Can I use a newer version of Output Designer with my installation of Central, to access the newer features?

There are many possible combinations here, so I’ll say that, generally speaking, it’s a very bad idea to try and use a Design and Central together that have different revision numbers.

One notable (recent) exception to this is Design 5.5.1, which is intended to work with Central 5.5.

Is it possible to multi-thread jobs in Central so that a large job that comes through won’t halt everything else behind it while it processes?  Or to increase processing speed?

Yes, it is.  It must be done within the licensing restrictions of the product (max. jobs per day, max. cpu’s, etc.), but it is possible.

What is required is the installation of multiple instances of Central (which the product will do itself) and then some sort of arbiter that can receive all jobs from the producing system(s) and then assign these to the extra instances as they become available.

This arbiter could be a simple script or a much more complex application that can distribute jobs to different instances based on their priority, size (and thus their estimated time to process) or one that can split large jobs into chunks for parallel processing.

If you’re running a large SAP system in Omaha, for example, you might want to have several Central servers scattered across the country…or the World.  Text is almost always smaller than printer language, so you might want to have your arbiter distribute jobs coming from the systems in Omaha to the other Central servers, perhaps based on the target device names or IP ranges.  This saves your SAP system from having to know or care about this, and you will get less network traffic and your users will get faster response.

On systems with a number of CPU’s and fast disk arrays, it is possible to run several instances of Central simply to increase throughput.  You’ll only see gains if the bottlenecks in the process aren’t on the Central server.  Such as if your network print queues are dispersed and take time to respond, or if your jobs need to access a database or some other external resource to complete.

Could you please tell me if the preamble file is created automatically by JetForm design or whether it’s created manually?

Well, it’s half and half. As long as you have a newer version of Output Designer, it will create the JFPREAMBLE_1 (and _2, _3 and so on as needed) and also make a stub JFPREAMBLE for you.

If you want to change the way it’s doing things, you need to edit the JFPREAMBLE. You can’t edit the others as they will be overwritten every time you recompile the form. Making edits in the JFPREAMBLE, you should put them *after* the ^FILE lines that pull in the other preambles, so that they override whatever might have been in those. Often you’ll find yourself copying lines from JFPREAMBLE_1 to JFPREAMBLE and making only minor changes.

I’ll probably write an intro to preambles at some point…it is a huge topic, though.