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XSM(1) XSM(1) NNAAMMEE xsm - X Session Manager SSYYNNOOPPSSIISS xxssmm [-display display] [-session sessionName] [-verbose] DDEESSCCRRIIPPTTIIOONN _x_s_m is a session manager. A session is a group of appli- cations, each of which has a particular state. _x_s_m allows you to create arbitrary sessions - for example, you might have a "light" session, a "development" session, or an "xterminal" session. Each session can have its own set of applications. Within a session, you can perform a "check- point" to save application state, or a "shutdown" to save state and exit the session. When you log back in to the system, you can load a specific session, and you can delete sessions you no longer want to keep. Some session managers simply allow you to manually specify a list of applications to be started in a session. _x_s_m is more powerful because it lets you run applications and have them automatically become part of the session. On a simple level, _x_s_m is useful because it gives you this ability to easily define which applications are in a ses- sion. The true power of _x_s_m, however, can be taken advan- tage of when more and more applications learn to save and restore their state. OOPPTTIIOONNSS --ddiissppllaayy _d_i_s_p_l_a_y Causes _x_s_m to connect to the specified X display. --sseessssiioonn _s_e_s_s_i_o_n_N_a_m_e Causes _x_s_m to load the specified session, bypass- ing the session menu. --vveerrbboossee Turns on debugging information. SSEETTUUPP ..xxsseessssiioonn ffiillee Using _x_s_m requires a change to your _._x_s_e_s_s_i_o_n file: The last program executed by your _._x_s_e_s_s_i_o_n file should be _x_s_m. With this configuration, when the user chooses to shut down the session using _x_s_m, the session will truly be over. Since the goal of the session manager is to restart clients when logging into a session, your .xsession file, in general, should not directly start up applications. Rather, the applications should be started within a ses- sion. When _x_s_m shuts down the session, _x_s_m will know to restart these applications. Note however that there are X Version 11 Release 6.1 1 XSM(1) XSM(1) some types of applications that are not "session aware". _x_s_m allows you to manually add these applications to your session (see the section titled _C_l_i_e_n_t _L_i_s_t). SSMM__SSAAVVEE__DDIIRR eennvviirroonnmmeenntt vvaarriiaabbllee If the _S_M___S_A_V_E___D_I_R environment variable is defined, _x_s_m will save all configuration files in this directory. Oth- erwise, they will be stored in the user's home directory. Session aware applications are also encouraged to save their checkpoint files in the _S_M___S_A_V_E___D_I_R directory, although the user should not depend on this convention. DDeeffaauulltt SSttaarrttuupp AApppplliiccaattiioonnss The first time _x_s_m is started, it will need to locate a list of applications to start up. For example, this list might include a window manager, a session management proxy, and an xterm. _x_s_m will first look for the file _._x_s_m_s_t_a_r_t_u_p in the user's home directory. If that file does not exists, it will look for the _s_y_s_t_e_m_._x_s_m file that was set up at installation time. Note that _x_s_m provides a "fail safe" option when the user chooses a session to start up. The fail safe option simply loads the default applications described above. Each line in the startup file should contain a command to start an application. A sample startup file might look this: <start of file> twm smproxy xterm <end of file> SSTTAARRTTIINNGG AA SSEESSSSIIOONN When _x_s_m starts up, it first checks to see if the user previously saved any sessions. If no saved sessions exist, _x_s_m starts up a set of default applications (as described above in the section titled _D_e_f_a_u_l_t _S_t_a_r_t_u_p _A_p_p_l_i_c_a_t_i_o_n_s). If at least one session exists, a session menu is presented. The [[--sseessssiioonn sseessssiioonnNNaammee]] option forces the specified session to be loaded, bypassing the session menu. TThhee sseessssiioonn mmeennuu The session menu presents the user with a list of sessions to choose from. The user can change the currently selected session with the mouse, or by using the up and down arrows on the keyboard. Note that sessions which are locked (i.e. running on a different display) can not be loaded or deleted. X Version 11 Release 6.1 2 XSM(1) XSM(1) The following operations can be performed from the session menu: LLooaadd SSeessssiioonn Pressing this button will load the currently selected session. Alter- natively, hitting the Return key will also load the currently selected session, or the user can double click a session from the list. DDeelleettee SSeessssiioonn This operation will delete the cur- rently selected session, along with all of the application checkpoint files associated with the session. After pressing this button, the user will be asked to press the button a second time in order to confirm the operation. DDeeffaauulltt//FFaaiill SSaaffee _x_s_m will start up a set of default applications (as described above in the section titled _D_e_f_a_u_l_t _S_t_a_r_t_u_p _A_p_p_l_i_c_a_t_i_o_n_s). This is useful when the user wants to start a fresh ses- sion, or if the session configura- tion files were corrupted and the user wants a "fail safe" session. CCaanncceell Pressing this button will cause _x_s_m to exit. It can also be used to cancel a "Delete Session" operation. CCOONNTTRROOLLLLIINNGG AA SSEESSSSIIOONN After _x_s_m determines which session to load, it brings up its main window, then starts up all applications that are part of the session. The title bar for the session man- ager's main window will contain the name of the session that was loaded. The following options are available from _x_s_m's main win- dow: CClliieenntt LLiisstt Pressing this button brings up a window containing a list of all clients that are in the current session. For each client, the host machine that the client is running on is presented. As clients are added and removed from the session, this list is updated to reflect the changes. The user is able to control how these clients are restarted (see X Version 11 Release 6.1 3 XSM(1) XSM(1) below). By pressing the VViieeww PPrrooppeerrttiieess button, the user can view the session management properties associated with the currently selected client. By pressing the CClloonnee button, the user can start a copy of the selected appli- cation. By pressing the KKiillll CClliieenntt button, the user can remove a client from the ses- sion. By selecting a restart hint from the RReessttaarrtt HHiinntt menu, the user can control the restarting of a client. The follow- ing hints are available: -- The RReessttaarrtt IIff RRuunnnniinngg hint indicates that the client should be restarted in the next session if it is connected to the session manager at the end of the current session. -- The RReessttaarrtt AAnnyywwaayy hint indicates that the client should be restarted in the next session even if it exits before the current session is terminated. -- The RReessttaarrtt IImmmmeeddiiaatteellyy hint is simi- lar to the RReessttaarrtt AAnnyywwaayy hint, but in addition, the client is meant to run continuously. If the client exits, the session manager will try to restart it in the current session. -- The RReessttaarrtt NNeevveerr hint indicates that the client should not be restarted in the next session. Note that all X applications may not be "session aware". Applications that are not session aware are ones that do not support the X Session Management Proto- col or they can not be detected by the Session Management Proxy (see the sec- tion titled _T_H_E _P_R_O_X_Y). _x_s_m allows the user to manually add such applications to the session. The bottom of the _C_l_i_e_n_t _L_i_s_t window contains a text entry field in which application commands can be typed in. Each command should go on X Version 11 Release 6.1 4 XSM(1) XSM(1) its own line. This information will be saved with the session at checkpoint or shutdown time. When the session is restarted, _x_s_m will restart these appli- cations in addition to the regular "ses- sion aware" applications. Pressing the DDoonnee button removes the CClliieenntt LLiisstt window. SSeessssiioonn LLoogg...... The Session Log window presents useful information about the session. For example, when a session is restarted, all of the restart commands will be dis- played in the log window. CChheecckkppooiinntt By performing a checkpoint, all applica- tions that are in the session are asked to save their state. Not every applica- tion will save its complete state, but at a minimum, the session manager is guaranteed that it will receive the com- mand required to restart the application (along with all command line options). A window manager participating in the session should guarantee that the appli- cations will come back up with the same window configurations. If the session being checkpointed was never assigned a name, the user will be required to specify a session name. Otherwise, the user can perform the checkpoint using the current session name, or a new session name can be spec- ified. If the session name specified already exists, the user will be given the opportunity to specify a different name or to overwrite the already exist- ing session. Note that a session which is locked can not be overwritten. When performing a checkpoint, the user must specify a SSaavvee TTyyppee which informs the applications in the session how much state they should save. The LLooccaall type indicates that the appli- cation should save enough information to restore the state as seen by the user. It should not affect the state as seen by other users. For example, an editor would create a temporary file containing the contents of its editing buffer, the X Version 11 Release 6.1 5 XSM(1) XSM(1) location of the cursor, etc... The GGlloobbaall type indicates that the application should commit all of its data to permanent, globally accessible storage. For example, the editor would simply save the edited file. The BBootthh type indicates that the appli- cation should do both of these. For example, the editor would save the edited file, then create a temporary file with information such as the loca- tion of the cursor, etc... In addition to the SSaavvee TTyyppee, the user must specify an IInntteerraacctt SSttyyllee. The NNoonnee type indicates that the appli- cation should not interact with the user while saving state. The EErrrroorrss type indicates that the application may interact with the user only if an error condition arises. The AAnnyy type indicates that the applica- tion may interact with the user for any purpose. Note that _x_s_m will only allow one application to interact with the user at a time. After the checkpoint is completed, _x_s_m will, if necessary, display a window containing the list of applications which did not report a successful save of state. SShhuuttddoowwnn A shutdown provides all of the options found in a checkpoint, but in addition, can cause the session to exit. Note that if the interaction style is EErrrroorrss or AAnnyy, the user may cancel the shut- down. The user may also cancel the shutdown if any of the applications report an unsuccessful save of state. The user may choose to shutdown the ses- sion with our without performing a checkpoint. X Version 11 Release 6.1 6 XSM(1) XSM(1) HHOOWW _X_S_M RREESSPPOONNDDSS TTOO SSIIGGNNAALLSS _x_s_m will respond to a SIGTERM signal by performing a shut- down with the following options: fast, no interaction, save type local. This allows the user's session to be saved when the system is being shutdown. It can also be used to perform a remote shutdown of a session. _x_s_m will respond to a SIGUSR1 signal by performing a checkpoint with the following options: no interaction, save type local. This signal can be used to perform a remote checkpoint of a session. TTHHEE PPRROOXXYY Since not all applications have been ported to support the X Session Management Protocol, a proxy service exists to allow "old" clients to work with the session manager. In order for the proxy to detect an application joining a session, one of the following must be true: - The application maps a top level window containing the WWMM__CCLLIIEENNTT__LLEEAADDEERR property. This property provides a pointer to the client leader window which contains the WWMM__CCLLAASSSS, WWMM__NNAAMMEE, WWMM__CCOOMMMMAANNDD, and WWMM__CCLLIIEENNTT__MMAACCHHIINNEE prop- erties. or ... - The application maps a top level window which does not contain the WWMM__CCLLIIEENNTT__LLEEAADDEERR property. However, this top level window contains the WWMM__CCLLAASSSS, WWMM__NNAAMMEE, WWMM__CCOOMMMMAANNDD, and WWMM__CCLLIIEENNTT__MMAACCHHIINNEE properties. An application that support the WWMM__SSAAVVEE__YYOOUURRSSEELLFF protocol will receive a WWMM__SSAAVVEE__YYOOUURRSSEELLFF client message each time the session manager issues a checkpoint or shutdown. This allows the application to save state. If an application does not support the WWMM__SSAAVVEE__YYOOUURRSSEELLFF protocol, then the proxy will provide enough information to the session man- ager to restart the application (using WWMM__CCOOMMMMAANNDD), but no state will be restored. RREEMMOOTTEE AAPPPPLLIICCAATTIIOONNSS _x_s_m requires a remote execution protocol in order to restart applications on remote machines. Currently, _x_s_m supports the _r_s_t_a_r_t protocol. In order to restart an application on remote machine XX, machine XX must have _r_s_t_a_r_t installed. In the future, additional remote execu- tion protocols may be supported. SSEEEE AALLSSOO smproxy(1), rstart(1) X Version 11 Release 6.1 7 XSM(1) XSM(1) AAUUTTHHOORRSS Ralph Mor, X Consortium Jordan Brown, Quarterdeck Office Systems X Version 11 Release 6.1 8