Responding to a Session Manager Save State Notice

Session Manager allows applications to save their current state when the user terminates the current session, so that when the user later restarts the session, an application can return to the state it was in. In dtksh, this is accomplished by setting up a handler in a similar way of handling a Close notification. If a handler is not set up, the application has to be restarted manually in the new session, and the application does not retain any state.

To set up a handler to save the current state, the application must:

• Define functions to save the state at the end of the session and to restore it on startup

• Register interest in the Session Manager notification

• Register the function to save the state

• At startup, determine whether the saved state should be restored

The following code illustrates this process.

#! /usr/dt/bin/dtksh 
# Function invoked when the session is being ended by the user 
SessionCallback()

{    
		# Get the name of the file into which we should save our 
		# session information    
		if DtSessionSavePath $TOPLEVEL PATH SAVEFILE; then 
exec 9>$PATH    
	
		# Save off whether we are currently in an iconified state 
		if DtShellIsIconified $TOPLEVEL ; then 
			print -u9 `Iconified'    
		else       
			print -u9 `Deiconified'  
		fi  

		# Save off the list of workspaces we currently reside in
		if DtWsmGetWorkspacesOccupied $(XtDisplay "-" $TOPLEVEL) \
			 $(XtWindow "-" $TOPLEVEL) \
			 CURRENT_WS_LIST ;
   then
           # Map the comma-separated list of atoms into
           # their string representation          
					oldIFS=$IFS
           IFS=","
           for item in $CURRENT_WS_LIST;         
				  do
           		XmGetAtomName NAME $(XtDisplay "-" $TOPLEVEL) \
                $item
              print -u9 $NAME
           done
           IFS=$oldIFS       
				  fi

          exec 9<&-
         # Let the session manager know how to invoke us when
         # the session is restored
         DtSetStartupCommand $TOPLEVEL \
           "/usr/dt/contrib/dtksh/SessionTest $SAVEFILE"
     else  
				echo "DtSessionSavePath FAILED!!"
				exit -3
     fi
  }
	  # Function invoked during a restore session; restores the
	  # application to its previous state
  RestoreSession()
  {
     # Retrieve the path where our session file resides
		 if DtSessionRestorePath $TOPLEVEL PATH $1; then
        exec 9<$PATH
       read -u9 ICONIFY
         # Extract and restore our iconified state
				 case $ICONIFY in Iconified) DtSetIconifyHint $TOPLEVEL True;;
				 *) DtSetIconifyHint $TOPLEVEL False;
				 esac
         # Extract the list of workspaces we belong in, convert
         # them to atoms, and ask the Workspace Manager to relocate     
 	      # us to those workspaces
          WS_LIST=""
          while read -u9 NAME 
          do
           XmInternAtom ATOM $(XtDisplay "-" $TOPLEVEL) \           
			     $NAME False             if [ ${#WS_LIST} -gt 0 ]; then              
				  WS_LIST=$WS_LIST,$ATOM
           else
                WS_LIST=$ATOM          
					fi
        done

         DtWsmSetWorkspacesOccupied $(XtDisplay "-" $TOPLEVEL) \
             $(XtWindow "-" $TOPLEVEL) $WS_LIST
         exec 9<&-     
			else
        echo "DtSessionRestorePath FAILED!!"
        exit -3
     fi
  } 

################## Create the Main UI #######################
XtInitialize TOPLEVEL wmProtTest Dtksh $0 "$@"  
XtCreateManagedWidget DA da XmDrawingArea $TOPLEVEL \
                        height:200 width:200  
XmInternAtom SAVE_SESSION_ATOM $(XtDisplay "-" $TOPLEVEL) \
        "WM_SAVE_YOURSELF" False

# If a command-line argument was supplied, then treat it as the  
# name of the session file  
if (( $# > 0))  
then     
		# Restore to the state specified in the passed-in session file     
		XtSetValues $TOPLEVEL mappedWhenManaged:False     
		XtRealizeWidget $TOPLEVEL     
		XSync $(XtDisplay "-" $TOPLEVEL) False
		RestoreSession $1     
		XtSetValues $TOPLEVEL mappedWhenManaged:True     
		XtPopup $TOPLEVEL GrabNone  
else     
		# This is not a session restore, so come up in the default state     
		XtRealizeWidget $TOPLEVEL     
		XSync $(XtDisplay "-" $TOPLEVEL) False  
fi   

# Register the fact that we are interested in participating in  
# session management 
XmAddWMProtocols $TOPLEVEL $SAVE_SESSION_ATOM  
XmAddWMProtocolCallback $TOPLEVEL $SAVE_SESSION_ATOM \
           SessionCallback  

XtMainLoop