndef __PJSIP_SIP_UA_LAYER_H__
+#define __PJSIP_SIP_UA_LAYER_H__
 
 /**
- * @file sip_ua.h
- * @brief SIP User Agent Module
+ * @file sip_ua_layer.h
+ * @brief SIP User Agent Layer Module
  */
+#include <pjsip/sip_types.h>
 
 
 PJ_BEGIN_DECL
@@ -32,26 +33,30 @@ PJ_BEGIN_DECL
  */
 
 /**
- * @defgroup PJSUA_UA SIP User Agent
+ * @defgroup PJSUA_UA SIP User Agent Module
  * @ingroup PJSUA
  * @{
  * \brief
  *   User Agent manages the interactions between application and SIP dialogs.
  */
 
-/** User agent type. */
-typedef pjsip_module pjsip_user_agent;
-
+/** User agent initialization parameter. */
+typedef struct pjsip_ua_init_param
+{
+    pjsip_dialog* (*on_dlg_forked)(pjsip_dialog *first_set, pjsip_rx_data *res);
+} pjsip_ua_init_param;
 
 /**
  * Initialize user agent layer and register it to the specified endpoint.
  *
  * @param endpt		The endpoint where the user agent will be
  *			registered.
+ * @param prm		UA initialization parameter.
  *
  * @return		PJ_SUCCESS on success.
  */
-PJ_DECL(pj_status_t) pjsip_ua_init(pjsip_endpoint *endpt);
+PJ_DECL(pj_status_t) pjsip_ua_init(pjsip_endpoint *endpt,
+				   const pjsip_ua_init_param *prm);
 
 /**
  * Get the instance of the user agent.
@@ -67,6 +72,26 @@ PJ_DECL(pjsip_user_agent*) pjsip_ua_instance(void);
  */
 PJ_DECL(pj_status_t) pjsip_ua_destroy(void);
 
+/**
+ * Get the endpoint instance of a user agent module.
+ *
+ * @param ua		The user agent instance.
+ *
+ * @return		The endpoint instance where the user agent is
+ *			registered.
+ */
+PJ_DECL(pjsip_endpoint*) pjsip_ua_get_endpt(pjsip_user_agent *ua);
+
+
+/*
+ * Internal.
+ */
+
+PJ_DECL(pj_status_t) pjsip_ua_register_dlg( pjsip_user_agent *ua,
+					    pjsip_dialog *dlg );
+PJ_DECL(pj_status_t) pjsip_ua_unregister_dlg(pjsip_user_agent *ua,
+					     pjsip_dialog *dlg );
+
 
 /**
  * @}
@@ -75,5 +100,5 @@ PJ_DECL(pj_status_t) pjsip_ua_destroy(void);
 PJ_END_DECL
 
 
-#endif	/* __PJSIP_UA_H__ */
+#endif	/* __PJSIP_SIP_UA_LAYER_H__ */
 
diff --git a/pjsip/include/pjsip/sip_uri.h b/pjsip/include/pjsip/sip_uri.h
index 3ee19354..6973c524 100644
--- a/pjsip/include/pjsip/sip_uri.h
+++ b/pjsip/include/pjsip/sip_uri.h
@@ -161,9 +161,9 @@ typedef struct pjsip_uri_vptr
      * @param size the size of the buffer.
      * @return the length printed.
      */
-    int	(*p_print)(pjsip_uri_context_e context,
-		   const void *uri, 
-		   char *buf, pj_size_t size);
+    pj_ssize_t (*p_print)(pjsip_uri_context_e context,
+			  const void *uri, 
+		          char *buf, pj_size_t size);
 
     /** 
      * Compare two URIs according to the context.
@@ -332,20 +332,20 @@ PJ_INLINE(void*) pjsip_uri_clone( pj_pool_t *pool, const void *uri )
  * @param secure    Tlag to indicate whether secure transport should be used.
  * @return SIP URL.
  */
-PJ_DECL(pjsip_sip_uri*) pjsip_url_create( pj_pool_t *pool, int secure );
+PJ_DECL(pjsip_sip_uri*) pjsip_sip_uri_create( pj_pool_t *pool, int secure );
 
 /**
  * Create new SIPS URL and initialize all fields with zero or NULL.
  * @param pool	    The pool.
  * @return	    SIPS URL.
  */
-PJ_DECL(pjsip_sip_uri*) pjsips_url_create( pj_pool_t *pool );
+PJ_DECL(pjsip_sip_uri*) pjsip_sips_uri_create( pj_pool_t *pool );
 
 /**
  * Initialize SIP URL (all fields are set to NULL or zero).
  * @param url	    The URL.
  */
-PJ_DECL(void)  pjsip_url_init(pjsip_sip_uri *url, int secure);
+PJ_DECL(void)  pjsip_sip_uri_init(pjsip_sip_uri *url, int secure);
 
 /**
  * Perform full assignment to the SIP URL.
@@ -353,8 +353,8 @@ PJ_DECL(void)  pjsip_url_init(pjsip_sip_uri *url, int secure);
  * @param url	    Destination URL.
  * @param rhs	    The source URL.
  */
-PJ_DECL(void)  pjsip_url_assign(pj_pool_t *pool, pjsip_sip_uri *url, 
-				const pjsip_sip_uri *rhs);
+PJ_DECL(void)  pjsip_sip_uri_assign(pj_pool_t *pool, pjsip_sip_uri *url, 
+				    const pjsip_sip_uri *rhs);
 
 /**
  * Create new instance of name address and initialize all fields with zero or