A job determines the program to be executed, its run time and what is to be done in the event of an error occurring. Further, any parameters to be used, pre and post processing, locks preventing simultaneous access to a file and possible follow-on jobs may also belong to a job configuration.

A Job is defined in the XML configuration using .

Job Configuration

The XML configuration of a job can be carried out in the central start configuration file, (which is usually ./config/scheduler.xml) or in a separate configuration file in the configuration directory which is monitored by the Job Scheduler (usually ./config/live) - see also

Implementation

The Job Scheduler starts executable programs and can start individually implemented jobs, which use the Job Scheduler's API.

Executable Programs

Executable programs may be implemented as executable, shell scripts or as batch files. This includes programs, such as JavaScript, VBScript, Perl, PHP, Ruby etc. for which an interpreter needs to be started with the executable program file, Java classes can be started using the Java Virtual Machine (JVM) configured for the Job Scheduler.

Executable programs can be configured using the following elements:


<script language="shell">

The Job Scheduler creates a shell for the execution of the program.

Example: 

<job name="simple_shell">
  <script language="shell"><![CDATA[
    echo hello world
    call my_script.cmd
    my_prog.exe
  ]]></script>
</job>  

<job name="simple_command">
  <script language="shell">
    <include file="my_script.cmd"/>
  </script>
</job>
Commands for the command line can be directly included as content of the <script> elements. Alternatively, shell scripts can be specified using <include>.

<script language="java">

The Job Scheduler starts a JVM for the execution of the Java class.

Example: 

<job name="simple_java">
  <script language   = "java" 
          java_class = "sos.scheduler.ftp.JobSchedulerFTPReceive"/>
</job>


The Job Scheduler starts the program without a separate shell.

Example: 

<job name="simple_job">
  <process file="c:\my_prog.exe"/>
</job>

<job name="interpreter_job">
  <process file="c:\php\php.exe"
           param="-f 'c:\test\phpinfo.php'"/>
</job>
Inhterpreting programmes must be configured as the executing programmes for programme files, which are to be started per interpreter.

Implementation with the Job Scheduler API

Job implementations can use the Job Scheduler API - for example for logging, informing per e-mail, calling job, task and order objects, etc.

The Job Scheduler does not start these scrips per interpreter (see above) but instead makes use of a sub-programme interface that is provided by the respective the script language. The Job Scheduler then makes the objects and methods of its API available to such languages.

Java

A Job implemented with the Java programming language inherits from the abstract class sos.spooler.Job_impl. (see Javadocs for details).

The Java Interface provides additional classes in the same manner as the COM, JavaScript and Perl interfaces. This allows the implementation of jobs in these languages.

The address of the implemented class is specified in .

JavaScript and JScript

JavaScript is available in the SpiderMonkey implementation (http://developer.mozilla.org/en/docs/SpiderMonkey) in the Job Scheduler installation package for all platforms.

Microsoft JScript is available on Windows platforms.

VBScript

Microsoft VBScript is available on Windows platforms.

Perl

Perl is generally already installed on Unix platforms. The Job Scheduler installation programme attempts to configure the sub-programme interface to an existing Perl installation.

A Perl implementation such as that from http://www.activestate.com, can be installed if required.

COM

A job can be implemented in any program language as a COM-Server (for Windows). Further information can be found in the section on Spooler Scripts.

The Status of a Job

Jobs have one of the following statuses:

pending No task is running. This is the starting status.
running At least one task is running.
stopping The job is stopping. The Job Scheduler will not start another task and all current tasks are being stopped. As soon as all tasks are stopped, the job status changes to stopped.
See also the command: .
stopped No tasks are running and no further tasks will be started by the Job Scheduler.
See also the command: .
read_error The reread command has caused an error and the job is unusable as the program code cannot be read from the underlying file.
See also the command: .
error The Job Scheduler does not start any new tasks after an error has occurred.

Changing the Status of a Job

The element is used to change the status of a job. The Job Scheduler has a built-in HTML interface with provision for the necessary operations.

Starting a Task

The parameter is used in the configuration to specify whether a task should be started once or repeatedly.

Both the and the API method can be used to start a task.

 

A task will start automatically when no other task is running and when one of the following conditions are true:

In addition, a task will start when:

A task will only start when it has a start time (at) or:

Locks

Jobs can be given locks, in order to stop the simultaneous processing by two tasks.

Directory Monitoring

The scheduler can start a job when a change takes place in a monitored directory. Further details can be found in the chapter Directory Monitoring.

Monitor Scripts

A monitor script can be configured for a job . The Job Scheduler calls the functions of this script at the beginning and end of a task and before and after the methods.

The monitor can be defined using the element.

Example:

    
        
<job name  = "simple_ftp"
  <params>
    <param name = "ftp_host"            value = "localhost"/>
    <param name = "ftp_user"            value = "anonymous"/>
    <param name = "ftp_password"        value = "anonymous"/>
  </params>

  <script language   = "java" 
          java_class = "sos.scheduler.ftp.JobSchedulerFTPReceive"/>

  <monitor>
    <script language="javascript"><![CDATA[]]></script>
  </monitor>
</job>
The monitor script uses a standard job included with the Job Scheduler installation package to transfer a file per FTP. Thereby the job parameters for the name of the file to be transferred is dynamically created from the current date.