A 21st Century Job Scheduler for the 3000
In using iJobSched, MPE/iX batch job scheduling meets the Internet

Review by John Burke

The Internet Job Scheduler For MPE, iJobSched, available from OmniSolutions after a recently concluded distribution and support agreement with iJobSched author Stordahl-Consulting, is a full-featured job scheduler and monitor for the HP e3000 and MPE/iX. iJobSched is not the first job scheduler for MPE, but it just might be the first utility of any kind written specifically for the HP e3000 that was developed with, and is used with, products from the Open Source arena that have been ported to MPE. iJobSched is a collection of CGI programs written in GNU g++ that are called from either the Apache/iX Web server or the WebWise secure Web server. Because it is for the HP e3000, iJobSched has at its heart an IMAGE database that contains all scheduling and job execution information.

How it Works

A batch initiator/monitor server job is continuously running in the background. It periodically wakes up (user configurable), checks the status of various job schedules, and initiates any ready jobs. The background monitor job determines the successful execution of a job, and thus whether certain dependencies have been satisfied, by the execution of a supplied EOJ UDC or by the execution of a program (what the EOJ UDC runs) that writes completion information in the iJobSched database. One particularly nice feature of iJobSched is its ability to define a processing ‘day’ to begin and end at a user-configurable time (see Figure 1).

The basic building blocks are Jobs (Figure 3) and Schedule Calendars (Figure 2). Each job may have an optional recovery option. Schedules (Figure 7) are built up from one or more jobs that are to be executed in sequence after the previous job has completed successfully. Schedules are related to schedule calendars by specifying a run time and schedule calendar (Figure 8). Schedules may have optional recovery options and may have file or schedule dependencies. A schedule will not start until all dependencies are satisfied.

Schedules may be put on “HOLD” status to temporarily delay the start of the schedule. Furthermore, schedules can be “FORCED” to start at other than the scheduled time.

System Requirements and Performance

iJobSched was created and tested on MPE/iX 6.0 with Apache/iX 1.3.4 and should work on any subsequent version of MPE or Apache/iX (or WebWise). The author warned me that I might find the CGI programs slow on a low-end machine. I did most of my testing on a 927 over a DSL connection and, while certainly not fast, performance was quite acceptable, on the order of navigating through NMMGR VPlus screens.

Installation

The product is provided as a tar ball which you can either FTP directly to your HP e3000 or indirectly via a PC. Create an account, unpack the tar ball and run a script to complete the installation. Start the background job, make a few modifications to your Apache/iX or WebWise configuration file and you are ready to start scheduling with iJobSched.

Documentation

The approximately 100-page reference manual for iJobSched is downloadable in PDF format. It is everything I look for in a manual. Since it is available as a PDF document, it is searchable, though that in itself is probably not a big deal since the manual contains a very complete Table of Contents. The thing that really turns me on is that virtually every page contains either a diagram or screen shot that shows you exactly how iJobSched works. A minor annoyance: There is no online help. The manual is so good this is not a real problem; I mention it only because it is unusual these days not to have online help.

Let’s take it out for a spin

Figure 1 shows the Change Control Master screen and the default values. Here you input the control values that determine how iJobSched operates. Cycle Time is used to specify when a schedule date begins. As noted above, this is a key feature of iJobSched. You can define a “business” or “processing” day to be anything you want. The default has the schedule “day” beginning at 7:00 AM. The Pause Interval controls how often the background job wakes up and checks the scheduler’s database. The default value is 60 seconds. More often than that might have too great an impact on system performance. A longer interval will, of course, decrease the batch job monitor’s responsiveness. All in all, I think the 60-second default will work well in most situations.

Finally, the History Retention field specifies how long the run-time schedules for a schedule date are retained. The default of 3 means that the current schedule date’s run-time schedules plus the previous two days’ run-time schedules are available. Run-time schedules beyond the retention period are deleted when the Cycle Time has elapsed and the run-time schedules for a new schedule date are generated.

The schedule day is a calendar event that associates schedules to a particular run date. It can be a particular day of the week, weekdays, workdays, etc. Figure 2 shows the screen for a schedule day calendar I created and called EOM for End Of Month. Notice how the last calendar date of each month is checked. Schedule day calendars are created a calendar year at a time. iJobSched makes it easy to schedule around holidays.

Jobs are defined independently of schedules and may therefore be used in more than one schedule. A job must be defined before it can be used in a schedule, but need not exist (the JCL file) to be defined in an iJobSched schedule. Figures 3 and 4 show the Change Job and List Job pages, respectively. Job Name is a unique identifier, Job Description is any meaningful descriptive text and File Name is the actual job file in either MPE or HFS format. There are three recovery options. “Continue” will allow any remaining jobs in the schedule to run even if this job does not complete successfully. The rest of the options are fairly self-explanatory. List Job supports wildcarding on job name, a nice touch.

Figure 5 shows the Add Schedule page. The Schedule Name is a unique identifier and, as for jobs, the List Schedules page supports wildcarding. Figure 6 shows the process for adding a job to a schedule; in this case, TESTJOBA to the schedule EOMPROCS. Figure 7 shows the listing for all jobs in the schedule EOMPROCS. In Figure 8, the EOMPROCS schedule is added to the EOM schedule calendar to execute at 11:50 PM. Thus, the EOMPROCS schedule will be started at 11:50 PM on the last calendar day of each month with TESTJOBA followed by TESTJOBB (on successful completion of TESTJOBA), followed by TESTJOBC (on successful completion of TESTJOBB)

iJobSched allows for more sophisticated job and schedule dependencies than this simple example shows, but hopefully you get the idea.

Conclusion

I found iJobSched to be a very interesting product worthy of consideration if you are looking for a single system job scheduler. It is easy to install and use, with the Web interface a particular delight. The only possible drawback is the need for a Web server to be running on the same machine as the scheduled jobs — some people might object to having a Web server on a production system. This also means you cannot manage the schedules for multiple machines from one instance of iJobSched. However, keeping in mind this is the first release of the product, it is actually quite impressive.

As this Test Drive was being finished, a distribution and support agreement was completed with OmniSolutions for the iJobSched product, which is still being maintained and developed by Stordahl Consulting. Contact OmniSolutions for details on support. An evaluation copy of iJobSched, along with the reference manual, is available for download at www.stordahl-inc.net during the transition.

John Burke is editor of the NewsWire’s net.digest and Hidden Value columns and has managed HP 3000 systems for more than 20 years.