Forum OpenACS Development: Re: JODconverter vs. OpenOffice/LibreOffice Command Line

Hi Brian,

Sorry, just saw the new posting right now...

We never faced the problem of parallel LibreOffice conversions before, and we don't have a solution for it. In typical ]po[ use scenarios, there is usually a single accountant in charge of generating printable invoices for customers. No other documents require conversion, usually.

My personal coding style for these type of structures would be to generate short BASH scripts from within OpenACS, and to place them in a specific directory. Then use cron or similar (once per second) to poll if one of these scripts is running, and start the next one.

But the solution from Gustaf appears to be much more elegant...

However, I'm not clear about how to return the converted result to the user. This is asynchronous, and may take minutes or even hours in a congested system. This is beyond any HTTP timeout.

I guess that is something you'd have to fix on the application level. Maybe by sending the result to the user via Email? Maybe using manually polling via a "check if ready" page? This problem would apply to both ns_job and BASH scripts...


The "-detached" flag of my ns_job example is for demo purposes, causing asynchronous behavior (many things are added to the queue, the jobs are executed one-by-one in the background). When ns_job is called without this flag, then the caller will wait for the result (or until the configurable timeout is reached).

... with "ns_job" one can run arbitrary commands, also including arbitrary db-operations or "exec"... so there is much flexibility. One possible feature missing in ns_job is persistency on server restarts, but that might or might not be an issue for some applications. For persistency, there is the option of xowf's at-commands or rolling your own db-based command queue, similar to acs-mail-lite.

Thanks Gustaf and Frank. Very useful ideas, and ns_job looks great, and could be a quick win to at least stop LibreOffice server from dying. I think we can live without persistency right now. Maybe in future, we'll look at a db-based command queue.