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=NetBatch T9190D30 - NBEXEC - User Manual=

==Introduction==

This document describes the NBEXEC process supplied with NetBatch. The document is supplied as an interim measure until the NBEXEC Reference Manual becomes available.

==What is NetBatch?==
NetBatch is a software product that provides extensive facilities for controlling background or "batch" processing on the NonStop systems. It is designed especially for operations management and should be viewed as a powerful tool for planning, implementation, and control of the batch environment. With NetBatch, operations management can optimize the use of system resources. More importantly, it can offer the user community an environment that leads to greater productivity.

==NetBatch System Overview==
NetBatch consists of a number of discrete components:

* BATCHCOM a User Interface program
* NetBatch a Batch Scheduler.
* NBEXEC a Batch Execution Process.

The NetBatch-Plus option adds a full PATHWAY based screen interface to NetBatch. NetBatch-Plus simplifies the management of large numbers of NetBatch jobs.

The NetBatch scheduler is the hub of an operating NetBatch system.

* Its process name identifies the NetBatch system and all references to the system are made via that name.
* It handles the queue of NetBatch jobs and dispatches jobs according to priority and other parameters.
* It initiates job execution by starting execution processes as required.

The user interface is related to the NetBatch  scheduler in the same way that PERUSE and SPOOLCOM are related to the TANDEM spooler.

It enables users to:
*  Submit and modify jobs.
*  Display job status.

The BATCHCOM interface is also used by the system manager to control the NetBatch system.


NBEXEC is the NetBatch execution process.  NBEXEC executes a control file. NBEXEC not only executes control file commands, it supplies data to started processes and collects and logs program output. The Execution process has some functional similarity to the TANDEM SPOOLER's print process.

NBEXEC supplied with NetBatch ensures full upward compatibility between the MIS-BATCH product and NetBatch.

NBEXEC includes facilities that enable programmers to define user variables and to do dynamic string substitution while a job is executing. Input to user programs can be included as a part of the job definition.

==Improved Use of Resources==

NBEXEC can detect errors during execution.  System productivity is improved when early detection of errors avoids unwanted processing.

==Automatic Restart==
Checkpoints can be specified in the NBEXEC job definition so that if a CPU fails, the system has a way to determine the point at which recovery processing should resume.

==Activity Log and Status Displays==

NBEXEC logs all activities under its control. The log is constantly updated and is immediately available to the user. If an error occurs during execution and automatic recovery has not been selected, the log can be used to reconstruct events that contributed to the error.

==The NBEXEC Process==

The NBEXEC process performs the following functions:

:# Reads and validates the control file.  If the control file is invalid, errors are logged and the job terminates.
:# Initiates and runs the job according to user specified options as a background process.
:# Executes the instructions contained in the control file and performs any string substitutions in control file commands.
:# Recognizes abnormal termination of application processes and initiates any user defined error recovery.
:# Gathers all program outputs into the defined list file (unless directed elsewhere).

    CONSIDERATIONS
    ______________

    *  The CPU used by NBEXEC, is determined by TACL or the executor
       allocated by NetBatch.

    *  NBEXEC starts processes, by default, in its own CPU unless a CPU
       parameter was provided in a RUN command.