What happens in the background when a job is scheduled!!!

Question

Hi,
   Can anyone tell me what exactly happens in the background in SAP when a job is set to "Scheduled" ( sm37) .
Can v see the code executed in the background during the transtion from " Scheduled" state of a job to" Cancelled" to "Complete" state.
Its urgent,
Answers will rewarded,
regards,
Rohan

Answer 1

Hi Rohan,
Jobs and job steps enable you to treat complex tasks as single units. That is, you can schedule several programs needed to complete a particular task as steps within a single job, with the advantage of the job being single logical container for all the steps needed to complete the task. You need to schedule or review only one background job in order to schedule or review any of the individual steps necessary for completing the task.
Assume that a particular data transfer with batch input requires that you start two programs, an external program to prepare the batch-input session and an internal program to process the session. Creating a job made up of two steps lets you handle the two programs as a single unit. Scheduling that one job schedules both programs. The results of each program's run can be seen in the job log.
Some background processing attributes apply to entire jobs and, therefore, to all job steps within a job. For example, the earliest possible start time for any job steps will be the start time for the job. Frequency of repetition, priority, and other global attributes also apply to the whole job.
To ensure that you can flexibly run individual programs, you can set important attributes individually for each job step, too. Each job step can:
have its own spool, or output, specifications
run under the authorizations of a separate user
use a different language
have its own runtime options (for programs external to the SAP System), such as handling of error output and synchronicity
In general, job steps run sequentially and synchronously in the order they're entered in a job: the first step starts, runs, and is completed, then the second step starts, and so on. The only exception is when you schedule an external program to run asynchronously. In this case, the background processing system starts the next job step without waiting for a return code from the external program. If the external program runs long enough, then the start of the next job step may overlap it.
Job steps run partially independently of each other’s status. That is, the abnormal termination of one job step does not roll back the work of a previously completed job step if this previous step was executing a commit. If any job step fails, however, then the entire job fails. No further job steps are carried out, and the job's status changes to Canceled.
There are two types of job steps:
An executable ABAP program
Only type 1, or executable, ABAP programs can be used as job steps. Module pools and function groups, which are collections of ABAP modules, are not allowed. The specifications required for an ABAP job step are:
ABAP program + Variant + Print and archiving parameters + Language
An external command or external program
This type of job step allows you to run programs outside the SAP System. External commands are predefined, authorization-protected commands for end users. External programs are unrestricted, directly entered commands reserved for system administrators.
The type of external command and external program is unrestricted, meaning that you can use either compiled programs or scripts. Such programs can be run on any computer that can be reached from the SAP System. Parameter passing to non-SAP programs is completely unrestricted except by the predefinition mechanism for external commands.
Output of non-SAP programs, particularly error messages, is included in the job's log file.
Specifications required for an external command or program are:
External command + Type of operating system + (Parameters) + Target host system
External program + Parameters + Target host system
Job Step Language
If your SAP System runs with an Arabic, Cyrillic, or Asian character set, then you may need to change the language specified in the standard background jobs listed above. Languages are assigned to jobs based on job steps. Be sure that the language specified in the job step definition in each of these jobs is set to English (EN).
This change is required because not all languages are available with all code pages. If the job’s specified language is not available, the job will not run.
<b>Reward pts if found usefull :)</b>
Regards
Sathish