System operation is possible from user tasks under an ID with the OPERATING privilege. The OPERATING privilege can be granted to any ID through SECOS. The system user ID SYSOPR is given the OPERATING and STD-PROCESSING privileges by default.
The data stream known to a console (so far only consoles) can be logically separated into a dialog stream in accordance with the active system operation and an event stream in accordance with the reactive system operation.
The dialog stream is the command-based portion of a data stream of a console. It processes the command dialog, i.e. the input of commands and output of command-based messages, and, if necessary, answers requests from command processing for additional information. The system-internal SCI interface (synchronous console interface) allows all operating commands to be input from a user task.
Command input in the dialog stream is synchronous, i.e. a command cannot be entered until the previous one has terminated. This is a significant difference from the command dialog on consoles where command input is asynchronous, i.e. commands can be entered irrespective of whether preceding commands have terminated. The synchronous function of the dialog stream allows the use of SDF-P for operating procedures in user tasks with the OPERATING privilege.
The event stream is the system-based, asynchronous portion of the data stream of a console. It basically handles unsolicited system messages (known to the consoles), to which the operator may have to respond. This functionality is integrated in a user task within the framework of the event stream service (ESS), which opens up new possibilities, even for users without the OPERATING privilege. An important feature of the event stream service is the ability to present messages of the system asynchronously, i.e. immediately after they have been generated on a data display terminal, within an interactive task.
A central system event-stream file (SESF) is created for this purpose, in which all system events are recorded by the system task SEST.
The name of the system event-stream file is $SYSAUDIT.SYSLOG.ESS.SYSTEM. It is created when the system is booted and is deleted again during shutdown.
The maximum size of the system event stream file can be set with the system parameter NBESSIZE. The default setting is 40000 PAM pages. The maximum retention period of the recorded events is 96 hours. They are deleted to reclaim space after this time.
System events are basically all unsolicited system messages distributed via routing codes and not linked to commands, which are also contained in the CONSLOG file. The ASSIGN-SYSEVENT command allows user tasks with the OPERATING privilege to assign themselves their own system event stream. For these, asynchronous messages directed to the user's own task and, depending on the setting in the ASSIGN-SYSEVENT command, parts of the user's own command dialog, are also recorded as system events in the system event-stream file.
The recorded events are displayed by a presentation function with mask-based display using FHS-TPR. The SHOW-SYSEVENT-LOG command starts the presentation function of the event stream. In user tasks with the OPERATING privilege, all system event streams present in the system can be displayed. Asynchronous messages directed at the user's own task and logged sections of the command dialog are always shown. The scope of the system event display depends on the so-called “viewer profile”, which must be set before the presentation function is called. This viewer profile is determined by the total number of routing codes set through the operator roles as well as by the settings for message suppression, message filtering and message ordering.
The presentation function provides a dynamic and a static mode. The dynamic mode allows immediate display of new, asynchronous events as they occur (as known from the console), but does not provide a dialog function. The static mode provides a mask-controlled user dialog for scrolling and positioning within the complete event stream, a search function, a function for answering open system questions and a help system. The presentation is available in either English or German, depending on how the message language is set for each particular task.
To prepare the output masks, the presentation function uses the subsystem FHS-TPR, which is usually available as of “System ready”. The necessary access to the FHS mask libraries SYSFHS.BS2CP.<version>.E or SYSFHS.BS2CP.<version>.D and SYSFHS.FHS-TPR.<version>.E or SYSFHS.FHS-TPR.<version>.D is made possible at system installation.
The SHOW-SYSEVENT-LOG-ATTRIBUTES command provides information on the characteristics and attributes of the accessible event streams.
Any user tasks can assign themselves their own user event streams which do not contain any operating functionality. For these, the events set with the ASSIGN-SYSEVENT command are recorded in a private user event-stream file (UESF). This file is created under the user's own ID and is called SYSLOG.ESS.USER.<log-id>.
User event streams are particularly suitable for recording and displaying asynchronous messages to the user (e.g. INFORM-JOBS or INFORM-ALL-JOBS) and for monitoring operations which hide behind a job command (e.g. ENTER-JOB). The presentation function is also started with the SHOW-SYSEVENT-LOG command. All existing user event streams of the user's own ID can be displayed.
In system operation from consoles, the operator is used to a mixed display of dialog stream and event stream. In system operation from a user task, this mixed form of display is not possible for technical reasons. A user-friendly workplace requires at least two interactive tasks with two terminals, or with one terminal emulation which supports multiwindowing. One interactive task is used for operating the dialog stream, the other for presenting the event stream. If further interactive tasks or presentation windows are available, several presentation functions with different viewer profiles according to different functional areas can be used in parallel. If only one interactive task is available, system operation is still possible from the user task, but in this case it is necessary to switch between the dialog stream and the event stream (starting and ending the presentation function as necessary).