XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy

                        VVeerrssiioonn 11..00

                   XX CCoonnssoorrttiiuumm SSttaannddaarrdd

                  XX VVeerrssiioonn 1111,, RReelleeaassee 77

                        lliibbSSMM 11..11..11


                         Ralph Mor

                        X Consortium






            Copyright © 1993, 1994 X Consortium







Permission  is hereby granted, free of charge, to any person
obtaining a copy of this software and associated  documenta‐
tion files (the ‘‘Software’’), to deal in the Software with‐
out restriction, including without limitation the rights  to
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and/or sell copies of the Software, and to permit persons to
whom the Software is furnished to do so, subject to the fol‐
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The above copyright notice and this permission notice  shall
be  included  in  all  copies or substantial portions of the
Software.

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WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR  THE  USE
OR OTHER DEALINGS IN THE SOFTWARE.

Except  as  contained  in  this  notice,  the  name of the X












Consortium shall not be used in advertising or otherwise  to
promote  the  sale,  use  or other dealings in this Software
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_1_.  _O_v_e_r_v_i_e_w _o_f _S_e_s_s_i_o_n _M_a_n_a_g_e_m_e_n_t

The purpose of the X Session Management Protocol  (XSMP)  is
to provide a uniform mechanism for users to save and restore
their sessions.  A _s_e_s_s_i_o_n is a group of  clients,  each  of
which  has a particular state.  The session is controlled by
a network service called the _s_e_s_s_i_o_n _m_a_n_a_g_e_r.   The  session
manager  issues  commands  to  its  clients on behalf of the
user.  These commands may cause clients to save their  state
or  to  terminate.  It is expected that the client will save
its state in such a way that the client can be restarted  at
a  later  time  and  resume its operation as if it had never
been terminated.  A client’s state might include information
about  the file currently being edited, the current position
of the insertion point within the file, or the start  of  an
uncommitted  transaction.   The  means  by which clients are
restarted is unspecified by this protocol.

For purposes of this protocol, a _c_l_i_e_n_t of the session  man‐
ager  is  defined as a connection to the session manager.  A
client is typically, though not necessarily, a process  run‐
ning an application program connected to an X display.  How‐
ever, a client may be connected to more than one  X  display
or not be connected to any X displays at all.

_2_.  _T_h_e _S_e_s_s_i_o_n _M_a_n_a_g_e_m_e_n_t _L_i_b_r_a_r_y

The  Session  Management  Library (SMlib) is a low‐level "C"
language interface to XSMP.   It  is  expected  that  higher
level toolkits, such as Xt, will hide many of the details of
session management  from  clients.   Higher  level  toolkits
might  also be developed for session managers to use, but no
such effort is currently under way.

SMlib has two parts to it:

·    One set of functions for clients that want to  be  part
     of a session

·    One set of functions for session managers to call

Some applications will use both sets of functions and act as
_n_e_s_t_e_d _s_e_s_s_i_o_n _m_a_n_a_g_e_r_s.  That is, they will be both a  ses‐
sion manager and a client of another session.  An example is
a mail program that could start a text  editor  for  editing
the  text  of a mail message.  The mail program is part of a
regular session and, at the same time, is also acting  as  a
session manager to the editor.

Clients  initialize by connecting to the session manager and
obtaining a _c_l_i_e_n_t_‐_I_D that uniquely identifies them  in  the
session.  The session manager maintains a list of properties
for each client in the session.  These  properties  describe
the client’s environment and, most importantly, describe how



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the client  can  be  restarted  (via  an  _S_m_R_e_s_t_a_r_t_C_o_m_m_a_n_d).
Clients are expected to save their state in such a way as to
allow multiple instantiations of themselves  to  be  managed
independently.  For example, clients may use their client‐ID
as part of a filename in which to store the state for a par‐
ticular  instantiation.   The  client‐ID  should be saved as
part of the _S_m_R_e_s_t_a_r_t_C_o_m_m_a_n_d so that the client will  retain
the same ID after it is restarted.

Once the client initializes itself with the session manager,
it must be ready to respond to  messages  from  the  session
manager.   For  example, it might be asked to save its state
or to terminate.  In the case of  a  shutdown,  the  session
manager might give each client a chance to interact with the
user and cancel the shutdown.

_3_.  _U_n_d_e_r_s_t_a_n_d_i_n_g _S_M_l_i_b_’_s _D_e_p_e_n_d_e_n_c_e _o_n _I_C_E

The X Session Management Protocol is layered on top  of  the
Inter‐Client  Exchange  (ICE) Protocol.  The ICE protocol is
designed to multiplex several protocols over a  single  con‐
nection.   As a result, working with SMlib requires a little
knowledge of how the ICE library works.

The ICE library  utilizes  callbacks  to  process  messages.
When  a  client detects that there is data to read on an ICE
connection, it should call the _I_c_e_P_r_o_c_e_s_s_M_e_s_s_a_g_e_s  function.
_I_c_e_P_r_o_c_e_s_s_M_e_s_s_a_g_e_s  will read the message header and look at
the major opcode in order to determine  which  protocol  the
message  was intended for.  The appropriate protocol library
will then be triggered to unpack the message and hand it off
to the client via a callback.

The  main  point to be aware of is that an application using
SMlib must have some code that detects when there is data to
read  on  an  ICE connection.  This can be done via a _s_e_l_e_c_t
call on the file descriptor for the ICE connection, but more
typically, _X_t_A_p_p_A_d_d_I_n_p_u_t will be used to register a callback
that will invoke _I_c_e_P_r_o_c_e_s_s_M_e_s_s_a_g_e_s each time there is  data
to read on the ICE connection.

To further complicate things, knowing which file descriptors
to call _s_e_l_e_c_t on requires an understanding of how ICE  con‐
nections  are  created.   On the client side, a call must be
made to _S_m_c_O_p_e_n_C_o_n_n_e_c_t_i_o_n in order to open a connection with
a session manager.  _S_m_c_O_p_e_n_C_o_n_n_e_c_t_i_o_n will internally make a
call into _I_c_e_O_p_e_n_C_o_n_n_e_c_t_i_o_n, which will, in turn,  determine
if  an  ICE connection already exists between the client and
session manager.  Most likely, a connection will not already
exist  and  a  new ICE connection will be created.  The main
point to be aware of is that, on the client side, it is  not
obvious  when  ICE  connections  get  created  or destroyed,
because connections are shared when possible.  To deal  with
this,  the  ICE  library lets the application register watch



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procedures that will be invoked each time an ICE  connection
is  opened  or closed.  These watch procedures could be used
to add or remove ICE  file  descriptors  from  the  list  of
descriptors to call _s_e_l_e_c_t on.

On  the session manager side, things work a bit differently.
The session manager has complete control over  the  creation
of  ICE  connections.  The session manager has to first call
_I_c_e_L_i_s_t_e_n_F_o_r_C_o_n_n_e_c_t_i_o_n_s in order to start listening for con‐
nections   from  clients.   Once  a  connection  attempt  is
detected, _I_c_e_A_c_c_e_p_t_C_o_n_n_e_c_t_i_o_n must be called, and  the  ses‐
sion  manager  can simply add the new ICE file descriptor to
the list of descriptors to call _s_e_l_e_c_t on.

For further information on the library functions related  to
ICE connections, see the _I_n_t_e_r_‐_C_l_i_e_n_t _E_x_c_h_a_n_g_e _L_i_b_r_a_r_y stan‐
dard.

_4_.  _H_e_a_d_e_r _F_i_l_e_s _a_n_d _L_i_b_r_a_r_y _N_a_m_e

Applications (both  session  managers  and  clients)  should
include  the header file <_X_1_1_/_S_M_/_S_M_l_i_b_._h>.  This header file
defines all of the SMlib data structures and function proto‐
types.   _S_M_l_i_b_._h  includes  the  header  file <_X_1_1_/_S_M_/_S_M_._h>,
which defines all of the SMlib constants.

Because SMlib is dependent on ICE, applications should  link
against SMlib and ICElib by using _‐_l_S_M _‐_l_I_C_E.

_5_.  _S_e_s_s_i_o_n _M_a_n_a_g_e_m_e_n_t _C_l_i_e_n_t _(_S_m_c_) _F_u_n_c_t_i_o_n_s

This section discusses how Session Management clients:

·    Connect to the Session Manager

·    Close the connection

·    Modify callbacks

·    Set, delete, and retrieve Session Manager properties

·    Interact with the user

·    Request a ‘‘Save Yourself’’

·    Request a ‘‘Save Yourself Phase 2’’

·    Complete a ‘‘Save Yourself’’

·    Use Smc informational functions

·    Handle Errors





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_5_._1_.  _C_o_n_n_e_c_t_i_n_g _t_o _t_h_e _S_e_s_s_i_o_n _M_a_n_a_g_e_r

To open a connection with a session manager, use _S_m_c_O_p_e_n_C_o_n_‐
_n_e_c_t_i_o_n.
__
││
SmcConn SmcOpenConnection(_n_e_t_w_o_r_k___i_d_s___l_i_s_t, _c_o_n_t_e_x_t, _x_s_m_p___m_a_j_o_r___r_e_v, _x_s_m_p___m_i_n_o_r___r_e_v,
                    _m_a_s_k, _c_a_l_l_b_a_c_k_s, _p_r_e_v_i_o_u_s___i_d, _c_l_i_e_n_t___i_d___r_e_t, _e_r_r_o_r___l_e_n_g_t_h, _e_r_r_o_r___s_t_r_i_n_g___r_e_t)
    char *_n_e_t_w_o_r_k___i_d_s___l_i_s_t;
    SmPointer _c_o_n_t_e_x_t;
    int _x_s_m_p___m_a_j_o_r___r_e_v;
    int _x_s_m_p___m_i_n_o_r___r_e_v;
    unsigned long _m_a_s_k;
    SmcCallbacks *_c_a_l_l_b_a_c_k_s;
    char *_p_r_e_v_i_o_u_s___i_d;
    char **_c_l_i_e_n_t___i_d___r_e_t;
    int _e_r_r_o_r___l_e_n_g_t_h;
    char *_e_r_r_o_r___s_t_r_i_n_g___r_e_t;


_n_e_t_w_o_r_k___i_d_s___l_i_s_t
          Specifies the network ID(s) of  the  session  man‐
          ager.

_c_o_n_t_e_x_t   A  pointer  to  an opaque object or NULL.  Used to
          determine if an ICE connection can be shared  (see
          below).

_x_s_m_p___m_a_j_o_r___r_e_v
          The highest major version of the XSMP the applica‐
          tion supports.

_x_s_m_p___m_i_n_o_r___r_e_v
          The highest minor version of the XSMP the applica‐
          tion  supports (for the specified xsmp_major_rev).

_m_a_s_k      A mask indicating which callbacks to register.

_c_a_l_l_b_a_c_k_s The callbacks to register.   These  callbacks  are
          used  to respond to messages from the session man‐
          ager.

_p_r_e_v_i_o_u_s___i_dThe client ID from the previous session.

_c_l_i_e_n_t___i_d___r_e_t
          The client ID for the current session is returned.

_e_r_r_o_r___l_e_n_g_t_h
          Length of the error_string_ret argument passed in.

_e_r_r_o_r___s_t_r_i_n_g___r_e_t
          Returns a null‐terminated error message,  if  any.
          The  error_string_ret argument points to user sup‐
          plied memory.  No more than error_length bytes are



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          used.
││__

The  network_ids_list  argument  is a null‐terminated string
containing a list of network IDs for  the  session  manager,
separated by commas.  If network_ids_list is NULL, the value
of the _S_E_S_S_I_O_N___M_A_N_A_G_E_R environment variable  will  be  used.
Each network ID has the following format:

     tcp/<hostname>:<portnumber>    or
     decnet/<hostname>::<objname>   or
     local/<hostname>:<path>


An  attempt  will  be  made to use the first network ID.  If
that fails, an attempt will be made using the second network
ID, and so on.

After  the connection is established, _S_m_c_O_p_e_n_C_o_n_n_e_c_t_i_o_n reg‐
isters the client with the session manager.  If  the  client
is  being  restarted  from  a  previous session, previous_id
should contain a null  terminated  string  representing  the
client ID from the previous session.  If the client is first
joining the session, previous_id should be set to NULL.   If
previous_id  is specified but is determined to be invalid by
the session manager, SMlib will re‐register the client  with
previous_id set to NULL.

If  _S_m_c_O_p_e_n_C_o_n_n_e_c_t_i_o_n succeeds, it returns an opaque connec‐
tion pointer of type _S_m_c_C_o_n_n and the client_id_ret  argument
contains  the  client  ID  to be used for this session.  The
client_id_ret should be freed with a call to  _f_r_e_e  when  no
longer  needed.  On failure, _S_m_c_O_p_e_n_C_o_n_n_e_c_t_i_o_n returns NULL,
and the reason for failure is returned in  error_string_ret.

Note that SMlib uses the ICE protocol to establish a connec‐
tion with the session manager.  If an ICE connection already
exists  between  the client and session manager, it might be
possible for the same ICE connection to be used for  session
management.

The  context argument indicates how willing the client is to
share the ICE connection with other protocols.   If  context
is NULL, then the caller is always willing to share the con‐
nection.  If context is not NULL, then  the  caller  is  not
willing to use a previously opened ICE connection that has a
different non‐NULL context associated with it.

As previously discussed (section 3, ‘‘Understanding  SMlib’s
Dependence  on ICE’’), the client will have to keep track of
when ICE connections are created or destroyed (using _I_c_e_A_d_d_‐
_C_o_n_n_e_c_t_i_o_n_W_a_t_c_h and _I_c_e_R_e_m_o_v_e_C_o_n_n_e_c_t_i_o_n_W_a_t_c_h), and will have
to call _I_c_e_P_r_o_c_e_s_s_M_e_s_s_a_g_e_s each time  a  _s_e_l_e_c_t  shows  that
there  is  data  to  read on an ICE connection.  For further



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information, see the _I_n_t_e_r_‐_C_l_i_e_n_t _E_x_c_h_a_n_g_e _L_i_b_r_a_r_y standard.

The  callbacks  argument contains a set of callbacks used to
respond to session manager events.  The mask argument speci‐
fies  which  callbacks are set.  All of the callbacks speci‐
fied in this version of SMlib are mandatory.  The mask argu‐
ment is necessary in order to maintain backwards compatibil‐
ity in future versions of the library.

The following values may be ORed together to obtain  a  mask
value:


_S_m_c_S_a_v_e_Y_o_u_r_s_e_l_f_P_r_o_c_M_a_s_k
_S_m_c_D_i_e_P_r_o_c_M_a_s_k
_S_m_c_S_a_v_e_C_o_m_p_l_e_t_e_P_r_o_c_M_a_s_k
_S_m_c_S_h_u_t_d_o_w_n_C_a_n_c_e_l_l_e_d_P_r_o_c_M_a_s_k


For  each  callback,  the  client  can register a pointer to
client data.  When SMlib invokes the callback, it will  pass
the client data pointer.

__
││
typedef struct {

     struct {
          SmcSaveYourselfProc callback;
          SmPointer client_data;
     } save_yourself;

     struct {
          SmcDieProc callback;
          SmPointer client_data;
     } die;

     struct {
          SmcSaveCompleteProc callback;
          SmPointer client_data;
     } save_complete;

     struct {
          SmcShutdownCancelledProc callback;
          SmPointer client_data;
     } shutdown_cancelled;

} SmcCallbacks;

││__







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_5_._1_._1_.  _T_h_e _S_a_v_e _Y_o_u_r_s_e_l_f _C_a_l_l_b_a_c_k

The Save Yourself callback is of type _S_m_c_S_a_v_e_Y_o_u_r_s_e_l_f_P_r_o_c.
__
││
typedef void (*SmcSaveYourselfProc)();

void SaveYourselfProc(_s_m_c___c_o_n_n, _c_l_i_e_n_t___d_a_t_a, _s_a_v_e___t_y_p_e, _s_h_u_t_d_o_w_n, _i_n_t_e_r_a_c_t___s_t_y_l_e, _f_a_s_t)
    SmcConn _s_m_c___c_o_n_n;
    SmPointer _c_l_i_e_n_t___d_a_t_a;
    int _s_a_v_e___t_y_p_e;
    Bool _s_h_u_t_d_o_w_n;
    int _i_n_t_e_r_a_c_t___s_t_y_l_e;
    Bool _f_a_s_t;


_s_m_c___c_o_n_n  The session management connection object.

_c_l_i_e_n_t___d_a_t_aClient  data specified when the callback was reg‐
          istered.

_s_a_v_e___t_y_p_e Specifies the type of information that  should  be
          saved.

_s_h_u_t_d_o_w_n  Specifies if a shutdown is taking place.

_i_n_t_e_r_a_c_t___s_t_y_l_e
          The type of interaction allowed with the user.

_f_a_s_t      If  _T_r_u_e,  the  client  should  save  its state as
          quickly as possible.
││__

The session manager sends a ‘‘Save Yourself’’ message  to  a
client either to checkpoint it or just before termination so
that it can save its state.  The client responds  with  zero
or  more  calls to _S_m_c_S_e_t_P_r_o_p_e_r_t_i_e_s to update the properties
indicating how to restart the client.  When all the  proper‐
ties have been set, the client calls _S_m_c_S_a_v_e_Y_o_u_r_s_e_l_f_D_o_n_e.

If  interact_style  is  _S_m_I_n_t_e_r_a_c_t_S_t_y_l_e_N_o_n_e, the client must
not interact with the user while saving  state.   If  inter‐
act_style  is _S_m_I_n_t_e_r_a_c_t_S_t_y_l_e_E_r_r_o_r_s, the client may interact
with the user only if an error condition arises.  If  inter‐
act_style  is _S_m_I_n_t_e_r_a_c_t_S_t_y_l_e_A_n_y, then the client may inter‐
act with the user for any purpose.  Because only one  client
can  interact  with the user at a time, the client must call
_S_m_c_I_n_t_e_r_a_c_t_R_e_q_u_e_s_t and wait for an ‘‘Interact’’ message from
the  session  manager.   When the client is done interacting
with the user, it calls  _S_m_c_I_n_t_e_r_a_c_t_D_o_n_e.   The  client  may
only  call  _S_m_c_I_n_t_e_r_a_c_t_R_e_q_u_e_s_t  after  it  receives a ‘‘Save
Yourself’’ message and before it calls  _S_m_c_S_a_v_e_Y_o_u_r_s_e_l_f_D_o_n_e.

If  save_type  is  _S_m_S_a_v_e_L_o_c_a_l,  the  client must update the



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properties to reflect its current state.   Specifically,  it
should  save enough information to restore the state as seen
by the user of this client.  It should not affect the  state
as  seen  by other users.  If save_type is _S_m_S_a_v_e_G_l_o_b_a_l, the
user wants the client to commit all of its  data  to  perma‐
nent,  globally accessible storage.  If save_type is _S_m_S_a_v_e_‐
_B_o_t_h, the client should do both of these  (it  should  first
commit  the  data  to  permanent storage before updating its
properties).

Some examples are as follows:


·    If a word processor were sent a ‘‘Save Yourself’’  with
     a type of _S_m_S_a_v_e_L_o_c_a_l, it could create a temporary file
     that included the current contents  of  the  file,  the
     location  of  the cursor, and other aspects of the cur‐
     rent  editing  session.   It  would  then  update   its
     SmRestartCommand  property  with  enough information to
     find this temporary file.

·    If a word processor were sent a ‘‘Save Yourself’’  with
     a  type  of _S_m_S_a_v_e_G_l_o_b_a_l, it would simply save the cur‐
     rently edited file.

·    If a word processor were sent a ‘‘Save Yourself’’  with
     a type of _S_m_S_a_v_e_B_o_t_h, it would first save the currently
     edited file.  It would then  create  a  temporary  file
     with  information  such  as the current position of the
     cursor and what file  is  being  edited.   Finally,  it
     would  update its SmRestartCommand property with enough
     information to find the temporary file.

The shutdown argument specifies whether the system is  being
shut  down.   The  interaction  is  different  depending  on
whether or not shutdown is set.  If not shutting  down,  the
client  should  save  its  state  and wait for a ‘‘Save Com‐
plete’’ message.  If shutting down,  the  client  must  save
state  and then prevent interaction until it receives either
a ‘‘Die’’ or a ‘‘Shutdown Cancelled.’’

The fast argument specifies that the client should save  its
state  as  quickly as possible.  For example, if the session
manager knows that power is about to fail, it would set fast
to _T_r_u_e.

_5_._1_._2_.  _T_h_e _D_i_e _C_a_l_l_b_a_c_k

The Die callback is of type _S_m_c_D_i_e_P_r_o_c.
__
││






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XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


typedef void (*SmcDieProc)();

void DieProc(_s_m_c___c_o_n_n, _c_l_i_e_n_t___d_a_t_a)
    SmcConn _s_m_c___c_o_n_n;
    SmPointer _c_l_i_e_n_t___d_a_t_a;


_s_m_c___c_o_n_n  The session management connection object.

_c_l_i_e_n_t___d_a_t_aClient  data specified when the callback was reg‐
          istered.
││__

The session manager sends a ‘‘Die’’ message to a client when
it  wants  it  to die.  The client should respond by calling
_S_m_c_C_l_o_s_e_C_o_n_n_e_c_t_i_o_n.  A session manager that behaves properly
will  send  a  ‘‘Save  Yourself’’ message before the ‘‘Die’’
message.

_5_._1_._3_.  _T_h_e _S_a_v_e _C_o_m_p_l_e_t_e _C_a_l_l_b_a_c_k

The Save Complete callback is of type _S_m_c_S_a_v_e_C_o_m_p_l_e_t_e_P_r_o_c.
__
││
typedef void (*SmcSaveCompleteProc)();

void SaveCompleteProc(_s_m_c___c_o_n_n, _c_l_i_e_n_t___d_a_t_a)
    SmcConn _s_m_c___c_o_n_n;
    SmPointer _c_l_i_e_n_t___d_a_t_a;


_s_m_c___c_o_n_n  The session management connection object.

_c_l_i_e_n_t___d_a_t_aClient data specified when the callback was  reg‐
          istered.
││__

When  the session manager is done with a checkpoint, it will
send each of the clients a ‘‘Save Complete’’  message.   The
client is then free to change its state.

_5_._1_._4_.  _T_h_e _S_h_u_t_d_o_w_n _C_a_n_c_e_l_l_e_d _C_a_l_l_b_a_c_k

The  Shutdown  Cancelled callback is of type _S_m_c_S_h_u_t_d_o_w_n_C_a_n_‐
_c_e_l_l_e_d_P_r_o_c.
__
││
typedef void (*SmcShutdownCancelledProc)();

void ShutdownCancelledProc(_s_m_c___c_o_n_n, _c_l_i_e_n_t___d_a_t_a)
    SmcConn _s_m_c___c_o_n_n;
    SmPointer _c_l_i_e_n_t___d_a_t_a;





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_s_m_c___c_o_n_n  The session management connection object.

_c_l_i_e_n_t___d_a_t_aClient data specified when the callback was  reg‐
          istered.
││__

The  session  manager sends a ‘‘Shutdown Cancelled’’ message
when the user cancelled the shutdown during  an  interaction
(see  section  5.5,  ‘‘Interacting  With  the  User’’).  The
client can now continue as if the shutdown  had  never  hap‐
pened.   If  the  client  has not called _S_m_c_S_a_v_e_Y_o_u_r_s_e_l_f_D_o_n_e
yet, it can either abort the save and then call _S_m_c_S_a_v_e_Y_o_u_r_‐
_s_e_l_f_D_o_n_e  with  the success argument set to _F_a_l_s_e, or it can
continue with the save  and  then  call  _S_m_c_S_a_v_e_Y_o_u_r_s_e_l_f_D_o_n_e
with  the success argument set to reflect the outcome of the
save.

_5_._2_.  _C_l_o_s_i_n_g _t_h_e _C_o_n_n_e_c_t_i_o_n

To close a connection with a session manager, use _S_m_c_C_l_o_s_e_C_‐
_o_n_n_e_c_t_i_o_n.

__
││
SmcCloseStatus SmcCloseConnection(_s_m_c___c_o_n_n, _c_o_u_n_t, _r_e_a_s_o_n___m_s_g_s)
    SmcConn _s_m_c___c_o_n_n;
    int _c_o_u_n_t;
    char **_r_e_a_s_o_n___m_s_g_s;


_s_m_c___c_o_n_n  The session management connection object.

_c_o_u_n_t     The number of reason messages.

_r_e_a_s_o_n___m_s_g_sThe reasons for closing the connection.
││__

The  reason_msgs argument will most likely be NULL if resig‐
nation is expected by the client.  Otherwise, it contains  a
list  of  null‐terminated Compound Text strings representing
the reason for termination.  The session manager should dis‐
play these reason messages to the user.

Note that SMlib used the ICE protocol to establish a connec‐
tion with the session manager, and various  protocols  other
than session management may be active on the ICE connection.
When _S_m_c_C_l_o_s_e_C_o_n_n_e_c_t_i_o_n is called, the ICE  connection  will
be  closed  only  if all protocols have been shutdown on the
connection.  Check the ICElib standard for _I_c_e_A_d_d_C_o_n_n_e_c_t_i_o_n_‐
_W_a_t_c_h  and _I_c_e_R_e_m_o_v_e_C_o_n_n_e_c_t_i_o_n_W_a_t_c_h to learn how to set up a
callback to be invoked each time an ICE connection is opened
or  closed.   Typically  this  callback adds/removes the ICE
file descriptor from the list of active descriptors to  call
_s_e_l_e_c_t on (or calls _X_t_A_p_p_A_d_d_I_n_p_u_t or _X_t_R_e_m_o_v_e_I_n_p_u_t).



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XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


_S_m_c_C_l_o_s_e_C_o_n_n_e_c_t_i_o_n returns one of the following values:

·    _S_m_c_C_l_o_s_e_d_N_o_w  −  the  ICE connection was closed at this
     time, the watch procedures were invoked, and  the  con‐
     nection was freed.

·    _S_m_c_C_l_o_s_e_d_A_S_A_P − an IO error had occurred on the connec‐
     tion, but _S_m_c_C_l_o_s_e_C_o_n_n_e_c_t_i_o_n is being called  within  a
     nested  _I_c_e_P_r_o_c_e_s_s_M_e_s_s_a_g_e_s.   The watch procedures have
     been invoked at this time, but the connection  will  be
     freed  as  soon  as  possible  (when  the nesting level
     reaches zero and _I_c_e_P_r_o_c_e_s_s_M_e_s_s_a_g_e_s returns a status of
     _I_c_e_P_r_o_c_e_s_s_M_e_s_s_a_g_e_s_C_o_n_n_e_c_t_i_o_n_C_l_o_s_e_d).

·    _S_m_c_C_o_n_n_e_c_t_i_o_n_I_n_U_s_e  −  the connection was not closed at
     this time, because it is being  used  by  other  active
     protocols.

_5_._3_.  _M_o_d_i_f_y_i_n_g _C_a_l_l_b_a_c_k_s

To modify callbacks set up in _S_m_c_O_p_e_n_C_o_n_n_e_c_t_i_o_n, use _S_m_c_M_o_d_‐
_i_f_y_C_a_l_l_b_a_c_k_s.
__
││
void SmcModifyCallbacks(_s_m_c___c_o_n_n, _m_a_s_k, _c_a_l_l_b_a_c_k_s)
    SmcConn _s_m_c___c_o_n_n;
    unsigned long _m_a_s_k;
    SmcCallbacks *_c_a_l_l_b_a_c_k_s;


_s_m_c___c_o_n_n  The session management connection object.

_m_a_s_k      A mask indicating which callbacks to modify.

_c_a_l_l_b_a_c_k_s The new callbacks.
││__

When specifying a value for the mask argument, the following
values may be ORed together:


_S_m_c_S_a_v_e_Y_o_u_r_s_e_l_f_P_r_o_c_M_a_s_k
_S_m_c_D_i_e_P_r_o_c_M_a_s_k
_S_m_c_S_a_v_e_C_o_m_p_l_e_t_e_P_r_o_c_M_a_s_k
_S_m_c_S_h_u_t_d_o_w_n_C_a_n_c_e_l_l_e_d_P_r_o_c_M_a_s_k


_5_._4_.   _S_e_t_t_i_n_g_,  _D_e_l_e_t_i_n_g_, _a_n_d _R_e_t_r_i_e_v_i_n_g _S_e_s_s_i_o_n _M_a_n_a_g_e_m_e_n_t
_P_r_o_p_e_r_t_i_e_s

To  set  session  management properties for this client, use






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XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


_S_m_c_S_e_t_P_r_o_p_e_r_t_i_e_s.
__
││
void SmcSetProperties(_s_m_c___c_o_n_n, _n_u_m___p_r_o_p_s, _p_r_o_p_s)
    SmcConn _s_m_c___c_o_n_n;
    int _n_u_m___p_r_o_p_s;
    SmProp **_p_r_o_p_s;


_s_m_c___c_o_n_n  The session management connection object.

_n_u_m___p_r_o_p_s The number of properties.

_p_r_o_p_s     The list of properties to set.
││__

The properties are specified as an array of property  point‐
ers.   Previously  set  property  values may be over‐written
using the _S_m_c_S_e_t_P_r_o_p_e_r_t_i_e_s function.  Note that the  session
manager  is not expected to restore property values when the
session is restarted.  Because of this, clients  should  not
try  to  use  the  session manager as a database for storing
application specific state.

For a description of session management properties  and  the
_S_m_P_r_o_p  structure, see section 7, ‘‘Session Management Prop‐
erties.’’


To delete properties  previously  set  by  the  client,  use
_S_m_c_D_e_l_e_t_e_P_r_o_p_e_r_t_i_e_s.
__
││
void SmcDeleteProperties(_s_m_c___c_o_n_n, _n_u_m___p_r_o_p_s, _p_r_o_p___n_a_m_e_s)
    SmcConn _s_m_c___c_o_n_n;
    int _n_u_m___p_r_o_p_s;
    char **_p_r_o_p___n_a_m_e_s;


_s_m_c___c_o_n_n  The session management connection object.

_n_u_m___p_r_o_p_s The number of properties.

_p_r_o_p___n_a_m_e_sThe list of properties to delete.
││__


To  get  properties  previously  stored  by  the client, use
_S_m_c_G_e_t_P_r_o_p_e_r_t_i_e_s.
__
││






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XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


Status SmcGetProperties(_s_m_c___c_o_n_n, _p_r_o_p___r_e_p_l_y___p_r_o_c, _c_l_i_e_n_t___d_a_t_a)
    SmcConn _s_m_c___c_o_n_n;
    SmcPropReplyProc _p_r_o_p___r_e_p_l_y___p_r_o_c;
    SmPointer _c_l_i_e_n_t___d_a_t_a;


_s_m_c___c_o_n_n  The session management connection object.

_p_r_o_p___r_e_p_l_y___p_r_o_c
          The callback to be  invoked  when  the  properties
          reply comes back.

_c_l_i_e_n_t___d_a_t_aThis pointer to client data will be passed to the
          _S_m_c_P_r_o_p_R_e_p_l_y_P_r_o_c callback.
││__

The return value of _S_m_c_G_e_t_P_r_o_p_e_r_t_i_e_s is zero for failure and
a positive value for success.

Note  that  the  library does not block until the properties
reply comes back.  Rather, a  callback  of  type  _S_m_c_P_r_o_p_R_e_‐
_p_l_y_P_r_o_c is invoked when the data is ready.
__
││
typedef void (*SmcPropReplyProc)();

void PropReplyProc(_s_m_c___c_o_n_n, _c_l_i_e_n_t___d_a_t_a, _n_u_m___p_r_o_p_s, _p_r_o_p_s)
    SmcConn _s_m_c___c_o_n_n;
    SmPointer _c_l_i_e_n_t___d_a_t_a;
    int _n_u_m___p_r_o_p_s;
    SmProp **_p_r_o_p_s;


_s_m_c___c_o_n_n  The session management connection object.

_c_l_i_e_n_t___d_a_t_aClient  data specified when the callback was reg‐
          istered.

_n_u_m___p_r_o_p_s The number of properties returned.

_p_r_o_p_s     The list of properties returned.
││__

To free each property, use _S_m_F_r_e_e_P_r_o_p_e_r_t_y  (see  section  8,
‘‘Freeing  Data’’).   To  free the actual array of pointers,
use _f_r_e_e.

_5_._5_.  _I_n_t_e_r_a_c_t_i_n_g _W_i_t_h _t_h_e _U_s_e_r

After receiving a ‘‘Save Yourself’’ message with  an  inter‐
act_style  of  _S_m_I_n_t_e_r_a_c_t_S_t_y_l_e_E_r_r_o_r_s  or _S_m_I_n_t_e_r_a_c_t_S_t_y_l_e_A_n_y,
the client may choose to interact with  the  user.   Because
only  one  client  can interact with the user at a time, the
client  must  call  _S_m_c_I_n_t_e_r_a_c_t_R_e_q_u_e_s_t  and  wait   for   an



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XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


‘‘Interact’’ message from the session manager.
__
││
Status SmcInteractRequest(_s_m_c___c_o_n_n, _d_i_a_l_o_g___t_y_p_e, _i_n_t_e_r_a_c_t___p_r_o_c, _c_l_i_e_n_t___d_a_t_a)
    SmcConn _s_m_c___c_o_n_n;
    int _d_i_a_l_o_g___t_y_p_e;
    SmcInteractProc _i_n_t_e_r_a_c_t___p_r_o_c;
    SmPointer _c_l_i_e_n_t___d_a_t_a;


_s_m_c___c_o_n_n  The session management connection object.

_d_i_a_l_o_g___t_y_p_eThe  type  of dialog the client wishes to present
          to the user.

_i_n_t_e_r_a_c_t___p_r_o_c
          The callback to be invoked when  the  ‘‘Interact’’
          message arrives from the session manager.

_c_l_i_e_n_t___d_a_t_aThis pointer to client data will be passed to the
          _S_m_c_I_n_t_e_r_a_c_t_P_r_o_c  callback  when  the  ‘‘Interact’’
          message arrives.
││__

The  return  value of _S_m_c_I_n_t_e_r_a_c_t_R_e_q_u_e_s_t is zero for failure
and a positive value for success.

The dialog_type  argument  specifies  either  _S_m_D_i_a_l_o_g_E_r_r_o_r,
indicating  that  the client wants to start an error dialog,
or _S_m_D_i_a_l_o_g_N_o_r_m_a_l, meaning that the client wishes to start a
nonerror dialog.

Note  that  if  a shutdown is in progress, the user may have
the option of cancelling the shutdown.  If the  shutdown  is
cancelled, the clients that have not interacted yet with the
user will receive a ‘‘Shutdown Cancelled’’  message  instead
of the ‘‘Interact’’ message.

The  _S_m_c_I_n_t_e_r_a_c_t_P_r_o_c  callback  will  be  invoked  when  the
‘‘Interact’’ message arrives from the session manager.
__
││
typedef void (*SmcInteractProc)();

void InteractProc(_s_m_c___c_o_n_n, _c_l_i_e_n_t___d_a_t_a)
    SmcConn _s_m_c___c_o_n_n;
    SmPointer _c_l_i_e_n_t___d_a_t_a;


_s_m_c___c_o_n_n  The session management connection object.

_c_l_i_e_n_t___d_a_t_aClient data specified when the callback was  reg‐
          istered.




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XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


││__


After  interacting with the user (in response to an ‘‘Inter‐
act’’ message), you should call _S_m_c_I_n_t_e_r_a_c_t_D_o_n_e.
__
││
void SmcInteractDone(_s_m_c___c_o_n_n, _c_a_n_c_e_l___s_h_u_t_d_o_w_n)
    SmcConn _s_m_c___c_o_n_n;
    Bool _c_a_n_c_e_l___s_h_u_t_d_o_w_n;


_s_m_c___c_o_n_n  The session management connection object.

_c_a_n_c_e_l___s_h_u_t_d_o_w_n
          If _T_r_u_e, indicates that the user requests that the
          entire shutdown be cancelled.
││__

The  cancel_shutdown argument may only be _T_r_u_e if the corre‐
sponding ‘‘Save Yourself’’ specified _T_r_u_e for  shutdown  and
_S_m_I_n_t_e_r_a_c_t_S_t_y_l_e_E_r_r_o_r_s  or  _S_m_I_n_t_e_r_a_c_t_S_t_y_l_e_A_n_y for the inter‐
act_style.

_5_._6_.  _R_e_q_u_e_s_t_i_n_g _a _S_a_v_e _Y_o_u_r_s_e_l_f

To request a checkpoint from the session manager, use _S_m_c_R_e_‐
_q_u_e_s_t_S_a_v_e_Y_o_u_r_s_e_l_f.
__
││
void SmcRequestSaveYourself(_s_m_c___c_o_n_n, _s_a_v_e___t_y_p_e, _s_h_u_t_d_o_w_n, _i_n_t_e_r_a_c_t___s_t_y_l_e, _f_a_s_t, _g_l_o_b_a_l)
    SmcConn _s_m_c___c_o_n_n;
    int _s_a_v_e___t_y_p_e;
    Bool _s_h_u_t_d_o_w_n;
    int _i_n_t_e_r_a_c_t___s_t_y_l_e;
    Bool _f_a_s_t;
    Bool _g_l_o_b_a_l;


_s_m_c___c_o_n_n  The session management connection object.

_s_a_v_e___t_y_p_e Specifies  the  type of information that should be
          saved.

_s_h_u_t_d_o_w_n  Specifies if a shutdown is taking place.

_i_n_t_e_r_a_c_t___s_t_y_l_e
          The type of interaction allowed with the user.

_f_a_s_t      If _T_r_u_e, the  client  should  save  its  state  as
          quickly as possible.

_g_l_o_b_a_l    Controls who gets the ‘‘Save Yourself.’’




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XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


││__

The  save_type, shutdown, interact_style, and fast arguments
are discussed in more detail in section  5.1.1,  ‘‘The  Save
Yourself Callback.’’

If  global  is  set to _T_r_u_e, then the resulting ‘‘Save Your‐
self’’ should be sent to all clients in  the  session.   For
example,  a  vendor  of a Uninterruptible Power Supply (UPS)
might include a Session Management client that would monitor
the  status  of  the UPS and generate a fast shutdown if the
power is about to be lost.

If global is set to _F_a_l_s_e, then the ‘‘Save Yourself’’ should
only be sent to the client that requested it.

_5_._7_.  _R_e_q_u_e_s_t_i_n_g _a _S_a_v_e _Y_o_u_r_s_e_l_f _P_h_a_s_e _2

In  response to a ‘‘Save Yourself, the client may request to
be informed when all the other clients are quiescent so that
it  can save their state.  To do so, use _S_m_c_R_e_q_u_e_s_t_S_a_v_e_Y_o_u_r_‐
_s_e_l_f_P_h_a_s_e_2.
__
││
Status SmcRequestSaveYourselfPhase2(_s_m_c___c_o_n_n, _s_a_v_e___y_o_u_r_s_e_l_f___p_h_a_s_e_2___p_r_o_c, _c_l_i_e_n_t___d_a_t_a)
    SmcConn _s_m_c___c_o_n_n;
    SmcSaveYourselfPhase2Proc _s_a_v_e___y_o_u_r_s_e_l_f___p_h_a_s_e_2___p_r_o_c;
    SmPointer _c_l_i_e_n_t___d_a_t_a;


_s_m_c___c_o_n_n  The session management connection object.

_s_a_v_e___y_o_u_r_s_e_l_f___p_h_a_s_e_2___p_r_o_c
          The callback to be invoked when the  ‘‘Save  Your‐
          self  Phase  2’’  message arrives from the session
          manager.

_c_l_i_e_n_t___d_a_t_aThis pointer to client data will be passed to the
          _S_m_c_S_a_v_e_Y_o_u_r_s_e_l_f_P_h_a_s_e_2_P_r_o_c callback when the ‘‘Save
          Yourself Phase 2’’ message arrives.
││__

The return value of _S_m_c_R_e_q_u_e_s_t_S_a_v_e_Y_o_u_r_s_e_l_f_P_h_a_s_e_2 is zero for
failure and a positive value for success.

This  request is needed by clients that manage other clients
(for example, window managers, workspace  managers,  and  so
on).   The  manager  must  make sure that all of the clients
that are being managed are in an idle state  so  that  their
state can be saved.

_5_._8_.  _C_o_m_p_l_e_t_i_n_g _a _S_a_v_e _Y_o_u_r_s_e_l_f

After  saving  state  in  response  to  a  ‘‘Save Yourself’’



                           − 16 −





XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


message, you should call _S_m_c_S_a_v_e_Y_o_u_r_s_e_l_f_D_o_n_e.
__
││
void SmcSaveYourselfDone(_s_m_c___c_o_n_n, _s_u_c_c_e_s_s)
    SmcConn _s_m_c___c_o_n_n;
    Bool _s_u_c_c_e_s_s;


_s_m_c___c_o_n_n  The session management connection object.

_s_u_c_c_e_s_s   If _T_r_u_e, the ‘‘Save Yourself’’ operation was  com‐
          pleted successfully.
││__

Before calling _S_m_c_S_a_v_e_Y_o_u_r_s_e_l_f_D_o_n_e, the client must have set
each required property at least once since the client regis‐
tered with the session manager.

_5_._9_.  _U_s_i_n_g _S_m_c _I_n_f_o_r_m_a_t_i_o_n_a_l _F_u_n_c_t_i_o_n_s

__
││
int SmcProtocolVersion(_s_m_c___c_o_n_n)
    SmcConn _s_m_c___c_o_n_n;
││__

_S_m_c_P_r_o_t_o_c_o_l_V_e_r_s_i_o_n  returns the major version of the session
management protocol associated with this session.


__
││
int SmcProtocolRevision(_s_m_c___c_o_n_n)
    SmcConn _s_m_c___c_o_n_n;
││__

_S_m_c_P_r_o_t_o_c_o_l_R_e_v_i_s_i_o_n returns the minor version of the session
management protocol associated with this session.


__
││
char *SmcVendor(_s_m_c___c_o_n_n)
    SmcConn _s_m_c___c_o_n_n;
││__

_S_m_c_V_e_n_d_o_r returns a string that provides some identification
of the owner of the session manager.  The string  should  be
freed with a call to _f_r_e_e.








                           − 17 −





XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11

__
││
char *SmcRelease(_s_m_c___c_o_n_n)
    SmcConn _s_m_c___c_o_n_n;
││__

_S_m_c_R_e_l_e_a_s_e returns a string that provides the release number
of the session manager.  The string should be freed  with  a
call to _f_r_e_e.


__
││
char *SmcClientID(_s_m_c___c_o_n_n)
    SmcConn _s_m_c___c_o_n_n;
││__

_S_m_c_C_l_i_e_n_t_I_D  returns a null‐terminated string for the client
ID associated with this connection.   This  information  was
also  returned in _S_m_c_O_p_e_n_C_o_n_n_e_c_t_i_o_n (it is provided here for
convenience).  Call _f_r_e_e on this pointer when the client  ID
is no longer needed.


__
││
IceConn SmcGetIceConnection(_s_m_c___c_o_n_n)
    SmcConn _s_m_c___c_o_n_n;
││__

_S_m_c_G_e_t_I_c_e_C_o_n_n_e_c_t_i_o_n  returns the ICE connection object asso‐
ciated with this session management connection object.   The
ICE  connection  object  can  be used to get some additional
information about the connection.  Some of the  more  useful
functions  which  can  be used on the IceConn are _I_c_e_C_o_n_n_e_c_‐
_t_i_o_n_N_u_m_b_e_r, _I_c_e_C_o_n_n_e_c_t_i_o_n_S_t_r_i_n_g,  _I_c_e_L_a_s_t_S_e_n_t_S_e_q_u_e_n_c_e_N_u_m_b_e_r,
_I_c_e_L_a_s_t_R_e_c_e_i_v_e_d_S_e_q_u_e_n_c_e_N_u_m_b_e_r,  and  _I_c_e_P_i_n_g.   For  further
information, see the _I_n_t_e_r_‐_C_l_i_e_n_t _E_x_c_h_a_n_g_e _L_i_b_r_a_r_y standard.

_5_._1_0_.  _E_r_r_o_r _H_a_n_d_l_i_n_g

If the client receives an unexpected protocol error from the
session manager, an error handler is invoked  by  SMlib.   A
default  error  handler  exists that simply prints the error
message to _s_t_d_e_r_r and exits if the severity of the error  is
fatal.   The client can change this error handler by calling
the _S_m_c_S_e_t_E_r_r_o_r_H_a_n_d_l_e_r function.
__
││
SmcErrorHandler SmcSetErrorHandler(_h_a_n_d_l_e_r)
    SmcErrorHandler _h_a_n_d_l_e_r;


_h_a_n_d_l_e_r   The  error  handler.   You  should  pass  NULL  to
          restore the default handler.



                           − 18 −





XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


││__

_S_m_c_S_e_t_E_r_r_o_r_H_a_n_d_l_e_r returns the previous error handler.

The _S_m_c_E_r_r_o_r_H_a_n_d_l_e_r has the following type:
__
││
typedef void (*SmcErrorHandler)();

void ErrorHandler(_s_m_c___c_o_n_n, _s_w_a_p, _o_f_f_e_n_d_i_n_g___m_i_n_o_r___o_p_c_o_d_e, _o_f_f_e_n_d_i_n_g___s_e_q_u_e_n_c_e___n_u_m, _e_r_r_o_r___c_l_a_s_s, _s_e_v_e_r_i_t_y, _v_a_l_u_e_s)
    SmcConn _s_m_c___c_o_n_n;
    Bool _s_w_a_p;
    int _o_f_f_e_n_d_i_n_g___m_i_n_o_r___o_p_c_o_d_e;
    unsigned long _o_f_f_e_n_d_i_n_g___s_e_q_u_e_n_c_e___n_u_m;
    int _e_r_r_o_r___c_l_a_s_s;
    int _s_e_v_e_r_i_t_y;
    IcePointer _v_a_l_u_e_s;


_s_m_c___c_o_n_n  The session management connection object.

_s_w_a_p      A flag that indicates if the specified values need
          byte swapping.

_o_f_f_e_n_d_i_n_g___m_i_n_o_r___o_p_c_o_d_e
          The minor opcode of the offending message.

_o_f_f_e_n_d_i_n_g___s_e_q_u_e_n_c_e___n_u_m
          The sequence number of the offending message.

_e_r_r_o_r___c_l_a_s_sThe error class of the offending message.

_s_e_v_e_r_i_t_y  _I_c_e_C_a_n_C_o_n_t_i_n_u_e, _I_c_e_F_a_t_a_l_T_o_P_r_o_t_o_c_o_l, or _I_c_e_F_a_t_a_l_T_o_‐
          _C_o_n_n_e_c_t_i_o_n.

_v_a_l_u_e_s    Any  additional error values specific to the minor
          opcode and class.
││__

Note that this error handler is invoked for protocol related
errors.   To  install an error handler to be invoked when an
IO error  occurs,  use  _I_c_e_S_e_t_I_O_E_r_r_o_r_H_a_n_d_l_e_r.   For  further
information, see the _I_n_t_e_r_‐_C_l_i_e_n_t _E_x_c_h_a_n_g_e _L_i_b_r_a_r_y standard.

_6_.  _S_e_s_s_i_o_n _M_a_n_a_g_e_m_e_n_t _S_e_r_v_e_r _(_S_m_s_) _F_u_n_c_t_i_o_n_s

This section discusses how Session Management servers:

·    Initialize the library

·    Register the client

·    Send a ‘‘Save Yourself’’ message




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XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


·    Send a ‘‘Save Yourself Phase 2’’ message

·    Send an ‘‘Interact’’ message

·    Send a ‘‘Save Complete’’ message

·    Send a ‘‘Die’’ message

·    Cancel a shutdown

·    Return properties

·    Ping a client

·    Clean up after a client disconnects

·    Use Sms informational functions

·    Handle errors

_6_._1_.  _I_n_i_t_i_a_l_i_z_i_n_g _t_h_e _L_i_b_r_a_r_y

_S_m_s_I_n_i_t_i_a_l_i_z_e is the first SMlib  function  that  should  be
called  by a session manager.  It provides information about
the session manager and registers a callback  that  will  be
invoked  each time a new client connects to the session man‐
ager.
__
││
Status SmsInitialize(_v_e_n_d_o_r, _r_e_l_e_a_s_e, _n_e_w___c_l_i_e_n_t___p_r_o_c, _m_a_n_a_g_e_r___d_a_t_a, _h_o_s_t___b_a_s_e_d___a_u_t_h___p_r_o_c,
                    _e_r_r_o_r___l_e_n_g_t_h, _e_r_r_o_r___s_t_r_i_n_g___r_e_t)
    char *_v_e_n_d_o_r;
    char *_r_e_l_e_a_s_e;
    SmsNewClientProc _n_e_w___c_l_i_e_n_t___p_r_o_c;
    SmPointer _m_a_n_a_g_e_r___d_a_t_a;
    IceHostBasedAuthProc _h_o_s_t___b_a_s_e_d___a_u_t_h___p_r_o_c;
    int _e_r_r_o_r___l_e_n_g_t_h;
    char *_e_r_r_o_r___s_t_r_i_n_g___r_e_t;


_v_e_n_d_o_r    A string specifying the session manager vendor.

_r_e_l_e_a_s_e   A string specifying the  session  manager  release
          number.

_n_e_w___c_l_i_e_n_t___p_r_o_c
          Callback to be invoked each time a new client con‐
          nects to the session manager.

_m_a_n_a_g_e_r___d_a_t_a
          When the  _S_m_s_N_e_w_C_l_i_e_n_t_P_r_o_c  callback  is  invoked,
          this pointer to manager data will be passed.

_h_o_s_t___b_a_s_e_d___a_u_t_h___p_r_o_c



                           − 20 −





XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


          Host based authentication callback.

_e_r_r_o_r___l_e_n_g_t_h
          Length of the error_string_ret argument passed in.

_e_r_r_o_r___s_t_r_i_n_g___r_e_t
          Returns a null‐terminated error message,  if  any.
          The  error_string_ret points to user supplied mem‐
          ory.  No more than error_length bytes are used.
││__

After the _S_m_s_I_n_i_t_i_a_l_i_z_e function is called, the session man‐
ager  should  call  the  _I_c_e_L_i_s_t_e_n_F_o_r_C_o_n_n_e_c_t_i_o_n_s function to
listen for new connections.  Afterwards, each time a  client
connects,  the  session manager should call _I_c_e_A_c_c_e_p_t_C_o_n_n_e_c_‐
_t_i_o_n.

See section  9,  ‘‘Authentication  of  Clients,’’  for  more
details  on authentication (including host based authentica‐
tion).  Also see the _I_n_t_e_r_‐_C_l_i_e_n_t _E_x_c_h_a_n_g_e _L_i_b_r_a_r_y  standard
for  further details on listening for and accepting ICE con‐
nections.

Each time a new client connects to the session manager,  the
_S_m_s_N_e_w_C_l_i_e_n_t_P_r_o_c  callback  is invoked.  The session manager
obtains a new opaque connection object that  it  should  use
for  all  future interaction with the client.  At this time,
the session manager must also register a set of callbacks to
respond  to  the  different  messages  that the client might
send.
__
││
typedef Status (*SmsNewClientProc)();

Status NewClientProc(_s_m_s___c_o_n_n, _m_a_n_a_g_e_r___d_a_t_a, _m_a_s_k___r_e_t, _c_a_l_l_b_a_c_k_s___r_e_t, _f_a_i_l_u_r_e___r_e_a_s_o_n___r_e_t)
    SmsConn _s_m_s___c_o_n_n;
    SmPointer _m_a_n_a_g_e_r___d_a_t_a;
    unsigned long *_m_a_s_k___r_e_t;
    SmsCallbacks *_c_a_l_l_b_a_c_k_s___r_e_t;
    char **_f_a_i_l_u_r_e___r_e_a_s_o_n___r_e_t;


_s_m_s___c_o_n_n  A new opaque connection object.

_m_a_n_a_g_e_r___d_a_t_a
          Manager data specified when the callback was  reg‐
          istered.

_m_a_s_k___r_e_t  On  return,  indicates which callbacks were set by
          the session manager.

_c_a_l_l_b_a_c_k_s___r_e_t
          On return, contains the  callbacks  registered  by
          the session manager.



                           − 21 −





XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


_f_a_i_l_u_r_e___r_e_a_s_o_n___r_e_t
          Failure reason returned.
││__

If  a  failure  occurs, the _S_m_s_N_e_w_C_l_i_e_n_t_P_r_o_c should return a
zero status as well as allocate and return a failure  reason
string in failure_reason_ret.  SMlib will be responsible for
freeing this memory.

The session manager must register  a  set  of  callbacks  to
respond  to  client events.  The mask_ret argument specifies
which callbacks are set.  All of the callbacks specified  in
this  version of SMlib are mandatory.  The mask_ret argument
is necessary in order to maintain backwards compatibility in
future versions of the library.

The  following  values may be ORed together to obtain a mask
value:


_S_m_s_R_e_g_i_s_t_e_r_C_l_i_e_n_t_P_r_o_c_M_a_s_k
_S_m_s_I_n_t_e_r_a_c_t_R_e_q_u_e_s_t_P_r_o_c_M_a_s_k
_S_m_s_I_n_t_e_r_a_c_t_D_o_n_e_P_r_o_c_M_a_s_k
_S_m_s_S_a_v_e_Y_o_u_r_s_e_l_f_R_e_q_u_e_s_t_P_r_o_c_M_a_s_k
_S_m_s_S_a_v_e_Y_o_u_r_s_e_l_f_P_2_R_e_q_u_e_s_t_P_r_o_c_M_a_s_k
_S_m_s_S_a_v_e_Y_o_u_r_s_e_l_f_D_o_n_e_P_r_o_c_M_a_s_k
_S_m_s_C_l_o_s_e_C_o_n_n_e_c_t_i_o_n_P_r_o_c_M_a_s_k
_S_m_s_S_e_t_P_r_o_p_e_r_t_i_e_s_P_r_o_c_M_a_s_k
_S_m_s_D_e_l_e_t_e_P_r_o_p_e_r_t_i_e_s_P_r_o_c_M_a_s_k
_S_m_s_G_e_t_P_r_o_p_e_r_t_i_e_s_P_r_o_c_M_a_s_k


For each  callback,  the  session  manager  can  register  a
pointer  to  manager  data  specific to that callback.  This
pointer will be passed to the callback when it is invoked by
SMlib.
__
││

typedef struct {
     struct {
          SmsRegisterClientProc callback;
          SmPointer manager_data;
     } register_client;

     struct {
          SmsInteractRequestProc callback;
          SmPointer manager_data;
     } interact_request;

     struct {
          SmsInteractDoneProc callback;
          SmPointer manager_data;
     } interact_done;



                           − 22 −





XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


     struct {
          SmsSaveYourselfRequestProc callback;
          SmPointer manager_data;
     } save_yourself_request;

     struct {
          SmsSaveYourselfPhase2RequestProc callback;
          SmPointer manager_data;
     } save_yourself_phase2_request;

     struct {
          SmsSaveYourselfDoneProc callback;
          SmPointer manager_data;
     } save_yourself_done;

     struct {
          SmsCloseConnectionProc callback;
          SmPointer manager_data;
     } close_connection;

     struct {
          SmsSetPropertiesProc callback;
          SmPointer manager_data;
     } set_properties;

     struct {
          SmsDeletePropertiesProc callback;
          SmPointer manager_data;
     } delete_properties;

     struct {
          SmsGetPropertiesProc callback;
          SmPointer manager_data;
     } get_properties;

} SmsCallbacks;

││__


_6_._1_._1_.  _T_h_e _R_e_g_i_s_t_e_r _C_l_i_e_n_t _C_a_l_l_b_a_c_k

The Register Client callback is the first callback that will
be invoked after the client connects to the session manager.
Its type is _S_m_s_R_e_g_i_s_t_e_r_C_l_i_e_n_t_P_r_o_c.
__
││
typedef Status (*SmsRegisterClientProc();

Status RegisterClientProc(_s_m_s___c_o_n_n, _m_a_n_a_g_e_r___d_a_t_a, _p_r_e_v_i_o_u_s___i_d)
    SmsConn _s_m_s___c_o_n_n;
    SmPointer _m_a_n_a_g_e_r___d_a_t_a;
    char *_p_r_e_v_i_o_u_s___i_d;




                           − 23 −





XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


_s_m_s___c_o_n_n  The session management connection object.

_m_a_n_a_g_e_r___d_a_t_a
          Manager  data specified when the callback was reg‐
          istered.

_p_r_e_v_i_o_u_s___i_dThe client ID from the previous session.
││__

Before any further interaction takes place with the  client,
the client must be registered with the session manager.

If  the  client  is being restarted from a previous session,
previous_id will contain a null‐terminated string represent‐
ing  the  client ID from the previous session.  Call _f_r_e_e on
the previous_id pointer when it is no longer needed.  If the
client  is  first  joining  the session, previous_id will be
NULL.

If previous_id is invalid, the session  manager  should  not
register  the  client  at  this  time.  This callback should
return a status of zero, which will cause an  error  message
to  be  sent  to  the client.  The client should re‐register
with previous_id set to NULL.

Otherwise, the session manager should  register  the  client
with  a unique client ID by calling the _S_m_s_R_e_g_i_s_t_e_r_C_l_i_e_n_t_R_e_‐
_p_l_y function (to be discussed shortly), and the _S_m_s_R_e_g_i_s_t_e_r_‐
_C_l_i_e_n_t_P_r_o_c callback should return a status of one.

_6_._1_._2_.  _T_h_e _I_n_t_e_r_a_c_t _R_e_q_u_e_s_t _C_a_l_l_b_a_c_k

The Interact Request callback is of type _S_m_s_I_n_t_e_r_a_c_t_R_e_q_u_e_s_t_‐
_P_r_o_c.
__
││
typedef void (*SmsInteractRequestProc)();

void InteractRequestProc(_s_m_s___c_o_n_n, _m_a_n_a_g_e_r___d_a_t_a, _d_i_a_l_o_g___t_y_p_e)
    SmsConn _s_m_s___c_o_n_n;
    SmPointer _m_a_n_a_g_e_r___d_a_t_a;
    int _d_i_a_l_o_g___t_y_p_e;


_s_m_s___c_o_n_n  The session management connection object.

_m_a_n_a_g_e_r___d_a_t_a
          Manager data specified when the callback was  reg‐
          istered.

_d_i_a_l_o_g___t_y_p_eThe  type  of dialog the client wishes to present
          to the user.
││__




                           − 24 −





XX SSeessssiioonn MMaannaaggeemmeenntt LLiibbrraarryy                     lliibbSSMM 11..11..11


When a client receives a ‘‘Save Yourself’’ message  with  an
interact_style   of   _S_m_I_n_t_e_r_a_c_t_S_t_y_l_e_E_r_r_o_r_s  or  _S_m_I_n_t_e_r_a_c_t_‐
_S_t_y_l_e_A_n_y, the client may choose to interact with  the  user.
Because  only  one  client  can  interact with the user at a
time, the client must request to  interact  with  the  user.
The session manager should keep a queue of all clients wish‐
ing to interact.  It should send an ‘‘Interact’’ message  to
one  client at a time and wait for an ‘‘Interact Done’’ mes‐
sage before continuing with the next client.

The dialog_type  argument  specifies  either  _S_m_D_i_a_l_o_g_E_r_r_o_r,
indicating  that  the client wants to start an error dialog,
or _S_m_D_i_a_l_o_g_N_o_r_m_a_l, meaning that the client wishes to start a
nonerror dialog.

If  a  shutdown is in progress, the user may have the option
of cancelling the shutdown.  If the  shutdown  is  cancelled
(specified  in  the  ‘‘Interact Done’’ message), the session
manager should send a ‘‘Shutdown Cancelled’’ message to each
client that requested to interact.

_6_._1_._3_.  _T_h_e _I_n_t_e_r_a_c_t _D_o_n_e _C_a_l_l_b_a_c_k

When  the  client  is  done  interacting  with the user, the
_S_m_s_I_n_t_e_r_a_c_t_D_o_n_e_P_r_o_c callback will be invoked.
__
││
typedef void (*SmsInteractDoneProc)();

void InteractDoneProc(_s_m_s___c_o_n_n, _m_a_n_a_g_e_r___d_a_t_a, _c_a_n_c_e_l___s_h_u_t_d_o_w_n)
    SmsConn _s_m_s___c_o_n_n;
    SmPointer _m_a_n_a_g_e_r___d_a_t_a;
    Bool _c_a_n_c_e_l___s_h_u_t_d_o_w_n;


_s_m_s___c_o_n_n  The session management connection object.

_m_a_n_a_g_e_r___d_a_t_a
          Manager data specified when the callback was  reg‐
          istered.

_c_a_n_c_e_l___s_h_u_t_d_o_w_n
          Specifies  if  the  user  requests that the entire
          shutdown be cancelled.
││__

Note that the shutdown can be cancelled only if  the  corre‐
sponding  ‘‘Save  Yourself’’ specified _T_r_u_e for shutdown and
_S_m_I_n_t_e_r_a_c_t_S_t_y_l_e_E_r_r_o_r_s or _S_m_I_n_t_e_r_a_c_t_S_t_y_l_e_A_n_y for  the  inter‐
act_style.

_6_._1_._4_.  _T_h_e _S_a_v_e _Y_o_u_r_s_e_l_f _R_e_q_u_e_s_t _C_a_l_l_b_a_c_k

The    Save   Yourself   Request   callback   is   of   type



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_S_m_s_S_a_v_e_Y_o_u_r_s_e_l_f_R_e_q_u_e_s_t_P_r_o_c.
__
││
typedef void (*SmsSaveYourselfRequestProc)();

void SaveYourselfRequestProc(_s_m_s___c_o_n_n, _m_a_n_a_g_e_r___d_a_t_a, _s_a_v_e___t_y_p_e, _s_h_u_t_d_o_w_n, _i_n_t_e_r_a_c_t___s_t_y_l_e, _f_a_s_t, _g_l_o_b_a_l)
    SmsConn _s_m_s___c_o_n_n;
    SmPointer _m_a_n_a_g_e_r___d_a_t_a;
    int _s_a_v_e___t_y_p_e;
    Bool _s_h_u_t_d_o_w_n;
    int _i_n_t_e_r_a_c_t___s_t_y_l_e;
    Bool _f_a_s_t;
    Bool _g_l_o_b_a_l;


_s_m_s___c_o_n_n  The session management connection object.

_m_a_n_a_g_e_r___d_a_t_a
          Manager data specified when the callback was  reg‐
          istered.

_s_a_v_e___t_y_p_e Specifies  the  type of information that should be
          saved.

_s_h_u_t_d_o_w_n  Specifies if a shutdown is taking place.

_i_n_t_e_r_a_c_t___s_t_y_l_e
          The type of interaction allowed with the user.

_f_a_s_t      If _T_r_u_e, the  client  should  save  its  state  as
          quickly as possible.

_g_l_o_b_a_l    Controls who gets the ‘‘Save Yourself.’’
││__

The  Save  Yourself  Request  prompts the session manager to
initiate a checkpoint or shutdown.  For information  on  the
save_type, shutdown, interact_style, and fast arguments, see
section 6.3, ‘‘Sending a Save Yourself Message.’’

If global is set to _T_r_u_e, then the  resulting  ‘‘Save  Your‐
self’’ should be sent to all applications.  If global is set
to _F_a_l_s_e, then the ‘‘Save Yourself’’ should only be sent  to
the client that requested it.

_6_._1_._5_.  _T_h_e _S_a_v_e _Y_o_u_r_s_e_l_f _P_h_a_s_e _2 _R_e_q_u_e_s_t _C_a_l_l_b_a_c_k

The Save Yourself  Phase  2  Request  callback  is  of  type
_S_m_s_S_a_v_e_Y_o_u_r_s_e_l_f_P_h_a_s_e_2_R_e_q_u_e_s_t_P_r_o_c.
__
││






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typedef void (*SmsSaveYourselfPhase2RequestProc)();

void SmsSaveYourselfPhase2RequestProc(_s_m_s___c_o_n_n, _m_a_n_a_g_e_r___d_a_t_a)
    SmsConn _s_m_s___c_o_n_n;
    SmPointer _m_a_n_a_g_e_r___d_a_t_a;


_s_m_s___c_o_n_n  The session management connection object.

_m_a_n_a_g_e_r___d_a_t_a
          Manager  data specified when the callback was reg‐
          istered.
││__

This request is sent by clients that  manage  other  clients
(for  example,  window  managers, workspace managers, and so
on).  Such managers must make sure that all of  the  clients
that  are  being  managed are in an idle state so that their
state can be saved.

_6_._1_._6_.  _T_h_e _S_a_v_e _Y_o_u_r_s_e_l_f _D_o_n_e _C_a_l_l_b_a_c_k

When the client is done saving its state in  response  to  a
‘‘Save  Yourself’’ message, the _S_m_s_S_a_v_e_Y_o_u_r_s_e_l_f_D_o_n_e_P_r_o_c will
be invoked.
__
││
typedef void (*SmsSaveYourselfDoneProc)();

void SaveYourselfDoneProc(_s_m_s___c_o_n_n, _m_a_n_a_g_e_r___d_a_t_a, _s_u_c_c_e_s_s)
    SmsConn _s_m_s___c_o_n_n;
    SmPointer _m_a_n_a_g_e_r___d_a_t_a;
    Bool _s_u_c_c_e_s_s;


_s_m_s___c_o_n_n  The session management connection object.

_m_a_n_a_g_e_r___d_a_t_a
          Manager data specified when the callback was  reg‐
          istered.

_s_u_c_c_e_s_s   If _T_r_u_e, the Save Yourself operation was completed
          successfully.
││__

Before the ‘‘Save Yourself Done’’ was sent, the client  must
have  set each required property at least once since it reg‐
istered with the session manager.

_6_._1_._7_.  _T_h_e _C_o_n_n_e_c_t_i_o_n _C_l_o_s_e_d _C_a_l_l_b_a_c_k

If the client properly terminates (that is,  it  calls  _S_m_c_‐
_C_l_o_s_e_C_o_n_n_e_c_t_i_o_n),  the  _S_m_s_C_l_o_s_e_C_o_n_n_e_c_t_i_o_n_P_r_o_c  callback  is




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invoked.
__
││
typedef void (*SmsCloseConnectionProc)();

void CloseConnectionProc(_s_m_s___c_o_n_n, _m_a_n_a_g_e_r___d_a_t_a, _c_o_u_n_t, _r_e_a_s_o_n___m_s_g_s)
    SmsConn _s_m_s___c_o_n_n;
    SmPointer _m_a_n_a_g_e_r___d_a_t_a;
    int _c_o_u_n_t;
    char **_r_e_a_s_o_n___m_s_g_s;


_s_m_s___c_o_n_n  The session management connection object.

_m_a_n_a_g_e_r___d_a_t_a
          Manager data specified when the callback was  reg‐
          istered.

_c_o_u_n_t     The number of reason messages.

_r_e_a_s_o_n___m_s_g_sThe reasons for closing the connection.
││__

The  reason_msgs  argument  will most likely be NULL and the
count argument zero (0) if resignation is  expected  by  the
user.  Otherwise, it contains a list of null‐terminated Com‐
pound Text strings representing the reason for  termination.
The  session manager should display these reason messages to
the user.

Call _S_m_F_r_e_e_R_e_a_s_o_n_s to free the reason messages.  For further
information, see section 8, ‘‘Freeing Data.’’

_6_._1_._8_.  _T_h_e _S_e_t _P_r_o_p_e_r_t_i_e_s _C_a_l_l_b_a_c_k

When the client sets session management properties, the _S_m_s_‐
_S_e_t_P_r_o_p_e_r_t_i_e_s_P_r_o_c callback will be invoked.
__
││
typedef void (*SmsSetPropertiesProc)();

void SetPropertiesProc(_s_m_s___c_o_n_n, _m_a_n_a_g_e_r___d_a_t_a, _n_u_m___p_r_o_p_s, _p_r_o_p_s)
    SmsConn _s_m_s___c_o_n_n;
    SmPointer _m_a_n_a_g_e_r___d_a_t_a;
    int _n_u_m___p_r_o_p_s;
    SmProp **_p_r_o_p_s;


_s_m_c___c_o_n_n  The session management connection object.

_m_a_n_a_g_e_r___d_a_t_a
          Manager data specified when the callback was  reg‐
          istered.




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_n_u_m___p_r_o_p_s The number of properties.

_p_r_o_p_s     The list of properties to set.
││__

The  properties are specified as an array of property point‐
ers.  For a description of session management properties and
the  _S_m_P_r_o_p  structure,  see section 7, ‘‘Session Management
Properties.’’

Previously set property values may  be  over‐written.   Some
properties  have  predefined semantics.  The session manager
is required to store nonpredefined properties.

To free each  property,  use  _S_m_F_r_e_e_P_r_o_p_e_r_t_y.   For  further
information,  see  section  8, ‘‘Freeing Data.’’  You should
free the actual array of pointers with a call to _f_r_e_e.

_6_._1_._9_.  _T_h_e _D_e_l_e_t_e _P_r_o_p_e_r_t_i_e_s _C_a_l_l_b_a_c_k

When the client deletes session management  properties,  the
_S_m_s_D_e_l_e_t_e_P_r_o_p_e_r_t_i_e_s_P_r_o_c callback will be invoked.
__
││
typedef void (*SmsDeletePropertiesProc)();

void DeletePropertiesProc(_s_m_s___c_o_n_n, _m_a_n_a_g_e_r___d_a_t_a, _n_u_m___p_r_o_p_s, _p_r_o_p___n_a_m_e_s)
    SmsConn _s_m_s___c_o_n_n;
    SmPointer _m_a_n_a_g_e_r___d_a_t_a;
    int _n_u_m___p_r_o_p_s;
    char **_p_r_o_p___n_a_m_e_s;


_s_m_c___c_o_n_n  The session management connection object.

_m_a_n_a_g_e_r___d_a_t_a
          Manager  data specified when the callback was reg‐
          istered.

_n_u_m___p_r_o_p_s The number of properties.

_p_r_o_p___n_a_m_e_sThe list of properties to delete.
││__

The properties are specified as an array of strings.  For  a
description  of session management properties and the _S_m_P_r_o_p
structure, see section 7, ‘‘Session Management Properties.’’

_6_._1_._1_0_.  _T_h_e _G_e_t _P_r_o_p_e_r_t_i_e_s _C_a_l_l_b_a_c_k

The _S_m_s_G_e_t_P_r_o_p_e_r_t_i_e_s_P_r_o_c callback is invoked when the client






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wants to retrieve properties it set.
__
││
typedef void (*SmsGetPropertiesProc)();

void GetPropertiesProc(_s_m_s___c_o_n_n, _m_a_n_a_g_e_r___d_a_t_a)
    SmsConn _s_m_s___c_o_n_n;
    SmPointer _m_a_n_a_g_e_r___d_a_t_a;


_s_m_c___c_o_n_n  The session management connection object.

_m_a_n_a_g_e_r___d_a_t_a
          Manager data specified when the callback was  reg‐
          istered.
││__

The session manager should respond by calling _S_m_s_R_e_t_u_r_n_P_r_o_p_‐
_e_r_t_i_e_s.  All of the properties set for this client should be
returned.

_6_._2_.  _R_e_g_i_s_t_e_r_i_n_g _t_h_e _C_l_i_e_n_t

To register a client (in response to a _S_m_s_R_e_g_i_s_t_e_r_C_l_i_e_n_t_P_r_o_c
callback), use _S_m_s_R_e_g_i_s_t_e_r_C_l_i_e_n_t_R_e_p_l_y.
__
││
Status SmsRegisterClientReply(_s_m_s___c_o_n_n, _c_l_i_e_n_t___i_d)
    SmsConn _s_m_s___c_o_n_n;
    char *_c_l_i_e_n_t___i_d;


_s_m_s___c_o_n_n  The session management connection object.

_c_l_i_e_n_t___i_d A null‐terminated  string  representing  a  unique
          client ID.
││__

The return value of _S_m_s_R_e_g_i_s_t_e_r_C_l_i_e_n_t_R_e_p_l_y is zero for fail‐
ure and a positive value for success.  Failure will occur if
SMlib  can  not allocate memory to hold a copy of the client
ID for it’s own internal needs.

If a non‐NULL previous_id was specified when the client reg‐
istered  itself,  client_id  should  be  identical to previ‐
ous_id.

Otherwise, client_id should be a unique ID freshly generated
by  the  session  manager.  In addition, the session manager
should send a ‘‘Save Yourself’’ message with type  =  Local,
shutdown  =  False,  interact‐style = None, and fast = False
immediately after registering the client.

Note that once a client ID has been assigned to the  client,



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the  client  keeps  this  ID indefinitely.  If the client is
terminated and restarted, it will be reassigned the same ID.
It  is  desirable  to be able to pass client IDs around from
machine to machine, from user to user, and from session man‐
ager to session manager, while retaining the identity of the
client.  This, combined with the indefinite  persistence  of
client  IDs,  means  that  client  IDs  need  to be globally
unique.

You should call the _S_m_s_G_e_n_e_r_a_t_e_C_l_i_e_n_t_I_D function to generate
a globally unique client ID.
__
││
char *SmsGenerateClientID(_s_m_s___c_o_n_n)
    SmsConn _s_m_s___c_o_n_n;


_s_m_s___c_o_n_n  The session management connection object.
││__

NULL  will  be  returned  if  the ID could not be generated.
Otherwise, the return value of the function  is  the  client
ID.   It  should be freed with a call to _f_r_e_e when no longer
needed.

_6_._3_.  _S_e_n_d_i_n_g _a _S_a_v_e _Y_o_u_r_s_e_l_f _M_e_s_s_a_g_e

To send a ‘‘Save Yourself’’ to a  client,  use  _S_m_s_S_a_v_e_Y_o_u_r_‐
_s_e_l_f.
__
││
void SmsSaveYourself(_s_m_s___c_o_n_n, _s_a_v_e___t_y_p_e, _s_h_u_t_d_o_w_n, _i_n_t_e_r_a_c_t___s_t_y_l_e, _f_a_s_t)
    SmsConn _s_m_s___c_o_n_n;
    int _s_a_v_e___t_y_p_e;
    Bool _s_h_u_t_d_o_w_n;
    int _i_n_t_e_r_a_c_t___s_t_y_l_e;
    Bool _f_a_s_t;


_s_m_s___c_o_n_n  The session management connection object.

_s_a_v_e___t_y_p_e Specifies  the  type of information that should be
          saved.

_s_h_u_t_d_o_w_n  Specifies if a shutdown is taking place.

_i_n_t_e_r_a_c_t___s_t_y_l_e
          The type of interaction allowed with the user.

_f_a_s_t      If _T_r_u_e, the  client  should  save  its  state  as
          quickly as possible.
││__

The  session  manager sends a ‘‘Save Yourself’’ message to a



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client either to checkpoint it or just before termination so
that  it  can save its state.  The client responds with zero
or more ‘‘Set Properties’’ messages to update the properties
indicating  how to restart the client.  When all the proper‐
ties have been set,  the  client  sends  a  ‘‘Save  Yourself
Done’’ message.

If  interact_style  is  _S_m_I_n_t_e_r_a_c_t_S_t_y_l_e_N_o_n_e, the client must
not interact with the user while saving  state.   If  inter‐
act_style  is _S_m_I_n_t_e_r_a_c_t_S_t_y_l_e_E_r_r_o_r_s, the client may interact
with the user only if an error condition arises.  If  inter‐
act_style  is _S_m_I_n_t_e_r_a_c_t_S_t_y_l_e_A_n_y, then the client may inter‐
act with the user for any purpose.  The client must send  an
‘‘Interact  Request’’  message  and wait for an ‘‘Interact’’
message from the session manager before it can interact with
the  user.   When  the  client  is done interacting with the
user, it should send  an  ‘‘Interact  Done’’  message.   The
‘‘Interact  Request’’  message  can be sent any time after a
‘‘Save Yourself’’ and before a ‘‘Save Yourself Done.’’

If save_type is _S_m_S_a_v_e_L_o_c_a_l,  the  client  must  update  the
properties  to  reflect its current state.  Specifically, it
should save enough information to restore the state as  seen
by  the user of this client.  It should not affect the state
as seen by other users.  If save_type  is  _S_m_S_a_v_e_G_l_o_b_a_l  the
user  wants  the  client to commit all of its data to perma‐
nent, globally accessible storage.  If save_type is  _S_m_S_a_v_e_‐
_B_o_t_h,  the  client  should do both of these (it should first
commit the data to permanent  storage  before  updating  its
properties).

The shutdown argument specifies whether the session is being
shut  down.   The  interaction  is  different  depending  on
whether  or not shutdown is set.  If not shutting down, then
the client can save and resume normal operation.   If  shut‐
ting down, the client must save and then must prevent inter‐
action until it receives either a ‘‘Die’’  or  a  ‘‘Shutdown
Cancelled,’’  because  anything the user does after the save
will be lost.

The fast argument specifies that the client should save  its
state  as  quickly as possible.  For example, if the session
manager knows that power is about to  fail,  it  should  set
fast to _T_r_u_e.

_6_._4_.  _S_e_n_d_i_n_g _a _S_a_v_e _Y_o_u_r_s_e_l_f _P_h_a_s_e _2 _M_e_s_s_a_g_e

In  order  to  send a ‘‘Save Yourself Phase 2’’ message to a
client, use _S_m_s_S_a_v_e_Y_o_u_r_s_e_l_f_P_h_a_s_e_2.
__
││
void SmsSaveYourselfPhase2(_s_m_s___c_o_n_n)
    SmsConn _s_m_s___c_o_n_n;




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_s_m_s___c_o_n_n  The session management connection object.
││__

The session manager sends this message to a client that  has
previously sent a ‘‘Save Yourself Phase 2 Request’’ message.
This message informs the client that all other  clients  are
in  a  fixed  state  and  this client can save state that is
associated with other clients.

_6_._5_.  _S_e_n_d_i_n_g _a_n _I_n_t_e_r_a_c_t _M_e_s_s_a_g_e

To send an ‘‘Interact’’ message to a client,  use  _S_m_s_I_n_t_e_r_‐
_a_c_t.
__
││
void SmsInteract(_s_m_s___c_o_n_n)
    SmsConn _s_m_s___c_o_n_n;


_s_m_s___c_o_n_n  The session management connection object.
││__

The  ‘‘Interact’’ message grants the client the privilege of
interacting with the user.  When the client is  done  inter‐
acting with the user, it must send an ‘‘Interact Done’’ mes‐
sage to the session manager.

_6_._6_.  _S_e_n_d_i_n_g _a _S_a_v_e _C_o_m_p_l_e_t_e _M_e_s_s_a_g_e

To send  a  ‘‘Save  Complete’’  message  to  a  client,  use
_S_m_s_S_a_v_e_C_o_m_p_l_e_t_e.
__
││
void SmsSaveComplete(_s_m_s___c_o_n_n)
    SmsConn _s_m_s___c_o_n_n;


_s_m_s___c_o_n_n  The session management connection object.
││__

The  session manager sends this message when it is done with
a checkpoint.  The client is then free to change its  state.

_6_._7_.  _S_e_n_d_i_n_g _a _D_i_e _M_e_s_s_a_g_e

To send a ‘‘Die’’ message to a client, use _S_m_s_D_i_e.
__
││
void SmsDie(_s_m_s___c_o_n_n)
    SmsConn _s_m_s___c_o_n_n;


_s_m_s___c_o_n_n  The session management connection object.




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││__

Before  the session manager terminates, it should wait for a
‘‘Connection Closed’’ message from each client that it  sent
a ‘‘Die’’ message to, timing out appropriately.

_6_._8_.  _C_a_n_c_e_l_l_i_n_g _a _S_h_u_t_d_o_w_n

To cancel a shutdown, use _S_m_s_S_h_u_t_d_o_w_n_C_a_n_c_e_l_l_e_d.
__
││
void SmsShutdownCancelled(_s_m_s___c_o_n_n)
    SmsConn _s_m_s___c_o_n_n;


_s_m_s___c_o_n_n  The session management connection object.
││__

The  client  can  now  continue as if the shutdown had never
happened.  If the client has  not  sent  a  ‘‘Save  Yourself
Done’’  message yet, it can either abort the save and send a
‘‘Save Yourself Done’’ with  the  success  argument  set  to
_F_a_l_s_e,  or  it  can continue with the save and send a ‘‘Save
Yourself Done’’ with the success argument set to reflect the
outcome of the save.

_6_._9_.  _R_e_t_u_r_n_i_n_g _P_r_o_p_e_r_t_i_e_s

In  response  to  a  ‘‘Get Properties’’ message, the session
manager should call _S_m_s_R_e_t_u_r_n_P_r_o_p_e_r_t_i_e_s.
__
││
void SmsReturnProperties(_s_m_s___c_o_n_n, _n_u_m___p_r_o_p_s, _p_r_o_p_s)
    SmsConn _s_m_s___c_o_n_n;
    int _n_u_m___p_r_o_p_s;
    SmProp **_p_r_o_p_s;


_s_m_s___c_o_n_n  The session management connection object.

_n_u_m___p_r_o_p_s The number of properties.

_p_r_o_p_s     The list of properties to return to the client.
││__

The properties are returned as an array of  property  point‐
ers.  For a description of session management properties and
the _S_m_P_r_o_p structure, see section  7,  ‘‘Session  Management
Properties.’’

_6_._1_0_.  _P_i_n_g_i_n_g _a _C_l_i_e_n_t

To  check  that  a client is still alive, you should use the
_I_c_e_P_i_n_g function provided by the ICE library.  To do so, the



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ICE  connection  must be obtained using the _S_m_s_G_e_t_I_c_e_C_o_n_n_e_c_‐
_t_i_o_n (see section  6.12,  ‘‘Using  Sms  Informational  Func‐
tions’’).

__
││
void IcePing(_i_c_e___c_o_n_n, _p_i_n_g___r_e_p_l_y___p_r_o_c, _c_l_i_e_n_t___d_a_t_a)
    IceConn _i_c_e___c_o_n_n;
    IcePingReplyProc _p_i_n_g___r_e_p_l_y___p_r_o_c;
    IcePointer _c_l_i_e_n_t___d_a_t_a;


_i_c_e___c_o_n_n  A valid ICE connection object.

_p_i_n_g___r_e_p_l_y___p_r_o_c
          The   callback  to  invoke  when  the  Ping  reply
          arrives.

_c_l_i_e_n_t___d_a_t_aThis pointer will be  passed  to  the  _I_c_e_P_i_n_g_R_e_‐
          _p_l_y_P_r_o_c callback.
││__

When the Ping reply is ready (if ever), the _I_c_e_P_i_n_g_R_e_p_l_y_P_r_o_c
callback will be invoked.  A  session  manager  should  have
some  sort  of  timeout  period,  after which it assumes the
client has unexpectedly died.

__
││
typedef void (*IcePingReplyProc)();

void PingReplyProc(_i_c_e___c_o_n_n, _c_l_i_e_n_t___d_a_t_a)
    IceConn _i_c_e___c_o_n_n;
    IcePointer _c_l_i_e_n_t___d_a_t_a;


_i_c_e___c_o_n_n  The ICE connection object.

_c_l_i_e_n_t___d_a_t_aThe client data specified in the call to _I_c_e_P_i_n_g.
││__


_6_._1_1_.  _C_l_e_a_n_i_n_g _U_p _A_f_t_e_r _a _C_l_i_e_n_t _D_i_s_c_o_n_n_e_c_t_s

When  the  session  manager receives a ‘‘Connection Closed’’
message or otherwise detects that  the  client  aborted  the
connection,  it should call the _S_m_s_C_l_e_a_n_U_p function in order
to free up the connection object.
__
││
void SmsCleanUp(_s_m_s___c_o_n_n)
    SmsConn _s_m_s___c_o_n_n;





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_s_m_s___c_o_n_n  The session management connection object.
││__


_6_._1_2_.  _U_s_i_n_g _S_m_s _I_n_f_o_r_m_a_t_i_o_n_a_l _F_u_n_c_t_i_o_n_s

__
││
int SmsProtocolVersion(_s_m_s___c_o_n_n)
    SmsConn _s_m_s___c_o_n_n;

││__

_S_m_s_P_r_o_t_o_c_o_l_V_e_r_s_i_o_n returns the major version of the  session
management protocol associated with this session.


__
││
int SmsProtocolRevision(_s_m_s___c_o_n_n)
    SmsConn _s_m_s___c_o_n_n;

││__

_S_m_s_P_r_o_t_o_c_o_l_R_e_v_i_s_i_o_n returns the minor version of the session
management protocol associated with this session.


__
││
char *SmsClientID(_s_m_s___c_o_n_n)
    SmsConn _s_m_s___c_o_n_n;

││__

_S_m_s_C_l_i_e_n_t_I_D returns a null‐terminated string for the  client
ID associated with this connection.  You should call _f_r_e_e on
this pointer when the client ID is no longer needed.


To obtain the host name of a client, use  _S_m_s_C_l_i_e_n_t_H_o_s_t_N_a_m_e.
This host name will be needed to restart the client.
__
││
char *SmsClientHostName(_s_m_s___c_o_n_n)
    SmsConn _s_m_s___c_o_n_n;
││__

The  string returned is of the form _p_r_o_t_o_c_o_l/_h_o_s_t_n_a_m_e, where
_p_r_o_t_o_c_o_l is one of {tcp, decnet, local}.   You  should  call
_f_r_e_e on the string returned when it is no longer needed.






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__
││
IceConn SmsGetIceConnection(_s_m_s___c_o_n_n)
    SmsConn _s_m_s___c_o_n_n;
││__

_S_m_s_G_e_t_I_c_e_C_o_n_n_e_c_t_i_o_n  returns the ICE connection object asso‐
ciated with this session management connection object.   The
ICE  connection  object  can  be used to get some additional
information about the connection.  Some of the  more  useful
functions  which  can  be used on the IceConn are _I_c_e_C_o_n_n_e_c_‐
_t_i_o_n_N_u_m_b_e_r, and _I_c_e_L_a_s_t_S_e_q_u_e_n_c_e_N_u_m_b_e_r.  For further informa‐
tion, see the _I_n_t_e_r_‐_C_l_i_e_n_t _E_x_c_h_a_n_g_e _L_i_b_r_a_r_y standard.

_6_._1_3_.  _E_r_r_o_r _H_a_n_d_l_i_n_g

If the session manager receives an unexpected protocol error
from a client, an error handler  is  invoked  by  SMlib.   A
default  error  handler exists which simply prints the error
message (it does not exit).  The session manager can  change
this error handler by calling _S_m_s_S_e_t_E_r_r_o_r_H_a_n_d_l_e_r.
__
││
SmsErrorHandler SmsSetErrorHandler(_h_a_n_d_l_e_r)
    SmsErrorHandler _h_a_n_d_l_e_r;


_h_a_n_d_l_e_r   The  error  handler.   You  should  pass  NULL  to
          restore the default handler.
││__

_S_m_s_S_e_t_E_r_r_o_r_H_a_n_d_l_e_r returns the previous error handler.   The
_S_m_s_E_r_r_o_r_H_a_n_d_l_e_r has the following type:
__
││
typedef void (*SmsErrorHandler)();

void ErrorHandler(_s_m_s___c_o_n_n, _s_w_a_p, _o_f_f_e_n_d_i_n_g___m_i_n_o_r___o_p_c_o_d_e, _o_f_f_e_n_d_i_n_g___s_e_q_u_e_n_c_e___n_u_m, _e_r_r_o_r___c_l_a_s_s, _s_e_v_e_r_i_t_y, _v_a_l_u_e_s)
    SmsConn _s_m_s___c_o_n_n;
    Bool _s_w_a_p;
    int _o_f_f_e_n_d_i_n_g___m_i_n_o_r___o_p_c_o_d_e;
    unsigned long _o_f_f_e_n_d_i_n_g___s_e_q_u_e_n_c_e___n_u_m;
    int _e_r_r_o_r___c_l_a_s_s;
    int _s_e_v_e_r_i_t_y;
    IcePointer _v_a_l_u_e_s;


_s_m_s___c_o_n_n  The session management connection object.

_s_w_a_p      A  flag  which  indicates  if the specified values
          need byte swapping.

_o_f_f_e_n_d_i_n_g___m_i_n_o_r___o_p_c_o_d_e
          The minor opcode of the offending message.




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_o_f_f_e_n_d_i_n_g___s_e_q_u_e_n_c_e___n_u_m
          The sequence number of the offending message.

_e_r_r_o_r___c_l_a_s_sThe error class of the offending message.

_s_e_v_e_r_i_t_y  _I_c_e_C_a_n_C_o_n_t_i_n_u_e, _I_c_e_F_a_t_a_l_T_o_P_r_o_t_o_c_o_l, or _I_c_e_F_a_t_a_l_T_o_‐
          _C_o_n_n_e_c_t_i_o_n.

_v_a_l_u_e_s    Any  additional error values specific to the minor
          opcode and class.
││__

Note that this error handler is invoked for protocol related
errors.   To  install an error handler to be invoked when an
IO error  occurs,  use  _I_c_e_S_e_t_I_O_E_r_r_o_r_H_a_n_d_l_e_r.   For  further
information, see the _I_n_t_e_r_‐_C_l_i_e_n_t _E_x_c_h_a_n_g_e _L_i_b_r_a_r_y standard.

_7_.  _S_e_s_s_i_o_n _M_a_n_a_g_e_m_e_n_t _P_r_o_p_e_r_t_i_e_s

Each property is defined by the _S_m_P_r_o_c structure:


typedef struct {
     char *name;         /* name of property */
     char *type;         /* type of property */
     int num_vals;       /* number of values */
     SmPropValue *vals;  /* the list of values */
} SmProp;

typedef struct {
     int length;         /* the length of the value */
     SmPointer value;    /* the value */
} SmPropValue;


The X Session Management Protocol defines a list  of  prede‐
fined properties, several of which are required to be set by
the client.  The following table  specifies  the  predefined
properties  and  indicates  which  ones  are required.  Each
property has a type associated with it.

A type of SmCARD8 indicates that there is  a  single  1‐byte
value.   A type of SmARRAY8 indicates that there is a single
array of bytes.  A type  of  SmLISTofARRAY8  indicates  that
there is a list of array of bytes.


─────────────────────────────────────────────────────────────
_N_a_m_e                 _T_y_p_e          _P_O_S_I_X _T_y_p_e       _R_e_q_u_i_r_e_d
─────────────────────────────────────────────────────────────
SmCloneCommand       OS‐specific   SmLISTofARRAY8     Yes
SmCurrentDirectory   OS‐specific   SmARRAY8            No
SmDiscardCommand     OS‐specific   SmLISTofARRAY8     No*




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─────────────────────────────────────────────────────────────
_N_a_m_e                 _T_y_p_e          _P_O_S_I_X _T_y_p_e       _R_e_q_u_i_r_e_d
─────────────────────────────────────────────────────────────
SmEnvironment        OS‐specific   SmLISTofARRAY8      No
SmProcessID          OS‐specific   SmARRAY8            No
SmProgram            OS‐specific   SmARRAY8           Yes
SmRestartCommand     OS‐specific   SmLISTofARRAY8     Yes
SmResignCommand      OS‐specific   SmLISTofARRAY8      No
SmRestartStyleHint   SmCARD8       SmCARD8             No
SmShutdownCommand    OS‐specific   SmLISTofARRAY8      No
SmUserID             SmARRAY8      SmARRAY8           Yes
─────────────────────────────────────────────────────────────


*  Required if any state is stored in an external repository
(for example, state file).

·    SmCloneCommand

     This is like the SmRestartCommand, except it restarts a
     copy  of  the application.  The only difference is that
     the application does not supply its client ID at regis‐
     ter  time.   On  POSIX  systems, this should be of type
     SmLISTofARRAY8.

·    SmCurrentDirectory

     On POSIX‐based systems, this specifies the value of the
     current  directory  that  needs  to  be set up prior to
     starting the SmProgram and should of type SmARRAY8.

·    SmDiscardCommand

     The discard command contains a command that when deliv‐
     ered  to the host that the client is running on (deter‐
     mined from the connection), will cause  it  to  discard
     any  information about the current state.  If this com‐
     mand is not specified, the Session Manager will  assume
     that  all  of  the  client’s  state  is  encoded in the
     SmRestartCommand.  On POSIX systems, the type should be
     SmLISTofARRAY8.

·    SmEnvironment

     On  POSIX  based systems, this will be of type SmLISTo‐
     fARRAY8, where the ARRAY8s alternate  between  environ‐
     ment variable name and environment variable value.

·    SmProcessID

     This   specifies  an  OS‐specific  identifier  for  the
     process.  On POSIX systems,  this  should  contain  the
     return  value of _g_e_t_p_i_d turned into a Latin‐1 (decimal)
     string.



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·    SmProgram

     This is the name of the program that  is  running.   On
     POSIX systems, this should be first parameter passed to
     _e_x_e_c_v_e and should be of type SmARRAY8.

·    SmRestartCommand

     The restart  command  contains  a  command  that,  when
     delivered  to  the  host  that the client is running on
     (determined from the connection), will cause the client
     to  restart  in its current state.  On POSIX‐based sys‐
     tems, this is of type SmLISTofARRAY8, and each  of  the
     elements in the array represents an element in the _a_r_g_v
     array.  This restart command  should  ensure  that  the
     client restarts with the specified client‐ID.

·    SmResignCommand

     A  client that sets the SmRestartStyleHint to SmRestar‐
     tAnway uses this property to  specify  a  command  that
     undoes  the  effect of the client and removes any saved
     state.  As  an  example,  consider  a  user  that  runs
     _x_m_o_d_m_a_p, which registers with the Session Manager, sets
     SmRestartStyleHint to SmRestartAnyway, and then  termi‐
     nates.   To  allow  the  Session Manager (at the user’s
     request) to undo this, _x_m_o_d_m_a_p would register  a  SmRe‐
     signCommand that undoes the effects of the _x_m_o_d_m_a_p.

·    SmRestartStyleHint

     If  the  RestartStyleHint  property is present, it will
     contain the style of restarting the client prefers.  If
     this  style  is  not  specified,  SmRestartIfRunning is
     assumed.  The possible values are as follows:

     ─────────────────────────────
     _N_a_m_e                   _V_a_l_u_e
     ─────────────────────────────
     SmRestartIfRunning       0
     SmRestartAnyway          1
     SmRestartImmediately     2
     SmRestartNever           3
     ─────────────────────────────


     The SmRestartIfRunning style is used in the usual case.
     The  client  should be restarted in the next session if
     it was running at the end of the current session.

     The SmRestartAnyway style is used to tell  the  Session
     Manager that the application should be restarted in the
     next session even if it exits before the  current  ses‐
     sion  is  terminated.   It should be noted that this is



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     only a hint and the Session  Manager  will  follow  the
     policies  specified  by  its  users in determining what
     applications to restart.

     A client that uses SmRestartAnyway should also set  the
     SmResignCommand  and  SmShutdownCommand  properties  to
     commands that undo the state of  the  client  after  it
     exits.

     The SmRestartImmediately style is like SmRestartAnyway,
     but, in addition, the client is meant to  run  continu‐
     ously.  If the client exits, the Session Manager should
     try to restart it in the current session.

     SmRestartNever style specifies that the client does not
     wish to be restarted in the next session.

·    SmShutdownCommand

     This  command  is executed at shutdown time to clean up
     after a client that is no longer running  but  retained
     its  state  by  setting SmRestartStyleHint to SmRestar‐
     tAnyway.  The client must not remove any saved state as
     the  client  is still part of the session.  As an exam‐
     ple, consider a client that turns on a camera at  start
     up time.  This client then exits.  At session shutdown,
     the user wants the  camera  turned  off.   This  client
     would set the SmRestartStyleHint to SmRestartAnyway and
     would register a SmShutdownCommand that would turn  off
     the camera.

·    SmUserID

     Specifies  the  user  ID.  On POSIX‐based systems, this
     will contain the user’s name  (the  pw_name  member  of
     struct _p_a_s_s_w_d).

_8_.  _F_r_e_e_i_n_g _D_a_t_a

To free an individual property, use _S_m_F_r_e_e_P_r_o_p_e_r_t_y.
__
││
void SmFreeProperty(_p_r_o_p)
    SmProp *_p_r_o_p;


_p_r_o_p      The property to free.
││__


To  free  the reason strings from the _S_m_s_C_l_o_s_e_C_o_n_n_e_c_t_i_o_n_P_r_o_c






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callback, use _S_m_F_r_e_e_R_e_a_s_o_n_s.
__
││
void SmFreeReasons(_c_o_u_n_t, _r_e_a_s_o_n_s)
    int _c_o_u_n_t;
    char **_r_e_a_s_o_n_s;


_c_o_u_n_t     The number of reason strings.

_r_e_a_s_o_n_s   The list of reason strings to free.
││__


_9_.  _A_u_t_h_e_n_t_i_c_a_t_i_o_n _o_f _C_l_i_e_n_t_s

As stated earlier, the session management protocol  is  lay‐
ered  on top of ICE.  Authentication occurs at two levels in
the ICE protocol:

·    The first is when an ICE connection is opened.

·    The second is when a Protocol Setup occurs  on  an  ICE
     connection.

The  authentication methods that are available are implemen‐
tation‐dependent (that is.,  dependent  on  the  ICElib  and
SMlib implementations in use).  For further information, see
the _I_n_t_e_r_‐_C_l_i_e_n_t _E_x_c_h_a_n_g_e _L_i_b_r_a_r_y standard.

_1_0_.  _W_o_r_k_i_n_g _i_n _a _M_u_l_t_i_‐_T_h_r_e_a_d_e_d _E_n_v_i_r_o_n_m_e_n_t

To declare that multiple threads in an application  will  be
using SMlib (or any other library layered on top of ICElib),
you should call _I_c_e_I_n_i_t_T_h_r_e_a_d_s.   For  further  information,
see the _I_n_t_e_r_‐_C_l_i_e_n_t _E_x_c_h_a_n_g_e _L_i_b_r_a_r_y standard.

_1_1_.  _A_c_k_n_o_w_l_e_d_g_e_m_e_n_t_s

Thanks  to  the  following people for their participation in
the X Session Management design: Jordan Brown, Ellis  Cohen,
Donna  Converse,  Stephen  Gildea,  Vania  Joloboff,  Stuart
Marks, Bob Scheifler, Ralph Swick, and Mike Wexler.














                           − 42 −











                      TTaabbllee ooff CCoonntteennttss



1. Overview of Session Management .....................    1
2. The Session Management Library .....................    1
3. Understanding SMlib’s Dependence on ICE ............    2
4. Header Files and Library Name ......................    3
5. Session Management Client (Smc) Functions ..........    3
5.1. Connecting to the Session Manager ................    4
5.1.1. The Save Yourself Callback .....................    7
5.1.2. The Die Callback ...............................    8
5.1.3. The Save Complete Callback .....................    9
5.1.4. The Shutdown Cancelled Callback ................    9
5.2. Closing the Connection ...........................   10
5.3. Modifying Callbacks ..............................   11
5.4. Setting, Deleting, and Retrieving Session Man‐
agement Properties ....................................   11
5.5. Interacting With the User ........................   13
5.6. Requesting a Save Yourself .......................   15
5.7. Requesting a Save Yourself Phase 2 ...............   16
5.8. Completing a Save Yourself .......................   16
5.9. Using Smc Informational Functions ................   17
5.10. Error Handling ..................................   18
6. Session Management Server (Sms) Functions ..........   19
6.1. Initializing the Library .........................   20
6.1.1. The Register Client Callback ...................   23
6.1.2. The Interact Request Callback ..................   24
6.1.3. The Interact Done Callback .....................   25
6.1.4. The Save Yourself Request Callback .............   25
6.1.5. The Save Yourself Phase 2 Request Callback .....   26
6.1.6. The Save Yourself Done Callback ................   27
6.1.7. The Connection Closed Callback .................   27
6.1.8. The Set Properties Callback ....................   28
6.1.9. The Delete Properties Callback .................   29
6.1.10. The Get Properties Callback ...................   29
6.2. Registering the Client ...........................   30
6.3. Sending a Save Yourself Message ..................   31
6.4. Sending a Save Yourself Phase 2 Message ..........   32
6.5. Sending an Interact Message ......................   33
6.6. Sending a Save Complete  Message .................   33
6.7. Sending a Die Message ............................   33
6.8. Cancelling a Shutdown ............................   34
6.9. Returning Properties .............................   34
6.10. Pinging a Client ................................   34
6.11. Cleaning Up After a Client Disconnects ..........   35
6.12. Using Sms Informational Functions ...............   36
6.13. Error Handling ..................................   37
7. Session Management Properties ......................   38
8. Freeing Data .......................................   41
9. Authentication of Clients ..........................   42



                             iii








10. Working in a Multi‐Threaded Environment ...........   42
11. Acknowledgements ..................................   42























































                             iv