Managing your Applications with PBS Application Services.Dan Stephenson, Manager, Product Specialization
If you’ve been keeping up with the latest trends in PBS Works, you’ve probably heard of the PBS Application Services (PAS). PAS is a piece of software that sits on top of your PBS Professional complex, exposing a collection of web services that allow front-end products such as Compute Manager and PBS Desktop to submit, monitor and manage jobs on your remote PBS Professional complex. In addition to all of these cool web services is an extremely powerful feature that PAS provides called Application Definitions (app-defs). App-defs are, put simply, a well structured mark-up language for describing your application (i.e. OptiStruct, RADIOSS, AcuSolve, LS-Dyna) to both PBS Professional and front-end products wanting to provide a cohesive interface to submitting users.
Although Compute Manager, PBS Desktop and PAS give rise to an amazing leap forward in end-user job submission, these technologies *could* add an additional maintenance burden to PBS Professional administrators. One major culprit here is the fact that now there are two or possibly even three entry points to your PBS Professional complex, and potentially two or three different variants of the same application (e.g. let’s say OptiStruct in this case). Many organizations do not want to remove the well proven and established command-line interface to their complexes, yet still want to take advantage of the more cutting edge approach of graphical submission, specifically for the younger generation of engineers and scientists. A common mind set might be, “I’ll leave my existing OptiStruct job scripts for the command-line, and author a new OptiStruct app-def” for say, Compute Manager.
Here’s a short list of possible issues people face with this mind set…
1.) In many cases the OptiStruct application available through Compute Manager is not consistent with the OptiStruct job script people are using via the command-line.
2.) Jobs submitted via the command-line don’t display properly via the Compute Manager monitoring page.
3.) Job files available in the job execution directory are not exposed to Compute Manager, essentially removing any remote file browsing functionality while the job is running.
It’s very important to keep in mind that all of the above issues in this approach could be solved with additional effort and changes to both variants of OptiStruct. And there may be some site-specifc requirements which encourage you to maintain two OptiStruct applications scripts/app-defs. But why go through all of this effort to maintain two OptiStruct applications and manage how they interoperate with one another if you don’t need to? The first step in walking away from this mindset is re-visiting a few notions that you may already have in your mind, and that is; PAS and app-defs aren’t just for graphical front-end products, they can be leveraged via the command-line interfaces as well.
The PAS team recently introduced a set of command-line tools that bridge the gap between GUI and CLI, opening up an entirely new way of approaching the authoring and maintenance of applications ran on PBS Professional complexes. Put simply, the very same OptiStruct app-def that is used in your installation of Compute Manager, can also be used by your command-line users who are more comfortable submitting their simulations via the command-line, removing the need for submitting via ‘qsub’ entirely. This is achieved by submitting an OptiStruct job using the ‘pas-submit’ command. Now submitting engineers and scientists have a common experience to submitting OptiStruct, regardless of which entry point to PBS Professional they are using.